Pub Date : 2018-11-16DOI: 10.1201/9781351045636-140000209
Xinyun Wang, L. Deng, Jinbo Li
Stamping-forging processing can significantly reduce the residual stress of sheet metal parts. First, the variation of residual stress field during stamping-forging processing and the influence of relative bending radii and forming temperature on the residual stresses of stamping-forged V-shaped parts have been studied by finite-element analysis. Then, the stamping-forging processing has been employed in the forming of 2024 aluminum alloy square cups with nonuniform thickness to investigate the effects of process parameters, such as punch radius, die entrance radius, and die corner radius, on the residual stresses of stamping-forged square cups. The optimum process parameters of stamping-forging have been obtained, which can produce square cups with low residual stresses, that is, the maximum residual stress value can be reduced from 190 MPa for deep drawn square cups to around 60 MPa for stamping-forged square cups. Therefore, it is indicated that the stamping-forging processing can significantly reduce the residual stress of sheet metal parts.
{"title":"Residual Stress During Stamping-Forging of 2024 Aluminum Alloy Sheet","authors":"Xinyun Wang, L. Deng, Jinbo Li","doi":"10.1201/9781351045636-140000209","DOIUrl":"https://doi.org/10.1201/9781351045636-140000209","url":null,"abstract":"Stamping-forging processing can significantly reduce the residual stress of sheet metal parts. First, the variation of residual stress field during stamping-forging processing and the influence of relative bending radii and forming temperature on the residual stresses of stamping-forged V-shaped parts have been studied by finite-element analysis. Then, the stamping-forging processing has been employed in the forming of 2024 aluminum alloy square cups with nonuniform thickness to investigate the effects of process parameters, such as punch radius, die entrance radius, and die corner radius, on the residual stresses of stamping-forged square cups. The optimum process parameters of stamping-forging have been obtained, which can produce square cups with low residual stresses, that is, the maximum residual stress value can be reduced from 190 MPa for deep drawn square cups to around 60 MPa for stamping-forged square cups. Therefore, it is indicated that the stamping-forging processing can significantly reduce the residual stress of sheet metal parts.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115405834","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 : 2018-11-16DOI: 10.1201/9781351045636-120050685
M. Fukumoto
In general, an essential target in the research and development of material process lies in how to establish the controlling principle on a designated material process. In this article, the current situation in the controlling of an ordinary thermal spray process, which is a representative of a thick coating formation process using particle deposition, is reviewed. Precise observation results were introduced to the ordinary thermal spray process. In the flattening behavior of the sprayed particle onto the substrate surface, critical conditions were recognized in both the substrate temperature and the ambient pressure. A transition temperature, Tt, and a transition pressure, Pt, were defined and introduced, respectively, for these critical conditions. Three-dimensional transition curvature, by combining both the Tt and the Pt dependence, was proposed as a control principle of the thermal spray process. Furthermore, particle melting in the ordinary thermal spray process has been recognized as a negative process. To overcome this problem, a new direction in coating technology development by using non-fusion solid particles has been tried recently, which is typically called the cold spray or the aerosol deposition process. As these processes have common characteristic for all, namely, a thick coating formation by the deposition of several micron-sized particles, the present state of the art, academic/technological issues, and the prospects for the future of these coating formation processes is comprehensively summarized in this article.
{"title":"Control Principle of Thermal Spray Process","authors":"M. Fukumoto","doi":"10.1201/9781351045636-120050685","DOIUrl":"https://doi.org/10.1201/9781351045636-120050685","url":null,"abstract":"In general, an essential target in the research and development of material process lies in how to establish the controlling principle on a designated material process. In this article, the current situation in the controlling of an ordinary thermal spray process, which is a representative of a thick coating formation process using particle deposition, is reviewed. Precise observation results were introduced to the ordinary thermal spray process. In the flattening behavior of the sprayed particle onto the substrate surface, critical conditions were recognized in both the substrate temperature and the ambient pressure. A transition temperature, Tt, and a transition pressure, Pt, were defined and introduced, respectively, for these critical conditions. Three-dimensional transition curvature, by combining both the Tt and the Pt dependence, was proposed as a control principle of the thermal spray process. Furthermore, particle melting in the ordinary thermal spray process has been recognized as a negative process. To overcome this problem, a new direction in coating technology development by using non-fusion solid particles has been tried recently, which is typically called the cold spray or the aerosol deposition process. As these processes have common characteristic for all, namely, a thick coating formation by the deposition of several micron-sized particles, the present state of the art, academic/technological issues, and the prospects for the future of these coating formation processes is comprehensively summarized in this article.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115720450","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 : 2018-11-16DOI: 10.1201/9781351045636-140000313
M. Tiryakioğlu
Mean pressure developed during Vickers and Rockwell hardness testing of Al-Zn-MgCualloys is reviewed. Relationships between mean pressure and yield strength are introduced for these alloys by using both Vickers and Rockwell hardness data from the literature. Results have shown that the slope of the mean pressure–yield strength relationships is 0.355 for Vickers tests and 0.264 for Rockwell B tests. The y-intercepts calculated for best fits are all negative, implying that the representative strains in both tests have exceeded the yield strain. Results also have indicated that mean pressure is affected by the indenter geometry and therefore is not a universal hardness number.
{"title":"Hardness–Yield Strength Relationships in Al-Zn-Mg(-Cu) Alloys","authors":"M. Tiryakioğlu","doi":"10.1201/9781351045636-140000313","DOIUrl":"https://doi.org/10.1201/9781351045636-140000313","url":null,"abstract":"Mean pressure developed during Vickers and Rockwell hardness testing of Al-Zn-MgCualloys is reviewed. Relationships between mean pressure and yield strength are introduced for these alloys by using both Vickers and Rockwell hardness data from the literature. Results have shown that the slope of the mean pressure–yield strength relationships is 0.355 for Vickers tests and 0.264 for Rockwell B tests. The y-intercepts calculated for best fits are all negative, implying that the representative strains in both tests have exceeded the yield strain. Results also have indicated that mean pressure is affected by the indenter geometry and therefore is not a universal hardness number.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124942912","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 : 2018-11-16DOI: 10.1201/9781351045636-140000432
W. Mao
Recrystallization occurs in all heating processes of aluminum alloys subjected to hot or cold deformation. The chemical, physical and mechanical property of aluminum alloys is dependent on recrystallization and grain growth. This article provides an overview of the mechanism and characteristics of deformation microstructure and defect structures in aluminum alloys.
{"title":"Recrystallization and Grain Growth","authors":"W. Mao","doi":"10.1201/9781351045636-140000432","DOIUrl":"https://doi.org/10.1201/9781351045636-140000432","url":null,"abstract":"Recrystallization occurs in all heating processes of aluminum alloys subjected to hot or cold deformation. The chemical, physical and mechanical property of aluminum alloys is dependent on recrystallization and grain growth. This article provides an overview of the mechanism and characteristics of deformation microstructure and defect structures in aluminum alloys.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126038577","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 : 2018-11-16DOI: 10.1201/9781351045636-140000434
Lifeng Zhang, Jianwei Gao, L. Damoah, D. Robertson
In this paper, the Fe-rich phases in and their detrimental effect on aluminum alloys are summarized. The existence of brittle platelet β-Fe-rich phases lowers the mechanical properties of aluminum alloys. The methods to neutralize the detrimental effect of iron are discussed. The use of high cooling rate, solution heat treatment, and addition of elements such as Mn, Cr, Be, Co, Mo, Ni, V, W, Cu, Sr, or the rare earth elements Y, Nd, La, and Ce are reported to modify the platelet Fe-rich phases in aluminum alloys. The mechanism of the modification is briefly described. Technologies to remove iron from aluminum are reviewed extensively. The precipitation and removal of Fe-rich phases (sludge) are discussed. The dense phases can be removed by methods such as gravitational separation, electromagnetic (EM) separation, and centrifuge. Other methods include electrolysis, electro-slag refining, fractional solidification, and fluxing refining. The expensive three-layer cell electrolysis process is the most successful technique to remove iron from aluminum so far.
{"title":"Iron: Removal from Aluminum","authors":"Lifeng Zhang, Jianwei Gao, L. Damoah, D. Robertson","doi":"10.1201/9781351045636-140000434","DOIUrl":"https://doi.org/10.1201/9781351045636-140000434","url":null,"abstract":"In this paper, the Fe-rich phases in and their detrimental effect on aluminum alloys are summarized. The existence of brittle platelet β-Fe-rich phases lowers the mechanical properties of aluminum alloys. The methods to neutralize the detrimental effect of iron are discussed. The use of high cooling rate, solution heat treatment, and addition of elements such as Mn, Cr, Be, Co, Mo, Ni, V, W, Cu, Sr, or the rare earth elements Y, Nd, La, and Ce are reported to modify the platelet Fe-rich phases in aluminum alloys. The mechanism of the modification is briefly described. Technologies to remove iron from aluminum are reviewed extensively. The precipitation and removal of Fe-rich phases (sludge) are discussed. The dense phases can be removed by methods such as gravitational separation, electromagnetic (EM) separation, and centrifuge. Other methods include electrolysis, electro-slag refining, fractional solidification, and fluxing refining. The expensive three-layer cell electrolysis process is the most successful technique to remove iron from aluminum so far.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116203313","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 : 2018-11-16DOI: 10.1201/9781351045636-140000441
M. Hyland
Understanding the microstructure and chemistry of the aluminum surface is the key to designing coating and structural bonding systems that endure. The focus of this article is the examination of concepts common to all polymer/aluminum bonding applications and to discuss some common surface treatments alter the surface chemistry and microstructure and how these treatments affect adhesion. Topics covered in this review include: discussion of the untreated aluminum surface, adhesion to aluminum surfaces, prevention of hydration of the bonded interface, and pretreatments,
{"title":"Surface Chemistry of Adhesion to Aluminum","authors":"M. Hyland","doi":"10.1201/9781351045636-140000441","DOIUrl":"https://doi.org/10.1201/9781351045636-140000441","url":null,"abstract":"Understanding the microstructure and chemistry of the aluminum surface is the key to designing coating and structural bonding systems that endure. The focus of this article is the examination of concepts common to all polymer/aluminum bonding applications and to discuss some common surface treatments alter the surface chemistry and microstructure and how these treatments affect adhesion. Topics covered in this review include: discussion of the untreated aluminum surface, adhesion to aluminum surfaces, prevention of hydration of the bonded interface, and pretreatments,","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"121 3 Suppl 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128492690","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 : 2018-11-16DOI: 10.1201/9781351045636-140000203
S. Murty, Sushant K. Manwatkar, P. Narayanan
Microstructure plays an important role in obtaining the desired properties in metallic materials in general and aluminum alloys in particular. Mechanical properties of aluminum alloys can be significantly altered by changing the microstructure. No other alloy system can boast of as many temper conditions as aluminum alloys. With the progress in the understanding of microstructure–mechanical property relationships in these materials, “tailor made” alloys to meet specific demands are being industrially developed. The broad spectrum of aluminum alloys in wide range of temper conditions offer materials with widely varying mechanical properties for structural designers. In order to select aluminum alloys with the desired properties for the intended application, it is essential to understand the role of microstructure under actual service conditions. It is in this context “Metallography of aluminum alloys” becomes very important. This chapter provides an insight in to the microstructural evolution of aluminum alloys from the as-cast condition to the final product. Typical examples of microstructural evolution in different aluminum alloys under various thermomechanical conditions are presented here. An atlas of microstructures of commercial and experimental wrought and cast aluminum alloys is presented in an appendix to this book. This appendix includes optical photomicrographs of both cast and wrought alloys and scanning electron micrographs of polished surfaces as well as fracture surfaces of various aluminum alloys as well as transmission electron micrographs as separate annexure. Readers are encouraged to go through the optical microstructures and fractographs along with this chapter for better understanding of the evolution of microstructure as a function of alloying additions, thermomechanical processing conditions, and fracture behavior under tension.
{"title":"Metallography of Aluminum Alloys: Atlas of Microstructures","authors":"S. Murty, Sushant K. Manwatkar, P. Narayanan","doi":"10.1201/9781351045636-140000203","DOIUrl":"https://doi.org/10.1201/9781351045636-140000203","url":null,"abstract":"Microstructure plays an important role in obtaining the desired properties in metallic materials in general and aluminum alloys in particular. Mechanical properties of aluminum alloys can be significantly altered by changing the microstructure. No other alloy system can boast of as many temper conditions as aluminum alloys. With the progress in the understanding of microstructure–mechanical property relationships in these materials, “tailor made” alloys to meet specific demands are being industrially developed. The broad spectrum of aluminum alloys in wide range of temper conditions offer materials with widely varying mechanical properties for structural designers. In order to select aluminum alloys with the desired properties for the intended application, it is essential to understand the role of microstructure under actual service conditions. It is in this context “Metallography of aluminum alloys” becomes very important. This chapter provides an insight in to the microstructural evolution of aluminum alloys from the as-cast condition to the final product. Typical examples of microstructural evolution in different aluminum alloys under various thermomechanical conditions are presented here. An atlas of microstructures of commercial and experimental wrought and cast aluminum alloys is presented in an appendix to this book. This appendix includes optical photomicrographs of both cast and wrought alloys and scanning electron micrographs of polished surfaces as well as fracture surfaces of various aluminum alloys as well as transmission electron micrographs as separate annexure. Readers are encouraged to go through the optical microstructures and fractographs along with this chapter for better understanding of the evolution of microstructure as a function of alloying additions, thermomechanical processing conditions, and fracture behavior under tension.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"95 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124686212","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 : 2018-11-16DOI: 10.1201/9781351045636-140000336
W. Mattos, B. Rivolta, G. Totten, L. Meekisho, L. Canale
This article aims to describe the media, procedures, and techniques applied to quenching for heat treatment of aluminum alloys besides problems related to this specific process. This article presents important topics such as quench sensitivity, cooling curves analysis, showing experimental apparatus details, influence of probe format and comparison between probe types used in quenching, and problems related to surface oxidation due quenching. Polymer quenchants types are analyzed besides quenching parameters. There is a discussion related to surface rewetting and its importance for quenching successful. Different quenching process are presented like “uphill” process comparing as cryo quenching, ultrasonic agitation, and ionic liquids besides topics related to corrosion types and residual stress after quenching.
{"title":"Quenching of Aluminum Alloys","authors":"W. Mattos, B. Rivolta, G. Totten, L. Meekisho, L. Canale","doi":"10.1201/9781351045636-140000336","DOIUrl":"https://doi.org/10.1201/9781351045636-140000336","url":null,"abstract":"This article aims to describe the media, procedures, and techniques applied to quenching for heat treatment of aluminum alloys besides problems related to this specific process. This article presents important topics such as quench sensitivity, cooling curves analysis, showing experimental apparatus details, influence of probe format and comparison between probe types used in quenching, and problems related to surface oxidation due quenching. Polymer quenchants types are analyzed besides quenching parameters. There is a discussion related to surface rewetting and its importance for quenching successful. Different quenching process are presented like “uphill” process comparing as cryo quenching, ultrasonic agitation, and ionic liquids besides topics related to corrosion types and residual stress after quenching.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124414807","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 : 2018-11-16DOI: 10.1201/9781351045636-140000403
H. Kuhn
In the design of aluminum forgings, the designer must specify the material and process and geometric details so that the component will meet performance requirements. Forging produces parts of high integrity because the process sequences refines and homogenizes metallurgical structure, elimination of material defects assuring maximum material strength. This article specifically addresses the following forging design considerations: material aspects, geometrical aspects, cost aspects, forging methods, process mechanics, and forged part design.
{"title":"Designing for Aluminum","authors":"H. Kuhn","doi":"10.1201/9781351045636-140000403","DOIUrl":"https://doi.org/10.1201/9781351045636-140000403","url":null,"abstract":"In the design of aluminum forgings, the designer must specify the material and process and geometric details so that the component will meet performance requirements. Forging produces parts of high integrity because the process sequences refines and homogenizes metallurgical structure, elimination of material defects assuring maximum material strength. This article specifically addresses the following forging design considerations: material aspects, geometrical aspects, cost aspects, forging methods, process mechanics, and forged part design.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132773806","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 : 2018-11-16DOI: 10.1201/9781351045636-140000278
G. Timelli
The effect of casting defects on the tensile properties of high-pressure die-cast AlSi9Cu3(Fe) alloys is reported. A series of U-shaped structural components has been die-cast using a combination of injection parameters and pouring temperatures in order to produce different types and amount of casting defects throughout the casting. The results reveal how the die-castings contain defects, primarily pores and oxides, and their presence and distribution are highly sensitive to the process conditions. The tensile properties are affected by the amount and distribution of defects and can be determined by the defect area fraction. The influence of casting defects on the tensile properties are investigated through a theoretical verification based both on constitutive and stochastic models. The analytical approach, based on the Ghosh constitutive model of tension instability, correctly indicates the trends of the experimental results, while the Weibull statistics evidences how the scale parameter and the Weibull modulus are strongly affected by the casting conditions.
{"title":"High-Pressure Die-Cast AlSi9Cu3(Fe) Alloys: Models for Casting Defects and Mechanical Properties","authors":"G. Timelli","doi":"10.1201/9781351045636-140000278","DOIUrl":"https://doi.org/10.1201/9781351045636-140000278","url":null,"abstract":"The effect of casting defects on the tensile properties of high-pressure die-cast AlSi9Cu3(Fe) alloys is reported. A series of U-shaped structural components has been die-cast using a combination of injection parameters and pouring temperatures in order to produce different types and amount of casting defects throughout the casting. The results reveal how the die-castings contain defects, primarily pores and oxides, and their presence and distribution are highly sensitive to the process conditions. The tensile properties are affected by the amount and distribution of defects and can be determined by the defect area fraction. The influence of casting defects on the tensile properties are investigated through a theoretical verification based both on constitutive and stochastic models. The analytical approach, based on the Ghosh constitutive model of tension instability, correctly indicates the trends of the experimental results, while the Weibull statistics evidences how the scale parameter and the Weibull modulus are strongly affected by the casting conditions.","PeriodicalId":348912,"journal":{"name":"Encyclopedia of Aluminum and Its Alloys","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133028159","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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