Through introducing the analytical problem of the plate with convection into the solution of the transient heat conduction thermal stress field model of the elastic plate, the stress reduction factor is presented expl...Through introducing the analytical problem of the plate with convection into the solution of the transient heat conduction thermal stress field model of the elastic plate, the stress reduction factor is presented explicitly in its dimensionless form. A new stress reduction factor is introduced for the purpose of comparison. The proper- ties and appropriate conditions of the stress reduction factor, the first and second ther- mal shock resistance （TSR） parameters for the high and low Biot numbers, respectively, and the approximation formulas for the intermediate Blot number-interval are discussed. To investigate the TSR of ceramics more accurately, it is recommended to combine the heat transfer theory with the theory of thermoelasticity or fracture mechanics or use a numerical method. The critical rupture temperature difference and the critical rup- ture dimensionless time can be used to characterize the TSR of ceramics intuitively and legibly.展开更多
The nanosize AIN particles were prepared by evaporation-condensation method in DC arc nitrogen plasma. Aluminium of high purity (99. 999%) was evaporated and nitrided in nitro-gen plasma by use of high temperature and...The nanosize AIN particles were prepared by evaporation-condensation method in DC arc nitrogen plasma. Aluminium of high purity (99. 999%) was evaporated and nitrided in nitro-gen plasma by use of high temperature and high re-activity of plasma gas. The purity of nanosize AIN particles is more than 98% (wt%) and the average particle size is about 50nm. The grain growth of nanosize AlN particle is also studied. The results show that the nanosize AlN particle begins to grow up at 900℃ and the grain growth increase rapidly at 1100℃. When the temperature is increased to 1600℃, the surface of nanosize AIN particle has been sintered softly. Results will be beneficial to pre-pare AIN ceramics.展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 90916009 and11172336)
文摘Through introducing the analytical problem of the plate with convection into the solution of the transient heat conduction thermal stress field model of the elastic plate, the stress reduction factor is presented explicitly in its dimensionless form. A new stress reduction factor is introduced for the purpose of comparison. The proper- ties and appropriate conditions of the stress reduction factor, the first and second ther- mal shock resistance （TSR） parameters for the high and low Biot numbers, respectively, and the approximation formulas for the intermediate Blot number-interval are discussed. To investigate the TSR of ceramics more accurately, it is recommended to combine the heat transfer theory with the theory of thermoelasticity or fracture mechanics or use a numerical method. The critical rupture temperature difference and the critical rup- ture dimensionless time can be used to characterize the TSR of ceramics intuitively and legibly.
文摘The nanosize AIN particles were prepared by evaporation-condensation method in DC arc nitrogen plasma. Aluminium of high purity (99. 999%) was evaporated and nitrided in nitro-gen plasma by use of high temperature and high re-activity of plasma gas. The purity of nanosize AIN particles is more than 98% (wt%) and the average particle size is about 50nm. The grain growth of nanosize AlN particle is also studied. The results show that the nanosize AlN particle begins to grow up at 900℃ and the grain growth increase rapidly at 1100℃. When the temperature is increased to 1600℃, the surface of nanosize AIN particle has been sintered softly. Results will be beneficial to pre-pare AIN ceramics.
