Aviation Engine Shaft Seal C / C Composites And Friction And Wear Characteristics

The seal ring is the critical part for the sealing of the main axis of aeroplane engine. According to the requirement of applying conditions, it must have high strength, excellent oxidation resistance and low coefficient of friction and wear ratio. The carbon-carbon composites were fabricated and their properties were analyzed. What's more, friction and wear properties of two types of materials, carbon-carbon composite and high strength graphite which was supposed to be used as the seal ring of the main axis of aeroplane engine, were investigated.According to the requirement of applying conditions and properties of the seal ring of the main axis of aeroplane engine, preforms were designed into the substrate that the carbon cloth and felt alternately were winded around the cylinder and then needled with carbon fiber in the radial direction and the other 3-D weaving substrate. To reinforce the fibre and the matrix connecting, preforms were densified by CVD firstly. The pyrolytic carbon with RL/SL structure or SL structure was obtained. After that, the materials were further densified with resin and heat treated at 2100 癈 . The strength and wear resistance was improved, and the resin would guarantee the sealing effect. After heat treatment, the degree of graphitization of the materials was about 30~50%, and the degree of graphitization of material l-6# was amount to 47.1%. The hardness of the 3-D preform material was close in the radial and circumambient direction. But the hardness of the other preform was almost anisotropic. The thermal conductivity was also anisotropic. The coefficient of thermal expansion decreased with the temperature increased. When 400X1!, it was at the bottom, and when to 500*C, it increased. And the mechanical property of carbon-carbon composite was pseudo-plastic.By studying friction and wear of the carbon-carbon composite andhigh strength graphite, it was found that the fibre laying pattern, the hardness of the material, the degree of graphitization and the wear field were related to friction and wear properties of carbon-carbon composites. The coefficient of friction of the carbon-carbon is from 0.08 to 0.15.And the coefficient of friction of graphite is higher, about 0.23, and its weight loss is more. When carbon-carbon composite was lubricated by water, the coefficient of friction decreased with water film formed. And the weight loss increased because the wear debris was taken away by the water. From the view of friction and wear, carbon-carbon composite has advantage over high strength graphite when it is used as the seal ring of the main axis of aeroplane engine.The gas-film sealing technology is a kind of advanced structure for the sealing of the main axis of aeroplane engine. Carbon-carbon composite which has high strength, excellent heat-resistance, excellent oxidation resistance, low coefficient of friction and wear ratio is suitable to be used as the seal ring of axis of aeroplane engine. It can replace high strength graphite. And it can also compensate the blank of this applying field.