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1
Martinelli, Antonio E., Rubens M. Nascimento, Tarcisio E. de Andrade, Augusto J. A. Buschinelli, Jorge C. L. B. S. Pereira, Sonja M. Gross e Uwe Reisgen. "Wetting Oxide and Non-Oxide Ceramics with Active Metals". Materials Science Forum 730-732 (novembre 2012): 164–69. http://dx.doi.org/10.4028/www.scientific.net/msf.730-732.164.
Testo completoAbstract (sommario):
Brazing has been used to join structural ceramics to devices mostly manufactured using metal alloys. Direct brazing employs filler alloys containing an active metal, usually Ti, to wet the ceramic substrate. However, the cost of active filler alloys is usually around 10 times higher than that of active metal-free alloys. In addition, the concentration of the active metal is usually small, thus limiting the formation of a continuous reaction layer onto the entire ceramic surface. Alternatively, ceramic substrates can be previously metallized and fully coated with an active element to be wetted by conventional active metal free filler alloys. Ceramics can be metallized by different techniques, including mechanical metallization. It consists in frictioning an active metal bit, traditionally made of Ti, against the ceramic. Conventional tools can be used and the method is easily automated to large batches. Moreover, contrary to other techniques, mechanical metallization is carried out at room temperature and no hazardous fluxing agents are used. Although Ti is traditionally employed in mechanical metallization, the technique is not limited to it. Indeed, the exclusive use of Ti univocally determines the microstructure of the resulting ceramic/titanium and titanium/filler alloy interfaces. Although the formation of a reaction layer is beneficial to the mechanical strength and reliability of brazed components, precipitation zones and intermetallics embrittle the joints and affect their mechanical behavior. Therefore, the objective of the present study was to assess the potential use of alternative active metals in the mechanical metallization of structural oxide (alumina e zirconia) and non-oxide (silicon carbide and nitride) ceramics. Ceramic substrates were mechanically metallized using Ti, Ta, Nb and Zircaloy 2 (mainly 98.25 % Zr and 1.45% Sn). These metals are abundant in Brazil and therefore strategically important. The wettability of the metallized surfaces was evaluated using three commercially available active metal free filler alloys: VH 780 (Ag-28 Cu), VH 950 (Au – 18 Ni) and SCP 2 (Ag – 31.5 Cu – 10 Pd). The results showed that it was possible to mechanically metallize all ceramic surfaces with the active metals investigated. The wetting tests revealed limited potential for the use of Nb and Ta. On the other hand Zircaloy 2 was successfully employed as active metal for both oxide and non oxide ceramics.
2
Gao, Xiong, Jingyi Chen, Xiaotong Chen, Wenqing Wang, Zengchan Li e Rujie He. "How to Improve the Curing Ability during the Vat Photopolymerization 3D Printing of Non-Oxide Ceramics: A Review". Materials 17, n. 11 (29 maggio 2024): 2626. http://dx.doi.org/10.3390/ma17112626.
Testo completoAbstract (sommario):
Vat photopolymerization (VP), as an additive manufacturing process, has experienced significant growth due to its high manufacturing precision and excellent surface quality. This method enables the fabrication of intricate shapes and structures while mitigating the machining challenges associated with non-oxide ceramics, which are known for their high hardness and brittleness. Consequently, the VP process of non-oxide ceramics has emerged as a focal point in additive manufacturing research areas. However, the absorption, refraction, and reflection of ultraviolet light by non-oxide ceramic particles can impede light penetration, leading to reduced curing thickness and posing challenges to the VP process. To enhance the efficiency and success rate of this process, researchers have explored various aspects, including the parameters of VP equipment, the composition of non-oxide VP slurries, and the surface modification of non-oxide particles. Silicon carbide and silicon nitride are examples of non-oxide ceramic particles that have been successfully employed in VP process. Nonetheless, there remains a lack of systematic induction regarding the curing mechanisms and key influencing factors of the VP process in non-oxide ceramics. This review firstly describes the curing mechanism of the non-oxide ceramic VP process, which contains the chain initiation, chain polymerization, and chain termination processes of the photosensitive resin. After that, the impact of key factors on the curing process, such as the wavelength and power of incident light, particle size, volume fraction of ceramic particles, refractive indices of photosensitive resin and ceramic particles, incident light intensity, critical light intensity, and the reactivity of photosensitive resins, are systematically discussed. Finally, this review discusses future prospects and challenges in the non-oxide ceramic VP process. Its objective is to offer valuable insights and references for further research into non-oxide ceramic VP processes.
3
Kusunose, Takafumi, e Tohru Sekino. "Non-Oxide Ceramic Nanocomposites with Multifunctionality". Key Engineering Materials 403 (dicembre 2008): 45–48. http://dx.doi.org/10.4028/www.scientific.net/kem.403.45.
Testo completoAbstract (sommario):
Two types of Aluminum nitride (AlN) based ceramic nanocomposite with multifunctionality were investigated to improve machinability or electrical conductivity of AlN ceramics with high thermal conductivity. The AlN/BN nanocomposite was fabricated by hot-pressing AlN-BN composite powder, which was prepared by reducing and heating AlN particles containing a mixture of boric acid, urea and carbon. The nanocomposite containing 20 vol.% BN showed high strength, good machinability and relatively high thermal conductivity. On the other hand, the sintered AlN ceramics with CeO2 as an additive indicated high thermal conductivity and electric conductivity which is possible for electric discharge machining.
4
Karadimas, George, e Konstantinos Salonitis. "Ceramic Matrix Composites for Aero Engine Applications—A Review". Applied Sciences 13, n. 5 (26 febbraio 2023): 3017. http://dx.doi.org/10.3390/app13053017.
Testo completoAbstract (sommario):
Ceramic matrix materials have attracted great attention from researchers and industry due to their material properties. When used in engineering systems, and especially in aero-engine applications, they can result in reduced weight, higher temperature capability, and/or reduced cooling needs, each of which increases efficiency. This is where high-temperature ceramics have made considerable progress, and ceramic matrix composites (CMCs) are in the foreground. CMCs are classified into non-oxide and oxide-based ones. Both families have material types that have a high potential for use in high-temperature propulsion applications. The oxide materials discussed will focus on alumina and aluminosilicate/mullite base material families, whereas for non-oxides, carbon, silicon carbide, titanium carbide, and tungsten carbide CMC material families will be discussed and analyzed. Typical oxide-based ones are composed of an oxide fiber and oxide matrix (Ox-Ox). Some of the most common oxide subcategories are alumina, beryllia, ceria, and zirconia ceramics. On the other hand, the largest number of non-oxides are technical ceramics that are classified as inorganic, non-metallic materials. The most well-known non-oxide subcategories are carbides, borides, nitrides, and silicides. These matrix composites are used, for example, in combustion liners of gas turbine engines and exhaust nozzles. Until now, a thorough study on the available oxide and non-oxide-based CMCs for such applications has not been presented. This paper will focus on assessing a literature survey of the available oxide and non-oxide ceramic matrix composite materials in terms of mechanical and thermal properties, as well as the classification and fabrication methods of those CMCs. The available manufacturing and fabrication processes are reviewed and compared. Finally, the paper presents a research and development roadmap for increasing the maturity of these materials allowing for the wider adoption of aero-engine applications.
5
Böttcher, Maike, Daisy Nestler, Jonas Stiller e Lothar Kroll. "Injection Moulding of Oxide Ceramic Matrix Composites: Comparing Two Feedstocks". Key Engineering Materials 809 (giugno 2019): 140–47. http://dx.doi.org/10.4028/www.scientific.net/kem.809.140.
Testo completoAbstract (sommario):
Ceramic materials are suitable for use in the high temperature range. Oxide ceramics, in particular, have a high potential for long-term applications under thermal cycling and oxidising atmosphere. However, monolithic oxide ceramics are unsuitable for use in high-temperature technical applications because of their brittleness. Thin-walled, oxidation resistant, and high-temperature resistant materials can be developed by reinforcing oxide ceramics with ceramic fibres such as alumina fibres. The increase of the mechanical stability of the composites in comparison to the non-fibre reinforced material is of outstanding importance. Possible stresses or cracks can be derived along the fibre under mechanical stress or deformation. Components made of fibre-reinforced ceramic composites with oxide ceramic matrix (OCMC) are currently produced in manual and price-intensive processes for small series. Therefore, the manufacturing should be improved. The ceramic injection moulding (CIM) process is established in the production of monolithic oxide ceramics. This process is characterised by its excellent automation capability. In order to realise large scale production, the CIM-process should be transferred to the production of fibre-reinforced oxide ceramics. The CIM-process enables the production of complicated component shapes and contours without the need for complex mechanical post-treatment. This means that components with complex geometries can be manufactured in large quantities.To investigate the suitability of the injection moulding process for the production of OCMCs, two different feedstocks and alumina fibres (Nextel 610) were compounded in a laboratory-scale compounder. The fibre volume fractions were varied. In a laboratory-scale injection moulding device, microbending specimens were produced from the compounds obtained in this way. To characterise the test specimens, microstructure examinations and mechanical-static tests were done. It is shown that the injection moulding process is suitable for the production of fibre-reinforced oxide ceramics. The investigations show that the feedstocks used have potential for further research work and for future applications as material components for high-temperature applications in oxidising atmospheres.
6
Mitomo, Mamoru, e Günter Petzow. "Recent Progress in Silicon Nitride and Silicon Carbide Ceramics". MRS Bulletin 20, n. 2 (febbraio 1995): 19–22. http://dx.doi.org/10.1557/s0883769400049162.
Testo completoAbstract (sommario):
We know from experience that ceramic materials are brittle and easily broken. This is one reason why ceramics have not been used as engineering materials. Fracture is the result of crack growth through the microstructure. It was Griffith who proposed that ceramics have intrinsic cracks which grow under applied stress. The concentration of the applied stress at the crack tip decreases the strength to a level of about 1% or less of the theoretical strength. If the crack starts to grow, strength decreases so sharply that a catastrophic fracture occurs.In spite of the brittle nature of ceramics, their application as engineering materials was proposed in the 1960s because ceramic materials made of silicon nitride or carbide have higher strength at high temperatures than metals and oxide ceramics. Non-oxide ceramics have lower thermal-expansion-coefficients than oxides, resulting in better thermal shock resistance, which is one of the most important requirements for engineering ceramics.
7
Wang, Ruzhuan, Dingyu Li e Weiguo Li. "Temperature dependence of hardness prediction for high-temperature structural ceramics and their composites". Nanotechnology Reviews 10, n. 1 (1 gennaio 2021): 586–95. http://dx.doi.org/10.1515/ntrev-2021-0041.
Testo completoAbstract (sommario):
Abstract Hardness is one of the important mechanical properties of high-temperature structural ceramics and their composites. In spite of the extensive use of the materials in high-temperature applications, there are few theoretical models for analyzing their temperature-dependent hardness. To fill this gap in the available literature, this work is focused on developing novel theoretical models for the temperature dependence of the hardness of the ceramics and their composites. The proposed model is just expressed in terms of some basic material parameters including Young’s modulus, melting points, and critical damage size corresponding to plastic deformation, which has no fitting parameters, thereby being simple for materials scientists and engineers to use in the material design. The model predictions for the temperature dependence of hardness of some oxide ceramics, non-oxide ceramics, ceramic–ceramic composites, diamond–ceramic composites, and ceramic-based cermet are presented, and excellent agreements with the experimental measurements are shown. Compared with the experimental measurements, the developed model can effectively save the cost when applied in the material design, which could be used to predict at any targeted temperature. Furthermore, the models could be used to determine the underlying control mechanisms of the temperature dependence of the hardness of the materials.
8
Silvestre, J., N. Silvestre e J. de Brito. "An Overview on the Improvement of Mechanical Properties of Ceramics Nanocomposites". Journal of Nanomaterials 2015 (2015): 1–13. http://dx.doi.org/10.1155/2015/106494.
Testo completoAbstract (sommario):
Due to their prominent properties (mechanical, stiffness, strength, thermal stability), ceramic composite materials (CMC) have been widely applied in automotive, industrial and aerospace engineering, as well as in biomedical and electronic devices. Because monolithic ceramics exhibit brittle behaviour and low electrical conductivity, CMCs have been greatly improved in the last decade. CMCs are produced from ceramic fibres embedded in a ceramic matrix, for which several ceramic materials (oxide or non-oxide) are used for the fibres and the matrix. Due to the large diversity of available fibres, the properties of CMCs can be adapted to achieve structural targets. They are especially valuable for structural components with demanding mechanical and thermal requirements. However, with the advent of nanoparticles in this century, the research interests in CMCs are now changing from classical reinforcement (e.g., microscale fibres) to new types of reinforcement at nanoscale. This review paper presents the current state of knowledge on processing and mechanical properties of a new generation of CMCs: Ceramics Nanocomposites (CNCs).
9
Galusek, D., Z. Lencés, P. Sajgalík e Ralf Riedel. "Thermal analysis study of polymer-to-ceramic conversion of organosilicon precursors". Journal of Mining and Metallurgy, Section B: Metallurgy 44, n. 1 (2008): 35–38. http://dx.doi.org/10.2298/jmmb0801035g.
Testo completoAbstract (sommario):
The organosilicon precursors attract significant attention as substances, which upon heating in inert or reactive atmosphere convert directly to oxide or non-oxide ceramics, like nitrides, carbides, carbonitrides, boroncarbonitrides, oxycarbides, alons, etc. In characterisation, and in study of conversion of these polymers to ceramics thermal analysis plays an important role. The degree of cross-linking of the polymer vital for achievement of high ceramic yield is estimated with the use of thermal mechanical analysis (TMA). Decomposition of polymers and their conversion to ceramics is studied by the combination of differential thermal analysis (DTA), differential scanning calorimetry (DSC) thermogravimetry(TG), and mass spectrometry (MS). The use of these methods in study of the polymer-to-ceramic conversion is illustrated by case studies of a commercially available poly(allyl)carbosilane as the precursor of SiC, and a poly(hydridomethyl)silazane as the precursor of SiCN.
10
Bao, X. Y., Song Li, Xiao Xia Tang e Yue Zhang. "Synthesis of Si-N-C Ceramic Composites by Pyrolysis of Polysilazane and Polycarbosilane". Key Engineering Materials 512-515 (giugno 2012): 306–9. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.306.
Testo completoAbstract (sommario):
Non-oxide ceramics derived from organo-elemental precursors in the system Si-N-C has attracted much attention for its excellent properties. Typically, the Si-N-C ceramic shows homogeneous elemental distribution, better high-temperature stability and oxidation resistance which making them attractive for applying in various branches of technology. A novel amorphous ceramic is fabricated from precursors mixed by polysilazane (PSZ) and polycarbosilane (PCS). The Si-N-C ceramics (PSZ/PCS=2 (w/w)) are heat-treated between 1200°C and 1500°C in nitrogen to crystallization of microcrystalline α-Si3N4 and nanocrystalline SiC. The obtained Si-N-C ceramics are characterized by density, ceramic yield, porosity, X-ray diffraction and Scanning electron microscope to analyze the crystallization and microstructure. The experimental results indicate that the ratio of PSZ/PCS and the annealing temperature have a big influence on the crystallization behavior.
11
Gogotsi, Yury G., e Masahiro Yoshimura. "Water Effects on Corrosion Behavior of Structural Ceramics". MRS Bulletin 19, n. 10 (ottobre 1994): 39–45. http://dx.doi.org/10.1557/s0883769400048211.
Testo completoAbstract (sommario):
Environmental degradation poses a serious limitation on the utility of engineering materials such as metals, plastics, glasses, and structural ceramics. However, at least water would seem to be a harmless environment for ceramics, which are considered to be the most corrosion-resistant of all materials. When we drink water from a glass or a ceramic cup, we never think about an aqueous alteration of these materials. We cannot imagine that our ceramic mug may be dissolved in water or fail due to stress corrosion during breakfast. Even hot water which we use to make coffee or tea does not seem to be a hazardous environment for our china and earthenware. Why then are we going to discuss the effect of water on structural ceramics? The answer is simple: Under conditions of normal use of structural ceramics, which include high temperatures, high pressures, and mechanical stresses (Figure 1), even the most stable and corrosion-resistant materials may interact with water and water may become a hostile environment. It can be adsorbed on the surface of ceramics and act as a solvent for oxide ceramics or as an oxidant for non-oxide ceramics (Figure 2). However, water can cause a degradation of glasses and oxide ceramics even at room temperature if mechanical stresses are simultaneously applied (so-called stress corrosion). Water or humid air can decrease significantly the mechanical properties of certain zirconia ceramics at only slightly elevated temperatures (~200°C).
12
Tressler, Richard E. "High-Temperature Stability of Non-Oxide Structural Ceramics". MRS Bulletin 18, n. 9 (settembre 1993): 58–63. http://dx.doi.org/10.1557/s0883769400038045.
Testo completoAbstract (sommario):
Oxide-based ceramics have long been used as linings in containment vessels for hot materials (metals, glasses, cement, etc.) and hot gases, at temperatures often in excess of 1500°C, because of their chemical compatibility with these hot materials and with the process ambient—conditions where metals and polymers simply can't perform. However, their low thermal conductivities and generally high thermal expansivities cause poor thermal shock resistance. In addition, their creep resistance (resistance to permanent deformation under load) is generally poorer than the more covalently bonded ceramic materials such as nitrides and carbides which also have excellent thermal shock resistance.
13
Hwang, Chuan Chou, Chen Chia Chou, Jyh Liang Wang, Tsang Yen Hsieh e Jui Te Tseng. "The Lithium Doping Effect on (Na0.5K0.5)NbO3 Lead-Free Piezo-Ceramics Structure Stability and Ferroelectric Characteristics". Applied Mechanics and Materials 217-219 (novembre 2012): 682–85. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.682.
Testo completoAbstract (sommario):
The structure stability、micro-structure and electrical properties of lithium doping on potassium sodium niobate ceramics (Na0.5K0.5)NbO3 (NKN) were investigated in this study. Solid oxide mixing method with post calcination and sintering was employed to fabricate(Na0.5K0.5)(1-x) LixNbO3 ceramic. Lithium oxide was adopted as the sintering aids. For Li doping x=6 mol% in (Na0.5K0.5)(1-x) LixNbO3 ceramic a optimal crystallization and electrical properties could be achieved after 650°C calcination and 1060°C sintering. Ferroelectric properties of the lead-free ceramic behaved a coercive field of 12.5kV/cm and remanent polarization as high as 30uC/cm2.
14
Li, Xingbang, Jingxian Zhang, Yusen Duan, Ning Liu, Jinhua Jiang, Ruixin Ma, Hongan Xi e Xiaoguang Li. "Rheology and Curability Characterization of Photosensitive Slurries for 3D Printing of Si3N4 Ceramics". Applied Sciences 10, n. 18 (16 settembre 2020): 6438. http://dx.doi.org/10.3390/app10186438.
Testo completoAbstract (sommario):
Among a series of 3D printing techniques, stereolithography provides a new route to produce ceramic architectures with the advantages of high-precision and short cycle time. However, up to now the stereolithography of non-oxide ceramics still face complex and difficult problems. This work focused on the analysis of rheological and curing ability of Si3N4 photocurable slurries. The effects of monomer type, coarse silicon powder, solid loading and ambient temperature on the rheological behavior were intensively studied. The relationships between powder characteristic (involving refractive index, absorbance and the introduce of coarse silicon powder), monomer type and curing ability were discussed in detail. It is expected that this study may benefit the development of Si3N4 or other non-oxide ceramic slurries for stereolithography.
15
Paione, Consiglio M., e Francesco Baino. "Non-Oxide Ceramics for Bone Implant Application: State-of-the-Art Overview with an Emphasis on the Acetabular Cup of Hip Joint Prosthesis". Ceramics 6, n. 2 (19 aprile 2023): 994–1016. http://dx.doi.org/10.3390/ceramics6020059.
Testo completoAbstract (sommario):
A rapidly developing area of ceramic science and technology involves research on the interaction between implanted biomaterials and the human body. Over the past half century, the use of bioceramics has revolutionized the surgical treatment of various diseases that primarily affect bone, thus contributing to significantly improving the quality of life of rehabilitated patients. Calcium phosphates, bioactive glasses and glass-ceramics are mostly used in tissue engineering applications where bone regeneration is the major goal, while stronger but almost inert biocompatible ceramics such as alumina and alumina/zirconia composites are preferable in joint prostheses. Over the last few years, non-oxide ceramics—primarily silicon nitride, silicon carbide and diamond-like coatings—have been proposed as new options in orthopaedics in order to overcome some tribological and biomechanical limitations of existing commercial products, yielding very promising results. This review is specifically addressed to these relatively less popular, non-oxide biomaterials for bone applications, highlighting their potential advantages and critical aspects deserving further research in the future. Special focus is also given to the use of non-oxide ceramics in the manufacturing of the acetabular cup, which is the most critical component of hip joint prostheses.
16
Kodentsov, Alexander. "Diffusion-Limited Reactions of Non-Oxide Ceramics with Transition Metals". Diffusion Foundations 21 (marzo 2019): 85–126. http://dx.doi.org/10.4028/www.scientific.net/df.21.85.
Testo completoAbstract (sommario):
Thermodynamic and diffusion models are given to describe morphological evolution of the reaction zone during diffusion-limited interaction between non-oxide Si-containing ceramics (SiC and Si3N4) and transition metals (Cr, Mo, Ti, Ni, Co, Pt). In the case of diffusion-controlled process in the ternary metal-ceramic systems, reaction phenomena can be rationalized using chemical potential diagrams. However, in some cases, a periodic layered morphology is found in the transition zone, which is not fully understood, and it is difficult to predict a priori. Silicide formation in systems based on dense Silicon Nitride and non-nitride forming metals can be explained by assuming a nitrogen pressure build-up at the contact surface. This pressure determines the chemical potential of Silicon at the interface, and hence, the product phases in the diffusion zone. Traces of Oxygen in the ambient atmosphere might affect the interaction in non-oxide ceramic/transition metal systems. The thermodynamic stability of the condensed phases in the systems where volatile species may form can be interpreted using predominant area-type diagrams.
17
Miller, P. R., R. H. J. Hannink e B. C. Muddle. "Quantitative Microanalysis of ZrO2/Non-Oxide Ceramic Composites". Proceedings, annual meeting, Electron Microscopy Society of America 48, n. 2 (12 agosto 1990): 438–39. http://dx.doi.org/10.1017/s0424820100135794.
Testo completoAbstract (sommario):
Addition of zirconia (ZrO2) to oxide and non-ox1de ceramics improves consolidation behaviour, strength and toughness of fabricated bodies. Such materials are generally referred to as zirconia-toughened ceramics, ZTC. Typical examples of such systems include oxide matrices such as α- and β"-Al2O3, MgO.Al2O3 (spinel), ZrSiO4 (zircon) and ZnO; non-oxide systems include Sic, Si3N4, TiN, TiCN and TiB2. In these materials an Improved toughness is anticipated as a result of the stress-activated tetragonal to monoclinic transformation in the dispersed ZrO2. In an effort to understand the consolidation mechanisms and microstructural features leading to the improved strength and toughness of ZrO2-TiX (X=C,N,B2) based composites, a systematic study has been made of the composition of the component phases using energy dispersive x-ray spectroscopy (EDXS) and electron energy loss spectroscopy (EELS).The experiments were conducted on two types of samples. Firstly, to establish the kTizr factors for EDXS analysis and to assess the detectability limits of the EELS technique, a series of TiO2-ZrO2 solid-solution standards containing 2.5-13 mole% TiO2 were prepared.
18
Egelja, A., J. Gulicovski, A. Devecerski, M. Ninic, A. Radosavljevic-Mihajlovic e B. Matovic. "Preparation of biomorphic SiC ceramics". Science of Sintering 40, n. 2 (2008): 141–45. http://dx.doi.org/10.2298/sos0802141e.
Testo completoAbstract (sommario):
This paper deals with a new method for producing non-oxide ceramic using wood as a template. SiC with a woodlike microstructure has been prepared by carbothermal reduction reactions of Tilia wood/TEOS composite at 1873K. The porous carbon preform was infiltrated with TEOS (Si(OC2H5)4), as a source of silica, without pressure at 298K. The morphology of resulting porous SiC ceramics, as well as the conversion mechanism of wood to SiC ceramics, have been investigated by scanning electron microscopy (SEM/EDS) and X-ray diffraction analysis (XRD). Obtained SiC ceramics consists of ?-SiC with traces of ?-SiC.
19
Sarraf, Fateme, Sergey V. Churakov e Frank Clemens. "Preceramic Polymers for Additive Manufacturing of Silicate Ceramics". Polymers 15, n. 22 (8 novembre 2023): 4360. http://dx.doi.org/10.3390/polym15224360.
Testo completoAbstract (sommario):
The utilization of preceramic polymers (PCPs) to produce both oxide and non-oxide ceramics has caught significant interest, owing to their exceptional characteristics. Diverse types of polymer-derived ceramics (PDCs) synthesized by using various PCPs have demonstrated remarkable characteristics such as exceptional thermal stability, resistance to corrosion and oxidation at elevated temperatures, biocompatibility, and notable dielectric properties, among others. The application of additive manufacturing techniques to produce PDCs opens up new opportunities for manufacturing complex and unconventional ceramic structures with complex designs that might be challenging or impossible to achieve using traditional manufacturing methods. This is particularly advantageous in industries like aerospace, automotive, and electronics. In this review, various categories of preceramic polymers employed in the synthesis of polymer-derived ceramics are discussed, with a particular focus on the utilization of polysiloxane and polysilsesquioxanes to generate silicate ceramics. Further, diverse additive manufacturing techniques adopted for the fabrication of polymer-derived silicate ceramics are described.
20
El Chawich, Ghenwa, Joelle El Hayek, Vincent Rouessac, Didier Cot, Bertrand Rebière, Roland Habchi, Hélène Garay et al. "Design and Manufacturing of Si-Based Non-Oxide Cellular Ceramic Structures through Indirect 3D Printing". Materials 15, n. 2 (8 gennaio 2022): 471. http://dx.doi.org/10.3390/ma15020471.
Testo completoAbstract (sommario):
Additive manufacturing of Polymer-Derived Ceramics (PDCs) is regarded as a disruptive fabrication process that includes several technologies such as light curing and ink writing. However, 3D printing based on material extrusion is still not fully explored. Here, an indirect 3D printing approach combining Fused Deposition Modeling (FDM) and replica process is demonstrated as a simple and low-cost approach to deliver complex near-net-shaped cellular Si-based non-oxide ceramic architectures while preserving the structure. 3D-Printed honeycomb polylactic acid (PLA) lattices were dip-coated with two preceramic polymers (polyvinylsilazane and allylhydridopolycarbosilane) and then converted by pyrolysis respectively into SiCN and SiC ceramics. All the steps of the process (printing resolution and surface finishing, cross-linking, dip-coating, drying and pyrolysis) were optimized and controlled. Despite some internal and surface defects observed by topography, 3D-printed materials exhibited a retention of the highly porous honeycomb shape after pyrolysis. Weight loss, volume shrinkage, roughness and microstructural evolution with high annealing temperatures are discussed. Our results show that the sacrificial mold-assisted 3D printing is a suitable rapid approach for producing customizable lightweight highly stable Si-based 3D non-oxide ceramics.
21
Pfeifer, Judit, Enikõ Horváth, Zófia Vértesy, Péter Arató e Csaba Balázsi. "Chemical Methods for Scanning Electron Microscope Characterization of Non-Oxide Ceramics and Composites". Key Engineering Materials 409 (marzo 2009): 382–85. http://dx.doi.org/10.4028/www.scientific.net/kem.409.382.
Testo completoAbstract (sommario):
The deformation of ceramic matrix composites (CMC) is controlled by several processes occurring in the matrix, in the enforcing phase, at the interfaces between different phases and at the surface of the body. The main tool to study morphology features of CMC-s is high resolution scanning electron microscopy (SEM). In this study destructive chemical methods such as chemical etching and burning of combustible phases were used to prepare samples for SEM investigations from three types of materials. I. SiC skeletons of C/C-SiC structures prepared of 2D woven fabric and chopped fiber bodies were produced by chemical elimination of the constituents: Si, reinforcing C- fibers and amorphous carbon. II. Silicon-nitride reaction bonded silicon-carbide samples with finishing surface oxide films – as produced and aged - were handled by HF etchants. Etching revealed cristobalite crystallites at the interface between ceramics and oxide film, and cracks in the glassy surface layer. III. Microstructure and pore structure of Si3N4 ceramics, carbon nanotube reinforced Si3N4 (CNT/Si3N4), and C/Si3N4 with graphite and carbon black addition were examined by HF etching.
22
Jothi, Sudagar, Sujith Ravindran e Ravi Kumar. "Corrosion of Polymer-Derived Ceramics in Hydrofluoric Acid and Sodium Salts". Advances in Science and Technology 89 (ottobre 2014): 82–87. http://dx.doi.org/10.4028/www.scientific.net/ast.89.82.
Testo completoAbstract (sommario):
Corrosion behavior of polymer-derived ceramics (PDCs) was investigated in aqueous hydrofluoric acid (HF) and sodium salts (NaCl or Na2SO4). Two oxides (SiCO and SiCNO-(Hf)) and two non-oxide PDCs (SiCN and SiCN-(B)) were examined in this study. The HF acid corroded the oxide PDCs, whereas non-oxide PDCs resisted acid corrosion. Nevertheless, the degradation is slow in some cases to extend the engineering ceramic materials lifespans. The PDCs composites were hot corroded by NaCl or Na2SO4. The Na-salt attacked the PDCs, producing corrosion layers. The cross-sectional X-ray elemental analysis and microstructure surveillance exhibited that the corroded layers comprised of distinct regions. The corrosion mechanism is discussed in line with the experimental discoveries.
23
Hösel, T., Claas Müller e Holger Reinecke. "Analysis of Surface Reaction Mechanisms on Electrically Non-Conductive Zirconia, Occurring within the Spark Erosion Process Chain". Key Engineering Materials 504-506 (febbraio 2012): 1171–76. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.1171.
Testo completoAbstract (sommario):
Electrically insulating high performance ceramics like zirconia are increasingly used for high technological applications due to their extraordinary properties. Meanwhile even the spark erosion process can be used to structure non-conductive ceramics by using an assisting electrode (AE). This conductive AE is placed on top of the work piece to enable the process. The electrical contact is sustained during the process by carbonic residua of cracked oil used as a dielectric. For an enhanced understanding of the removal mechanisms during the spark erosion process of such non-conductive ceramics, we analysed the surface of ceramic samples during the entire spark erosion process chain. In our investigation a zirconium oxide with yttrium oxide stabilisation was chosen. For this purpose X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis was performed. The XRD results showed that the zirconium oxide reacts under the presence of carbonic residua during processing into zirconium carbide. This material supports sustaining the conductivity additionally, as it is conductive itself. In a subsequent thermal cleaning step with oxide atmosphere (T = 750°C), remaining carbonic residua are oxidised and thus removed. The XRD measurements after cleaning showed that the zirconium carbide was no longer detectable. Instead a monoclinic zirconium phase was found. This shows that a reverse reaction of zirconium carbide into zirconium oxide took place. To prevent the formation of a non-stabilised monoclinic phase, the oven process was adapted to higher temperatures of 900°C with higher heating and active cooling rates of up to 10 K/s. This adjustment shows that the monoclinic phase can be supressed and the reverse reaction leads to a tetragonal zirconium oxide like the bulk material.
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Zhao, Bingqing, Qibin Liu, Geng Tang e Dunying Wang. "Microstructure and Biocompatibility of Graphene Oxide/BCZT Composite Ceramics via Fast Hot-Pressed Sintering". Coatings 14, n. 6 (1 giugno 2024): 689. http://dx.doi.org/10.3390/coatings14060689.
Testo completoAbstract (sommario):
Improving fracture toughness, electrical conductivity, and biocompatibility has consistently presented challenges in the development of artificial bone replacement materials. This paper presents a new strategy for creating high-performance, multifunctional composite ceramic materials by doping graphene oxide (GO), which is known to induce osteoblast differentiation and enhance cell adhesion and proliferation into barium calcium zirconate titanate (BCZT) ceramics that already exhibit good mechanical properties, piezoelectric effects, and low cytotoxicity. Using fast hot-pressed sintering under vacuum conditions, (1 − x)(Ba0.85Ca0.15Zr0.1Ti0.9)O3−xGO (0.2 mol% ≤ x ≤ 0.5 mol%) composite piezoelectric ceramics were successfully synthesized. Experimental results revealed that these composite ceramics exhibited high piezoelectric properties (d33 = 18 pC/N, kp = 62%) and microhardness (173.76 HV0.5), meeting the standards for artificial bone substitutes. Furthermore, the incorporation of graphene oxide significantly reduced the water contact angle and enhanced their wettability. Cell viability tests using Cell Counting Kit-8, alkaline phosphatase staining, and DAPI staining demonstrated that the GO/BCZT composite ceramics were non-cytotoxic and effectively promoted cell proliferation and growth, indicating excellent biocompatibility. Consequently, with their superior mechanical properties, piezoelectric performance, and biocompatibility, GO/BCZT composite ceramics show extensive potential for application in bone defect repair.
25
Fan, Hong Wei, Bing Hai Lv, Ju Long Yuan, Q. F. Deng e W. F. Yao. "Fillers and Dissolvent in Porous Self-Generating Fine Super-Hard Abrasive Tool". Advanced Materials Research 135 (ottobre 2010): 398–403. http://dx.doi.org/10.4028/www.scientific.net/amr.135.398.
Testo completoAbstract (sommario):
In order to obtain low surface damage and high machining efficiency for advanced ceramics, overcome clogging and dressing difficulties of traditional metal bonded super-hard abrasive, a novel fine super-hard abrasive with porous self-generating ability is proposed in this paper. And the matching of filler and dissolvent in abrasive are studied. Soluble filler is a key technology of porous self-generating fine super-hard abrasive. In this paper, metal, metal oxide and non-metallic oxide are respectively used as soluble fillers. Results of the experimental shows: In metal bonded super-hard abrasive, metal, metal oxide and non-metallic oxide as soluble filler are feasible, correspondingly, FeCl3 solution, aqueous solution and weak alkaline solution are used as dressing dissolvent, respectively. It can be met the requirement of high precision machining for advanced ceramic materials, hard and brittle machining materials.
26
Podzorova, L. I., A. A. Il’icheva, N. A. Mikhayilina, O. I. Pen’kova, O. S. Antonova, I. Yu Lebedenko e D. A. Shumskaya. "Ceramic based on complex oxide solid solution of zirconia in tetragonal form for prosthetic dentistry". Perspektivnye Materialy 1 (2024): 30–37. http://dx.doi.org/10.30791/1028-978x-2024-1-30-37.
Testo completoAbstract (sommario):
The paper deals with physical and mechanical properties of ceramic material containing complex oxide solid solution Zr1–n[YbNd]nO2 and corundum microfase, taking into account aesthetic and strength requirements of clinical practice of prosthetic dentistry. It has been shown that the developed ceramic has a static bending strength of 850 MPa and according to the international standard ISO 6872:2015 “Dentistry – Ceramic materials” belongs to the 4th and 5th class of dental ceramic materials. This makes it possible to use it for the manufacture of not only single crowns, but also four-units dentures of any localization and any type of fixation. The developed ceramics meet the requirements of prosthetic dentistry and color characteristics, have high opacity, which makes it possible to mask the color of supporting structures.
27
Gadzhiev, Makhach Kh, Arsen E. Muslimov, Damir I. Yusupov, Maksim V. Il’ichev, Yury M. Kulikov, Andrey V. Chistolinov, Ivan D. Venevtsev, Ivan S. Volchkov, Vladimir M. Kanevsky e Alexander S. Tyuftyaev. "Gas-Thermal Spraying Synthesis of β-Ga2O3 Luminescent Ceramics". Materials 17, n. 24 (12 dicembre 2024): 6078. https://doi.org/10.3390/ma17246078.
Testo completoAbstract (sommario):
This paper presents the initial results of the synthesis of β-Ga2O3 luminescent ceramics via plasma gas-thermal spraying synthesis, where low-temperature plasma of an argon and nitrogen mixture was employed. A direct current electric arc generator of high-enthalpy plasma jet with a self-aligning arc length and an expanding channel of an output electrode served as a plasma source. The feedstock material consisted of a polydisperse powder of monocrystalline β-Ga2O3 with particle sizes ranging from 5 to 50 μm. The study presents the results of both theoretical and experimental studies on the heating rate and average temperature of gallium oxide particles in a plasma jet. The results of computational modelling of the synthesis process of β-Ga2O3 via plasma gas-thermal spraying are shown. The obtained ceramic samples were characterized using scanning electron microscopy and X-ray diffraction analysis. Our results indicate that the synthesis process yielded ceramics with a layered texture. The stoichiometric composition of ceramics exhibited a shift towards gallium-rich content. X-ray diffraction data demonstrated a reduction in the lattice parameters and unit cell volume of β-Ga2O3 ceramic structure. Radioluminescence spectra of β-Ga2O3 ceramics revealed an intensive emission band with a maximum at ~360 nm and non-exponential decay. The synthesized β-Ga2O3 ceramics possess potential applications in scintillation detectors.
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Melekhin, N. V., M. S. Boldin, A. A. Popov, A. M. Bragov, V. V. Balandin, Vl Vl Balandin, O. G. Krutova, N. N. Berendeev e V. N. Chuvil'deev. "INVESTIGATION OF THE EFFECT OF INTERNAL STRESSES ON THE BALLISTIC RESISTANCE OF FINE-GRAINED ALUMINUM OXIDE OBTAINED BY SPARK PLASMA SINTERING". Problems of Strength and Plasticity 84, n. 2 (2022): 272–81. http://dx.doi.org/10.32326/1814-9146-2022-84-2-272-281.
Testo completoAbstract (sommario):
The results of tests for ballistic resistance of ceramic samples based on aluminum oxide (Al2O3 + 0.25MgO) obtained by high-speed electric pulse plasma sintering (EIPS) are presented. Samples 30 mm in diameter, 6.5 and 7 mm thick had a high relative density (more than 99%), a uniform fine-grained microstructure (average grain size ~1–1.5 mm), and increased hardness (more than 17 GPa). Using the finite element method, using the ANSYS Workbench package, it is shown that during rapid cooling at a rate of 50 °C/min, an uneven temperature field is formed in the samples and a difference in temperatures arises on two opposite sides of the ceramic samples. It has been established that non-uniform cooling during SPS leads to the formation of compressive internal stresses (up to –450 MPa), and there is a significant difference in the magnitude of internal stresses on opposite sides of ceramic samples. The differences in the parameters of the microstructure and microhardness on opposite sides of the samples are insignificant. Ballistic resistance tests were carried out at a speed of 700 m/s, using cylindrical-conical impactors made of hardened steel 52100. The ballistic resistance of the ceramics was evaluated by the anti-barrier action, i.e., the penetration depth of the striker into the aluminum witness sample located behind the tested ceramic plate. It is shown that the barrier action during testing of a ceramic plate with a large value of compressive internal stresses (from –390 to –450 MPa) is 1.5–2 times less than during ballistic testing of a ceramic plate, in the surface layer of which internal compressive stresses are small (from –60 to –90 MPa). The results obtained for the first time demonstrated the importance of the formation of compressive fields of internal stresses in ceramics, which makes it possible to further increase the ballistic resistance of protective ceramic plates.
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Butskhrikidze, David. "Diamond Grinding Technology of Flexural Strength Test Pieces of Super hard, Brittle, Composite-ceramic Materials and Technological Equipment". Works of Georgian Technical University, n. 4(522) (21 dicembre 2021): 105–13. http://dx.doi.org/10.36073/1512-0996-2021-4-105-113.
Testo completoAbstract (sommario):
At the present stage of the revolutionary development of technologies, scientists from the leading countries of the world are working intensively to create qualitatively new materials whose physical-mechanical, electrical, thermal or other properties far exceed the basic constructions, armament or other metals used. Such materials are surface, brittle, composite ceramic materials (based on oxide and carbide ceramics, state-of-the-art surface compositions, polycrystalline diamond + Si SiC and etc.). A progressive process for diamond grinding test samples from composite ceramic materials to determine the bending strength is discussed. The proposed technological process is based on an original and effective method for polishing the flat surfaces of articles made of difficult-to-process and composite materials - low-temperature precision grinding (LPG). Based on the results of many years and multilateral studies in the field of diamond processing of various non-metallic, composite and ceramic materials, optimum conditions for diamond polishing of mentioned materials have been determined and recommended. Technological equipment and equipment for processing composite and ceramic materials are also disclosed.
30
Volosova, Marina A., Anna A. Okunkova, Sergey V. Fedorov, Khaled Hamdy e Mariya A. Mikhailova. "Electrical Discharge Machining Non-Conductive Ceramics: Combination of Materials". Technologies 8, n. 2 (28 maggio 2020): 32. http://dx.doi.org/10.3390/technologies8020032.
Testo completoAbstract (sommario):
One of the promising processing methods for non-conductive structural and functional ceramics based on ZrO2, Al2O3, and Si3N4 systems is electrical discharge machining with the assistance of an auxiliary electrode that can be presented in the form of conductive films with a thickness up to 4–10 µm or nanoparticles - granules, tubes, platelets, multidimensional particles added in the working zone as a free poured powder the proper concentration of which can be provided by ultrasound emission or by dielectric flows or as conductive additives in the structure of nanocomposites. However, the described experimental approaches did not reach the production market and industry. It is related mostly to the chaotic development of the knowledge and non-systematized data in the field when researchers often cannot ground their choice of the material for auxiliary electrodes, assisting powders, or nano additives or they cannot explain the nature of processes that were observed in the working tank during experiments when their results are not correlated to the measured specific electrical conductivity of the electrodes, particles, ceramic workpieces or nanocomposites but depends on something else. The proposed review includes data on the main electrophysical and chemical properties of the components in the presence of heat when the temperature in the interelectrode gap reaches 10,000 °C, and the systematization of data on ceramic pressing methods, including spark plasma sintering, the chemical reactions that occur in the interelectrode gap during sublimation of primary (brass and copper) and auxiliary electrodes made of transition metals Ti, Cr, Co, and carbon, auxiliary electrodes made of metals with low melting point Zn, Ag, Au, Al, assisting powder of oxide ceramics TiO2, CeO2, SnO2, ITO, conductive additives Cu, W, TiC, WC, and components of Al2O3 and Zr2O workpieces in interaction with the dielectric fluid - water and oil/kerosene medium.
31
Fedotov, Anatoliy V., Aleksey S. Dorokhov e Dmitriy A. Kovalev. "PROSPECTS FOR THE USE OF CERAMIC MATERIALS FOR THE NEEDS OF THE AGRO-INDUSTRIAL COMPLEX". Tekhnicheskiy servis mashin 2, n. 143 (giugno 2021): 91–102. http://dx.doi.org/10.22314/2618-8287-2021-59-2-91-102.
Testo completoAbstract (sommario):
As a result of poor quality, parts of tillage equipment have to be replaced 3-7 times a year. One of the reasons is the lack of attention to the possibility of using technical ceramics in agricultural engineering to improve the wear resistance and durability of machine parts. (Research purpose) The research purpose is in assessing the state of research and prospects for the use of ceramic materials in the Russian Federation for the needs of the agro- industrial complex. (Materials and methods) For the experiments has been used nanostructured boehmite obtained by hydrothermal synthesis to improve the properties of materials and coatings. The crack resistance was determined by the indentation method, and the methane content in the biogas was determined by the chromatographic method. (Results and discussion) The article presents the results of the use of aluminum oxide ceramics for the manufacture of parts of tillage equipment, which allows increasing the resource of parts for processing loamy soils by 2.4-4.5 times. The creation of nanocomposites is promising to increase the strength, wear resistance and crack resistance of the material. In the composition of the non-stick coating, the addition of boehmite increases the abrasion strength of the coating and the compressive strength of the samples by 2.2-2.7 times, and improves the quality of casting. The use of highly porous ceramic materials in the gating system helps to reduce waste, reduce production costs, and improve the quality of foundry products. (Conclusions) Ceramic materials due to their high hardness, wear resistance and corrosion resistance are becoming promising for use in the agro-industrial complex. The widespread use of modern ceramic materials as parts of tillage equipment, non-stick coatings and for the filtration of melts will improve the quality of casting, the durability of products, and reduce the cost of their production. Positive results on wastewater treatment with the use of highly porous ceramics allow us to consider it an innovative material for such purposes and it is advisable to continue research in this direction.
32
Carter, C. Barry. "Dislocations in Ceramics". Microscopy and Microanalysis 4, S2 (luglio 1998): 550–51. http://dx.doi.org/10.1017/s143192760002287x.
Testo completoAbstract (sommario):
Of the four groups of crystal lattice defects, i.e., point defects, dislocations, interfaces and particles, dislocations are often thought to be the least important for ceramic materials. However, they not only give considerable insight into interfaces (they can be thought of as the link between point defects and interfaces), but they are becoming more important as interest grows in epitactic oxide heterostructures.The present paper provides a review of our current understanding of dislocations in ceramics. To simplify the discussion, we can separate the task into the following sections, namely Simple oxides (MgO, ZnO etc.)Simple non-oxides (A1N, GaN, SiC, TiC, etc.)More complex binary oxides (AI2O3, Fe203, etc.)Multicomponent oxides and complex non-oxides (spinels, garnets, S13N4)Interfacial dislocations (misfit, grain boundary, etc.)The features which are most often associated with ceramic materials are their complex structures and large unit cells. For example in bcc garnets, the smallest Burgers vector for a perfect lattice dislocation is ∼0.8nm long.
33
Glukharev, Artem, Oleg Glumov, Ivan Smirnov, Evgeniy Boltynjuk, Olga Kurapova e Vladimir Konakov. "Phase Formation and the Electrical Properties of YSZ/rGO Composite Ceramics Sintered Using Silicon Carbide Powder Bed". Applied Sciences 12, n. 1 (24 dicembre 2021): 190. http://dx.doi.org/10.3390/app12010190.
Testo completoAbstract (sommario):
Fully stabilized zirconia/graphene composites are very promising advanced structural materials having mixed ion–electron conductivity for energy storage and energy conversion applications. The existing methods of the composite manufacturing have a number of disadvantages that limit their practical use. Thus, the search for new sintering methods is an actively developing area. In this work, we report for the first time the application of the SiC powder bed sintering technique for fully stabilized zirconia (YSZ) composite fabrication. The reduced graphene oxide (rGO) was used as a graphene derivative. As a result, well-formed ceramics with high density and crystallinity, the maximal microhardness of 13 GPa and the values of the ionic conductivity up to 10−2 S/cm at 650 °C was obtained. The effects of the sintering conditions and rGO concentration on the microstructure and conductivities of ceramics are discussed in detail. The suggested powder bed sintering technique in a layered graphite/SiC/graphite powder bed allowed well-formed dense YSZ/rGO ceramics fabrication and can become a suitable alternative to existing methods for various oxide ceramic matrix composite fabrication: both conventional sintering and non-equilibrium (SPS, flash sintering) approaches.
34
Suastiyanti, Dwita, Sri Yatmani e YuliNurul Maulida. "A CHEMICAL ROUTE TO THE SYNTHESIS OF Bi1-xMgxFeO3 (x=0.1 and x=0.07) NANOPARTICLE WITH ENHANCED ELECTRICAL PROPERTIES AS MULTIFERROIC MATERIAL". International Journal of Engineering Technologies and Management Research 5, n. 6 (20 marzo 2020): 103–12. http://dx.doi.org/10.29121/ijetmr.v5.i6.2018.250.
Testo completoAbstract (sommario):
Bismuth ferrite (BiFeO3) is one of multiferroic material group, but it is difficult to produce BiFeO3 in single phase as multiferroic material because it occurs leakage of current arising from non stoichiometric. So, to minimize it, it has already been engineering processed to synthesis BiFeO3 doped by Mg to produce Bi0.9Mg0.1FeO3 and Bi0.93Mg0.07FeO3. It used sol-gel method to produce the ceramics. The result of TGA/DTA(Thermo Gravimetric Analysis/Differential Thermal Analysis) test shows that the temperature of calcination is about of 150 and 175oC and temperature of sintering is about of 650oC. Characterization of the powder has already been done by using X-Ray Diffraction (XRD) test and electrical properties test. The results of XRD test show that the powder of Bi0.9Mg0.1FeO3has minimum impurities with total oxide of 6.9% (bismite 3.5% and silenite 3.4%) at calcination temperature of 175oC for 4 hours and sintering at 650oC for 6 hours. Meanwhile at same parameter, Bi0.93Mg0.07FeO3 has more oxide phases with total oxide of 14.5% which consists of silenite (2.5%) and Bi2O4 (12%). Presence of oxide phases could cause leakage of current decreasing electrical properties. The values of electrical saturation polarization for ceramic having minimum total oxide (Bi0.9Mg0.1FeO3) is higher than ceramic having more oxide (Bi0.93Mg0.07FeO3). The value of electric saturation polarization for Bi0.9Mg0.1FeO3 is of 0.26 kv/cm and for Bi0.93Mg0.07FeO3 is of 0.11 kV/cm.
35
Olvera, Mauricio, Marla Berenice Hernández Hernández, Sergio Garcia Villarreal, Eden Amaral Rodríguez Castellanos, Cristian Gomez, Linda Garcia e Josue Amilcar Aguilar Martinez. "Inhibition grain growth and electrical properties by adding In2O3 to SnO2-Co3O4-Ta2O5 ceramics". Revista Mexicana de Física 65, n. 1 (31 dicembre 2018): 25. http://dx.doi.org/10.31349/revmexfis.65.25.
Testo completoAbstract (sommario):
In this contribution the effect of In2O3 additions on the microstructure, physical, and electrical properties of the SnO2-Co3O4-Ta2O5 ceramic system was investigated. Since the effect of In2O3 has been studied typically at low levels, special attention has been paid to the effect of high levels (1 and 2 mol % In2O3) in the ceramics. Results show that up to 0.1 mol % In2O3, an increase of indium oxide content is correlated with grain size reduction and an increase of the nonlinearity coefficient (a) and breakdown voltage (EB), producing an augmentation by a factor of 2 in the nonlinearity coefficient and an increment by a factor of 8 in the breakdown voltage. However, shrinkage () and measured density are not influenced by the addition of indium oxide. For samples with 1 and 2 mol % In2O3, in non-calcined condition, In2O3 is present with cubic structure. However, in calcined specimens, In2O3 is not detected anymore and SnO2-crystal structure undergoes a change from tetragonal to cubic. These ceramic samples exhibit high resistivity, behaving like dielectric materials.
36
Guerra, J. D. S., Y. Leyet, F. Guerrero, Y. Romaguera, J. Pérez e L. Aguilera. "Microstructure and Electrical Properties of Bi3+ Modified ZnO Ceramics". Key Engineering Materials 434-435 (marzo 2010): 318–223. http://dx.doi.org/10.4028/www.scientific.net/kem.434-435.318.
Testo completoAbstract (sommario):
High-quality bismuth modified zinc oxide ceramics were obtained by conventional ceramic method. The phase analysis revealed pure hexagonal ZnO phase in all the samples. High relative density (above 95%), when compared with theoretical density of ZnO, was achieved by the Arquimides’ method. Non-linear coefficients, obtained from the J-E curves, shown an increase in their values as the bismuth content increases. Complex impedance analysis revealed an increase of the semicircle diameters with the increase of the bismuth content. The obtained results will be discussed within the framework of the current theoretical model proposed in the literature.
37
Shin, Hyun-Ho, Yolande Berta e Robert F. Speyer. "Effect of processing temperature on interfacial layer formation in SiC fiber-reinforced glass-ceramic composites". Proceedings, annual meeting, Electron Microscopy Society of America 50, n. 1 (agosto 1992): 62–63. http://dx.doi.org/10.1017/s0424820100120710.
Testo completoAbstract (sommario):
The high fracture toughness and non-catastrophic fracture behavior of fiber-reinforced ceramic matrix composites are due to the weak interfacial shear strength between fiber and matrix, permitting fiber-matrix sliding during failure. In SiC fiber-reinforced glass or glass-ceramic composites, such low interfacial shear strength is obtained by the presence of a carbon-rich interfacial layer. This provides a path for crack propagation, fiber pull-out, and fiber delamination during fracture. Hence, these composites have demonstrated very high fracture toughness (critical stress intensity factor of ∼ 17 MPam1/2) and high fracture strength (3 to 4 times larger than that of monolithic glass or glass-ceramics). The carbon-rich interfacial layer in these glass or glass-ceramic composites is formed by oxidation of the SiC fiber by the oxide matrix during hot pressing. Its thickness is governed by hot pressing time, temperature, and pressure. In our results on Nicalon SiC fiber-reinforced lithium aluminosilicate glass-ceramic composites, hot pressing temperature governed not only the thickness of the interfacial layer, but also the phases residing within it. In this paper, the effect of hot pressing temperature on the phases formed in the interfacial area is described.
38
Fontana, Andreia Cristina Brenner, e Alvaro Luiz Mathias. "Characterization and thermal analysis of metalworking sludge as a partial substitute for clays in ceramic production". Revista Gestão & Sustentabilidade 7, n. 1 (1 febbraio 2025): e14672. https://doi.org/10.36661/2596-142x.2025v7n1.14672.
Testo completoAbstract (sommario):
This study evaluates the feasibility of using sludge from the metalworking industry (SMWI) as a partial substitute for clays in producing red ceramics for civil construction. The analysis of the white goods production process predicted the components of SMWI, potentially reducing the need for additional chemical analyses. According to the chemical analyses provided, SMWI is a non-hazardous solid waste, but not inert, due to the presence of aluminum, chlorine, and phenols, by Brazilian standards. The oxide composition of SMWI showed compatibility with the studied clays and data from the literature, suggesting its potential as an additive in ceramics. Rich in CaO and Al2O3, SMWI can enhance the mechanical strength of ceramics, although excessive addition may increase water absorption. Loss on ignition tests, thermogravimetry, and SEM-EDS analyses on SMWI and pure and 5% SMWI-added clays revealed the loss of volatile compounds and the formation of thermostable clay minerals. However, its distinct composition, with lower levels of Fe2O3 and SiO2, and the need for adequate homogenization, requires caution to avoid impacts on the final properties of the ceramic products, such as water absorption and mechanical strength. Thus, the use of SMWI as a ceramic additive presents itself as a sustainable and viable alternative, although further studies are necessary to validate its application in compliance with Brazilian technical standards.
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Rondinella, Alfredo, Elia Marin, Brian J. McEntire, Ryan Bock, B. Sonny Bal, Wen Liang Zhu, Kengo Yamamoto e Giuseppe Pezzotti. "Bioceramics are Not Bioinert: The Role of Oxide and Non-Oxide Bioceramics on the Oxidation of UHMWPE Components in Artificial Joints". Key Engineering Materials 782 (ottobre 2018): 165–75. http://dx.doi.org/10.4028/www.scientific.net/kem.782.165.
Testo completoAbstract (sommario):
The following research is aimed at understanding the influence of Zirconia-Toughened Alumina (ZTA) and Silicon Nitride (Si3N4) on Ultra-High Molecular Weight Polyethylene (UHMWPE) acetabular liners. Bioceramic femoral heads were systematically tested against UHMWPE in controlled environment according to static/load-free coupling in hydrothermal environment, pin-on-ball wear testing, and hip-simulator wear testing. In addition, a retrieved ZTA femoral head has been analyzed and results have been compared to the simulations. Experimental results from X-ray photoelectron (XPS), cathodoluminescence (CL), Raman and Fourier-Transformed Infrared spectroscopy suggest that, despite conventional notions imply that bioceramics are inert, the surface chemistry of bioceramics was relevant to the oxidation rate of polyethylene liners. Non-biointertness could either be advantageous or disadvantageous toward polyethylene oxidation. The main reason resides in the peculiar chemical interactions between polyethylene and different ceramics, and, more specifically, depends on the direction of oxygen flow at the interface between the ceramic and the polymer. ZTA femoral heads were found to release a non-negligible amount of oxygen moieties from their surfaces, thus accelerating oxidative degradation of polyethylene. Conversely, Si3N4 ceramics exerted a protective role towards the polyethylene liner by scavenging oxygen from the tribolayer. The results of this work provide new insights into the interaction between bioceramics and polymers, which should also be considered when designing the next generation artificial hip joints with significantly elongated lifetimes.
40
Dunyushkina, Liliya A. "Field-assisted sintering of refractory oxygen-ion and proton conducting ceramics". Electrochemical Materials and Technologies 3, n. 3 (Special Issue) (2024): 20243040. http://dx.doi.org/10.15826/elmattech.2024.3.040.
Testo completoAbstract (sommario):
Solid oxides with high oxygen-ion and proton conductivity have been extensively studied for applications in electrochemical devices such as fuel cells, electrolyzers, sensors, hydrogen separators, etc. However, the preparation of high-density ceramic electrolytes is often complicated by the exceptional refractoriness of most oxygen-ion conducting solid oxide phases. Therefore, conventional sintering of these materials is very energy consuming and low effective. In recent years, non-conventional field-assisted sintering technologies (FASTs) such as spark plasma sintering, flash sintering and microwave sintering, have been developed and applied for sintering dense ceramic electrolytes at reduced temperatures. In this article, the applications of FASTs for densification of refractory oxygen-ion and proton conducting ceramics are reviewed, while the mechanisms, advantages and limitations of these technologies are discussed, with special emphasis on the effects of FASTs on the microstructural and transport properties of sintered materials, and the performance of FAST-processed electrochemical cells.
41
Mahnicka-Goremikina, Ludmila, Ruta Svinka, Visvaldis Svinka, Liga Grase, Inna Juhnevica, Maris Rundans, Vadims Goremikins, Sanat Tolendiuly e Sergey Fomenko. "Thermal Properties of Porous Mullite Ceramics Modified with Microsized ZrO2 and WO3". Materials 15, n. 22 (10 novembre 2022): 7935. http://dx.doi.org/10.3390/ma15227935.
Testo completoAbstract (sommario):
Mullite ceramics are well known as materials with a high temperature stability, strength and creep resistance. In this research, the effect of a modification with magnesia-stabilized zirconia and yttria-stabilized zirconia, separately, as well as in a mixture with WO3, in 1:1 and 1:2 ratios on the thermal properties of porous mullite ceramics was investigated. The porous mullite-containing ceramics were prepared by a slip casting of the concentrated slurry of raw materials with the addition of a suspension of Al paste for the pore formation due to the H2 evolution as a result of the reaction of Al with water. The formed samples were sintered at 1600 °C and the holding time was 1 h. The materials were characterized using X-ray diffractometry, scanning electron microscopy, mercury porosimetry, the laser flash contactless method, thermal shock resistance testing and the non-destructive impulse excitation method for determining the elasticity modulus. The modification of the porous mullite ceramic with a mixture of ZrO2 and WO3 oxides had a positive effect by decreasing the thermal conductivity, due to the increased porosity, in comparison to the undoped samples and samples with only ZrO2. The doubling of the WO3 amount in the modifying oxide mixtures improved the ceramic thermal shock resistance. The porous mullite ceramics which were modified with magnesia-stabilized zirconia (2.8 mol% MgO) and WO3 had a lower thermal conductivity and improved thermal shock resistance than the samples with yttria-stabilized zirconia (8 mol% Y2O3) and WO3.
42
Men'shikova, V., e L. Demina. "NON-PLASTIC RAW MATERIALS FOR THE PRODUCTION OF CONSTRUCTION CERAMICS". Construction Materials and Products 3, n. 4 (2 novembre 2020): 31–38. http://dx.doi.org/10.34031/2618-7183-2020-3-4-31-38.
Testo completoAbstract (sommario):
research by some scientists shows that the most expensive element in the manufacture of construction ceramics are clay materials, in particular kaolins. They allow getting products with high strength, but at the same time increase significantly the mass refractoriness. In this connection, a significant amount of melt is added or the firing temperature is increased. Of course, this leads to an increase in the cost of products. In Russia, the reserves of these raw materials are insufficient and it is advisable to look for new non-traditional types of raw materials. There is a need to adjust the component composition of ceramic masses and use non-plastic raw materials. An example is natural wollastonites or their analogues in the form of diopside, which are a little-used type of mineral raw material. In the Siberian region, there are several deposits of non-plastic varieties of raw materials for the production of fired construction products. The most famous are the deposits of the Slyudyansky and Sayan districts. The authors present the results of analysis of diopside rocks, where the chemical, mineral compositions and behavior of samples under heating are studied. The absence of alkali and alkaline earth metal oxides in diopsides was determined. The content of iron oxide in the amount of 0.1% indicates the purity of the raw material. More than half of the composition is occupied by silica, which is 53% and 58% in the rocks of the Burutuysky and Sayan deposits, respectively. The basis of the mineral composition of the samples is diopside, with the presence of quartz, calcite, mica and magnesium carbonate. This range of minerals is traditional in many charges of ceramic materials. Therefore, the possibility of using diopside rocks in the production of building ceramic materials is quite high.
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Nickel, Klaus G. "Corrosion of non-oxide ceramics". Ceramics International 23, n. 2 (gennaio 1997): 127–33. http://dx.doi.org/10.1016/s0272-8842(96)00008-9.
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Sato, Tsugio, e Masahiko Shimada. "Corrosion of Non-oxide Ceramics". CORROSION ENGINEERING 37, n. 6 (1988): 373–78. http://dx.doi.org/10.3323/jcorr1974.37.6_373.
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de la Torre, Guido Manuel Olvera, Monika Tatarková, Zuzana Netriová, Martin Barlog, Luca Bertolla, Miroslav Hnatko e Gianmarco Taveri. "Applying the Alkali-Activation Method to Encapsulate Silicon Nitride Particles in a Bioactive Matrix for Augmented Strength and Bioactivity". Materials 17, n. 2 (9 gennaio 2024): 328. http://dx.doi.org/10.3390/ma17020328.
Testo completoAbstract (sommario):
The development of bioactive ceramics still poses challenges in finding a good compromise between bioactivity and mechanical robustness. Moreover, a facile, low-cost and energy-saving synthesis technique is still needed. This study concerns the synthesis of a bioactive material by growing a bioactive Na-Ca-Mg-Si-based ceramic matrix produced using the alkali-activation method on silicon nitride (Si3N4) particles. This technique simultaneously forms the matrix precursor and functionalizes the Si3N4 particles’ surface. The optimal strength–bioactivity compromise was found for the composition containing 60 wt.% Si3N4 and 40 wt.% of the matrix exhibiting good compressive strength of up to 110 MPa and extensive precipitation of hydroxyapatite on the sample surface after 7 days of soaking in simulated body fluid. This innovative approach merging strong non-oxide binary ceramics with the versatile and low-cost alkali-activation method holds great expectations for the future in biomaterials.
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Sawaoka, Akira B. "Dynamic consolidation of non-oxide ceramic powders". Physica B+C 139-140 (maggio 1986): 809–12. http://dx.doi.org/10.1016/0378-4363(86)90707-2.
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Dhanasekar, S., Arul Thayammal Ganesan, Taneti Lilly Rani, Venkata Kamesh Vinjamuri, Medikondu Nageswara Rao, E. Shankar, Dharamvir, P. Suresh Kumar e Wondalem Misganaw Golie. "A Comprehensive Study of Ceramic Matrix Composites for Space Applications". Advances in Materials Science and Engineering 2022 (8 settembre 2022): 1–9. http://dx.doi.org/10.1155/2022/6160591.
Testo completoAbstract (sommario):
Ceramic matrix composites (CMCs) have grown in popularity as a material for a range of high as well as protection components, increasing the need to better understand the impacts of multiple machining methods. It is primarily composed of ceramic fibers embedded in the matrix. Ceramic materials, especially carbon fibers and carbon were used to create the matrix and fibers. These ceramics include a huge variety of non-metallic inorganic materials that are regularly utilized under high temperatures. The aircraft industry became revolutionized by this unique combination of materials, which made parts better resistant under extreme conditions as well as lighter than the earlier technology. The development, properties, and production of ceramic matrix composites, as well as space applications, are discussed in this article. Ceramic materials have an interesting set of properties, including great strength and stiffness under extremely high temperatures, chemical inertness, low density, etc. In CMC, ceramics are used in the matrix as well as reinforcement. The matrix material keeps things running smoothly while the reinforcement delivers unique special properties. Ceramic matrix composites are developed for applications that required high thermal and mechanical characteristics, which include nuclear power plants, aircraft, chemical plants, space structures, and transportation services. Even though advanced aircraft relies on high-performance propulsion systems, improving the total impulses over the total mass ratio for rocket engines becomes essential for improving their performance that demands reduced engine structural weight as well as higher component heat resistance. The evolution of new ultra-high-temperature composites having high-temperature resistance as well as low density that a substitute super alloy and refractory metal material has become so essential and laid the foundation for high-performance engine design. The benefits of continuous fiber- reinforced CMC with high-temperature engine designs have long been recognized as a better measure of a country’s ability to design and produce spacecraft, modern aircraft, and weapons. Ceramic matrix composites materials are used in various aircraft type engines, aircraft brake disks, high-temperature gas turbines components, slide bearing components, hot gas duct, flame holders and components for burners are made by using oxide CMCs.
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Thaddeus. C. Azubuike, Paulinus. N. Nnabo, Norbert Okechinyere Osonwa, Chukwuemeka Emmanuel Odoala, Emma Onochie Nwabineli e Victor Dorawa Koreyo. "Mineralogical, geochemical and physical properties assessment of clay deposits in Umuoke Obowo Southeastern Nigeria for industrial applications". World Journal of Advanced Research and Reviews 21, n. 3 (30 marzo 2024): 533–45. http://dx.doi.org/10.30574/wjarr.2024.21.3.0699.
Testo completoAbstract (sommario):
This study assessed the suitability of clay deposits from Umuoke, Obowo in southeastern Nigeria as local raw materials for industrial applications. Ten samples were collected from different mining pits across the locality. X-ray fluorescence, X-ray diffraction and physical property tests characterized the clays based on geochemical composition, mineralogy and key attributes. The clays showed high silica (56.41%) and alumina (32.82%) contents typical of aluminosilicate clays. Iron oxide levels were moderately elevated (3.34% Fe2O3). Clay minerals kaolinite (18.9-37.0%) and illite (0.5-4.15%) occurred predominantly alongside non-clay minerals like quartz, feldspars and metal oxides. The clays exhibited high plasticity (avg. plasticity index 26.61%) enabling easy moulding and shaping. Porosity averaged 21.33% appropriate for refractories. Firing shrinkage (6.5-19.2%) and density (1.54-1.76 g/cm3) were in acceptable ranges. Strength post-firing reached the 15 N/mm2 minimum standard. Estimated refractoriness was 1680.22°C. Overall, the Umuoke clays demonstrate favourable chemistry, mineralogy and physical properties for refractories and structural ceramics applications pending some processing adjustments. Locally exploiting these deposits can promote import substitution, rural industrialization and sustainable development in Nigeria. Further pilot testing can optimize formulations and processes for targeted ceramic products. Comprehensive nationwide clay deposit prospecting is also recommended. The clays are suitable for refractory bricks, ceramic tableware, architectural ceramics, wall tiles, pottery items.
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Lazar, Iwona, Małgorzata Adamczyk-Habrajska, Marian Pawełczyk, Michał Górny, Anna Zawada e Krystian Roleder. "Piezoelectric and elastic properties of relaxor-like PZT:Ba ceramics". Journal of Electroceramics 40, n. 3 (20 febbraio 2018): 203–10. http://dx.doi.org/10.1007/s10832-018-0121-6.
Testo completoAbstract (sommario):
Abstract The solid solutions of PbZr1-xTixO3 (PZT) are the most known and widely applicable piezoelectric ceramic materials. The influence of different dopants on PZT properties has been studied for many years. Some of such compositions have revealed a behavior typical for ferroelectric relaxors. In the case of Pb0.75Ba0.25Zr0.70Ti0.30O3 ceramics (abbreviation PBZT 25/70/30), prepared by mixed-oxide processing technique elastic, it was found that macroscopic piezoelectric activity is present far above the temperature at which structural changes and maximum of permittivity occur in unpoled samples (~ 200 °C). Anomalies of the elastic and piezoelectric properties have been observed very clearly near the temperature of 152 °C. Within the temperature range of 152–220 °C, unstable piezoelectric properties have been detected due to the existence of polar micro/nano-clusters and non-trivial elastic-electric interactions between them, through the non-polar paraelectric matrix. The origin of such interactions could be lattice instabilities, dynamic change in polar cluster sizes, and fluctuations in chemical composition. Based on the results of the research, it can be said that PZT ceramics of such composition is a relaxor-like material and it is not a ferroelectric relaxor.
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Hafner, Thomas, Jonas Hafner, Frank Kimm, Vira Bovda, Oleksandr Bovda, Oleksandr Kuprin, Anatoliy Pikalov et al. "Structural and Mechanical Properties of SiC-Rich By-Products of the Metal Grade Si Process". Materials Science Forum 1113 (15 febbraio 2024): 87–94. http://dx.doi.org/10.4028/p-v1q03d.
Testo completoAbstract (sommario):
Mechanical properties of composites produced from the SiC-rich furnace slag using traditional stone and ceramic machining technologies were studied. A non-uniform mixture of coarse monocrystalline SiC grains soaked with Si-metal and glassy oxide phases represented the microstructure of dense monolithic SiC-rich samples. The fracture mechanism of coarse-grained SiC-rich composites was susceptible to the grain size/sample geometry and machining conditions yielding flexural strength in the range of 50-106 MPa and high compression strength of 750 MPa. Despite inhomogeneous macro and microstructure, mechanical and thermal properties are comparable to the traditionally produced siliconized SiSiC ceramics. It opens up the opportunity for the circular economy and value-added recycling of the Si/FeSi industries’ wastes.