TiC-Al_2O_3陶瓷裂纹治愈及强度的研究

Study on crack-healing and its effect on strength of TiC-Al_2O_3 ceramics

以Al2O3和TiC粉体为原料,经热压烧结制备了TiC-Al2O3复合陶瓷材料,采用Vickers硬度仪在TiC-Al2O3复合陶瓷材料表面引入裂纹,结合扫描电镜组织分析及XRD衍射仪物相分析,研究了不同热处理温度对TiC-Al2O3复合陶瓷材料裂纹愈合情况及其力学性能的影响规律。结果表明,TiC-Al2O3复合陶瓷材料光滑试样的平均抗弯强度为600MPa,引入裂纹后平均抗弯强度下降至200MPa;分别经800℃、1000℃1、200℃×4h治愈后,抗弯强度明显回升,治愈温度为800℃时,平均强抗弯度接近500MPa,是未经热处理试样平均抗弯强度的2.5倍;1000℃时平均抗弯强度为352MPa,1200℃时平均抗弯强度为259MPa。XRD衍射分析表明,热处理使TiC-Al2O3陶瓷中的TiC发生氧化反应,生成TiO2填充裂纹是材料愈合和抗弯强度提高的主要原因;治愈温度超过800℃后,锐钛矿TiO2转变为金红石TiO2时产生裂纹,降低了材料的强度。

TiC-Al2O3 composite ceramics was facboricated by hot press and sinter process.Crack was introduced at the surface of the prepared ceramics specimen by a vickers hardness tester.Crack-healing under various heat treatment processes and its effect on mechanical properties of TiC-Al2O3 composite ceramics were investigated by SEM and XRD.The results show that the average bending strength of the smooth ceramics specimens is 600 MPa,and the average bending strength of the specimens after introducing cracks reduces to 200 MPa. After heat treatment at 259MPa, respectively. The proper healing temperature is 800℃ in the present investigation. The XRD analysis shows that TiC （s） ＋ O2 （g）→TiO2 （s） ＋ CO（g） occurs during heat treatment process. It is the TiO2 that fills in cracks to improve bending strength of the ceramics.