激光照射原位生成SiC晶须的晶须形态

Morphology of SiC whisker in-situ growth by laser irradiation

利用冷等静压法将掺有粘结剂的SiC纳米颗粒压制成块体并经大功率CO2激光器照射,在激光照射区域获得SiC晶须,利用扫描电镜对晶须进行观察,分析照射层不同区域和不同气氛环境下晶须形态的变化。结果表明:不同气氛环境下晶须形态有显著区别,分别表现为放射状团簇特征、螺旋状团簇特征和密排短棒状团簇特征;同一照射层内,不同区域晶须形态也不一致,沿光束入射方向,可见以较大晶粒为核心的团簇状小长径比晶须和数量丰富、形态良好的大长径比晶须;不同的气氛组分和光强梯度分布是造成晶须形态不同的主要原因。

The in-situ growth of SiC whiskers by laser irradiation directly on nano-particles mixed with binder and compressed by the cold isostatic pressing method was performed.The morphologies of SiC whiskers were observed by means of the scanning electron microscopy.The results show that the whiskers exhibit,respectively,as the feature of actinomorphic cluster,helical cluster and short-rod cluster,which grow in the specimen with the binder.In the different irradiation regions within discretionary specimen,the whiskers morphologies are not alike.Along the direction of incidence of laser beam,the whiskers with small long-diameter ratio grow around the large crystal grain in the middle region of irradiation layer,the shape of them is the short-rod.At the bottom,the abundant and fine whiskers with the feature of large long-diameter ratio are observed.The gasification products of different binders and the grads distributing of laser intensity are the master factors to cause different whisker morphologies.