Study On The Preparation Of The Bulk Isotropic Pyrolytic Carbon

Isotropic bulk pyrocarbon has many great natures such as high strength, high hardness, low friction, low wear extent and so on. That makes it a perfect material to make moving gland ring severing rugged environment like in rocket, oscar and heliogyro. The research about making this kind of material has been included in 863 national project twice.Normally the bulk isotropic pyrocarbon materials are prepared by mechanical fluidized bed method at home and abroad. This method has several shortcomings including control difficulties and easy impurities introduction. In this experiment we prepared the bulk isotropic carbon using carbon source gas fluidized under the electromagnetic fields generated by high-frequency alternating current. This process possessed the advantages of simple operation and no impurities introduction and so on.The self-designed deposition reactor was applied to fabricate isotropic bulk pyrocarbon.The depositing process was under positive pressure condition with temperrature 1000-1300℃,using C3H6 as carbon source gas and N2 as thinning gas. The density and micro-hardness of isotropic bulk pyrocarbon had been studied. The microstructure porosity and degree of graphitization of the deposited bulk pyrocarbon was investigated by polarized-light microscopy, SEM and XRD respectively. With this research,the mechanics of deposition of bulk pyrocarbon has been discussed and a simple model has been applied to it.Through adjusting depositing temperature composition of carbon source gas and density of carbon source gas etc.,It is found that with temperature 1300℃,when the discharge of C3H6 was 0.2 L/min, the discharge of H2 was 0.3 L/min and the discharge of N2 was 4 L/min,we get isotropy bulk pyrocarbon with the highest density 1.67 g/m3 and its highest part density is 1.93 g/m3...