A. Bhattacharya, J. Henry, B. Décamps, S. Zinkle, E. Meslin
Single and dual-beam self-ion irradiations were performed at 500 °C on ultra-high purity Fe14%Cr alloy to ~0.33 displacements-per-atom (dpa), and 0 or 3030 atomic-parts-per-million (appm) helium/dpa, respectively. Using transmission electron microscopy, we reveal that helium can drastically modify the dislocation loop Burgers vector in Fe-Cr alloys. Helium co-implantation caused complete disappearance of a/2<111> type dislocation loops, and the microstructure consisted of only a<100> loops. Conversely, a/2<111> type loops were predominant without He co-implantation. The total loop density remained largely unaffected. The results strikingly contrast literature asserting that helium stabilizes a/2<111> type loops in bcc Fe alloys, based on low temperature irradiations. Collectively analyzing the results with literature suggests that the small positive interaction between helium and self-interstitial atoms (SIA) in Fe, predicted by atomistic simulations, maybe insufficient to holistically explain the dislocation loop microstructure development in presence of helium. Helium-SIA positive binding inadvertently implies elevated a/2<111> loop fraction and higher loop densities that the present results contradict. Helium induced high cavity density causing a preferential loss of highly glissile <111> clusters, leaving the matrix saturated with <100> type clusters is proposed as a potential mechanism. Further, the in-situ irradiations combined with Burgers vector analysis strengthened the evidence of Cr-induced dislocation loop mobility reduction that appears to stabilize the a/2<111> type loops and causes higher loop densities in Fe-Cr alloys.
{"title":"Helium Causing Disappearance of ½ a<111> Dislocation Loops in Binary Fe-Cr Ferritic Alloys","authors":"A. Bhattacharya, J. Henry, B. Décamps, S. Zinkle, E. Meslin","doi":"10.2139/ssrn.3828269","DOIUrl":"https://doi.org/10.2139/ssrn.3828269","url":null,"abstract":"Single and dual-beam self-ion irradiations were performed at 500 °C on ultra-high purity Fe14%Cr alloy to ~0.33 displacements-per-atom (dpa), and 0 or 3030 atomic-parts-per-million (appm) helium/dpa, respectively. Using transmission electron microscopy, we reveal that helium can drastically modify the dislocation loop Burgers vector in Fe-Cr alloys. Helium co-implantation caused complete disappearance of a/2<111> type dislocation loops, and the microstructure consisted of only a<100> loops. Conversely, a/2<111> type loops were predominant without He co-implantation. The total loop density remained largely unaffected. The results strikingly contrast literature asserting that helium stabilizes a/2<111> type loops in bcc Fe alloys, based on low temperature irradiations. Collectively analyzing the results with literature suggests that the small positive interaction between helium and self-interstitial atoms (SIA) in Fe, predicted by atomistic simulations, maybe insufficient to holistically explain the dislocation loop microstructure development in presence of helium. Helium-SIA positive binding inadvertently implies elevated a/2<111> loop fraction and higher loop densities that the present results contradict. Helium induced high cavity density causing a preferential loss of highly glissile <111> clusters, leaving the matrix saturated with <100> type clusters is proposed as a potential mechanism. Further, the in-situ irradiations combined with Burgers vector analysis strengthened the evidence of Cr-induced dislocation loop mobility reduction that appears to stabilize the a/2<111> type loops and causes higher loop densities in Fe-Cr alloys.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"55 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73269382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, (La, Eu) co-doped CaCu3Ti4O12 ceramics (Ca1-xLaxCu3Ti4-xEuxO12, x = 0.1, 0.3, and 0.5) were prepared by the traditional solid-state method. The XRD results of ceramics confirmed the formation of the single-phase CCTO and a residual amount of CaTiO3. The refined calculation found that the lattice constant of CLCTEO ceramics will be significantly increased due to the co-doping of La and Eu. The FESEM analysis showed a smaller grain size for the co-doped CCTO. Impedance measurements indicated that the (La, Eu) co-doped CCTO ceramics have higher dielectric permittivity than the single-doped with La and Eu. The most negligible dielectric loss was achieved in CLCTEO ceramics with x = 0.1, and a low tanδ of 0.013 was observed at 800kHz for room temperature. The results indicated that the co-doping method is an effective method to improve the dielectric properties.
本文采用传统固相法制备了(La, Eu)共掺杂cau3ti4o12陶瓷(Ca1-xLaxCu3Ti4-xEuxO12, x = 0.1, 0.3, 0.5)。陶瓷的XRD结果证实了单相CCTO的形成和CaTiO3的残留。精细化计算发现，La和Eu的共掺杂会显著提高CLCTEO陶瓷的晶格常数。FESEM分析表明，共掺杂的CCTO晶粒尺寸较小。阻抗测量结果表明，(La, Eu)共掺CCTO陶瓷的介电常数高于单掺La和Eu的陶瓷。在室温下，当x = 0.1时，CLCTEO陶瓷的介电损耗最小，在800kHz时，tanδ低至0.013。结果表明，共掺杂方法是改善介电性能的有效方法。
{"title":"Microstructure and Improved Dielectric Properties of CaCu 3Ti 4O 12 Ceramics by Lanthanum/Europium Co-Doping","authors":"Yongmei Guo, Junlang Tan, J. Zhao","doi":"10.2139/ssrn.3878348","DOIUrl":"https://doi.org/10.2139/ssrn.3878348","url":null,"abstract":"In this work, (La, Eu) co-doped CaCu3Ti4O12 ceramics (Ca1-xLaxCu3Ti4-xEuxO12, x = 0.1, 0.3, and 0.5) were prepared by the traditional solid-state method. The XRD results of ceramics confirmed the formation of the single-phase CCTO and a residual amount of CaTiO3. The refined calculation found that the lattice constant of CLCTEO ceramics will be significantly increased due to the co-doping of La and Eu. The FESEM analysis showed a smaller grain size for the co-doped CCTO. Impedance measurements indicated that the (La, Eu) co-doped CCTO ceramics have higher dielectric permittivity than the single-doped with La and Eu. The most negligible dielectric loss was achieved in CLCTEO ceramics with x = 0.1, and a low tanδ of 0.013 was observed at 800kHz for room temperature. The results indicated that the co-doping method is an effective method to improve the dielectric properties.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"74 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88966456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Heat capacity is among the most well-known thermal properties of cellulosic biomass samples. This study assembles a general machine learning model to estimate the heat capacity of the cellulosic biomass samples with different origins. Combining the uncertainty and ranking analyses over 819 artificial intelligence (AI) models from seven different categories confirmed that the least-squares support vector regression (LSSVR) with the Gaussian kernel function is the best estimator. This model is validated using 700 laboratory heat capacities of four cellulosic biomass samples in wide temperature ranges (AARD=0.32%, MSE=1.88×10-3, and R2=0.999991). The data validity investigation approved that only one out of 700 experimental data is an outlier. The LSSVR model considers the effect of crystallinity, temperature, and sulfur and ash content of the cellulosic samples on their heat capacity. The LSSVR improves the achieved accuracy using the empirical correlation by more than 62%.
{"title":"Employing Machine Learning Approaches to Determine the Heat Capacity of Cellulosic Biomass Samples with Different Origins","authors":"M. Karimi, B. Vaferi","doi":"10.2139/ssrn.3935555","DOIUrl":"https://doi.org/10.2139/ssrn.3935555","url":null,"abstract":"Heat capacity is among the most well-known thermal properties of cellulosic biomass samples. This study assembles a general machine learning model to estimate the heat capacity of the cellulosic biomass samples with different origins. Combining the uncertainty and ranking analyses over 819 artificial intelligence (AI) models from seven different categories confirmed that the least-squares support vector regression (LSSVR) with the Gaussian kernel function is the best estimator. This model is validated using 700 laboratory heat capacities of four cellulosic biomass samples in wide temperature ranges (AARD=0.32%, MSE=1.88×10-3, and R2=0.999991). The data validity investigation approved that only one out of 700 experimental data is an outlier. The LSSVR model considers the effect of crystallinity, temperature, and sulfur and ash content of the cellulosic samples on their heat capacity. The LSSVR improves the achieved accuracy using the empirical correlation by more than 62%.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75299992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cong-hui Liu, R. Thomas, T. Sun, J. Donoghue, Xun Zhang, T. Burnett, J. Quinta da Fonseca, M. Preuss
During service of gas turbine engines, high cycle fatigue of titanium is a leading cause of component failure highlighting the need for better understanding of the crack initiation mechanism to predict initiation sites. In this study, the relationship between plastic slip activity and fatigue crack initiation was investigated in a near-a titanium alloy using cyclic four-point bending at up to 90% of the proof stress. Detailed surface characterization demonstrates that plasticity at such low stress levels is dominated by basal slip. Two types of crack mode were seen among four short cracks. Transgranular cracking parallel to basal slip traces was observed within three primary a grains and one case of intergranular cracking was seen along the boundary between primary a grain pairs, which have their c-axes aligned nearly parallel to each other but with mis-aligned prismatic planes. Detailed 3D analysis highlights out-of-plane Burgers vector activity for the observed basal slip associated with crack initiation, consistent with the classic surface roughening mechanism. The plane of the short crack was identified to be a basal facet and lattice rotation around the c-axis close to the crack plane suggests additional prismatic slip activation during multi-step crack formation. Statistical evaluation highlighted that grains combining a moderately high Schmid factor for basal slip, high resolved tensile stress along the c-axis and the Burgers vector being orientated strongly out-of-surface plane favour crack initiation. Based on those observations a new parameter involving these three geometrical factors has been developed that predicts surface crack initiation sites.
{"title":"Multi-Dimensional Study of the Early Slip Activity on Crack Initiation in a Near α Titanium Alloy","authors":"Cong-hui Liu, R. Thomas, T. Sun, J. Donoghue, Xun Zhang, T. Burnett, J. Quinta da Fonseca, M. Preuss","doi":"10.2139/ssrn.3757765","DOIUrl":"https://doi.org/10.2139/ssrn.3757765","url":null,"abstract":"During service of gas turbine engines, high cycle fatigue of titanium is a leading cause of component failure highlighting the need for better understanding of the crack initiation mechanism to predict initiation sites. In this study, the relationship between plastic slip activity and fatigue crack initiation was investigated in a near-a titanium alloy using cyclic four-point bending at up to 90% of the proof stress. Detailed surface characterization demonstrates that plasticity at such low stress levels is dominated by basal slip. Two types of crack mode were seen among four short cracks. Transgranular cracking parallel to basal slip traces was observed within three primary a grains and one case of intergranular cracking was seen along the boundary between primary a grain pairs, which have their c-axes aligned nearly parallel to each other but with mis-aligned prismatic planes. Detailed 3D analysis highlights out-of-plane Burgers vector activity for the observed basal slip associated with crack initiation, consistent with the classic surface roughening mechanism. The plane of the short crack was identified to be a basal facet and lattice rotation around the c-axis close to the crack plane suggests additional prismatic slip activation during multi-step crack formation. Statistical evaluation highlighted that grains combining a moderately high Schmid factor for basal slip, high resolved tensile stress along the c-axis and the Burgers vector being orientated strongly out-of-surface plane favour crack initiation. Based on those observations a new parameter involving these three geometrical factors has been developed that predicts surface crack initiation sites.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85473076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-30DOI: 10.15587/2706-5448.2020.218492
I. Demchuk
The object of research is the process of improving the quality of urea granules by processing. The subject of research is the physicochemical properties of granular urea after processing with a new composite. Granular urea has a wide range of uses, but during storage and sale it is capable of caking with a significant loss of its flowability, static and dynamic strength of granules. When transporting over long distances, these phenomena cause inconvenience in loading and unloading operations, and also affect the quality of the supplied goods. Therefore, the search for methods to improve its quality is still important. The paper considers the results of theoretical studies of ways to improve the quality of granular urea. As a rule, at most enterprises, an additive is introduced into the urea melt - urea-formaldehyde concentrate, which promotes the formation of isometric forms of urea crystals and reduces the growth rate of faces with the third pinacoid. Due to the toxicity of formaldehyde, the market for such urea is limited. The results are presented for laboratory tests of the processing of urea produced by pouring without a fluidized bed, a new anti-caking composite – a hydrolyzed solution of protein raw materials from the family of fibrillar proteins with a protein raw material concentration of 10 %. The main purpose of the granule processing was to improve the quality of urea through the use of a new composite anti-caking agent, which leads to an increase in the shelf life without changing the physicochemical properties and provides an environmentally friendly condition. As a result of laboratory studies, a decrease in moisture absorption was revealed. It has been established that the proposed anti-caking agent exhibits a hydrophobilization effect. The effectiveness of the conditioning action of the proposed composite has been proven, which consists in achieving fixation of a hydrophobic coating of natural origin on the surface of fertilizer granules and, as a consequence, reducing the percentage of caking of fertilizers. The disadvantages of the developed composite were also established, namely: the fact of a decrease in the static strength of granules after processing was established. Therefore, work on improving the composition of the composite will continue.
{"title":"Improvement of the Process of Improving the Quality of Urea Granules","authors":"I. Demchuk","doi":"10.15587/2706-5448.2020.218492","DOIUrl":"https://doi.org/10.15587/2706-5448.2020.218492","url":null,"abstract":"The object of research is the process of improving the quality of urea granules by processing. The subject of research is the physicochemical properties of granular urea after processing with a new composite. Granular urea has a wide range of uses, but during storage and sale it is capable of caking with a significant loss of its flowability, static and dynamic strength of granules. When transporting over long distances, these phenomena cause inconvenience in loading and unloading operations, and also affect the quality of the supplied goods. Therefore, the search for methods to improve its quality is still important. The paper considers the results of theoretical studies of ways to improve the quality of granular urea. As a rule, at most enterprises, an additive is introduced into the urea melt - urea-formaldehyde concentrate, which promotes the formation of isometric forms of urea crystals and reduces the growth rate of faces with the third pinacoid. Due to the toxicity of formaldehyde, the market for such urea is limited. The results are presented for laboratory tests of the processing of urea produced by pouring without a fluidized bed, a new anti-caking composite – a hydrolyzed solution of protein raw materials from the family of fibrillar proteins with a protein raw material concentration of 10 %. The main purpose of the granule processing was to improve the quality of urea through the use of a new composite anti-caking agent, which leads to an increase in the shelf life without changing the physicochemical properties and provides an environmentally friendly condition. As a result of laboratory studies, a decrease in moisture absorption was revealed. It has been established that the proposed anti-caking agent exhibits a hydrophobilization effect. The effectiveness of the conditioning action of the proposed composite has been proven, which consists in achieving fixation of a hydrophobic coating of natural origin on the surface of fertilizer granules and, as a consequence, reducing the percentage of caking of fertilizers. The disadvantages of the developed composite were also established, namely: the fact of a decrease in the static strength of granules after processing was established. Therefore, work on improving the composition of the composite will continue.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"603 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77419744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Francoise M. Amombo Noa, M. Abrahamsson, E. Ahlberg, O. Cheung, C. McKenzie, Elin Sundin, L. Öhrström
Metal-Organic Frameworks made from discrete multi-metal-ion units in the shape of clusters and rods (termed dot-MOFs and rod-MOFs) are well-known. Here, we introduce MOFs with multi-metallic units in the form of sheets, sheet-MOFs. We show exemplars of all three type of units based on structures containing Y3+, Ce3+, or Gd3+ linked by benzene-1,2,4,5-tetracarboxylate to give crystals of a dot-MOF in H2NMe2[Y(btec)(H2O)] CTH-14, a sheet-MOF in [Ce3 (btec)(Hbtec)(NO3)2]·½dmf CTH-15, and a rod-MOF in [Gd2(Hbtec)2](4,4’-azopyridine) CTH-16. Cyclic voltammetry shows that sheet-MOF CTH-15 stabilize the Ce(IV) oxidation state and suggests catalytic ability for electrochemical nitrate reduction. Given the fact that sheet-MOFs represent an intellectual advance in the evolution of the MOF field, a unified approach is proposed for the topological classification of dot-, rod- and sheet-MOFs. It is suggested that the stability of MOFs follow in the trend dot
{"title":"A Unified Approach to Dot-, Rod-, and Sheet-MOFs and Electrochemistry of Exemplars Containing Y, Ce, Gd, and Benzene-Tetracarboxylate","authors":"Francoise M. Amombo Noa, M. Abrahamsson, E. Ahlberg, O. Cheung, C. McKenzie, Elin Sundin, L. Öhrström","doi":"10.2139/ssrn.3756487","DOIUrl":"https://doi.org/10.2139/ssrn.3756487","url":null,"abstract":"Metal-Organic Frameworks made from discrete multi-metal-ion units in the shape of clusters and rods (termed dot-MOFs and rod-MOFs) are well-known. Here, we introduce MOFs with multi-metallic units in the form of sheets, sheet-MOFs. We show exemplars of all three type of units based on structures containing Y3+, Ce3+, or Gd3+ linked by benzene-1,2,4,5-tetracarboxylate to give crystals of a dot-MOF in H2NMe2[Y(btec)(H2O)] CTH-14, a sheet-MOF in [Ce3 (btec)(Hbtec)(NO3)2]·½dmf CTH-15, and a rod-MOF in [Gd2(Hbtec)2](4,4’-azopyridine) CTH-16. Cyclic voltammetry shows that sheet-MOF CTH-15 stabilize the Ce(IV) oxidation state and suggests catalytic ability for electrochemical nitrate reduction. Given the fact that sheet-MOFs represent an intellectual advance in the evolution of the MOF field, a unified approach is proposed for the topological classification of dot-, rod- and sheet-MOFs. It is suggested that the stability of MOFs follow in the trend dot","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85857624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Farming and other occupations which require the operation of heavy machinery like tractors expose the operator to whole-body vibrations. This could cause various ailments and discomforts in the human body and could even lead to premature mortality. This paper presents a survey into the exposure of seated occupants to the whole-body vibrations and their effects. Various standard terms used for quantifying the whole body vibration exposure and their limiting values are discussed in this paper. The different variables which could influence the distribution of vibrations on the body of the occupants and their effects on the biodynamic response of the body are discussed in detail. A review of various modelling approaches to predict the biodynamic responses of the body and their key variables is also carried out.
{"title":"A Review of Whole-Body Vibration of Seated Occupants in Moving Vehicles","authors":"A. Anand, Sudheesh Kumar C. P.","doi":"10.2139/ssrn.3790350","DOIUrl":"https://doi.org/10.2139/ssrn.3790350","url":null,"abstract":"Farming and other occupations which require the operation of heavy machinery like tractors expose the operator to whole-body vibrations. This could cause various ailments and discomforts in the human body and could even lead to premature mortality. This paper presents a survey into the exposure of seated occupants to the whole-body vibrations and their effects. Various standard terms used for quantifying the whole body vibration exposure and their limiting values are discussed in this paper. The different variables which could influence the distribution of vibrations on the body of the occupants and their effects on the biodynamic response of the body are discussed in detail. A review of various modelling approaches to predict the biodynamic responses of the body and their key variables is also carried out.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80203799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Plates are essential elements of many structures and are found to have numerous applications in different fields of engineering such as vehicles, bridges, offshore installations, aircrafts, etc. Plates can be exposed to high dynamic loads, such as blast, in some special applications. Blast is a rapid release of energy, leading to the creation of blast waves and hot gases, which in turn, will destroy plates and lead to a complete or partial collapse of the structure. Thus, observing the blasting reaction of the plates allows to explain and develop the blasting resistance of the plates and to gain greater insight into the blasting damage phenomena. Various researches have been carried out in this area over the past decades. A review of these works which includes the types of loading, types of material, orientation of plates and explosives, standoff distance and modes of failure is presented in this paper. The primary objective is to help the researchers and engineers to achieve a better design for plates against blast loads.
{"title":"Response of Plates Subjected To Blast Loading: A Review","authors":"J. P, Sudheesh Kumar C. P.","doi":"10.2139/ssrn.3791077","DOIUrl":"https://doi.org/10.2139/ssrn.3791077","url":null,"abstract":"Plates are essential elements of many structures and are found to have numerous applications in different fields of engineering such as vehicles, bridges, offshore installations, aircrafts, etc. Plates can be exposed to high dynamic loads, such as blast, in some special applications. Blast is a rapid release of energy, leading to the creation of blast waves and hot gases, which in turn, will destroy plates and lead to a complete or partial collapse of the structure. Thus, observing the blasting reaction of the plates allows to explain and develop the blasting resistance of the plates and to gain greater insight into the blasting damage phenomena. Various researches have been carried out in this area over the past decades. A review of these works which includes the types of loading, types of material, orientation of plates and explosives, standoff distance and modes of failure is presented in this paper. The primary objective is to help the researchers and engineers to achieve a better design for plates against blast loads.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83838989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Dias, M. Rosiński, P. Rodrigues, J. B. Correia, P. Carvalho
Liquid film migration is of great practical importance in materials engineering. The phenomenon depends on thermal gradients and coherency strain, but no single driving mechanism seems capable of justifying all experimental observations. On the other hand, the inevitable capillarity effects are often indeterminable due to the unknown three-dimensional geometry of the system. Here, we present evidence of liquid film migration governed primarily by the Gibbs-Thomson effect through a microstructural setup of cylindrical interfaces designed to allow clear interpretation and modeling. The experiment relies on the strong oxygen-gettering ability of tantalum fibers dispersed in a tungsten matrix and on field-enhanced diffusivity provided by pulse plasma compaction. Tantalum scavenges residual oxygen present in the W powder and, as a result, oxide films grow around the fibers. These oxide tubes, in liquid state during sintering, migrate toward the fiber axis and become surrounded by external rims of metallic Ta. An analytical description of the film evolution is implemented by combining the incoming O flux with capillarity driven migration. P ossible contributions from other mechanisms are examined and the r elevance of the Gibbs-Thomson effect to liquid film migration is established .
{"title":"Gibbs-Thompson Effect as Driving Force for Liquid Film Migration","authors":"M. Dias, M. Rosiński, P. Rodrigues, J. B. Correia, P. Carvalho","doi":"10.2139/ssrn.3753887","DOIUrl":"https://doi.org/10.2139/ssrn.3753887","url":null,"abstract":"Liquid film migration is of great practical importance in materials engineering. The phenomenon depends on thermal gradients and coherency strain, but no single driving mechanism seems capable of justifying all experimental observations. On the other hand, the inevitable capillarity effects are often indeterminable due to the unknown three-dimensional geometry of the system. Here, we present evidence of liquid film migration governed primarily by the Gibbs-Thomson effect through a microstructural setup of cylindrical interfaces designed to allow clear interpretation and modeling. The experiment relies on the strong oxygen-gettering ability of tantalum fibers dispersed in a tungsten matrix and on field-enhanced diffusivity provided by pulse plasma compaction. Tantalum scavenges residual oxygen present in the W powder and, as a result, oxide films grow around the fibers. These oxide tubes, in liquid state during sintering, migrate toward the fiber axis and become surrounded by external rims of metallic Ta. An analytical description of the film evolution is implemented by combining the incoming O flux with capillarity driven migration. P ossible contributions from other mechanisms are examined and the r elevance of the Gibbs-Thomson effect to liquid film migration is established .","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81141550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-23DOI: 10.15587/1729-4061.2020.218291
B. Vasyliv, V. Kulyk, Z. Duriagina, D. Mierzwiński, T. Kovbasiuk, T. Tepla
The effect of reduction treatment in a high-temperature (600 °C) hydrogen-containing environment on the microstructure and tendency to brittle fracture of YSZ–NiO(Ni) materials for solid oxide fuel cell anodes has been studied. To assess the crack growth resistance of the ceramics, the Vickers indentation technique was adapted, which allowed estimating the microhardness and fracture toughness of the material in the complex.
The requirements for high porosity of the anodes to ensure functional properties show that the strength may be an insufficient characteristic of the bearing capacity of the anode. More structurally sensitive characteristics are needed to assess its crack growth resistance.
The average levels of microhardness of YSZ–NiO ceramics in the as-sintered state and YSZ–NiO(Ni) cermets (2.0 GPa and 0.8 GPa, respectively) and their fracture toughness (3.75 MPa·m1/2 and 2.9 MPa·m1/2, respectively) were experimentally determined.
It was found that the microstructure of YSZ–NiO(Ni) cermet after redox treatment is formed by a YSZ ceramic skeleton with refined Ni-phase grains combined in a network, which provides increased electrical conductivity. Along with higher porosity of the cermet, its fracture toughness is not lower than that of the one-time reduced cermet due to the implementation of the bridging toughening mechanism of fracture.
The proposed treatment method allowed forming the microstructure of the anode material, resistant to crack propagation under mechanical load. The propensity of the anode material to brittle fracture on the basis of evaluation of its crack growth resistance and analysis of the microstructure and fracture micromechanism was substantiated. This result is interesting from a theoretical point of view. From a practical point of view, the developed technique allows determining the conditions of redox treatment in the technology of manufacturing fuel cell anodes.
{"title":"Estimation of the Effect of Redox Treatment on Microstructure and Tendency to Brittle Fracture of Anode Materials of Ysz–NiO(Ni) System","authors":"B. Vasyliv, V. Kulyk, Z. Duriagina, D. Mierzwiński, T. Kovbasiuk, T. Tepla","doi":"10.15587/1729-4061.2020.218291","DOIUrl":"https://doi.org/10.15587/1729-4061.2020.218291","url":null,"abstract":"The effect of reduction treatment in a high-temperature (600 °C) hydrogen-containing environment on the microstructure and tendency to brittle fracture of YSZ–NiO(Ni) materials for solid oxide fuel cell anodes has been studied. To assess the crack growth resistance of the ceramics, the Vickers indentation technique was adapted, which allowed estimating the microhardness and fracture toughness of the material in the complex.<br><br>The requirements for high porosity of the anodes to ensure functional properties show that the strength may be an insufficient characteristic of the bearing capacity of the anode. More structurally sensitive characteristics are needed to assess its crack growth resistance.<br><br>The average levels of microhardness of YSZ–NiO ceramics in the as-sintered state and YSZ–NiO(Ni) cermets (2.0 GPa and 0.8 GPa, respectively) and their fracture toughness (3.75 MPa·m1/2 and 2.9 MPa·m1/2, respectively) were experimentally determined.<br><br>It was found that the microstructure of YSZ–NiO(Ni) cermet after redox treatment is formed by a YSZ ceramic skeleton with refined Ni-phase grains combined in a network, which provides increased electrical conductivity. Along with higher porosity of the cermet, its fracture toughness is not lower than that of the one-time reduced cermet due to the implementation of the bridging toughening mechanism of fracture.<br><br>The proposed treatment method allowed forming the microstructure of the anode material, resistant to crack propagation under mechanical load. The propensity of the anode material to brittle fracture on the basis of evaluation of its crack growth resistance and analysis of the microstructure and fracture micromechanism was substantiated. This result is interesting from a theoretical point of view. From a practical point of view, the developed technique allows determining the conditions of redox treatment in the technology of manufacturing fuel cell anodes.","PeriodicalId":10639,"journal":{"name":"Computational Materials Science eJournal","volume":"2663 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86591953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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