热压烧结Al2O3-ZrB2-SiC复相陶瓷的高温力学性能研究

Hot mechanical properties of hot pressed sintering Al_2O_3-ZrB_2-SiC composite ceramics

为提高Al2O3陶瓷的高温力学性能,采用热压烧结工艺(烧结温度1 800℃,烧结压力20 MPa,保温1 h)制备了Al2O3-ZrB2-SiC复相陶瓷(简称AZS),并研究了ZrB2含量对Al2O3基陶瓷高温抗折强度和抗热震性的影响。结果表明:1)在Al2O3基陶瓷中加入第二相ZrB2能有效改善材料的高温抗折强度和高温强度保持率,在1 000和1 200℃时,加入20%体积分数ZrB2的AZS陶瓷试样具有最高的高温抗折强度,而加入24%体积分数ZrB2的AZS陶瓷试样具有最高的高温强度保持率。2)AZS陶瓷的抗热震性能优于纯Al2O3陶瓷。经100℃温差急冷后,加入20%体积分数ZrB2的AZS陶瓷具有最高的残余强度,比纯Al2O3陶瓷提高了17.2%;经300和500℃温差急冷后,加入24%体积分数ZrB2的AZS陶瓷都具有最高的残余强度,比Al2O3陶瓷分别提高了35.3%和20.9%。

Magnesia tundish coatings were prepared using fused magnesia and sodium hexametaphos- phate as starting materials with sodium hexametaphosphate mass percent of 1% ,2% ,3%, and 5%, re- spectively. The prepared magnesia tundish coatings were cast into crucibles. Then the crucibles added with IF steel were put into a vacuum carbon tube furnace at 1 600 ~C for 2 h for smelting test. The crucibles and IF steel samples were studied by SEM and EDS. The total oxygen content and inclusion element con- tent of the steel samples were tested. The results show that：with the increase of sodium hexametaphos- phate addition in the magnesia coatings,the contents of O,C,and P in the IF steel increase gradually,and contents of Mn,Si,AI,and Ti in the IF steel change slightly;oxide inclusions in IF steel are mainly P205 and MnO.