Investment casting has been widely recognized as the best option in producing TiAl components with key benefits of accuracy,versatility and integrity.The collapsibility of ceramic moulds for investment casting is crit...Investment casting has been widely recognized as the best option in producing TiAl components with key benefits of accuracy,versatility and integrity.The collapsibility of ceramic moulds for investment casting is critical in the manufacturing process of TiAl components due to TiAl's intrinsic brittleness at room temperature.The aim of the present research is to provide a method for production of TiAl components by investment casting in ZrO2 ceramic moulds with improved collapsibility.Slurries prepared with high polymer additions were utilized during the preparation of ceramic moulds.The stress/strain curves obtained from green and baked ceramic moulds demonstrate that the green strength was increased with the application of high polymer,while baked strength decreased,thus the collapsibility of ceramic moulds was improved.It is suggested that this result is related to the burn-out of high polymer which left a lot of cavities.The experimental findings were also verified by the investment casting of "I"-shaped TiAl components.展开更多
The basic requirement of mechanical construction of cast-in-situ concrete is that it could not only conduct quality qualification and safety production, but also achieve most economic benefits with less investment und...The basic requirement of mechanical construction of cast-in-situ concrete is that it could not only conduct quality qualification and safety production, but also achieve most economic benefits with less investment under the condition to meet the needs of project duration. Therefore, the selection of construction machinery scheme plays an important role. However, in the actual construction, it is usually that operators rely on their own experience and field conditions to determine the mechanics. Such a method is subjective and arbitrary, and it is not conducive to make the construction rationally. Considering the above reasons, an improved weight coefficient method was used to establish an estimation model to estimate the construction machinery scheme of cast-in-situ concrete, so as to make the procedure much rational.展开更多
A new improved investment casting technology （IC） has been presented and compared with the existing IC technology such as lost foam casting （LFC）. The effect of thermophysical property and coating thickness on cas...A new improved investment casting technology （IC） has been presented and compared with the existing IC technology such as lost foam casting （LFC）. The effect of thermophysical property and coating thickness on casting solidification temperature field, microstructure and hardness has been investigated. The results show that the solidification rate decreases inversely with the coating thickness when the coating contains silica sol, zircon powder, mullite powder and defoaming agent. In contrast, the solid cooling rate increases as the coating thickness increases. However, the solidification rate and solid cooling rate of the casting produced by the existing IC and the improved IC are very similar when the coating thickness is 5 mm, so the microstructure and hardness of a container corner fitting produced by the improved IC and the existing IC are similar. The linear regression equation for the grain size （d） and cooling rate （v） of the castings is d= -0.41v＋206.1. The linear regression equation for the content of pearlite （w） and solid cooling rate （t） is w=1.79t ＋ 6.71. The new improved IC can greatly simplify the process and decrease the cost of production compared with the existing IC. Contrasting with LI=C, container corner fittings produced by the new improved IC have fewer defects and better properties. It was also found that the desired microstructure and properties can be obtained by changing the thermophysical property and thickness of the coating.展开更多
Up to now,so much casting analysis software has been continuing to develop the new access way to real casting processes. Those include the melt flow analysis,heat transfer analysis for solidification calculation,mecha...Up to now,so much casting analysis software has been continuing to develop the new access way to real casting processes. Those include the melt flow analysis,heat transfer analysis for solidification calculation,mechanical property predictions and microstructure predictions. These trials were successful to obtain the ideal results comparing with real situations,so that CAE technologies became inevitable to design or develop new casting processes. But for manufacturing fields,CAE technologies are not so frequently being used because of their difficulties in using the software or insufficient computing performances. To introduce CAE technologies to manufacturing field,the high performance analysis is essential to shorten the gap between product designing time and prototyping time. The software code optimization can be helpful,but it is not enough,because the codes developed by software experts are already optimized enough. As an alternative proposal for high performance computations,the parallel computation technologies are eagerly being applied to CAE technologies to make the analysis time shorter. In this research,SMP (Shared Memory Processing) and MPI (Message Passing Interface) (1) methods for parallelization were applied to commercial software "Z-Cast" to calculate the casting processes. In the code parallelizing processes,the network stabilization,core optimization were also carried out under Microsoft Windows platform and their performances and results were compared with those of normal linear analysis codes.展开更多
The compositions, technical principles and construction equipments of a new piling method used for ground improvement plastic tube cast-in-place concrete pile were introduced. The results from static load tests on sin...The compositions, technical principles and construction equipments of a new piling method used for ground improvement plastic tube cast-in-place concrete pile were introduced. The results from static load tests on single piles with different forms of pile shoes and on their composite foundations were analyzed. The distribution patterns of axial force, shaft friction and toe resistance were studied based on the measurements taken from buried strain gauges. From the point of engineering application, the pile has merits in convenient quality control, high bearing capacity and reliable quality, showing higher reasonability, advancement and suitability than other ground improvement methods. The pile can be adopted properly to take place of ordinary ground improvement method, achieving greater economical and social benefits.展开更多
基金supported by the National Natural Science Foundation of China under grant No. 51001040the Specialized Research Fund for the Doctoral Program of Higher Education within project No. 200802130014+1 种基金the Fundamental Research Funds for the Central Universities (grant No. HIT NSRIF.2010116)the Development program for Outstanding Young Teachers in Harbin Institute of Technology (HITQNJS 2009022)
文摘Investment casting has been widely recognized as the best option in producing TiAl components with key benefits of accuracy,versatility and integrity.The collapsibility of ceramic moulds for investment casting is critical in the manufacturing process of TiAl components due to TiAl's intrinsic brittleness at room temperature.The aim of the present research is to provide a method for production of TiAl components by investment casting in ZrO2 ceramic moulds with improved collapsibility.Slurries prepared with high polymer additions were utilized during the preparation of ceramic moulds.The stress/strain curves obtained from green and baked ceramic moulds demonstrate that the green strength was increased with the application of high polymer,while baked strength decreased,thus the collapsibility of ceramic moulds was improved.It is suggested that this result is related to the burn-out of high polymer which left a lot of cavities.The experimental findings were also verified by the investment casting of "I"-shaped TiAl components.
文摘The basic requirement of mechanical construction of cast-in-situ concrete is that it could not only conduct quality qualification and safety production, but also achieve most economic benefits with less investment under the condition to meet the needs of project duration. Therefore, the selection of construction machinery scheme plays an important role. However, in the actual construction, it is usually that operators rely on their own experience and field conditions to determine the mechanics. Such a method is subjective and arbitrary, and it is not conducive to make the construction rationally. Considering the above reasons, an improved weight coefficient method was used to establish an estimation model to estimate the construction machinery scheme of cast-in-situ concrete, so as to make the procedure much rational.
文摘A new improved investment casting technology （IC） has been presented and compared with the existing IC technology such as lost foam casting （LFC）. The effect of thermophysical property and coating thickness on casting solidification temperature field, microstructure and hardness has been investigated. The results show that the solidification rate decreases inversely with the coating thickness when the coating contains silica sol, zircon powder, mullite powder and defoaming agent. In contrast, the solid cooling rate increases as the coating thickness increases. However, the solidification rate and solid cooling rate of the casting produced by the existing IC and the improved IC are very similar when the coating thickness is 5 mm, so the microstructure and hardness of a container corner fitting produced by the improved IC and the existing IC are similar. The linear regression equation for the grain size （d） and cooling rate （v） of the castings is d= -0.41v＋206.1. The linear regression equation for the content of pearlite （w） and solid cooling rate （t） is w=1.79t ＋ 6.71. The new improved IC can greatly simplify the process and decrease the cost of production compared with the existing IC. Contrasting with LI=C, container corner fittings produced by the new improved IC have fewer defects and better properties. It was also found that the desired microstructure and properties can be obtained by changing the thermophysical property and thickness of the coating.
文摘Up to now,so much casting analysis software has been continuing to develop the new access way to real casting processes. Those include the melt flow analysis,heat transfer analysis for solidification calculation,mechanical property predictions and microstructure predictions. These trials were successful to obtain the ideal results comparing with real situations,so that CAE technologies became inevitable to design or develop new casting processes. But for manufacturing fields,CAE technologies are not so frequently being used because of their difficulties in using the software or insufficient computing performances. To introduce CAE technologies to manufacturing field,the high performance analysis is essential to shorten the gap between product designing time and prototyping time. The software code optimization can be helpful,but it is not enough,because the codes developed by software experts are already optimized enough. As an alternative proposal for high performance computations,the parallel computation technologies are eagerly being applied to CAE technologies to make the analysis time shorter. In this research,SMP (Shared Memory Processing) and MPI (Message Passing Interface) (1) methods for parallelization were applied to commercial software "Z-Cast" to calculate the casting processes. In the code parallelizing processes,the network stabilization,core optimization were also carried out under Microsoft Windows platform and their performances and results were compared with those of normal linear analysis codes.
基金Project (2007H03) supported by Communications Department of Zhejiang Province
文摘The compositions, technical principles and construction equipments of a new piling method used for ground improvement plastic tube cast-in-place concrete pile were introduced. The results from static load tests on single piles with different forms of pile shoes and on their composite foundations were analyzed. The distribution patterns of axial force, shaft friction and toe resistance were studied based on the measurements taken from buried strain gauges. From the point of engineering application, the pile has merits in convenient quality control, high bearing capacity and reliable quality, showing higher reasonability, advancement and suitability than other ground improvement methods. The pile can be adopted properly to take place of ordinary ground improvement method, achieving greater economical and social benefits.
