Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low h...Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low humidity resistance. The purpose of this study is to prepare a water-soluble potassium carbonate sand core with addition of kaolin by the hot-temping method. The effects of kaolin on tensile strength, humidity resistance, fracture mechanism, as well as the gas evolution and collapsibility of WSCs were investigated. Results show that both the crystal morphology and the fracture mechanism of the inorganic salt are changed under the participation of kaolin, contributing to the increase of the tensile strength and the humidity resistance of the core. With the addition of 3wt.% kaolin, the tensile strength could be increased by a factor of 2, reached 1.50 MPa and the hygroscopic rate could be decreased by 14%, achieved 0.559%(after stored for 8 h), respectively. As the addition amount of kaolin increases from 0wt.% to 3wt.%, the main fracture mechanism changes from a adhesive to a cohesive fracture mechanism. The water-soluble potassium carbonate core obtained has the low gas evolution and excellent collapsibility, which makes it suitable for casting low melting metal with complex cavities and crooked channels.展开更多
Using a special coated sand as the material of the selected laser sintering (SLS), the authors test and investigate the strength change of the test samples in terms of different sintering parameters (scanning speed, l...Using a special coated sand as the material of the selected laser sintering (SLS), the authors test and investigate the strength change of the test samples in terms of different sintering parameters (scanning speed, laser power, sintering thickness, and so on). The characteristics of coated sand hardening by laser beam are analyzed. The sintered mold (or core) for given casting is poured with molten metal.展开更多
By using Visual C++, a model with post processing was carried out to simulate the temperature and strength distributions of the mold(core). The results are shown in 256 color graphic mode. With this model, the tempera...By using Visual C++, a model with post processing was carried out to simulate the temperature and strength distributions of the mold(core). The results are shown in 256 color graphic mode. With this model, the temperature and strength distributions of the mold(core) both in case of heating process for core in the furnace and solidification process for a thin wall aluminum alloy casting in the mold(core) are numerically simulated. The results show that the temperature and strength distributions of the mold(core) were uneven because the thermal conductivity of the resin sand was much small. This study laid a basis for the optimum design of the mold(core) properties. [展开更多
Water-soluble salt-based ceramic cores can be recycled and have excellent high-temperature chemical stability.In this work,vat photopolymerization was successfully applied to water-soluble salt-based ceramic cores for...Water-soluble salt-based ceramic cores can be recycled and have excellent high-temperature chemical stability.In this work,vat photopolymerization was successfully applied to water-soluble salt-based ceramic cores for the first time.The powder raw materials of the printing suspension were sodium chloride and alumina.High-precision green bodies were manufactured by optimizing suspensions and parameters.In addition,the postprocessing method was optimized according to the microstructure and mechanical properties.The sintered part had a high bending strength and smooth surface.Finally,the dissolution rate and moisture resistance were compared under different dissolution and storage conditions.Compared to traditional manufacturing methods,vat photopolymerization enables the production of complex structures without molds and reduces production costs.This technology is suitable for the rapid iteration of complex structural parts and can be applied to precision parts in aerospace,military,and other technical fields with high cost-effectiveness and sustainability.展开更多
基金supported by the National Natural Science Foundation of China(No.51405002)
文摘Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low humidity resistance. The purpose of this study is to prepare a water-soluble potassium carbonate sand core with addition of kaolin by the hot-temping method. The effects of kaolin on tensile strength, humidity resistance, fracture mechanism, as well as the gas evolution and collapsibility of WSCs were investigated. Results show that both the crystal morphology and the fracture mechanism of the inorganic salt are changed under the participation of kaolin, contributing to the increase of the tensile strength and the humidity resistance of the core. With the addition of 3wt.% kaolin, the tensile strength could be increased by a factor of 2, reached 1.50 MPa and the hygroscopic rate could be decreased by 14%, achieved 0.559%(after stored for 8 h), respectively. As the addition amount of kaolin increases from 0wt.% to 3wt.%, the main fracture mechanism changes from a adhesive to a cohesive fracture mechanism. The water-soluble potassium carbonate core obtained has the low gas evolution and excellent collapsibility, which makes it suitable for casting low melting metal with complex cavities and crooked channels.
文摘Using a special coated sand as the material of the selected laser sintering (SLS), the authors test and investigate the strength change of the test samples in terms of different sintering parameters (scanning speed, laser power, sintering thickness, and so on). The characteristics of coated sand hardening by laser beam are analyzed. The sintered mold (or core) for given casting is poured with molten metal.
文摘By using Visual C++, a model with post processing was carried out to simulate the temperature and strength distributions of the mold(core). The results are shown in 256 color graphic mode. With this model, the temperature and strength distributions of the mold(core) both in case of heating process for core in the furnace and solidification process for a thin wall aluminum alloy casting in the mold(core) are numerically simulated. The results show that the temperature and strength distributions of the mold(core) were uneven because the thermal conductivity of the resin sand was much small. This study laid a basis for the optimum design of the mold(core) properties. [
基金the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2021160)the National Natural Science Foundation of China(No.51802319)the Technology and Engineering Center for Space(No.CSU-QZKT-2019-04).
文摘Water-soluble salt-based ceramic cores can be recycled and have excellent high-temperature chemical stability.In this work,vat photopolymerization was successfully applied to water-soluble salt-based ceramic cores for the first time.The powder raw materials of the printing suspension were sodium chloride and alumina.High-precision green bodies were manufactured by optimizing suspensions and parameters.In addition,the postprocessing method was optimized according to the microstructure and mechanical properties.The sintered part had a high bending strength and smooth surface.Finally,the dissolution rate and moisture resistance were compared under different dissolution and storage conditions.Compared to traditional manufacturing methods,vat photopolymerization enables the production of complex structures without molds and reduces production costs.This technology is suitable for the rapid iteration of complex structural parts and can be applied to precision parts in aerospace,military,and other technical fields with high cost-effectiveness and sustainability.
