The bonding quality of bronze/steel bimetallic laminated composite is the key factor to whether it can be used in poor working conditions.In this study,bimetallic billets were prepared by the protective atmosphere cas...The bonding quality of bronze/steel bimetallic laminated composite is the key factor to whether it can be used in poor working conditions.In this study,bimetallic billets were prepared by the protective atmosphere casting process.The microstructural characteristics,mechanical properties and interface bonding mechanism of the bronze/steel bimetallic composites were analyzed comprehensively through a series of microstructure analysis(inicluding OM,SEM,and EDS)and mechanical properties tests.The experimental results demonstrate that the vaporization of lead(Pb)element in the bronze is only 0.4%in weight,and alloy elements are diffused into both sides at the interface.Moreover,the hardness in the bronze region exceeds 100.0 HV which indicates excellent wear resistance.Tensile and shear tests indicate that the fractures mainly occur on the bronze side with the interaction of the brittle fracture of Pb particles and the ductile fracture of Cu-Sn solid solution.The maximum tensile strength and shear strength reach 204.0 MPa and 211.0 MPa,respectively.These results demonstrate that the protective atmosphere casting process is applicable for the preparation of bronze/steel bimetallic laminated composite with high quality.展开更多
In China,the northeastern region has preserved many valuable modern built heritage buildings,which are undergoing difficult exploratory protection during the industrial and urbanisation process.Taking Dalian city as a...In China,the northeastern region has preserved many valuable modern built heritage buildings,which are undergoing difficult exploratory protection during the industrial and urbanisation process.Taking Dalian city as a case study,this article retraces the history of Dalian’s opening up and colonial management from the perspective of urban planning and historic district protection and management systems.This article sorts out the influence of national and local institutional policies on Dalian’s urban construction and development to analyse the past evolution,current problems and internal causes of the renovation and protection of Dalian’s typical historic districts.This influence is mainly reflected in the lack of protection and damage done to unofficial heritage,the disconnection between historic districts and the surrounding environments and urban textures,and the Chinese-style transformation and economic decline of exotic areas.This paper calls for attention to and the rapid clarification of the built heritage list,the improvement of planning and protection systems and related supporting policies,and a focus on the protection of the authenticity of colonial heritage.This paper provides strategic guidance for improving the protection of historic districts in Dalian in Northeast China and hopes to serve as a reference for the protection of built heritage in other nonfamous historic and cultural cities.展开更多
文摘The bonding quality of bronze/steel bimetallic laminated composite is the key factor to whether it can be used in poor working conditions.In this study,bimetallic billets were prepared by the protective atmosphere casting process.The microstructural characteristics,mechanical properties and interface bonding mechanism of the bronze/steel bimetallic composites were analyzed comprehensively through a series of microstructure analysis(inicluding OM,SEM,and EDS)and mechanical properties tests.The experimental results demonstrate that the vaporization of lead(Pb)element in the bronze is only 0.4%in weight,and alloy elements are diffused into both sides at the interface.Moreover,the hardness in the bronze region exceeds 100.0 HV which indicates excellent wear resistance.Tensile and shear tests indicate that the fractures mainly occur on the bronze side with the interaction of the brittle fracture of Pb particles and the ductile fracture of Cu-Sn solid solution.The maximum tensile strength and shear strength reach 204.0 MPa and 211.0 MPa,respectively.These results demonstrate that the protective atmosphere casting process is applicable for the preparation of bronze/steel bimetallic laminated composite with high quality.
基金Part of the outcome of the research project‘Research on the Synergistic Mechanism of Spatial Reconstruction and Resilient Governance of Northeast Urban Historic Districts’funded by the Humanities and Social Sciences Project of the Ministry of Education.(Project Approval No.21YJC630162).
文摘In China,the northeastern region has preserved many valuable modern built heritage buildings,which are undergoing difficult exploratory protection during the industrial and urbanisation process.Taking Dalian city as a case study,this article retraces the history of Dalian’s opening up and colonial management from the perspective of urban planning and historic district protection and management systems.This article sorts out the influence of national and local institutional policies on Dalian’s urban construction and development to analyse the past evolution,current problems and internal causes of the renovation and protection of Dalian’s typical historic districts.This influence is mainly reflected in the lack of protection and damage done to unofficial heritage,the disconnection between historic districts and the surrounding environments and urban textures,and the Chinese-style transformation and economic decline of exotic areas.This paper calls for attention to and the rapid clarification of the built heritage list,the improvement of planning and protection systems and related supporting policies,and a focus on the protection of the authenticity of colonial heritage.This paper provides strategic guidance for improving the protection of historic districts in Dalian in Northeast China and hopes to serve as a reference for the protection of built heritage in other nonfamous historic and cultural cities.
