Journal articles: 'Metal defects'

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CONRAD, EDWARD H. "THE STABILITY OF LOW INDEX METAL SURFACES TO TOPOLOGICAL DEFECTS." International Journal of Modern Physics B 05, no. 03 (February 10, 1991): 427–59. http://dx.doi.org/10.1142/s0217979291000274.

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The study of defect formation at metal surfaces is a fundamental problem in surface physics. An understanding of defect formation is pertinent to growth and diffusion mechanisms. In addition, surface roughening, faceting, and surface melting are all defect mediated phase transitions involving the formation of different topological defects. While the importance of defects at surfaces is well recognized, the study of surface defects has been hampered by the lack of sufficiently accurate experimental techniques. In fact, it is only in the past 6 years that experiments on the thermal generation of defects on metal surfaces have been performed. This review attempts to outline both the theoretical and experimental work on surface defect formation on metal systems.

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Nagata, Shoichiro, Takemi Sakamoto, and Masato Enokizono. "Quantitative Defect Detection inside Metal Casting Specimens by Means of MFES." Materials Science Forum 792 (August 2014): 104–9. http://dx.doi.org/10.4028/www.scientific.net/msf.792.104.

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An NDE measurement for internal defects of metal casting products is presented. The internal defects are often made in the manufacturing process of metal casting. From the view point of non-destructive evaluation (NDE), it is very difficult to make artificial defects that simulate actual internal defects. Therefore, we prepared a lot of metal casting samples that may include defects, and investigated the relation between the defect dimensions and the spectrogram that were generated by Multi-Frequency Excitation and Spectrogram Method (MFES).

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Horichok, Ihor, Myroslava Shevchuk, Taras Parashchuk, and Mar’jan Galushchak. "INTRINSIC POINT DEFECTS OF SAMARIUM MONOSULPHIDE CRYSTALS IN METAL PHASE." Chemistry & Chemical Technology 11, no. 3 (August 28, 2017): 319–26. http://dx.doi.org/10.23939/chcht11.03.319.

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Sika, Robert, Michał Rogalewicz, Paweł Popielarski, Dorota Czarnecka-Komorowska, Damian Przestacki, Katarzyna Gawdzińska, and Paweł Szymański. "Decision Support System in the Field of Defects Assessment in the Metal Matrix Composites Castings." Materials 13, no. 16 (August 12, 2020): 3552. http://dx.doi.org/10.3390/ma13163552.

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This paper presented a new approach to decision making support of defects assessment in metal matrix composites (MMC). It is a continuation of the authors’ papers in terms of a uniform method of casting defects assessment. The idea of this paper was to design an open-access application (follow-up system called Open Atlas of Casting Defects (OACD)) in the area of industry and science. This a new solution makes it possible to quickly identify defect types considering the new classification of casting defects. This classification complements a classical approach by adding a casting defect group called structure defects, which is especially important for metal matrix composites. In the paper, an application structure, and the possibility of its use in casting defects assessment were introduced.

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Luo, Yun, Chuanlong Wang, Wenchun Jiang, Yu Wan, Weiya Zhang, and Yu Wang. "Effects of Inner Defects on Creep Damage and Crack Initiation for a Brazed Joint." High Temperature Materials and Processes 37, no. 9-10 (October 25, 2018): 863–72. http://dx.doi.org/10.1515/htmp-2017-0098.

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AbstractIn the brazing process, some brazing defects like semicircular or straight type are generated due to incomplete filling. In this paper, the creep damage and creep crack initiation (CCI) time of Hastelloy C276-BNi2 brazed joint with defects are investigated by a ductility exhaustion damage model. The effects of defect dimension and filler metal thickness are also discussed. The results show that the different defects have different creep damage distributions and CCI times. The maximum creep damage is located at the defect frontier due to the larger stress concentration. With the increase of semicircular defect radius and straight defect length, the CCI time decreases. The creep fracture is inclined to generate in semicircular defect for the smaller defect area ratio, while it is easy to generate in straight defect for the bigger defect area ratio. As the filler metal thickness increases, the CCI time increases. For the thicker filler metal, the creep crack is easy to initiate in semicircular defect.

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Shan, Ning, Xia Liu, and Yong Zhong Ma. "Experiment Research on an Optical Fiber F-p Ultrasound Sensor for Detecting Internal Defects of Metal Materials." Advanced Materials Research 549 (July 2012): 593–96. http://dx.doi.org/10.4028/www.scientific.net/amr.549.593.

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Metal materials have been used in aero industry widely because of its excellent characteristics. So its internal defects are very important. Ultrasound detection technology for detecting metal materials internal defects is related to piezoelectric ultrasonic sensor. This has a few of disadvantages. So the double wavelength optical fiber F-P ultrasound sensing system is designed in this paper. The ultrasound detecting experiment devices for internal defects of metal materials is established based on the optical fiber F-P sensing system. Experimental research of detecting the internal defects is developed. The experimental results show this sensor can detect the ultrasound signals effectively. And it’s proved that this method can be effective used in the internal defect of metal materials.

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Sheu, Ruey-Kai, Lun-Chi Chen, Mayuresh Sunil Pardeshi, Kai-Chih Pai, and Chia-Yu Chen. "AI Landing for Sheet Metal-Based Drawer Box Defect Detection Using Deep Learning (ALDB-DL)." Processes 9, no. 5 (April 27, 2021): 768. http://dx.doi.org/10.3390/pr9050768.

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Sheet metal-based products serve as a major portion of the furniture market and maintain higher quality standards by being competitive. During industrial processes, while converting a sheet metal to an end product, new defects are observed and thus need to be identified carefully. Recent studies have shown scratches, bumps, and pollution/dust are identified, but orange peel defects present overall a new challenge. So our model identifies scratches, bumps, and dust by using computer vision algorithms, whereas orange peel defect detection with deep learning have a better performance. The goal of this paper was to resolve artificial intelligence (AI) as an AI landing challenge faced in identifying various kinds of sheet metal-based product defects by ALDB-DL process automation. Therefore, our system model consists of multiple cameras from two different angles to capture the defects of the sheet metal-based drawer box. The aim of this paper was to solve multiple defects detection as design and implementation of Industrial process integration with AI by Automated Optical Inspection (AOI) for sheet metal-based drawer box defect detection, stated as AI Landing for sheet metal-based Drawer Box defect detection using Deep Learning (ALDB-DL). Therefore, the scope was given as achieving higher accuracy using multi-camera-based image feature extraction using computer vision and deep learning algorithm for defect classification in AOI. We used SHapley Additive exPlanations (SHAP) values for pre-processing, LeNet with a (1 × 1) convolution filter, and a Global Average Pooling (GAP) Convolutional Neural Network (CNN) algorithm to achieve the best results. It has applications for sheet metal-based product industries with improvised quality control for edge and surface detection. The results were competitive as the precision, recall, and area under the curve were 1.00, 0.99, and 0.98, respectively. Successively, the discussion section presents a detailed insight view about the industrial functioning with ALDB-DL experience sharing.

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Martinez, L. M., M. D. Teran, R. R. Chianelli, S. R. J. Hennadige, and S. R. Singamaneni. "Magnetic Defects in Transitional Metal Di-Chalcogenide Semiconducting Layers." MRS Advances 3, no. 6-7 (2018): 351–57. http://dx.doi.org/10.1557/adv.2018.110.

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ABSTRACTIn this work, we report on the electron spin resonance (ESR) studies performed on few-layered nanocrystalline (NCs) MoS2, WS2, and TiS2 prepared using hydrothermal and vapor transport methods. From the temperature dependent ESR spectra collected from MoS2 NCs, we have identified adsorbed oxygen species, sulphur vacancies, thio- and oxo-Mo5+ related paramagnetic defect centers. WS2 NCs have exhibited W+3 and oxo-W+5 paramagnetic defect spin species. TiS2 NCs showed defects such as Fe3+ (unwanted), oxygen and sulfur vacancies. This work demonstrates the usage of spin-sensitive spectroscopy such as ESR in unravelling the defects which contain unpaired electron spin centers in layered NCs two-dimensional materials.

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Drożdż, Monika, Bartek Wierzba, and Zbigniew Grzesik. "Concentration of Point Defects in Metal Deficient Zn1-yO." High Temperature Materials and Processes 37, no. 1 (January 26, 2018): 17–23. http://dx.doi.org/10.1515/htmp-2016-0256.

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AbstractIn this paper the doping effect has been used to indirectly calculate point defect concentration in metal-deficient Zn1-yO zinc oxide. The proposed method consists of determining the concentration of prevailing point defects in the studied oxide from the influence of chromium addition on the point defect situation in doped zinc oxide. It has been found that chromium addition into the crystal lattice of zinc oxide changes its ionic disorder, enabling calculation of predominant point defects in Zn1-yO. The concentration of predominant point defects in Zn1-yO is the following function of oxygen pressure and temperature: $$\eqalign{\left[{\,{{\rm V''}_{\rm Zn}}\,} \right]\, &= \,{1 \over 2}\left[{\,{\rm h^ \bullet}\,} \right]\, = \,0.63 \cdot \,\rm p_{{O_2}}^{1/6}\, \cdot {K^{1/3}}\,_{}^{}\, \cr& = \,\,5.6 \cdot {10^{- 3}} \cdot \,\rm p_{{O_2}}^{1/6}\, \cdot \exp \left({- {{27\,kJ/mol} \over {RT}}} \right)\cdot}$$

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Liu, Zixi, Zhengliang Hu, Longxiang Wang, Tianshi Zhou, Jintao Chen, Zhenyu Zhu, Hao Sui, Hongna Zhu, and Guangming Li. "Effective detection of metal surface defects based on double-line laser ultrasonic with convolutional neural networks." Modern Physics Letters B 35, no. 15 (April 15, 2021): 2150263. http://dx.doi.org/10.1142/s0217984921502638.

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The time–frequency analysis by smooth Pseudo-Wigner-Ville distribution (SPWVD) is utilized for the double-line laser ultrasonic signal processing, and the effective detection of the metal surface defect is achieved. The double-line source laser is adopted for achieving more defects information. The simulation model by using finite element method is established in a steel plate with three typical metal surface defects (i.e. crack, air hole and surface scratch) in detail. Besides, in order to improve the time resolution and frequency resolution of the signal, the SPWVD method is mainly used. In addition, the deep learning defect classification model based on VGG convolutional neural network (CNN) is set up, also, the data enhancement method is adopted to extend training data and improve the defects detection properties. The results show that, for different types of metal surface defects with sub-millimeter size, the classification accuracy of crack, air holes and scratch surface are 94.6%, 94% and 94.6%, respectively. The SPWVD and CNN algorithm for processing the laser ultrasonic signal and defects classification supplies a useful way to get the defect information, which is helpful for the ultrasonic signal processing and material evaluation.

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Han, Bao An, Hui Yu Xiang, Zhe Li, and Jia Jun Huang. "Defects Detection of Sheet Metal Parts Based on HALCON and Region Morphology." Applied Mechanics and Materials 365-366 (August 2013): 729–32. http://dx.doi.org/10.4028/www.scientific.net/amm.365-366.729.

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In order to realize the manufacturing defects detection of sheet metal parts, a kind of defects detection method of the sheet metal parts based on region morphology has been put forward based on HALCON using the mathematical morphology knowledge: by choosing the proper structuring element and neatly applying dilation, erosion, opening and closing on the defects images, the defect part is extracted. The experiment shows that the effect of this method is good and the calculation and processing speed is fast.

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12

Dieckmann, Rüdiger. "Point Defects and Diffusion in Nonstoichiometric Metal Oxides." MRS Bulletin 16, no. 12 (December 1991): 27–32. http://dx.doi.org/10.1557/s0883769400055317.

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This article briefly reviews the relationships between point defects and ion diffusion in nonstoichiometric ionic crystals, with special emphasis on cubic oxides. It focuses on crystalline materials with negligibly small concentrations of nonequilibrium defects such as dislocations and grain boundaries. First, the concepts used to analyze the point defect structure and the diffusion of ions in nonstoichiometric crystals will be discussed. Then, specific oxides will be considered as examples. These oxides are manganosite, Mn1−ΔO, and spinels of the type Me3−δO4 with Fe and Mn cations, respectively.

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Kang, Kwan, Trinh Tien, Myung Lee, Kwon-Yong Lee, Bongju Kim, and Dohyung Lim. "Suitability of Metal Block Augmentation for Large Uncontained Bone Defect in Revision Total Knee Arthroplasty (TKA)." Journal of Clinical Medicine 8, no. 3 (March 19, 2019): 384. http://dx.doi.org/10.3390/jcm8030384.

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This study was performed to determine whether metal block augmentation is suitable for large uncontained bone defect via evaluations of differences in biomechanical characteristics among the configurations of metal block augmentations for medium or large uncontained bone defects in revision total knee arthroplasty (TKA). Three-dimensional finite element (FE) models of the proximal tibia with revision TKA were developed and analyzed considering the configurations of the metal block augmentations for medium and large uncontained bone defects. To identify differences in biomechanical characteristics according to the configurations of metal block augmentations, the stress transfer, strain distribution, and peak von Mises stresses (PVMSs) were assessed. Large and medium uncontained bone defects had similar ranges of strain below the critical bone-damage strain for the metal block augmentations, but the strain distribution characteristics differed in response to the metal block-augmentation configurations. PVMSs exceeding the yield strength of the bone cement for the single metal block-augmentation configurations were, on average, 1.4 times higher than those for double metal block-augmentation configurations for both medium and large uncontained bone defects. These findings suggest that metal block augmentation may be suitable for large uncontained bone defects (≤20 mm), compared with the results obtained for metal block augmentation used in medium uncontained bone defects (≤10 mm). If possible, double metal block augmentation is recommended for both medium and large uncontained bone defects rather than single metal block augmentation. It is also recommended that the metal block augmentation should be customized to meet the contact characteristics with the cortical bone, thereby ensuring better stress transfer and reducing the risk of the bone resorption due to stress shielding and bone-cement failure.

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Cliffe, Matthew, Wei Wan, Xiaodong Zou, François-Xavier Coudert, and Andrew Goodwin. "Correlated defects in group 4 metal-organic frameworks." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1124. http://dx.doi.org/10.1107/s2053273314088755.

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The importance of defects for inorganic functional framework materials is well established, being crucial for properties from relaxor ferroelectricity to superconductivity. The corresponding study of defects in metal-organic frameworks (MOFs) is still however in its infancy. Recent studies have established that ligand-absence defects can be controllably introduced into frameworks and that these defects can drastically improve the material properties, but have so far shown no evidence of correlation between defects. Much of this research has focussed on UiO-66, a zirconium dicarboxylate MOF that was amongst the first very stable MOFs to be discovered.[1] As a result of its stability, it and its derivatives have been investigated for a wide range of properties including photo- and Brønsted acid catalysis, sensing and gas sorption properties. The ability to introduce defects has been demonstrated to substantially enhance both the sorption and catalytic properties of UiO-66.[2][3] We have demonstrated, using a combination of powder X-ray diffraction, total scattering and electron diffraction measurements, that UiO-66 can be engineered, under the appropriate synthetic conditions, to accommodate correlated defect nanodomains. These correlations offer exciting opportunities for manipulating the physical properties, including mass transport, chemical activity and mechanical flexibility.

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Zhao, Chao Fan, and Zhao Xia Li. "Influence of Geometrical Features of Meso-Defects on Damage Evolution of Metal Structure." Applied Mechanics and Materials 723 (January 2015): 21–25. http://dx.doi.org/10.4028/www.scientific.net/amm.723.21.

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To study the failure process of metal structure with meso-defects, RVE (representative volume element) with various initial meso-defects were analyzed by using ABAQUS software, the parameter f (void volume fraction) of GTN damage model was regarded as the criterion of structural damage. The result shows that f increased more obvious with volume of defects for spherical defects with the same shape but different size. When the radius of defects is less than 0.15mm, the influence of defects’ volume on increases of f is clear enough. When the radius is greater than 0.15mm, the effects is diminishing. For ellipsoidal defects with the same volume but different aspect ratio, when the long axis perpendicular to the direction of load, the increased trend of f according to plastic deformation more obvious along with aspect ratio of defects. Apparently, as aspect ratio approaches infinity, f would have the fastest growth. Consequently, the bigger defect volume and aspect ratio, the more conducive for damage evolution of the metal structure.

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Li, Mingzhi, Bin Wu, Xiucheng Liu, and Cunfu He. "Highly non-linear solitary wave imaging method for detecting cylindrical defects in the metal plate of an adhesive composite metal structure." Insight - Non-Destructive Testing and Condition Monitoring 62, no. 6 (June 1, 2020): 331–37. http://dx.doi.org/10.1784/insi.2020.62.6.331.

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In this paper, a non-destructive testing (NDT) method based on highly non-linear solitary waves (HNSWs) was employed to detect defects in the metal plate of an adhesive composite metal structure. Firstly, HNSWs were generated by applying impulses to a one-dimensional granular chain of steel spheres. Proof-of-concept finite element (FE) simulations were then performed using Abaqus software to investigate the reflection behaviour of HNSWs at the interface of the chain and the two-layer material with defects. The time-of-flight (TOF) of primary reflected solitary waves (PSWs) was confirmed as a good indicator for defect localisation and sizing. A HNSW generator and detector device was used in the experiment and HNSW B-scan and C-scan inspections of adhesive composite steel specimens were achieved. The TOF imaging results accurately indicated the locations of cylindrical defects in the bottom steel block. The linear correlation between the peak value of the pulsed TOF profile and the defect diameter was determined. The contours of TOF with different values were introduced to reconstruct the shape of the circular defective region. Through selecting the correct threshold of TOF, the relative error of the area surrounded by the contour compared to the actual area of the five investigated defects could be less than 6.5%.

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Widyawati, Fauzi, and Lino Marano. "IDENTIFIKASI CACAT LASAN FCAW PADA FONDASI MESIN KAPAL MENGGUNAKAN METODE ULTRASONIC TESTING." Jurnal TAMBORA 5, no. 2 (July 21, 2021): 53–58. http://dx.doi.org/10.36761/jt.v5i2.1124.

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Ultrasonic testing is one of the non-destructive inspection methods for welding results. The ultrasonic testing method has several advantages, namely it can be used to analyze the position of the defect in the object, both the depth of the defect and the dimensions of the defect, and it is an environmentally friendly method. Physical defects that are in solid objects of course cannot be known from direct vision so it is necessary to carry out an inspection of an object to see whether or not there are defects that occur in solid objects. Ultrasonic testing of the results of FCAW welding on the foundation of the ship's engine. FCAW welding is applied to the foundation with two types of welding positions, namely the overhead position coded P1 and the horizontal position coded P2. The test was carried out using a wave frequency of 4 MHz and using a 0° probe for analysis of defects in the area around the weld metal and a 70° probe for analysis of the weld metal. The tests were carried out using the ASME section V and ASTM E164 standards as the standard for determining defects. The test results at the P1 welding position found two types of defects, namely incomplete fusion defects with five welding points with the longest defect length of 40mm and porosity defects with two points with the longest defect length of 30mm. While the results of ultrasonic testing at the P2 welding position found two types of defects, namely slag inclusion defects with a defect length of 35mm and incomplete penetration defects with a defect length of 20 mm. The conclusion of ultrasonic testing is that the difference in welding positions is that the welding position greatly affects the quality of the welding results. The defects resulting from the welding position also vary.

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Nagata, Shoichiro, Hisafumi Kai, and Masato Enokizono. "Non-Destructive Evaluation for Internal Defect of Metal Casting." Materials Science Forum 670 (December 2010): 151–57. http://dx.doi.org/10.4028/www.scientific.net/msf.670.151.

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An NDE measurement for internal defects of metal casting products is presented. An experimental system for ECT is developed in order to inspect internal defects of brass casting which have complicated and inaccurate shapes. In the measurement, artificial defect specimen made for fundamental experiments and brass casting specimens are evaluated by multi-frequency excitation and spectrogram (MFES) method. From the results, validity of our measurement system is discussed.

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Malyuskin, Oleksandr. "Ultra-Resonance Microwave Defectoscopy of Metal Surfaces." Proceedings 42, no. 1 (November 14, 2019): 22. http://dx.doi.org/10.3390/ecsa-6-06551.

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A novel microwave high-resolution near-field non-destructive testing technique is proposed and experimentally evaluated in reflectometry imaging scenarios involving planar metal surfaces. Traditionally, microwave reflectometry does not provide high dynamic contrast between the defect and background material in the case of metal structures due to intrinsically high reflection magnitude from the metal surfaces masking defect a microwave signature. A high-Q resonant sensor based on the loaded aperture is designed to interact very strongly even with small defects on the metal surface providing very high two-dimensional spatial resolution of approximately one tenth of a wavelength, λ, at λ/20–λ/10 standoff distance. Experimental results demonstrate a defect-to-background contrast greater than 5 dB amplitude and 50° phase in raw microwave data. To further enhance the spatial resolution and defect contrast, a phase-modulated near field imaging technique is proposed and experimentally evaluated in the case of a defected metal plate. This technique is based on fast variation of the reflection phase in the narrow frequency band around the resonance, which essentially enables elimination of background a microwave signature from the reflected signal. The proposed imaging technique should find applications in non-destructive surface testing and evaluation of metal and alloy structures.

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Wu, Guo, Keyna O'Reilly, and Marina Galano. "Characterization of Casting Defects in Aluminium Alloys." Advanced Materials Research 430-432 (January 2012): 984–87. http://dx.doi.org/10.4028/www.scientific.net/amr.430-432.984.

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In this paper, typical defects in aluminium alloys cast by conventional pouring of liquid metal into a cylindrical alumina crucible and an induction melting process are characterized by using macroetching, optical microscopy and scanning electron microscopy. Oxide film defects are generated in both processing methods. Oxide films formed during casting are a major type of defect observed in the microstructures of aluminium alloys products. It has been found that pouring of molten metal into a mould and induction stirring lead to different forms of oxide defects. Under induction stirring, such low-density entrained defects are found to be carried to near the surface of the liquid aluminium alloys and submerged surface oxide films become entangled.

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Bolotina, Irina O., and Victoria A. Portenko. "Review of Defect Types in Metal Mold Castings." Key Engineering Materials 769 (April 2018): 269–74. http://dx.doi.org/10.4028/www.scientific.net/kem.769.269.

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Evtushenko, Sergej, and Timofey Krakhmalnyy. "DEFECTS AND DAMAGES OF METAL COLUMNS OF INDUSTRIAL BUILDINGS." Construction and Architecture 9, no. 2 (June 2, 2021): 11–15. http://dx.doi.org/10.29039/2308-0191-2021-9-2-11-15.

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This article is a continuation of the series of articles by the authors about the characteristic defects and damage to the building structures of industrial buildings. In earlier articles, there were descriptions of defects in ground foundations, damage to foundations, as well as arti-cles about damage to reinforced concrete columns and facades. The article presents a sys-tematization of defects and damage to metal columns of industrial buildings, based on the analysis of the results of the survey of many objects. The possible consequences of the de-velopment of the identified defects and damages are described. Recommendations for the assessment of the technical condition of damaged structures and recommendations for the elimination of identified defects and damage are given. The unique damages associated with the operation of lifting and transport equipment, road and rail transport are also given. The article concludes with an analysis of the characteristic zones of defect formation in the met-al columns of buildings for the created automated system for monitoring the state of indus-trial facilities.

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Tereshchenko, A. V., and I. A. Kovaleva. "Establishing the true causes of defects to ensure the quality of continuously cast billets and hot‑rolled products at all stages of the process chain at OJSC “BSW – Management Company of the Holding “BMC”." Litiyo i Metallurgiya (FOUNDRY PRODUCTION AND METALLURGY), no. 3 (September 10, 2021): 35–39. http://dx.doi.org/10.21122/1683-6065-2021-3-35-39.

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Establishing the true causes of defects is one of the main prerequisites for improving the quality of metal products. One of the undesirable phenomena in the production of continuously cast billets, hot‑rolled products is the oxidation of hot metal in the environment with the formation of scale on its surface. Defects, which are violations of the continuity of the metal and deviations from the normal specified macro‑and microstructure, signifi antly reduce the technological plasticity of the metal in the conditions of its processing and operational stability.After hot rolling of a circle of 95 mm steel grade 30MpV4, surface defects were found in the finishing line. To study and establish the nature of surface defects from hot‑rolled blanks, as well as continuously cast blanks, samples were taken.Analyzing metallographic studies of defects and the production technology of the studied steel grade 30MnB4, it was found that the defects were formed as a result of mechanical damage to the continuously cast billet in the area of the pulling‑correct unit. The reason for the formation of the defect is the ingress of scale on the guide rollers.

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Selezneva, Liudmila V., and Andrei V. Nazarov. "The Effect of Point Defects Interaction on Hydrogen Atom Diffusion in FCC- and BCC-Metals." Defect and Diffusion Forum 277 (April 2008): 133–38. http://dx.doi.org/10.4028/www.scientific.net/ddf.277.133.

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This work is devoted to simulation of potential barrier spectrum for hydrogen atom and vacancy jumps in fcc- and bcc- metals taking into account the mutual effect of the point defects on the potential barrier spectrum and as a result the effect on complex defect diffusion in bcc- and fccmetals. The molecular static and the Monte Carlo methods are used. The developed model allows us to determine a diffusion coefficient of the impurity atom depending on temperature and other parameters. The simulation of point defect random walk in lattice on the basis MC-method and potential barrier spectrum has gave an impulse toward an understanding of hydrogen motion on the atomic scale in metals, which is required to determine such important parameters as the diffusion coefficient of H. As well it allows us to understand reasons of more complicated behaviour of H in realistic metal in comparison with perfect metal.

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Dubinets, Aleksandr, Evgeny Vladislavovich Pustovalov, Evgeny B. Modin, Aleksandr N. Fedorets, and Vladimir Plotnikov. "Using Methods of Multi Scale Modeling for Investigation of Sample Defects." Advanced Materials Research 1088 (February 2015): 814–18. http://dx.doi.org/10.4028/www.scientific.net/amr.1088.814.

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In this paper we consider using multi scale modeling methods for reproduce structural and composite defects of amorphous metal alloys for quality improvement to improve process of getting information from experimental electron microscopic images. We used amorphous metal alloys with known structural defects as a studying objects. Also for this objects were generated models, which were designed for simulating real defects. For final model there was calculated the electron microscope images, which then was compared to the experimentally obtained one, after that were made conclusions about similarity of the real defect and the modeled one.

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Tang, Qing Ju. "Numerical Simulation of Infrared Nondestructive Testing to Metal Sample with Subsurface Defects." Advanced Materials Research 179-180 (January 2011): 1075–79. http://dx.doi.org/10.4028/www.scientific.net/amr.179-180.1075.

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The transient heat transfer equation of the sample with defects is built. Numerical simulation of PT(Pulsed Thermography, ‘PT’) testing is done against C30Steel sample with hole defects via finite element method. Results show that, both the maximum value of the surface temperature and the time of the appearance of the inflection points change with the change of the defect diameter and depth. The surface temperature curves can be used for quantitative study of the defect characteristics.

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Zhu, Yunmin, Xi Liu, Shiguang Jin, Huijun Chen, Wonyoung Lee, Meilin Liu, and Yan Chen. "Anionic defect engineering of transition metal oxides for oxygen reduction and evolution reactions." Journal of Materials Chemistry A 7, no. 11 (2019): 5875–97. http://dx.doi.org/10.1039/c8ta12477a.

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Nowick, Arthur S. "Defects in Ceramic Oxides." MRS Bulletin 16, no. 11 (November 1991): 38–41. http://dx.doi.org/10.1557/s0883769400055500.

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The topic that I am attempting to cover easily requires a whole book to do it justice. To deal with it in a short article, I will focus on a few basic principles that dominate the behavior of defects in oxides and then present some examples taken from well-studied and relatively well-understood materials.The study of defects in oxides differs from the study of defects in metals and alloys or in semiconductors in several important ways. First, oxides generally have very high melting points so that intrinsic point defect concentrations at temperatures below ~1500°C are usually negligibly small. Second, an oxide does not always maintain the composition at which it was fabricated, as alloys do, but can exchange oxygen with the ambient atmosphere, according to the ambient partial pressure of oxygen, P(O2). Thus, the stoichiometry, and accordingly the defect concentration, can be controlled by annealing in a specific P(O2) atmosphere. Third, and most important, oxides have a high degree of ionicity so that most point defects possess an effective charge. The consequences of this fact are far reaching; some of them are as follows:1. In a binary oxide, e.g. a metal oxide (MO), there are two sublattices. The diffusion of cations and of anions proceeds each on its own sublattice, involving different point defects. Accordingly, cation and anion diffusion rates can be very different and, in fact, usually are.

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Canivet, J., M. Vandichel, and D. Farrusseng. "Origin of highly active metal–organic framework catalysts: defects? Defects!" Dalton Transactions 45, no. 10 (2016): 4090–99. http://dx.doi.org/10.1039/c5dt03522h.

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Seidman, David, and Donglu Shi. "Point Defects in Materials Part II: Applications to Different Materials Problems." MRS Bulletin 16, no. 12 (December 1991): 18–21. http://dx.doi.org/10.1557/s0883769400055299.

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This issue of the MRS Bulletin follows up on the November issue's five articles on point defect phenomena in a wide range of materials with five more articles on point defects. The present articles emphasize the behavior of different phenomena in various materials—nonstoichiometric metal oxides, intermetallic compounds, type II superconductors and semiconductors—in terms of fundamental properties of point defects. Again, point defects is the unifying theme but the emphasis shifts to material behavior.This issue begins with Marshall Stoneham's article on the roles theory plays in predicting and understanding material behavior in terms of point defects in the different classes of materials. The following article by Rüdiger Dieckmann discusses the relationships between point defect concentrations in nonstoichiometric metal oxides and diffusion, i.e., mass transport. Next, Georges Martin and Pascal Bellon review their new approach for analyzing the role played by antisite defects in nonequilibrium phase transitions in intermetallic compounds. Then, Donglu Shi focuses on the effect of point, line, and planar defects on three major properties of type II superconductors—the critical transition temperature, the upper critical magnetic field, and the critical current density. Finally, Lionel Kimerling shows how defect engineering is used to achieve a high degree of complexity in product fabrication and greater sophistication in product performance; he illustrates what he means by defect engineering with examples from basic processes used in electronic materials processing.

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Zhang, Si Quan, Yu Liu, Hao Jun Xu, and Chang Yin. "Eddy Current Testing Probe to Improve the Defect Detection Sensitivity of Metal Tube." Advanced Materials Research 945-949 (June 2014): 1987–90. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.1987.

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The structure of conventional bobbin probe was modified to improve the detection sensitivity of defects in metal tube. Based on the results of finite element simulation, several types of modified probes are fabricated and used to detect artificial defects in tube and the defect signals are acquired and analyzed. The simulation and experimental results verified that the modified eddy current probes are more sensitive to non-axial defects than conventional bobbin probe and can improve the reliability of tube inspection.

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Liu, Dayong, and Guifa Teng. "Partial Discharge Detection and Discharge Type Identification of Gas Insulated Switchgear Based on Photoelectric Detection." Journal of Nanoelectronics and Optoelectronics 14, no. 11 (November 1, 2019): 1625–33. http://dx.doi.org/10.1166/jno.2019.2678.

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Gas insulated switchgear (GIS) is a relatively common high-voltage substation equipment. Due to the internal complex structure and integrated switch, it is easy to cause insulation defects, burrs and partial discharge of metal particles, thereby reducing the insulation of equipment performance, which has attracted the attention of many researchers. In this study, aiming at the problem of partial discharge in GIS, a detection device of partial discharge based on photomultiplier instrument is proposed. In this device, Zemax software is used to simulate a front-end optical signal receiving module that enhances the photosensitive surface and enhances the optical signal aggregation effect. In terms of signal processing, the output voltage signal of the photomultiplier instrument is filtered, and the corresponding signal is extracted for amplification. The partial discharge detecting device designed in the experiment is used to judge the internal insulation defects of the GIS, and to discriminate the metal protrusion defects, the metal particle defects on the insulator surface, the free metal particle defects, and the air gap defects between the insulator and the high voltage conductor, respectively. The partial discharge signal ϕ-u-v spectra of different defect models are constructed. Through the image simulation of partial discharge signals corresponding to defects, it is verified that the detection device can distinguish the partial discharge caused by different defects, which is helpful to prevent the occurrence of malignant discharge accidents and maintain the stable operation of GIS equipment.

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El Kamel, F. "Electrical active defects in HfO2based metal/oxide/metal devices." Journal of Physics D: Applied Physics 49, no. 1 (November 25, 2015): 015306. http://dx.doi.org/10.1088/0022-3727/49/1/015306.

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Xie, Ruidong, Dichen Li, Bin Cui, Lianzhong Zhang, and Feng Gao. "A defects detection method based on infrared scanning in laser metal deposition process." Rapid Prototyping Journal 24, no. 6 (August 13, 2018): 945–54. http://dx.doi.org/10.1108/rpj-04-2017-0053.

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Purpose Laser metal deposition (LMD) is an important additive manufacturing (AM) technology, but the metallurgical defects, such as cracks and porosities, produced in LMD process will seriously affect the mechanical properties of the parts. The purpose of this paper is to propose a novel in-process defects detection method based on infrared scanning for LMD. Design/methodology/approach The defects detection principle is that, after every three to five layers have been deposited, the optical head of a high-precision infrared two-color pyrometer is driven to scan the defects by measuring the abnormal temperature peaks on the deposited surface. The experiments for verifying the defects detection principle were carried out. Findings The relationship between the temperature peak value and the dimensions of the defect was analyzed based on the heat conduction theory and curves of temperature peak value versus crack width or diameter of porosity. Originality/value This method can effectively improve the detection accuracy and the defects can be precisely located, which can meet the requirement of laser targeting re-melting and elimination of the defects.

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Zhou, Wei, Jianchun Fan, Xiangyuan Liu, and Shujie Liu. "Quantitative research of defects for pipelines based on metal magnetic memory testing." Insight - Non-Destructive Testing and Condition Monitoring 62, no. 5 (May 1, 2020): 292–99. http://dx.doi.org/10.1784/insi.2020.62.5.292.

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Pipelines are widely used in the oil & gas industry but defects seriously affect their safe operation. Therefore, it is necessary to perform non-destructive testing (NDT) to quantify the defects. In this study, a magnetic dipole model was established to characterise the defects and magnetic flux leakage (MFL) of defects was simulated using the finite element method (FEM) to reveal the spatial distribution of the magnetic vector. Magnetic signals were measured using a tunnel magnetoresistance (TMR) sensor array and the results showed that defects with different sizes could be quantified using the metal magnetic memory (MMM) method. Three-dimensional distribution of the magnetic signal and its gradient reflected the defect profile well and the gradient of the magnetic signal was found to reduce the effect of non-uniform magnetisation. Furthermore, experimental results were verified by comparison with the simulation results and the comparison results showed a consistent variation trend. Quantitative analysis was conducted and the characteristic parameters of the gradients could be used to quantify the defects.

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Kuzmin, Dmitry A., Alexander Yu Kuzmichevsky, and Marina V. Vertashenok. "Investigation of the probability of existence of defects with a size exceeding the allowed value." Structural Mechanics of Engineering Constructions and Buildings 16, no. 5 (December 15, 2020): 414–23. http://dx.doi.org/10.22363/1815-5235-2020-16-5-414-423.

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Relevance. Non-destructive testing of metal determines the actual state of the metal, the presence of discontinuities and their sizes, and also allows to determine what mechanisms of metal degradation were subjected to. One of the main characteristics of the quality of non-destructive testing is the detectability of discontinuities and defects. If no defects were missed, then its possible to guarantee the reliable operation of the facility until the next scheduled inspection. The article is devoted to the study of the probability function of detecting defects and determining the probability of the existence of a residual defect with a size exceeding the permissible value. The aim of the work - to develop a method to determine the probability of the existence of a residual defect with a size exceeding the permissible value after non-destructive testing and repairs of equipment and pipelines of a nuclear power plant. Methods. During the work formulas for the probability of detecting a defect and initial defectiveness, regulatory requirements in the field of certification of flaw detectors, and the results of research on non-destructive testing were used. Results. A method for determining the probability of defects with a size exceeding the allowed value, using the example of a reactor vessel, is presented. The method is based on residual defects, which takes into account the detectability of defects. The value of the coefficient that takes into account the influence of the human factor, instrument and methodological shortcomings or complexity of access to the control point is determined, which reduces the degree of uncertainty in determining the residual defect. The results of this work permit to evaluate the probability of the existence of a defect with a size exceeding the allowed value. The development of a residual defect to critical values characterizes the initial event for the destruction of the integrity of the structure. Thus, the probability of a residual defect can be used when performing a safety analysis of the water-water energetic reactor vessel.

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Kameda, Toshihiro, and Bao Rong Zhang. "Molecular Dynamics Based Observations of Grain Boundaries and Lattice Defects Functions in Fine Grained Metal." Materials Science Forum 654-656 (June 2010): 1582–85. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1582.

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In order to study the characteristics of fine grained polycrystalline metals, it is important to recognize the function of grain boundaries (GB), crystal defects such as dislocation and/or nanoscale voids, since the fraction of GB increases as grain sizes decreases, the deformation process of these metals could be different from those in larger size grains. In this study, we first evaluate the hypothesis that GB behaves as dislocation source and sink during the deformation of fine grained metal, then compare the behavior between GB and a tiny defect from the view point of dislocation source and sink phenomena. Since continuous dislocation supplies could be considered as the key issue to improve the toughness of fine grained metals, this concept could be helpful to design next generation polycrystalline metals.

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Sapnik, Adam F., Duncan N. Johnstone, Sean M. Collins, Giorgio Divitini, Alice M. Bumstead, Christopher W. Ashling, Philip A. Chater, et al. "Stepwise collapse of a giant pore metal–organic framework." Dalton Transactions 50, no. 14 (2021): 5011–22. http://dx.doi.org/10.1039/d1dt00881a.

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Defect engineering is used to augment the porosity of MIL-100. Incorporation of defects leads to structural collapse and ultimately causes amorphisation. Pair distribution function analysis reveals a stepwise collapse of the hierarchical structure.

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Deng, Weiquan, Bo Ye, Jun Bao, Guoyong Huang, and Jiande Wu. "Classification and Quantitative Evaluation of Eddy Current Based on Kernel-PCA and ELM for Defects in Metal Component." Metals 9, no. 2 (February 1, 2019): 155. http://dx.doi.org/10.3390/met9020155.

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Eddy current testing technology is widely used in the defect detection of metal components and the integrity evaluation of critical components. However, at present, the evaluation and analysis of defect signals are still mostly based on artificial evaluation. Therefore, the evaluation of defects is often subjectively affected by human factors, which may lead to a lack in objectivity, accuracy, and reliability. In this paper, the feature extraction of non-linear signals is carried out. First, using the kernel-based principal component analysis (KPCA) algorithm. Secondly, based on the feature vectors of defects, the classification of an extreme learning machine (ELM) for different defects is studied. Compared with traditional classifiers, such as artificial neural network (ANN) and support vector machine (SVM), the accuracy and rapidity of ELM are more advantageous. Based on the accurate classification of defects, the linear least-squares fitting is used to further quantitatively evaluate the defects. Finally, the experimental results have verified the effectiveness of the proposed method, which involves automatic defect classification and quantitative analysis.

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Khan, Muhammad Azhar Ali. "Simulation Based Mold Design Optimization of a Spring Flap Casting." Solid State Phenomena 305 (June 2020): 178–84. http://dx.doi.org/10.4028/www.scientific.net/ssp.305.178.

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The complex nature of metal casting process brings about a need to simulate it before undertaken in a foundry. Casting simulations provide insights on flow of molten metal within the mold, solidification sequence, nature and location of defects etc. Moreover, mold design can be optimized to minimize defects without undergoing physical trials-and-errors as previously practiced in traditional metal casting. This study is based on casting an ASTM A216 WCB steel spring flap for automotive suspension system using a simulation based optimized mold design. The initial and optimized mold designs are simulated in MAGMASoft for mold filling, solidification, stress distribution and defects prediction. The results of simulations and actual castings are found to be in good agreement. It is concluded that simulations are accurate in modeling casting process and in predicting defects followed by their minimization through mold design optimization. The use of auxiliary components in a carefully designed mold can lead to a nearly defect-free and high quality cast product.

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Berdiyorov, G. R., F. Boltayev, G. Eshonqulov, and H. Hamoudi. "Effect of vacancy defects on the electronic transport properties of an Ag–ZnO–Pt sandwich structure." Journal of Computational Electronics 20, no. 2 (March 3, 2021): 798–804. http://dx.doi.org/10.1007/s10825-021-01663-1.

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AbstractThe effect of zinc and oxygen vacancy defects on the electronic transport properties of Ag(100)–ZnO(100)–Pt(100) sandwich structures is studied using density functional theory in combination with the nonequilibrium Green’s functional formalism. Defect-free systems show clear current rectification due to voltage dependent charge localization in the system as revealed in our transmission eigenstates analysis. Regardless of the location, oxygen vacancies result in enhanced current in the system, whereas Zn vacancy defects reduce the charge transport across the junction. The current rectification becomes less pronounced in the presence of both types of vacancy defects. Our findings can be of practical importance for developing metal-insulator-metal diodes.

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42

Gao, Jiang-Dong, Jian-Li Zhang, Xin Zhu, Xiao-Ming Wu, Chun-Lan Mo, Shuan Pan, Jun-Lin Liu, and Feng-Yi Jiang. "Detailed surface analysis of V-defects in GaN films on patterned silicon(111) substrates by metal–organic chemical vapour deposition." Journal of Applied Crystallography 52, no. 3 (May 31, 2019): 637–42. http://dx.doi.org/10.1107/s1600576719005521.

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The growth mechanism of V-defects in GaN films was investigated. It was observed that the crystal faces of both the sidewall of a V-defect and the sidewall of the GaN film boundary belong to the same plane family of \{ {{{10\bar 11}}} \}, which suggests that the formation of the V-defect is a direct consequence of spontaneous growth like that of the boundary facet. However, the growth rate of the V-defect sidewall is much faster than that of the boundary facet when the V-defect is filling up, implying that lateral growth of \{ {{{10\bar 11}}} \} planes is not the direct cause of the change in size of V-defects. Since V-defects originate from dislocations, an idea was proposed to correlate the growth of V-defects with the presence of dislocations. Specifically, the change in size of the V-defect is determined by the growth rate around dislocations and the growth rate around dislocations is determined by the growth conditions.

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Nurakhmetov, T. N., K. A. Kuterbekov, D. H. Daurenbekov, Zh M. Salikhodzha, A. K. Kainarbay, A. M. Zhunusbekov, and K. Bekmyrza. "Radiation defects in alkali metal sulfates." Radiation Physics and Chemistry 119 (February 2016): 218–22. http://dx.doi.org/10.1016/j.radphyschem.2015.10.031.

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Koch, J. M., and C. Koenig. "Antistructure defects in transition-metal aluminides." Philosophical Magazine B 55, no. 3 (March 1987): 359–75. http://dx.doi.org/10.1080/13642818708208620.

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45

Jacobs, Patrick W. M. "Defects in alkali-metal halide crystals." Journal of the Chemical Society, Faraday Transactions 2 85, no. 5 (1989): 415. http://dx.doi.org/10.1039/f29898500415.

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46

Brennan, M. C., J. S. Keist, and T. A. Palmer. "Defects in Metal Additive Manufacturing Processes." Journal of Materials Engineering and Performance 30, no. 7 (July 2021): 4808–18. http://dx.doi.org/10.1007/s11665-021-05919-6.

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Schwarz, Michael, Jannik Summa, Steven Quirin, and Hans Georg Herrmann. "New Approaches in Nondestructive Characterisation of Defects in Metal - CFRP Hybrids." Materials Science Forum 825-826 (July 2015): 976–82. http://dx.doi.org/10.4028/www.scientific.net/msf.825-826.976.

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In this paper a new metal - CFRP (Carbon Fibre Reinforced Polymer) hybrid concept is introduced. The new aspect of this hybrid is a thermoplastic polymer component inserted between the metal and CFRP structure to reduce the gap of the different stiffnesses in each structure. To characterise defects in the hybrid, both destructive and nondestructive testing (NDT) approaches are shown. Especially the interface between the metal structure and the thermoplastic polymer component as well as the interface between the thermoplastic polymer component and the CFRP structure, where is most-likely the starting point for cracks, are investigated. An additional probability of detection (POD) approach enables to connect fracture mechanics with crack values of NDT. In consequence it is possible to achieve the assessment of defect-caused damage progress, so called effects of defects.

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Seibt, Michael, Philipp Saring, Philipp Hahne, Linda Stolze, M. A. Falkenberg, Carsten Rudolf, Doaa Abdelbarey, and Henning Schuhmann. "Transmission Electron Microscopy Investigations of Metal-Impurity-Related Defects in Crystalline Silicon." Solid State Phenomena 178-179 (August 2011): 275–84. http://dx.doi.org/10.4028/www.scientific.net/ssp.178-179.275.

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This contribution summarizes recent efforts to apply transmission electron microscopy (TEM) techniques to recombination-active extended defects present in a low density. In order to locate individual defects, electron beam induced current (EBIC) is applied in situ in a focused ion beam (FIB) machine combined with a scanning electron microscope. Using this approach defect densities down to about 10cm-2 are accessible while a target accuracy of better than 50nm is achieved. First applications described here include metal impurity related defects in multicrystalline silicon, recombination and charge collection at NiSi2 platelets, internal gettering of copper by NiSi2 precipitates and site-determination of copper atoms in NiSi2.

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Xu, Wen Ji, Ji Shang Jiang, Xu Yue Wang, and Wen Qing Song. "Temperature Field Model in Plasma Arc Forming of Laminated Clad Metal Sheets Containing Defects." Advanced Materials Research 97-101 (March 2010): 4160–63. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.4160.

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A FEM model, based on the structural characteristics of laminated clad metal sheets (LCMS) containing defects, was developed to study the variations of temperature field in the flexible forming using plasma arc. The typical LCMS Q235A/1Cr18Ni9Ti was selected as the sample, and the effects of different defects in the bonding interface on the temperature field were analyzed. The results show that the peak value of temperature containing defect is 107 oC higher than that without defect under the same processing parameters. The peak values of temperature and temperature difference increase with the increasing of defect size, but decrease when the location of defect is far away from the heating surface of LCMS. Compared with spherical defect, cubic defect has more power to impede heat conduction along the thickness direction of LCMS.

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Bęczkowski, R. "Repair Welding of the Massive Cast." Archives of Foundry Engineering 17, no. 2 (June 27, 2017): 5–8. http://dx.doi.org/10.1515/afe-2017-0041.

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Abstract The rebuilding technologies are used to develop surface of ladle. Among many welding methods currently used to obtain surface layer without defects one of the most effective way of rebuilding is using metal arc welding. This additional material gives more possibilities to make expected quality of rebuild surface. Chemical composition, property and economic factors allow to use metal wire. Because of these reasons, solid wire gives opportunity to be wildly used as material to rebuild or repair the surface in different sectors of industry. The paper shows a few ways to rebuild the surface in the massive cast with the use of metal active gas welding for repair. The work presents studies of defect in the massive cast. It contains the pictures of microstructures and defects. The method of removing defects and the results of checking by visual and penetrant testing methods are shown. The paper describes the methodology of repair the ladle with metal active gas welding, preheating process and standards nondestructive testing method.

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Journal articles on the topic 'Metal defects'

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