Clvd France C / C Friction And Wear Performance Studies

Carbon-carbon composite (in short, C/C) has unapproachable advantages as brake material in the field of aviation. The friction property of C/C is influenced by its carbon microstructure. So appropriate carbon microstructure prepared by relevant method is the important factor for eligible brake material. The conventional preparing method -chemical vapor deposition (CVD) need a long period and expensive cost. But the period and cost of the new preparing method - chemical liquid vapor deposition (CLVD) is much lower, it is one of the preferable method of preparing C/C. C/C has different pyrocarbon and property prepared by different method. The method of CLVD is being researched in our country. It could be important and practical to study the carbon microstructure and property of C/C prepared by CLVD especially used as brake material.Friction property of carbon-carbon composite prepared by chemical liquid-vapor deposition was studied in this paper.Three sets (six pieces) of C/C samples that numbered No. 1-2, No.3-4 and No.5-6 were prepared by CLVD. The main pyrocarbon found in No. 1-2 C/C was rough laminar and smooth laminar (RL+SL), and that in No.3-4 was rough laminar and a few smooth laminar (RL+a few SL), and that in No.5-6 was smooth laminar and isotropic (SL+ISO). Heat treatment of the three sets C/C samples with different density and microstructures was made at the same condition, and different graphitizations were obtained.The graphitization of each set C/C was 43%,46% and 40%. Each set C/C sample was machined to a rolling brake-block and a static brake-block. The three samples were investigated on the MM-1000 friction-test apparatus at simulating airplane normal landing. The test results showed the friction coefficient and torque stabilization coefficient of No.3-4 were better, the brake time was shorter and the brake-block temperature-rise was lower. This showed the material such as No.3-4 C/C could be a promising candidate as airplane brake material.The cause of the different friction properties of the three sets C/C was connected with their own pyrocarbon microstructure. Because the friction property of C/C was connected with the debris layer cover the worn surface in braking test. The No.3-4 C/C with RL pyrocarbon and high graphitization had formed a continuous and compact debris layer cover its worn surface in braking test. This made its friction coefficient keeping on the high level and its brake torque curve keeping stable. Because the No. 1-2 C/C with RL and SL pyrocarbon and lower graphitization had formed some hard debris layer on its worn surface in braking test, the continuous and compact debris layer was influenced, so its friction coefficient and brake torque stabilization coefficient showed lower than that of No.3-4 C/C. The No.5-6 C/C with RL and ISO pyrocarbon and lowest graphitization was difficult to form the continuous and compact debris layer on its worn surface, so its friction coefficient was the lowest and its brake torque was unstable.The test and research results showed that the pyrocarbon of C/C prepared by CLVD was an important influence factor on its friction property. The C/C with RL pyrocarbon showed excellent friction property , so it could be a promising candidate as airplane brake material.