The wetting behavior of molten Cu on the B_(4)C-xTiB_(2)ceramic composites was investigated in this work.The results show that the contact angle of molten Cu alloy on B_(4)C-TiB_(2)ceramic composites is linear with th...The wetting behavior of molten Cu on the B_(4)C-xTiB_(2)ceramic composites was investigated in this work.The results show that the contact angle of molten Cu alloy on B_(4)C-TiB_(2)ceramic composites is linear with the composition rate of TiB_(2)or B_(4)C while the temperature is in the range of 1300 to 1350℃,consistent with the expectation of the commonly used theoretical method.However,a nonlinear relationship between the contact angle and the composition rate unexpectedly occurred at temperatures ranging from 1400 to 1500℃.The big difference of the contact angles between the molten metal and the components in the composites was found to be the key point.This result identifies that the commonly used theoretical method only works at a limited difference of the contact angle of the liquid on the different phases in the composites,and fails at a big difference.展开更多
The effects of particle size,gradation and solid loading of silicon nitride (Si_(3)N_(4)) on the rheological behavior and curing properties of ceramic slurry are studied by stereolithography (SLA).The results show tha...The effects of particle size,gradation and solid loading of silicon nitride (Si_(3)N_(4)) on the rheological behavior and curing properties of ceramic slurry are studied by stereolithography (SLA).The results show that the particle size of Si_(3)N_(4) powder has a signif icant influence on the rheological properties and stability of the slurry.When m_(D50=1.3μm):m_(D50=2.3μm)=3:7,the slurry viscosity is low and the sedimentation is slow.The most important thing is that with the increase of the solid loading of the slurry,the viscosity of the slurry increases,the stability becomes higher,and the curing thickness decreases.The curing thickness of Si_(3)N_(4) ceramic slurry with solid loading of 50 vol% can reach nearly 50μm.The above results finally show that the process optimizes the formulation of the slurry in rheological and curing properties.展开更多
B_(4)C-SiC-TiB_(2)ceramics were prepared by in situ reactive hot-pressing sintering with TiSi_(2)as an additive.The reaction pathways of TiSi_(2)and B_(4)C were investigated.The sintering was found to be a multistep p...B_(4)C-SiC-TiB_(2)ceramics were prepared by in situ reactive hot-pressing sintering with TiSi_(2)as an additive.The reaction pathways of TiSi_(2)and B_(4)C were investigated.The sintering was found to be a multistep process.The reaction started at approximately 1000℃,and TiB_(2)was formed first.Part of Si and C started to react at 1300℃,and the unreacted Si melted at 1400℃to form a liquid phase.TiSi_(2)predominantly affected the intermediate sintering process of B_(4)C and increased the sintering rate.Due to the unique reaction process of TiSi_(2)and B_(4)C,a large number of aggregates composed of SiC and TiB_(2)were generated.The results showed that composite ceramics with the optimal flexural strength of 807 MPa,fracture toughness of 3.2 MPa·m1/2,and hardness of 32 GPa,were obtained when the TiSi_(2)content was 10 wt%.展开更多
Based on the mechanical properties and microstructure of polyurethane foam solidified material, a two-dimensional model of polyurethane foam solidified material was constructed. Polyurethane foam was obtained by fully...Based on the mechanical properties and microstructure of polyurethane foam solidified material, a two-dimensional model of polyurethane foam solidified material was constructed. Polyurethane foam was obtained by fully and uniformly mixing the two components. The research was carried out through the combination of experimental test and finite element simulation. The experimental results show that when the pore density is constant, the size of the bubble hole is an important factor affecting the mechanical properties of the model. The smaller the size of the bubble hole, the less likely it is to produce stress concentration inside the model, and the stronger the resistance to material deformation. Under the random distribution, the lower the density of the polyurethane cured material, the higher the probability of damage between the adjacent bubbles, which is not conducive to the stability of the material. The density of the cured material should not be lower than 199 kg/m^3.展开更多
基金Funded by National Natural Science Foundation of China(Nos.51521001,51832003,and 51911530153)。
文摘The wetting behavior of molten Cu on the B_(4)C-xTiB_(2)ceramic composites was investigated in this work.The results show that the contact angle of molten Cu alloy on B_(4)C-TiB_(2)ceramic composites is linear with the composition rate of TiB_(2)or B_(4)C while the temperature is in the range of 1300 to 1350℃,consistent with the expectation of the commonly used theoretical method.However,a nonlinear relationship between the contact angle and the composition rate unexpectedly occurred at temperatures ranging from 1400 to 1500℃.The big difference of the contact angles between the molten metal and the components in the composites was found to be the key point.This result identifies that the commonly used theoretical method only works at a limited difference of the contact angle of the liquid on the different phases in the composites,and fails at a big difference.
基金Funded by National Natural Science Foundation of China (No.43200021)。
文摘The effects of particle size,gradation and solid loading of silicon nitride (Si_(3)N_(4)) on the rheological behavior and curing properties of ceramic slurry are studied by stereolithography (SLA).The results show that the particle size of Si_(3)N_(4) powder has a signif icant influence on the rheological properties and stability of the slurry.When m_(D50=1.3μm):m_(D50=2.3μm)=3:7,the slurry viscosity is low and the sedimentation is slow.The most important thing is that with the increase of the solid loading of the slurry,the viscosity of the slurry increases,the stability becomes higher,and the curing thickness decreases.The curing thickness of Si_(3)N_(4) ceramic slurry with solid loading of 50 vol% can reach nearly 50μm.The above results finally show that the process optimizes the formulation of the slurry in rheological and curing properties.
基金Funded by the National Natural Science Foundation of China(No.52002299)。
文摘B_(4)C-SiC-TiB_(2)ceramics were prepared by in situ reactive hot-pressing sintering with TiSi_(2)as an additive.The reaction pathways of TiSi_(2)and B_(4)C were investigated.The sintering was found to be a multistep process.The reaction started at approximately 1000℃,and TiB_(2)was formed first.Part of Si and C started to react at 1300℃,and the unreacted Si melted at 1400℃to form a liquid phase.TiSi_(2)predominantly affected the intermediate sintering process of B_(4)C and increased the sintering rate.Due to the unique reaction process of TiSi_(2)and B_(4)C,a large number of aggregates composed of SiC and TiB_(2)were generated.The results showed that composite ceramics with the optimal flexural strength of 807 MPa,fracture toughness of 3.2 MPa·m1/2,and hardness of 32 GPa,were obtained when the TiSi_(2)content was 10 wt%.
基金Funded by the National Innovation Platform Open Fund(No.2017YJ163)
文摘Based on the mechanical properties and microstructure of polyurethane foam solidified material, a two-dimensional model of polyurethane foam solidified material was constructed. Polyurethane foam was obtained by fully and uniformly mixing the two components. The research was carried out through the combination of experimental test and finite element simulation. The experimental results show that when the pore density is constant, the size of the bubble hole is an important factor affecting the mechanical properties of the model. The smaller the size of the bubble hole, the less likely it is to produce stress concentration inside the model, and the stronger the resistance to material deformation. Under the random distribution, the lower the density of the polyurethane cured material, the higher the probability of damage between the adjacent bubbles, which is not conducive to the stability of the material. The density of the cured material should not be lower than 199 kg/m^3.
