反应烧结氮化硅的热压

Hot-Pressed RBSN

以添加 Y_2O_3、La_2O_3的反应烧结氮化硅为起始材料,研究热压工艺参数(温度、压力和保温时间)和添加物数量对材料性能的影响。当热压反应烧结氮化硅时,材料的致密化速度较慢,而α-Si_3N_4向β-Si_3N_4转化的速度较快,为了获得较佳性能的材料,采用了适当的热压温度、较大的热压压力和充分的保温时间,使反应烧结氮化硅变成致密的高性能陶瓷材料,其抗弯强度(≥800 MPa)可保持到1300℃,目前,通过严格控制微观结构的形成已能获得抗弯强度>1000MPa 的制品。TEM 的研究表明:材料的晶界相为含 Y、La 的玻璃相。

Using RBSN with Y_2O_3 and La_2O_3 additives as raw materials,we have investi-gated the effects of hot-pressing parameters(temperature,pressure and holoing time)and amount of the additives on the properties of products.For RBSN hot-pressed,the densificating rate is slower,but the transition rate of α-Si_3N_4→β-Si_3N_4 is fasterthan that of Si_3N_4 powders hot-pressed.In order to get better materials,it is neces-sary to control the hot-pressing temperature,pressure and holding time strictly.The results obtained by TEM show that the glass phase in grain boundariesconsists of Y_2O_3-La_2O_3-SiO_2.It is possible to make RBSN densified with highperformance by hot-pressing process;the bending strength of 800 MPa can be retai-ned up to 1300℃.Through carefully controlling the formation of its microstructure,we have obtained the strength of the product closed to 1000 MPa.