In this work,Yb2O3 and Mg O were used as sintering aids in preparing silicon nitride ceramics by gas pressure sintering（ 0. 6 MPa N2atmosphere） to investigate how the amounts of Yb2O3- Mg O influence the mechanical ...In this work,Yb2O3 and Mg O were used as sintering aids in preparing silicon nitride ceramics by gas pressure sintering（ 0. 6 MPa N2atmosphere） to investigate how the amounts of Yb2O3- Mg O influence the mechanical properties and thermal conductivity of silicon nitride ceramics. The total contents of Yb2O3- Mg O added were 1 mol%,2 mol%,4 mol%,6 mol%,8 mol%,10 mol%,12 mol%,14 mol%,keeping the Yb2O3-Mg O molar ratio of 1 ∶ 1 steadily. Curves of the relative density,thermal conductivity and bending strength plotted against the aids content present a ‘mountain＇shape with a maximum at nearly 10 mol% aids. The fracture toughness increased with the amounts of additives up to10 mol% and decreased slightly thereafter. The mechanical properties and thermal conductivity were almost proportional to the amount of the additives before10 mol%. When the content of aids exceeded 10 mol%,it would weaken the mechanical properties and thermal conductivity of the ceramics. The optimum content of Yb2O3- Mg O was 10 mol% by gas pressure sintering（ 0. 6MPa） at 1 850 ℃ for 4 h,which led to a relative density of 98. 9%,a flexural strength of（ 966 ± 38）MPa as well as a fracture toughness of（ 6. 29 ± 0. 29）MPa·m1 /2and thermal conductivity of 82 W /（ m·K）.展开更多
基于MBD(Model Based Definition)技术的船舶数字化工艺设计是对船舶设计模式的创新。分析三维工艺设计流程,利用不锈钢化学品船隔舱分段统一的三维模型进行隔舱分段的工艺流程设计,将工艺模型和船舶产品模型进行中间产品装配体的划分,...基于MBD(Model Based Definition)技术的船舶数字化工艺设计是对船舶设计模式的创新。分析三维工艺设计流程,利用不锈钢化学品船隔舱分段统一的三维模型进行隔舱分段的工艺流程设计,将工艺模型和船舶产品模型进行中间产品装配体的划分,利用DELMIA对隔舱分段中间产品和资源设备进行人机交互式工艺仿真设计,使用优化后的工艺模型完成三维工艺文档的设计。结果表明:基于MBD的三维工艺设计能够打通模型在设计、仿真、建造等多个环节的数据链路,从而有效提升船舶的建造效率和质量。展开更多
Highly porous silica ceramics with different pore sizes were fabricated by adjusting the mixed surfactants addition.The effect of the pore size on the cold compressive strength and the thermal conductivity of the cera...Highly porous silica ceramics with different pore sizes were fabricated by adjusting the mixed surfactants addition.The effect of the pore size on the cold compressive strength and the thermal conductivity of the ceramics was researched.The results show that the smaller pore size can improve the compressive strength and the thermal conductivity.With the mixed surfactants addition increasing from 0.1 mass%to 0.4 mass%,the porosity is close,in the range of 88.10%-88.31%,and the average pore size decreases from 190μm to 97μm;the compressive strength is enhanced from 2.97 MPa to 3.55 MPa;and the thermal conductivity decreases from 0.104 W·m-1·K-1 to 0.089 W·m-1·K-1.展开更多
文摘In this work,Yb2O3 and Mg O were used as sintering aids in preparing silicon nitride ceramics by gas pressure sintering（ 0. 6 MPa N2atmosphere） to investigate how the amounts of Yb2O3- Mg O influence the mechanical properties and thermal conductivity of silicon nitride ceramics. The total contents of Yb2O3- Mg O added were 1 mol%,2 mol%,4 mol%,6 mol%,8 mol%,10 mol%,12 mol%,14 mol%,keeping the Yb2O3-Mg O molar ratio of 1 ∶ 1 steadily. Curves of the relative density,thermal conductivity and bending strength plotted against the aids content present a ‘mountain＇shape with a maximum at nearly 10 mol% aids. The fracture toughness increased with the amounts of additives up to10 mol% and decreased slightly thereafter. The mechanical properties and thermal conductivity were almost proportional to the amount of the additives before10 mol%. When the content of aids exceeded 10 mol%,it would weaken the mechanical properties and thermal conductivity of the ceramics. The optimum content of Yb2O3- Mg O was 10 mol% by gas pressure sintering（ 0. 6MPa） at 1 850 ℃ for 4 h,which led to a relative density of 98. 9%,a flexural strength of（ 966 ± 38）MPa as well as a fracture toughness of（ 6. 29 ± 0. 29）MPa·m1 /2and thermal conductivity of 82 W /（ m·K）.
文摘基于MBD(Model Based Definition)技术的船舶数字化工艺设计是对船舶设计模式的创新。分析三维工艺设计流程,利用不锈钢化学品船隔舱分段统一的三维模型进行隔舱分段的工艺流程设计,将工艺模型和船舶产品模型进行中间产品装配体的划分,利用DELMIA对隔舱分段中间产品和资源设备进行人机交互式工艺仿真设计,使用优化后的工艺模型完成三维工艺文档的设计。结果表明:基于MBD的三维工艺设计能够打通模型在设计、仿真、建造等多个环节的数据链路,从而有效提升船舶的建造效率和质量。
基金This work was supported by National Key Research and Development Program of China(Grant No.2017YFB0406203,No.2017YFB0703200,and No.2017YFB0306500)National Natural Science Foundation of China(Grant No.51302290 and No.51501215)。
文摘Highly porous silica ceramics with different pore sizes were fabricated by adjusting the mixed surfactants addition.The effect of the pore size on the cold compressive strength and the thermal conductivity of the ceramics was researched.The results show that the smaller pore size can improve the compressive strength and the thermal conductivity.With the mixed surfactants addition increasing from 0.1 mass%to 0.4 mass%,the porosity is close,in the range of 88.10%-88.31%,and the average pore size decreases from 190μm to 97μm;the compressive strength is enhanced from 2.97 MPa to 3.55 MPa;and the thermal conductivity decreases from 0.104 W·m-1·K-1 to 0.089 W·m-1·K-1.
