Journal articles: 'Powder compacts'

1

Kwon, Y. S., and K. T. Kim. "Densification Forming of Alumina Powder—Effects of Power Law Creep and Friction." Journal of Engineering Materials and Technology 118, no. 4 (October 1, 1996): 471–77. http://dx.doi.org/10.1115/1.2805944.

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High temperature forming processes of alumina powder compacts were analyzed by using constitutive equations which are capable of predicting densification and grain growth under diffusional creep and power law creep. Experimental results for alumina powder compacts were compared with finite element calculations by using the constitutive equations. The effects of friction between alumina powder compact and punches during sinter forging of alumina powder compacts were also investigated. Densification mechanism maps of alumina powder, which can be used for the optimization of various process variables, were constructed under hot pressing and general states of stresses.

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Kim, Youn Che, and Myung Jin Suk. "Expansion Behavior of Iron-Copper Compact from (FeCu) Pre-Alloyed Powder." Materials Science Forum 534-536 (January 2007): 517–20. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.517.

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Dilatometric curves of iron-copper compact made from elemental or pre-alloyed powder were compared in order to study its expansion mechanism. The compacts from a mixture of elemental iron and copper powders showed the maximum expansion at the copper powder content of 7.44mass% and at the sintering temperatures above the copper melting-point. In the case of the compacts from a mixture of iron pre-alloyed powder of (Fe- 3.44mass%Cu) and copper powder, the maximum expansion which is lower than the former case was obtained at the additive copper powder content of 4.00mass%. But the compact from a mixture of iron pre-alloyed powder of (Fe-7.18mass%Cu) and copper powder showed only shrinkages at any additive copper powder content. The penetration of liquid copper into the interstices between solid grains was observed in all sintered compacts. The iron-copper compacts containing the same content of copper powder showed a very different expansion behavior depending on the amount of copper content in the starting iron raw powder.

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3

Jia, Ming Tu, De Liang Zhang, and Brian Gabbitas. "Comparison of Blended Elemental (BE) and Mechanical Alloyed (MA) Powder Compact Forging into Ti-6Al-4V Rocker Arms." Key Engineering Materials 520 (August 2012): 82–88. http://dx.doi.org/10.4028/www.scientific.net/kem.520.82.

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Ti-6Al-4V rocker arms for internal combustion engines were produced by forging of compacts of blended powder consisting of elemental hydride-dehydride (HDH) titanium powder and Al60V40 (wt%) master alloy powder or mechanical alloyed (MA) powder synthesized by high energy mechanical milling of a mixture of HDH titanium and Al60V40 master alloy powders. The powder compacts were made by warm compaction, and their relative density was 90%. The mechanical properties and microstructures of as-forged parts made using blended powder were improved significantly with increasing holding time at forging temperature, and close to those of as-forged parts produced by powder compact forging of HDH Ti-6Al-4V pre-alloyed powder. However, the as-forged part produced by powder compact forging of MA powder was brittle, and fractured prematurely during tensile testing.

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Rajković, V., D. Božić, D. Vračarić, and E. Romhanji. "Properties of Dispersion-Hardened Copper Made by Internal Oxidation of Prealloyed Copper Powder Containing 2.5 wt. % Al." Materials Science Forum 494 (September 2005): 493–98. http://dx.doi.org/10.4028/www.scientific.net/msf.494.493.

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Prealloyed copper powder containing 2.5wt. %Al was processed in a planetary ball mill to evaluate matrix hardening due to formation of Al2O3 particles in situ by internal oxidation. After milling, the powders were heat treated in hydrogen in order to reduce copper oxide formed on particle surfaces during milling. The compacts were made by hot pressing. The examinations show that the compacts possess a good combination of high strength and high electrical conductivities. After 5h of milling the microhardness of the prealloyed compact was 3 to 4 times higher than that of the as-received electrolytic copper compacted under the same conditions, while the conductivity was 68% IACS. Also, it was found that the prealloyed compacts preserved much of the hardness after exposure to high temperature in inert atmospheres.

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Shen, Ye Qing, and Min Deng. "Capillary Absorption of Liquid by Powder Compact and its Application on Preparation of Repeatable Cement Compacts." Advanced Materials Research 163-167 (December 2010): 2916–19. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.2916.

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Preparation of repeatable cement compacts may contribute to quantitively research of processing, structure and properties of cement materials. Capillary absorption of liquid by powder compact was briefly reviewed. Deviation degree of absorption coefficient (Dac) was designed for evaluation on repeatable preparation of cement compacts. Dry cement was compacted in special moulds. A group of orthogonal experiments were designed to investigate repeatable preparation of the compacts. Results show the most important factor influencing on repeatable preparation is the cavity size of mould. The influence of force and specific surface area of cement is generally below 1.41%. According to optimum scheme for preparation, Dac is 0.00%. Repeatable preparation of cement compacts may provide a new method for quantitatively research of cement materials.

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CHIBA, AKIRA, and YASUHIRO MORIZONO. "FABRICATION OF TRICALCIUM PHOSPHATE COMPACTS BY UNDERWATER-SHOCK CONSOLIDATION." International Journal of Modern Physics B 22, no. 09n11 (April 30, 2008): 1783–88. http://dx.doi.org/10.1142/s0217979208047419.

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The present study is to fabricate dense tricalcium phosphate (TCP) compacts by our newly developed underwater-shock consolidation technique and to investigate the characteristics of the compacts. By adding Al 2 O 3 powder to β-TCP powder, the biocomposites were fabricated to improve the fracture toughness. Sound compacts of α- and β-TCP powders and β-TCP/ Al 2 O 3 biocomposite powder were fabricated without any cracks and tears. The relative densities of α- and β-TCP compacts were about 85% in as-compacted state and more 94% after annealing at 1373K for 7.2ks. Compressive strengths of α- and β-TCP compacts are 160 and 140MPa after annealing at 1373K for 7.2ks, respectively. Compressive strength and fracture toughness of β-TCP/ Al 2 O 3 biocomposites after annealed at 1373K for 7.2ks were 188MPa and 2.54MPa·m1/2, which are comparable to values of human bone, respectively.

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Raynova, Stella, De Liang Zhang, D. Polo, L. Gonthier, W. Egea, and V. N. Nadakuduru. "Tensile Properties and Fracture Behaviour of Induction Sintered Ti and Ti-6Al-4V (wt %) Powder Compacts." Advanced Materials Research 275 (July 2011): 196–99. http://dx.doi.org/10.4028/www.scientific.net/amr.275.196.

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Induction heating of powder compacts could be a very effective method for metal powder consolidation to get the final product or as an intermediate consolidation step to produce feedstock for metal powder forging or extrusion. Our study has proven that only a few minutes of induction heating, of Ti and Ti-6Al-4V (wt %) powder compacts, increases their density dramatically and causes a significant sintering effect, as evidenced by the formation of interparticle diffusion bonding and reflected by the tensile properties of the induction sintered powder compacts. This paper presents and discusses the results of a study on the tensile properties and fracture behaviour of the Ti and Ti-6Al-4V powder compacts sintered under a variety of induction heating conditions. Keywords: Titanium alloys, powder consolidation, powder compact sintering, induction heating.

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Miura, Hideshi, Hiroyuki Maeda, Makoto Uemura, Teruie Takemasu, and Masaaki Otsu. "Establishment of Laser Sintering Technique for Titanium Powder." Materials Science Forum 534-536 (January 2007): 465–68. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.465.

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This paper investigates the characteristic of single-layered and multi-layered compacts made by selective laser sintering using titanium powder. The surface texture and tensile strength were investigated by using single-layered compacts. There were few defects in surface of specimen laser sintered in vacuum, and the roughness was smoother than that of the specimen laser sintered in argon. Maximum tensile strength of single-layered compact laser sintered in vacuum was about 200MPa. The shrinkage and mechanical strength were investigated by using multi-layered compacts. There was a unique tendency in the shrinkage of multi-layered compacts, which the density was around 75% and the adhesive bonding was not observed between layers, resulted in 70MPa of maximum bending strength and 50MPa of maximum tensile strength.

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Liu, Yan Chun, An Ze Shui, Xue Tan Ren, and Ling Ke Zeng. "Sintering Shrinkage Anisotropy of Spherical Alumina Powder Compacts with Particle Orientation." Key Engineering Materials 334-335 (March 2007): 293–96. http://dx.doi.org/10.4028/www.scientific.net/kem.334-335.293.

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Spherical alumina powder and dispersant were mixed with distilled and deionized water, and ball milled to make alumina slurry. The slurry was dried in a high magnetic field to make a compact. Subsequently, the compact was cold-isostatic-pressed (CIP) to enhance the homogeneity in particle packing density. Anisotropy of shrinkage during sintering was examined for the alumina compacts in detail. Particle orientation existed in the spherical alumina powder compacts prepared in 10T, and made them shrink anisotropically during sintering. Sintering shrinkage was larger in the direction parallel to magnetic field direction (i.e., the c-axis direction of alumina crystal) than that in its perpendicular direction. The particle orientation structure in the compacts was confirmed with the immersion liquid method of polarized light microscope, and the grain alignment structure in the sintered bodies was also observed with X-ray diffraction, the c-plane was perpendicular to the magnetic field direction. On the other hand, isotropic sintering shrinkage occurred in the spherical alumina powder compacts prepared in 0T, which did not hold the particle orientation. The experimental results indicate that sintering shrinkage of spherical alumina powder compact depends on alumina crystal axis direction. Origin of the sintering shrinkage anisotropy for the spherical alumina powder compacts can be attributed to the particle orientation caused by high magnetic field.

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Zhu, Y. M., Xia Wan Wu, and Zhi Hong Li. "Sintering and Crystallization of Glass-Ceramics for Optical Fiber Ferrule." Key Engineering Materials 336-338 (April 2007): 1840–42. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.1840.

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The crystallization and sintering of the Li2O-Al2O3-SiO2 glass powder compacts were studied. Results showed the relative densities of the sintered compacts with lower crystallization temperatures were higher than those with higher crystallization temperatures. A small amount of residual glass in the crystallized compact was good for sintering and densification. Compared with the heat treatment time, the heat treatment temperature was an important factor for the crystallization and sintering of glass powder compacts. The crystallized compacts with a small amount of residual glass should be sintered at a relatively higher heating rate under the prerequisite of keeping sintered compacts from deformation.

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11

Li, Zhi, and Stavros A. Argyropoulos. "Determination of Thermal Conductivity of Mn-Al Powder Compacts using An Inverse Heat Transfer Procedure." High Temperature Materials and Processes 31, no. 4-5 (October 30, 2012): 581–92. http://dx.doi.org/10.1515/htmp-2012-0095.

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AbstractThe effective thermal conductivities of various Mn-Al powder compact compositions were measured using an Inverse Heat Transfer Procedure, and extensive validation work was also carried out. Specially fabricated cylindrical compact specimens were used equipped with two thermocouples at strategic locations. The porosity of these specimens was also measured.The estimated effective thermal conductivities of various Mn-Al compacts were in the range of 5.5 to 10.5 W m−1 °C−1, which are much lower than that of Al (237 W m−1 °C−1), and close to that of Mn (7.8 W m−1 °C−1). The effective thermal conductivities of Mn-Al powder compacts decreased with an increase in the compact's Mn composition and porosity. Within the examined temperature range of 250 to 600 °C, the effect of temperature on the effective thermal conductivity was minimal. A purely theoretically derived prediction of Mn-Al compact thermal conductivity is substantially higher than the estimates of using the IHTP.

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12

Rosato, A. D., T. Vreeland, and F. B. Prinz. "Manufacture of powder compacts." International Materials Reviews 36, no. 1 (January 1991): 45–79. http://dx.doi.org/10.1179/imr.1991.36.1.45.

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13

Nono, Maria do Carmo de Andrade. "Compaction Behavior Study of Powder Composed by Nanoparticle Agglomerates and Aggregates." Materials Science Forum 530-531 (November 2006): 461–66. http://dx.doi.org/10.4028/www.scientific.net/msf.530-531.461.

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Ceramic powder compaction by pressing requires weak-agglomerated powders to obtain high dense compacts and consequently dense sintered ceramic body. In this work powders with different agglomerated and/or aggregated size distributions was compacted by uniaxial and isostatic pressing. The powder and compacts were characterized by mercury and nitrogen porosimetry, BET and SEM. Analysis of X-rays diffraction peaks was used to determine the particle size (diameter). The Scherrer method was used to obtain the estimated average nanoparticle size. The results showed that all aggregated and weak agglomerated powders were composed by nanoparticles. This study indicated that the nanoparticle aggregates and weak agglomerates were destroyed during the pressing stage conducting to a increase of the packing degree of the powder particles.

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14

Çavdar, U., E. Atik, and A. Ataç. "Mechanical properties and hardness results of the medium frequency induction sintered iron based powder metal bushings." Science of Sintering 46, no. 2 (2014): 195–203. http://dx.doi.org/10.2298/sos1402195c.

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In this study; iron based powder metal (PM) bushing compacts were sintered via medium frequency induction heating system. Iron based powders were mixed with 2 wt.% copper (Cu), 0.3 wt.% carbon (C) and 1 wt.% zinc stearat (Zn-st) via V-Type mixer. PM compacts were sintered by 2 different sintering processes. One of them was conventional sintering method other was medium frequency induction sintering method. In conventional sintering process, PM bushing compacts were sintered under inert environmental at 1120?C for 30 minutes. In medium frequency induction sintering process, PM bushing compacts were sintered between 30-50 kHz frequency (Medium frequency) at 2 kW, 1120?C for 1 or 3 minutes under atmospheric environmental. Mechanical properties, densities and micro hardness? were investigated for all sintered processes. SEM and micro structural images were taken from polished broken surface of the sintered PM bushing compacts. 3 minutes induction sintered compacts were reached the compressive strength, microhardness and density values of the conventional sintered PM bushing compact.

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Clasen, Rolf, and Christian Oetzel. "Near Net Shaping with Bimodal Powders on Shaped Membranes via EPD." Key Engineering Materials 412 (June 2009): 45–50. http://dx.doi.org/10.4028/www.scientific.net/kem.412.45.

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The electrophoretic deposition (EPD) is a very promising process for shaping compacts, especially for nanopowders. Up till now EPD is not used on a large-scale production of ceramic products. Additionally, the higher cost of nanopowders was also a barrier for the development of new products. As the deposition rate at EPD is independent of particle size, it is an ideal process for shaping compacts of powder mixtures with nanopowders. Silica and zirconia powders were used as model systems to demonstrate the advantages of EPD. Applications might be the preparation of high-purity silica glass for processing of semiconductors and zirconia ceramics for near net-shaped dental crowns. In both cases the optimum green density was achieved for approx. 10 % addition of nanopowders to a coarser matrix powder. The compacts were homogenous. Alternatively, compacts of different powders can be prepared in a two-step process. Examples are shown for the electrophoretic impregnation (EPI) and a reactive forming of nanoparticles inside the pore volume of a compact consisting of coarser particles.

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Ternero, Fátima, Eduardo S. Caballero, Raquel Astacio, Jesús Cintas, and Juan M. Montes. "Nickel Porous Compacts Obtained by Medium-Frequency Electrical Resistance Sintering." Materials 13, no. 9 (May 4, 2020): 2131. http://dx.doi.org/10.3390/ma13092131.

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A commercially pure (c.p.) nickel powder was consolidated by Medium-Frequency Electrical Resistance Sintering (MF-ERS). In this consolidation technique, a pressure and the heat released by a high-intensity and low-voltage electrical current are concurrently applied to a metal powder mass. A nickel powder with a high tap porosity (86%) and a low applied pressure (only 100 MPa) is chosen in order to be able to obtain compacts with different levels of porosity, to facilitate the study of the porosity influence on the compact properties. The influence of current intensity and heating time on the global porosity values, the porosity and microhardness distribution, and the electrical conductivity of the sintered compacts is studied. The properties of the compacts consolidated by MF-ERS are compared with the results obtained by the conventional powder metallurgy route, consisting of cold pressing and furnace sintering. A universal equation to describe the porosity influence on all the analyzed properties of powder aggregates and sintered compacts is proposed and validated.

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Jia, Ming Tu, and Brian Gabbitas. "Powder Consolidation of Titanium and Titanium Alloys by a Powder Compact Forging Process." Key Engineering Materials 704 (August 2016): 68–74. http://dx.doi.org/10.4028/www.scientific.net/kem.704.68.

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Powder compact forging in combination with induction sintering, a field assisted sintering technique (FAST), was used to produce commercially pure (CP) Ti and Ti-13V-11Cr-3Al parts. Green powder compacts with high relative density were manufactured by cold compaction and warm compaction, respectively. During the powder compact forging process, CP titanium powder was consolidated completely to produce a near net shaped top cover for a diving helmet with full density and good mechanical properties. Also, a Ti-13V-11Cr-3Al alloy was fully consolidated into a cylinder using blended elemental powders. As a comparison, raw titanium powder with different oxygen contents was used to make a Ti-13V-11Cr-3Al powder compact forging. Using a starting powder with low oxygen content, a forged cylinder with good mechanical properties was produced.

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18

Block, T., S. Wurmehl, C. Felser, and J. Windeln. "Powder magnetoresistance of Co2Cr0.6Fe0.4Al∕Al2O3 powder compacts." Applied Physics Letters 88, no. 20 (May 15, 2006): 202504. http://dx.doi.org/10.1063/1.2200571.

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Kishimura, Hiroaki, Yuki Yano, and Hitoshi Matsumoto. "Consolidation of Mg₂Si Powder Using Shockwave Generated by Projectile Impact." Materials Science Forum 767 (July 2013): 177–82. http://dx.doi.org/10.4028/www.scientific.net/msf.767.177.

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A series of shock compaction experiments on as-received and ball-milled Mg2Si powder were conducted. The crystalline size in the shocked compacts obtained from the ball-milled powder was equivalent to that of the compacts obtained from the as-received powder. Although the shock pressure was higher than the phase transition pressure, the crystal structure reverted to its original structure under ambient conditions. For the shocked compact obtained from the ball-milled powder, a MgO peak appeared in the X-ray diffraction pattern.

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Lim, Joong Yeon, Jung Min Seo, and Beong Bok Hwang. "A Numerical Analysis of Powdered Metal Compaction Processes for Two-Level Flanged Solid Cylindrical Components." Materials Science Forum 475-479 (January 2005): 3251–54. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.3251.

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A finite element method for the compaction process of metallic powder is introduced in the present work. Basic equations for the finite element formulation are summarized. A yield criterion, which is modified by describing asymmetric behavior of powder metal compacts, is introduced and applied to a certain class of powdered metal compaction processes. Two-level flanged solid cylindrical components are analyzed in three different compacting methods with three different compact geometries. The simulation results are summarized in terms of relative density distribution within compacts, pressure distributions along the die-wall interfaces, load-stroke relationships of each punch, average densities as functions of height and radius of the compact, respectively, and average densities of pin and head. For each compact from different compacting method, the best pressing method is chosen for uniform density distributions within the compact.

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Ueta, Márcia Christina Carneiro, Carlos Augusto Fracote, Vinicius André Rodrigues Henriques, Mario Lima de Alencastro Graça, and Carlos Alberto Alves Cairo. "Densification Study of Titanium Powder Compacts." Materials Science Forum 498-499 (November 2005): 211–16. http://dx.doi.org/10.4028/www.scientific.net/msf.498-499.211.

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Powder compaction characteristics is a very important parameter to control in order to obtain products with best mechanical properties made by P/M techniques. This work presents a study on the densification of titanium powders trying to optimize the particle size distribution for the best packing and the maximum densification by pressure compaction. The powders used were made from titanium sponge obtained by the Kroll process. The powders were embrittled by mean of the Hydride-Dehydride process (HDH) and milled in a rotative ball-mill under vacuum. Powders with different particles sizes distributions were mixed in several proportions according to Alfred's and Andreasen’s Theory. The samples were compacted by uniaxial and isostatic pressing and sintered under vacuum. The evaluation of the densification was made following the Standard method of test for density of glass by Buoyancy (ASTM – C693-74) and by scanning electron microscopy (SEM). The samples made with powder milled during 36 hours and 12 hours presented better densification than the ones milled during shorter time and the ones with distributions combinations.

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22

Ngai, Tungwai Leo, Zhi Yu Xiao, Yuan Biao Wu, and Yuan Yuan Li. "Studies on Preparation of Ti₃SiC₂ Particulate Reinforced Cu Matrix Composite by Warm Compaction and Its Tribological Behavior." Materials Science Forum 534-536 (January 2007): 929–32. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.929.

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Conventional powder metallurgy processing can produce copper green compacts with density less than 8.3 g/cm3 (a relative density of 93%). Performances of these conventionally compacted materials are substantially lower than their full density counterparts. Warm compaction, which is a simple and economical forming process to prepare high density powder metallurgy parts or materials, was employed to develop a Ti3SiC2 particulate reinforced copper matrix composite with high density, high electrical conductivity and high strength. In order to clarify the warm compaction behaviors of copper powder and to optimize the warm compaction parameters, effects of lubricant concentration and compaction pressure on the green density of the copper compacts were studied. Copper compact with a green density of 8.57 g/cm3 can be obtained by compacting Cu powder with a pressure of 700 MPa at 145°C. After sintered at 1000°C under cracked ammonia atmosphere for 60 minutes, density of the sintered compact reached 8.83 g/cm3 (a relative density of 98.6%). Based on these fabrication parameters a Ti3SiC2 particulate reinforced copper matrix composite was prepared. Its density, electrical conductivity, ultimate tensile strength, elongation percentage and tribological behaviors were studied.

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Çavdar, Uǧur, and Ibrahim Gülșahin. "Ultra high frequency induction welding of powder metal compacts." Revista de Metalurgia 50, no. 2 (June 25, 2014): e016. http://dx.doi.org/10.3989/revmetalm.016.

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Lim, Ju Beom, Colleen J. Bettles, Barry C. Muddle, and Nho Kwang Park. "Effects of Impurity Elements on Green Strength of Powder Compacts." Materials Science Forum 654-656 (June 2010): 811–14. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.811.

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The green strength of a powder compact results from the mechanical interlocking of the irregularities on the particle surfaces. During compaction, particle rearrangement, plastic deformation and particularly surface deformation of powders occur. Titanium powder is susceptible to interstitial element contamination, which may lead to solid solution strengthening of the particles and/or the formation of non-metallic compounds on the surface. However, the influence of these various impurities, namely oxygen and nitrogen, on the green strength has not been investigated. This work investigates and quantitatively evaluates the factors influencing the green strength of the powder compacts. The indirect tensile test was applied for the determination of the green strength of the powder compacts, and test results were compared to that of a more conventional 3-point bending test. The substantial dependence of green strength on both the amount of impurity element in the core of the powder particles and the compaction pressure is demonstrated. The effect of the surface condition of the powder particles on green strength is also reported.

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Zhang, De Liang, Stella Raynova, Vijay Nadakuduru, Peng Cao, Brian Gabbitas, and Barry Robinson. "Consolidation of Titanium, and Ti-6Al-4V Alloy Powders by Powder Compact Forging." Materials Science Forum 618-619 (April 2009): 513–16. http://dx.doi.org/10.4028/www.scientific.net/msf.618-619.513.

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Consolidation of titanium and titanium alloy powders using thermomechanical powder metallurgy (TPM) processes (powder compact forging, extrusion and rolling) is one way that can lead to cost-effective production of high value-added consolidated titanium and titanium alloy products such as near-net shaped components, tubes and plates. This paper provides an overview of the quality, microstructure (to limited depth), porosity level and mechanical properties of disks produced using open die forging of powder compacts of CP titanium and Ti-6Al-4V alloy powders. The general materials science principles underlying the relationships between processing conditions, microstructure and the mechanical properties of the disks made by using the powder compact forging are discussed.

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Mineiro, Sergio Luiz, and Maria do Carmo de Andrade Nono. "Compaction Behaviour of Yttria-Zirconia Powders Obtained from Micro and Nanoparticles Mixtures." Materials Science Forum 591-593 (August 2008): 504–9. http://dx.doi.org/10.4028/www.scientific.net/msf.591-593.504.

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The densification behavior of mixtures of nanocrystalline and conventional microcrystalline zirconia powders undergoing uniaxial pressing was investigated. The mixtures were obtained with ratios between 10 and 80 wt.% of nanoparticulate powder added to the microparticulate powder. Nitrogen and Mercury porosimetry were used to measure the pore size distributions of the compacts. The powders and the fracture surfaces of the compacts were observed via SEM. The results showed that compacts of the powder mixtures attain higher densities during pressing than the unmixed powders. The powder mixture with 80 wt. % of nanoparticles showed the better particle packing efficiency. A comparison between density values of uniaxial and isostatic pressing also was done and indicated that the best results were obtained by the isostatic method.

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Uematsu, Keizo. "Processing defects in ceramic powders and powder compacts." Advanced Powder Technology 25, no. 1 (January 2014): 154–62. http://dx.doi.org/10.1016/j.apt.2014.01.009.

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Zhou, Rui, Lian Hong Zhang, and Yu Hong Liu. "Investigation of Residual Stress in Green Compacts of Metal Powder Using X-Ray Diffraction." Advanced Materials Research 554-556 (July 2012): 461–64. http://dx.doi.org/10.4028/www.scientific.net/amr.554-556.461.

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Residual stresses in green compacts have a significant influence on the quality of the compact and post-compaction processes like part handling. In this study, the latest European and American standard for residual stress measurement by X-ray diffraction have been used to obtain more exact residual stresses in surface of green compacts as experimental evidence for simulation. The influence of kinds of powders, compacting pressure and friction on residual stresses in green compact has been studied.

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Xu, L., R. Helstroom, O. J. Scott, and A. J. Chambers. "Fracture characteristics of powder compacts." Powder Technology 83, no. 3 (June 1995): 193–99. http://dx.doi.org/10.1016/0032-5910(94)02958-q.

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CASTRO, DANIEL, TERRY A. RING, and JOHN S. HAGGERTY. "Drying of Silicon Powder Compacts." Advanced Ceramic Materials 3, no. 2 (March 1988): 162–66. http://dx.doi.org/10.1111/j.1551-2916.1988.tb00192.x.

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Khraisat, W., H. Borgström, L. Nyborg, and W. Abu al Jadayil. "Optimising grey iron powder compacts." Powder Metallurgy 52, no. 4 (December 2009): 291–97. http://dx.doi.org/10.1179/003258908x370168.

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Fahmy, Yusef, and Hans Conrad. "Electrosintering of iron powder compacts." Metallurgical and Materials Transactions A 32, no. 3 (March 2001): 811–19. http://dx.doi.org/10.1007/s11661-001-0097-7.

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Fahmy, Yusef, and Hans Conrad. "Electrosintering of iron powder compacts." Metallurgical and Materials Transactions A 32, no. 13 (March 2001): 811–19. http://dx.doi.org/10.1007/s11661-001-1016-7.

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Yanai, K., S. Ishimoto, T. Kubo, K. Ito, T. Ishikawa, and H. Hayashi. "Characterization of ceramic powder compacts." Journal of Nuclear Materials 224, no. 1 (July 1995): 79–84. http://dx.doi.org/10.1016/0022-3115(95)00034-8.

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Hirata, Yoshihiro, Ichiroh Haraguchi, and Yoshimi Ishihara. "Particle size effects on colloidal processing of oxide powders." Journal of Materials Research 7, no. 9 (September 1992): 2572–78. http://dx.doi.org/10.1557/jmr.1992.2572.

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Rheological behavior, properties of colloidal solids consolidated by filtration, and their structure change during drying were studied with aqueous suspensions of a mullite powder of nanometer size and two kinds of alumina powders of submicrometer sizes. The rheological properties of non-Newtonian flow suspensions were analyzed by a power law equation of S = K γn, where S is the shear stress, γ the shear rate, and K and n (O ⋚ n ⋚ 1) constants. The critical solids content (Vc) at n = O (indicating colloidal solids) depended greatly on the zeta potential of particles in suspensions, and dominated the densities of dried green compacts (Vg) of submicrometer sized powders. In a nanometer sized powder, the densities of dried green compacts were dependent on both Vc value and the solid contents of suspensions. Phase diagrams of one-component colloidal systems were constructed by plotting the Vc and Vg values against the zeta potential of particles. These phase diagrams indicate that the colloidal solids range (surrounded by Vc and a minimum Vg lines) is narrow for nanometer sized powder and wide for submicrometer sized powder. The solids content range of dried green compacts was very narrow for submicrometer sized powder but relatively wide for nanometer sized powder due to the low flexibility of colloidal structure during drying.

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de Vasconcelos, G., R. Cesar Maia, Carlos Alberto Alves Cairo, R. Riva, N. A. S. Rodrigues, and F. C. Mello. "Laser Sintering of Greens Compacts of MoSi₂." Materials Science Forum 530-531 (November 2006): 364–68. http://dx.doi.org/10.4028/www.scientific.net/msf.530-531.364.

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In this study, the results of the feasibility of sintering green compacts of metallic powder of MoSi2 by a CO2 laser beam as the heating source has been investigated. The main advantage of this technique is to promote a dense material in a reduced time when compared to the conventional sintering process. In order to sintering the MoSi2 powder, green compacts of 6mm of diameter and 1.6mm thickness were produced in a steel die in a uniaxial press at 100MPa and after, isostatic pressed at 350MPa. The micrograph of the samples exposed to the laser radiation performed by scanning electron microcopy (SEM) reveal the efficiency of the sintering process and the X-ray diffraction of the powders confirmed the presence of single phase after and before laser processing. The average microhardness of these compacts reached near to 700 Hv0.2 in the cross section to the laser irradiation, indicating the all sintering of the green compact.

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Hashemi, Seyed, Mohammed Ardestani, and Ali Nemati. "Cold compaction behavior and pressureless sinterability of ball milled WC and WC/Cu powders." Science of Sintering 48, no. 1 (2016): 71–79. http://dx.doi.org/10.2298/sos1601071h.

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In this research, cold compaction behavior and pressureless sinterability of WC, WC-10%wtCu and WC-30%wtCu powders were investigated. WC and WC/Cu powders were milled in a planetary ball mill for 20h. The milled powders were cold compacted at 100, 200, 300 and 400 MPa pressures. The compressibility behavior of the powders was evaluated using the Heckel, Panelli-Ambrosio and Ge models. The results showed that the Panelli-Ambrosio was the preferred equation for description the cold compaction behavior of the milled WC and WC-30%wtCu powders. Also, the most accurate model for describing the compressibility of WC-10%wtCu powders was the Heckel equation. The cold compacts were sintered at 1400?C. It was found that by increasing the cold compaction pressure of powder compacts before sintering, the sinterability of WC-30%wtCu powder compacts was enhanced. However, the cold compaction magnitude was not affected significantly on the sinterability of WC and WC-10%wtCu powders. The microstructural investigations of the sintered samples by Scanning Electron Microscopy (SEM) confirmed the presence of porosities at the interface of copper-tungsten carbide phases.

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Narayan, S., and A. Rajeshkannan. "Workability Behaviour of Powder Metallurgy Aluminium Composites." Journal of Powder Technology 2014 (July 1, 2014): 1–7. http://dx.doi.org/10.1155/2014/368721.

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An efficient way to find the workability limit for powder metallurgy parts has been suggested. Compacts of Al-4%TiC, Al-4%WC, Al-4%Fe3C, and Al-4%Mo2C were produced to the relative density of 0.82 and 0.86 with three different geometries through primary operations of powder metallurgy routes. Each sintered compact was hot deformed to various strain levels till a visible crack appeared at the free surface. Oyane’s fracture principle was used to develop a theory to study powder metallurgy compacts. A least square technique was used to determine the constants in fracture criteria and these equations were finally used to find workability limit. It is found that the projected technique was well in agreement with the experimental values.

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Taştan, Mehmet, Hayrettin Gökozan, Pınar Çavdar, Gürkan Soy, and Uğur Çavdar. "Cost analysis of T6 induction heat treatment for the aluminum-copper powder metal compacts." Science of Sintering 52, no. 1 (2020): 77–85. http://dx.doi.org/10.2298/sos2001077t.

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This work compares an energy cost and an energy consumption results of the 4 wt.% cupper mixed aluminum based powder metal (PM) compacts processing under induction or furnace heating. Total power and energy consumptions and total energy costs per kilogram and compact have been analyzed. T6 precipitation heat treatment applications have been applied with two different methods, one with 2.8 kW, 900 kHz ultra-high frequency induction heating system (UHFIHS), other with 2 kW chamber furnace. In the first method, Al-Cu PM compacts have been heated by induction at 580 ?C in one minute and then cooled down by water. Afterwards, the samples have been heated 170, 180, 190 and 200?C respectively for artificial ageing and cooled naturally. In the second treatment, unlike the first study, Al-Cu PM compacts are heated by chamber furnace at 540?C in 5 hours and cooled by water. Then PM compacts are artificially aged at 190?C in 10 hours with same furnace. During both processes, energy and power consumptions for each defined process have been measured. Optimum heat treatment of the induction is determined. The cheaper energy cost is obtained by the induction heat treatment.

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Gazawi, A., De Liang Zhang, K. L. Pickering, and Aamir Mukhtar. "Microstructure and Mechanical Behaviour of Ultrafine Grained Al-4wt%Cu-(2.5-10) Vol.% SiC Metal Matrix Composites Produced by Powder Compact Forging." Advanced Materials Research 275 (July 2011): 208–13. http://dx.doi.org/10.4028/www.scientific.net/amr.275.208.

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Ultrafine grained Al-4wt%Cu-(2.5-10) vol.% SiC metal matrix composite powders were produced from a mixture of Al, Cu and SiC powders using high energy mechanical milling (HEMM). The composite powders produced were first hot pressed at 300°C with a pressure of 240 MPa to produce cylindrical powder compacts with a relative density in the range of 80-94% which decreased with increasing the SiC volume fraction. Powder compact forging was utilized to consolidate the powder compacts into nearly fully dense forged disks. With increasing the volume fraction of SiC from 2.5% to 10%, the average microhardness of the forged disks increased from 73HV to 162HV. The fracture strength of the forged disks increased from 225 to 412 MPa with increasing the volume fraction of SiC particles from 2.5 to 10%. The Al-4wt%Cu-2.5vol.%SiC forged disk did not show any macroscopic plastic yielding, while the Al-4wt%Cu-(7.5 and 10)vol.% SiC forged disk showed macroscopic plastic yielding with a small plastic strain to fracture (~1%).

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Paranin, S., Victor Ivanov, Alexey Nikonov, A. Spirin, Vladimir Khrustov, S. Ivin, A. Kaygorodov, and P. Korolev. "Densification of Nano-Sized Alumina Powders under Radial Magnetic Pulsed Compaction." Advances in Science and Technology 45 (October 2006): 899–904. http://dx.doi.org/10.4028/www.scientific.net/ast.45.899.

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An influence of aggregation degree of alumina nanopowder and of radial magnetic pulsed compaction conditions on the powder densification and on the density distribution inside compacts has been investigated experimentally. The usage of radial magnetic pulsed compaction allows to compact alumina nanopowders up to high densities at low degree of aggregation. The compacts homogeneity is attained by appropriate compaction pulse duration and by the usage of powder packing prior to compaction until the condition with high local sound speed is achieved.

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Sato, Yoshimi, Naoyuki Nomura, S. Fujinuma, and Akihiko Chiba. "Microstructure and Mechanical Properties of Hot-Pressed Co-Cr-Mo Alloy Compacts." Advanced Materials Research 26-28 (October 2007): 769–72. http://dx.doi.org/10.4028/www.scientific.net/amr.26-28.769.

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The microstructure and mechanical properties of compacts produced from hot-pressing the Co-29Cr-6Mo alloy powder, fabricated by gas atomization, were investigated in this study. The average diameter of the alloy powder is 41 μm. Electron probe micro analysis revealed that the concentration scattering of chromium and molybdenum is relatively small between the powders. The compact hot-pressed at 1273 K in Ar with an applied pressure of 80 MPa possesses the relative density of 97% and the fine grain (2.7 μm). The ultimate tensile strength of the compact is 1240 MPa, which is comparable to that of the forged Co-29Cr-6Mo alloy.

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Eskandari, H., and R. Gholamipouri. "Properties of Nd-Fe-B Powder Explosively Compacted." Materials Science Forum 673 (January 2011): 237–42. http://dx.doi.org/10.4028/www.scientific.net/msf.673.237.

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Nd-Fe-B magnets are used in wide range of industrial applications. In this research we studied the possibility of producing bulk Nd-Fe-B magnetic compact by using the direct cylinder explosive compaction. After compaction the density of compact was measured by the Archimedes method. Highly dense compact (> 98% relative density) without cracks was obtained by this technique. A concentric hole was observed at center of some compacts. The magnetic properties of the compact are Br=7.95KG, iHc=10.5kOe, (BH)max= 14MOe, and these values are same as those before explosive compaction.

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Ismail, Roslina, and Iskandar Idris Yaacob. "Synthesis and Characterization of Nanocrystalline Ni₃Al Intermetallic via Mechanical Alloying and Reaction Synthesis." Key Engineering Materials 306-308 (March 2006): 1121–26. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.1121.

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Stoichiometric nanocrystalline Ni3Al was prepared by mechanical alloying of elemental Ni and Al powders under argon gas atmosphere for different time (4-48h). The nanostructured Ni3Al powders were consolidated into bulk compacts and sintered in a small DTA furnace under flowing Argon to observe the exothermic reaction between the stoichiometric Ni and Al. The estimated crystallite size showed that the mechanically alloyed Ni3Al grain size decrease from 127 nm to 9.36nm with increasing mechanical alloying time from 4h to 48h. Agglomerations of the powder particles prevalently occurred as observed from the SEM micrographs. Saturation magnetization, Ms value of the mechanically alloyed powders decreases as milling time increases due to smaller amount of elemental nickel responding to the applied fields. Following reaction synthesis of the compacted powders, thermal profile analysis revealed the presence of exothermic peaks in the DTA curves at about 400oC. Relative densities of the sintered compact were measured and found to be from 77- 88% with the exception for the 48h mechanically alloyed sintered compact from milling balls contaminations. XRD results of the sintered compacts mechanically alloyed for 18h and above revealed the formation of pure nanocrystalline Ni3Al. Crystallites size estimations showed the occurrence of grain growth during sintering.

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Çavdar, Uğur, Ayberk Altintaş, and Yetkin Sarigün. "Effect of Ekabor 2 powder on the mechanical properties of pure iron powder metal compacts." Revista de Metalurgia 52, no. 3 (September 30, 2016): e073. http://dx.doi.org/10.3989/revmetalm.073.

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Danninger, Herbert, Raquel de Oro Calderon, and Christian Gierl-Mayer. "Oxygen Transfer Reactions during Sintering of Ferrous Powder Compacts." Advanced Engineering Forum 27 (April 2018): 3–13. http://dx.doi.org/10.4028/www.scientific.net/aef.27.3.

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Powder metallurgy products may be started from powders with widely varying oxygen affinity. Thus the natural oxygen content of the powder compacts also varies in reducibility in the early stages of sintering. Here it is shown that prealloyed powders containing Cr require higher temperatures for oxygen removal than e.g. unalloyed or Ni-Cu alloyed grades. In case of powder mixes of base iron powder with Cr, Mn or Si, oxygen transfer from Fe to the additive powders may occur during heating up to sintering temperature, the “internal getter effect”. A similar effect can be observed in Cr prealloyed powders in which iron oxides initially present on the powder surfaces are transformed to more stable oxides in a fairly early stage of heating. Finally, also the formation of CH4observed when sintering alloy steels containing Si, Mn or Cr in H2can be attributed to an oxygen transfer effect.

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Dimčić, B., M. Vilotijević, D. Božić, D. Rajnović, and M. T. Jovanović. "Microstructural and Mechanical Properties of Ti₃Al-Based Intermetallics Produced by Powder Metallurgy." Materials Science Forum 494 (September 2005): 211–16. http://dx.doi.org/10.4028/www.scientific.net/msf.494.211.

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The structural and compression mechanical properties of Ti3Al-based intermetallics produced by powder metallurgy techniques have been studied. The as-milled powders were compacted by hot pressing to non-porous homogenous compacts. Prior to compression tests, all compacts were homogenized by a solution treatment at 1050°C (a+β region) for 1h, followed by water quenching. The compression tests were performed from room temperature to 500°C in vacuum at a strain rate of 1 3 10 4 . 2 − − × s . Detailed microstructural characterization was evaluated by scanning electron microscopy (SEM), followed by energy dispersive spectroscopy (EDS) and X-ray diffraction analysis.

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KO, SE-HYUN, WONSIK LEE, JIN MAN JANG, IL-HO KIM, and SEONG-GUN SHIN. "GRAPHITE REINFORCED Fe–Al–X COMPOSITES FOR SLIDE BEARING APPLICATIONS." Surface Review and Letters 17, no. 02 (April 2010): 241–44. http://dx.doi.org/10.1142/s0218625x10013990.

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The Fe–Al–X(Cu, Ni, Ti) composites reinforced with graphite particles were fabricated employing the powder metallurgy process for slide bearing applications. In all samples, graphite particles of 6 wt.% were added. Elemental powders were mixed to specific compositions with a powder lubricant, and then the mixed powders were compacted at 500 MPa. The green compacts were heated to 450°C to remove the lubricant and sintered at 1200°C for 1 h. The sintering was conducted in vacuum. The sintering of binary Fe–Al –graphite system showed low density and growth in dimension. Complex addition of Cu , Ni and Ti improved the sinterability of green compacts due to occurrence of partial liquid phases. Hardness of sintered samples strongly depended on dimensional change during sintering. The samples of high hardness showed better wear resistance properties.

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Blanco, B. Agea, C. Blaess, S. Reinsch, D. Brauer, and R. Müller. "Sintering and Foaming of Barium and Calcium Silicate Glass Powders." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2015, CICMT (September 1, 2015): 000031–37. http://dx.doi.org/10.4071/cicmt-ta21.

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Sintering and foaming of barium and calcium silicate glass powder compacts have been studied for different powder milling. Sintering was measured by means of heating microscopy backed up by XRD, DTA, Vacuum Hot Extraction (VHE) and electron microscopy. Foaming intensity strongly increased with decreasing glass particle size. Although powder compacts were uniaxially pressed and sintered in ambient air, foaming was affected by the milling atmosphere and most intensive for milling in CO2. Conformingly, VHE studies revealed that foaming of fully sintered samples was mainly driven by CO2, even for powders milled in technical air, Ar and N2. Prolonged storage of air milled barium silicate glass powders in ambient air before pressing and sintering caused further increase of foaming intensity. These findings indicate that carbonaceous species are preferentially trapped to or close beneath the powder surface during milling and later storage. The temperature range of CO2 degassing from fully sintered barium and calcium silicate glass powder compacts fits the temperature ranges of decomposition of BaCO3 and CaCO3 mix-milled with the respective barium and calcium silicate glass powders.

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Kim, Woo Chang, and Jong Kook Lee. "Effect of Powder Characteristics on Slip Casting Fabrication of Dental Zirconia Implants." Journal of Nanoscience and Nanotechnology 20, no. 9 (September 1, 2020): 5385–89. http://dx.doi.org/10.1166/jnn.2020.17610.

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Dense zirconia compacts were fabricated by slip casting and sintering of nanoscale zirconia powders, and the effect of the powder characteristics (crystallite size, specific surface area, yttria content, and agglomeration) on the slurry and sintered properties was investigated. Three types of commercial 3 mol% yttria-stabilized tetragonal zirconia polycrystals powders were used as the starting powders after the powder characteristic analysis. A zirconia slurry for slip casting was prepared by mixing zirconia powder (solid loading of 60, 65, and 70 wt.%), distilled water, and a dispersant of Darvan C. The green compacts obtained from slip casting were cold isostatic pressed to enhance the close packing and densified by sintering at 1450 °C for 2 h. Highly dense zirconia compacts with a relative density of 99.5% and grain size of 350 nm were obtained based on the powder type and solid loading in the slurry. The microstructure and mechanical hardness of the sintered specimen after slip casting were dependent on the yttria content in the 3 mol% yttria-stabilized tetragonal zirconia polycrystal powder and the solid loading within the slurry.

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Journal articles on the topic 'Powder compacts'

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