ZrB_2-SiC层状高强界面复合陶瓷材料高温力学性能研究

Study on High Temperature Hechanical Properties of ZrB_2-SiC Laminated High Strength Interface Composite Ceramics

强界面硼化锆陶瓷材料是一种性能优异的高温陶瓷材料,在较高的温度下具有较高的强度以及抗氧化性能,广泛应用于可回收式航空航天飞行器领域中。将强界面ZrB_2-SiC材料抛光后置于不同温度下进行高温力学性能测试,在到达测试温度后进行保温30min后对其施加应力直到材料试样完全断裂为止,可以获得材料相应施加的最大力及其对应强度,并通过扫描电镜照片对测试后的试样表面和断口进行分析。结果表明:在平行和垂直两个方向上,材料的弯曲强度不同。首先在平行方向上随着温度的升高而降低;其次在垂直方向上材料的弯曲强度随着温度升高而降低,其强度在1200℃时为396.78MPa和435.90MPa,在1 500℃时强度达到最小值,分别为220.7MPa和195.15MPa。通过分析可知,垂直方向的弯曲强度高于平行方向,随温度升高弯曲强度会下降,但在1 300℃时出现了一个最小值,是因为B_2O_3受热分解和材料本身受高温引起的缺陷共同作用引起的,垂直方向高于平行方向是由于材料的各向异性,垂直时强度比较大。

It has excellent performance at high temperature, high strength or high oxidation resistance at relatively high tem- perature with the ceramic of strong interface and was a kind of high performance ceramic material with excellent performance. It is widely used in the field of recyclable. There was no doubt that the material was polished and placed at different temperatures.It can help us to test the high temperature mechanical properties. After the temperature was reached for 30 minutes, the test temperatuerwas reached, the stress was applied to the material until the material sample was completely broken. The maximum applied force and the corresponding intensity will through the scanning electron microscope samples on the test after the sample surface and fracture analysis. The results showed that the bending strength of the material is different in both parallel and vertical directions, first decreases in the parallel direction with increasing temperature,decreases of increasing temperature in the vertical direction, and its strength is at 1 200 ℃, there are 396.78 MPa and 435.90 MPa two peaks, when the intensity reaches the minimum, 220.7 MPa and 195.15 MPa in 1 500 ℃. With the analysis, the bending strength in the vertical direction was higher than the parallel direction, and the bending strength decreases with the temperature. However, there is a minimum value at 1 300 ℃ because B2O3 was decomposed by heat and the defects caused by the high temperature of the material itself caused by the vertical direction above the parallel direction. It is due to the anisotropy of the material, the vertical strength was relatively larged.