TiB_2-Cu-Ni金属陶瓷的抗热震和抗烧蚀行为

THERMAL SHOCK RESISTANCE AND ABLATION BEHAVIOUR OF TITANIUM DIBORIDE-COPPER-NICKEL CERMET

利用Ti和B元素之间的化学反应放热,采用燃烧合成与同时致密化技术制备了TiB2-Cu-Ni金属陶瓷。利用等离子火炬电弧加热器来考察材料的抗热震性能以及抗烧蚀性能,利用扫描电镜、电子探针和能谱分析等方法对材料烧蚀前后的微观组织形貌及成分进行了检测。结果表明,金属陶瓷材料具有较好的抗热震性能,在瞬间热冲击时未出现崩裂,在烧蚀刚结束时有宏观裂纹产生。同时该材料还具有良好的抗烧蚀性能,经过20s烧蚀后,其质量损失仅为0.9g,质量烧蚀率为0.045g/s。材料的抗烧蚀机理为金属粘接剂挥发损失、热化学烧蚀和机械冲刷。

Titanium diboride-copper-nickel cermet was fabricated from titanium, boron, copper and nickel powders by combustion synthesis under conditions of pseudo hot isostatic pressing. The TiB2-Cu-Ni cermet was heated by using a plasma torch to investigate the thermal shock resistance and ablation behaviour. The microstructures of the cermet pre- and post-ablation were examined by SEM, EPMA and EDX. The result shows that the thermal shock resistance of the cermet is good, and the cermet does not burst apart when the material is instantly heated. However, a macro-crack is immediately formed on the surface of cermet when the ablation is just over. The mass loss of cermet after ablation for 20 s is 0.9 g and the mass loss ratio is 0.045 g/s, which shows a good ablation property of the material. The ablation mechanism of TiB2-Cu-Ni cermet is the volatilization of metal binder, hot chemical ablation and mechanical erosion.