热解碳基C/C复合材料纤维--基体界面的精细结构

采用JEM-2010型高分辨透射电镜考察了热解碳基碳/碳复合材料的纤维-基体界面结构.实验发现,由化学气相渗透工艺所获得的热解碳并非仅与碳纤表面进行单一的机械粘合,也不是一个简单平面.其间存在具有感应结构的界面层,它是受碳纤维表面微晶感应而形成的由基本平行于表面且更为细小的微晶所组成的厚约数纳米至数十纳米的过渡层,碳纤维微晶越大,取向性越好,则界面层的厚度也越大,取向性也相应提高.由此可定性解释高模量碳纤维与热解碳粘合效果弱于高强碳纤维.

Interfacial Microstructures of Fiber-Matrix in As-received Carbon/Carbon Composites Prepared by CVI

Interfacial microstructures in as-receivedcarbon/carbon composites prepared by CVI were investigated by means of high resolutiontransmission electron microscope(HREM) JEM-2010.It has been found that the pyrolyticcarbon matrix does not merely bond mechanically with carbon fiber surface,and theinterface is not a simple plane yet.There exists a transitional layer with a thickness ofabout several nanometres to several tenfold nanometres between carbon fibre and carbonmatrix because of the induction of basal planes of crystallites on the surface layer ofthe fibers.The transitional layer with an induction sturcture is composed of finercrystallits that are basically parallel to the carbon fibre surface.The bigger in size andthe more regular of orientation of the crystallites on carbon fibre surface,the thickerthe transitional layer and the better orientations of the crystallites.So this can give aqualtative explanation for why there is different bonding effect between pyrolytic carbonmatrix and different kinds of carbon fibres.