原始粉末尺寸对Ti(C,N)基金属陶瓷烧结特性和组织结构的影响

Effect of initial powder size on the sintering characteristic and microstructure of Ti(C,N)-based cermet

用热分析仪、扫描电镜和透射电镜对主要硬质相分别以亚微粉、亚微粉与纳米粉的混合粉(以下简称混合粉)、纳米粉为原料制成的Ti(C,N)基金属陶瓷的烧结特性、组织结构和性能进行了研究。结果表明:主要硬质相TiC、TiN的粉末粒度越细,金属陶瓷的液相点越低,并且其快速致密化过程开始得越早,但主要硬质相全为纳米粉时,最终无法使其达到较高的致密度。用亚微粉制得的金属陶瓷具有常规金属陶瓷的典型结构,即"黑芯-白壳"。用纳米混合粉制得的金属陶瓷,没有明显Rim相的小颗粒和具有"白芯-黑壳"结构的小颗粒的数量大大增加,而具有"黑芯-白壳"结构的大颗粒的数量没有明显的增加。部分纳米粉的加入使金属陶瓷的综合力学性能得到了较大的提高。

The sintering characteristic, microstructures and properties of Ti(C,N)-based cermets produced with submicron, nano-composite and nanostructured powders respectively, were investigated by means of differential thermal analysis meter, SEM and TEM to improve their mechanical properties. The results show that the finer the main ceramic powders are, the lower the melting point temperatures will be and the earlier the quick consolidation will start. However, when the ceramic powders are all nanostructured, the cermet couldn't be consolidated completely because of too much adsorbent oxygen. The cermet produced with submicron powders is characterized with typical black core-white rim structure. But it is found that in the cermet produced with nano-composite the number of small grains without obvious rim phase and with white core-black rim structure increases greatly, and the number of big grains with black core-white rim nearly keeps unchanged. The addition of nanostructured powders improves the mechanical properties of cermets greatly.