密封用炭/炭复合材料的摩擦磨损性能

Friction and Wear Properties of C/C Composites Used as Sealing Materials

针对液体火箭发动机涡轮泵密封件磨损量较大问题,在MVF-1A多功能立式摩擦磨损试验机上,以GCr15钢环为对偶件,研究低载荷高线速度(12N,2.25m/s)以及高载荷低线速度(50N,1.25m/s)工况条件下热处理温度不同时(2 250、2 400和2 500℃)对炭/炭(C/C)密封材料摩擦磨损性能的影响,采用扫描电镜观察摩擦表面形貌,利用能谱仪确定摩擦表面元素组成。结果表明:低温(2 250℃)热处理材料石墨化度程度低,弯曲强度高,摩擦因数小,线性磨损量大;随着热处理温度的升高,材料石墨化程度升高、界面结合强度弱化,弯曲强度降低;当热处理温度升高到2 500℃后,材料表面易形成完整致密的磨屑膜,磨损机制由磨粒磨损转变为粘着磨损,摩擦因数大,线性磨损量低。此外,在高载荷条件下,适当增大线速度(1.50、1.88m/s),有利于降低摩擦因数及线性磨损量。由此可知,采用高温(2 500℃)热处理的C/C复合材料具有良好抗磨性能,可较好地满足密封件使用要求。

To solve the problem that the seal component of the turbine pump of a liquid rocket engine is badly worn the friction coefficient and line wear of C/C composites （heat-treated at different temperatures 2250℃, 2400℃ and 2500℃）to GCrl5 steel vice were tested on the MVF-1A multifunction vertical friction and wear machine under the conditions of lower load but higher line speed （12 N, 2.25 m/s）, higher load but lower line speed （50 N, 1.25 m/s）. The effects of heat-treated temperature （HTT） on tribology of C/C composites were investigated, the wear surfaces morphologies were examined by SEM, and the element of the wear surfaces were analyzed by EDAX. The results show that the sam- ples heat-treated at 2250℃ attain the lower degree of graphitization, higher flexural strength, lower friction coefficient and a larger amount of line wear. With the increase of HTT, the degree of graphitization increases, the interface bonding strength is weakened, and the flexural strength decreases. When the HTT of the samples is raised to 2500℃, the fric- tion coefficient increases but the line wear decrease. The SEM shows that it is easy to form an integrated and dense film on wear surface, and the mechanism of wear is transferred from abrasion to adhesion wear. Additionally, under the high load condition, appropriately increasing the line speed （1.50 m/s and 1.88 m/s） can help to reduce the friction coefficient and line wear. Heat-treated at high temperature （2500℃） can improve the wear resistance of the C/C composites and better meet the seal component requirements.