碳化硅/石墨复合陶瓷密封材料的显微结构与性能
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摘要
以碳化硅微粉为原料、石墨为固体润滑添加剂,采用无压烧结技术制备碳化硅/石墨复合陶瓷密封材料,研究了石墨添加量对复合陶瓷密封材料烧结性能、显微结构、力学性能和摩擦性能的影响。结果表明,加入的石墨能以片状颗粒形态均匀分布在碳化硅陶瓷基体中;随着石墨添加量增加,复合陶瓷密封材料的体积密度、抗弯强度、弹性模量、断裂韧性、硬度均逐渐降低,但干、湿静摩擦系数则随之减小;当石墨添加量达到20%(质量分数)时,复合陶瓷的相对密度仅为90.6%,弯曲强度降至189 MPa,弹性模量降至295 GPa,断裂韧性为1.82 MPa·m1/2,Vickers硬度为19.2 GPa,而干、湿摩擦系数则分别减小到0.14和0.10。综合考虑复合陶瓷的力学性能和摩擦性能,石墨添加量控制在10%~15%之间为宜。
Silicon carbide(Si C)/graphite composite ceramic seals were prepared with Si C powder as a raw material and graphite as a lubricant via pressureless sintering. The effect of graphite content on the sintering behaviors, microstructure, and mechanical and friction properties of composite ceramic seals were investigated. The results show that the flake-shaped particles of graphite are uniformly distributed in the Si C ceramic matrix. The bulk density, flexural strength, elastic modulus and dry and wet frictional coefficients of the composite ceramic seals gradually decrease with the increase of graphite content. The relative density of the composite ceramic is only 90.6 %, the flexural strength decreases to 189 MPa, the elastic modulus decreases to 295 GPa, the fracture toughness decreases to 1.82 MPa·m1/2, and the Vickers hardness decreases to 19.2 GPa, and the dry and wet friction coefficient reduce to 0.14 and 0.10, respectively, when the graphite content increases to 20 %(mass fraction). It is indicated that the graphite content of 10 %–15 % is suitable for Si C ceramic seals based on the corresponding mechanical and friction properties.
Silicon carbide(Si C)/graphite composite ceramic seals were prepared with Si C powder as a raw material and graphite as a lubricant via pressureless sintering. The effect of graphite content on the sintering behaviors, microstructure, and mechanical and friction properties of composite ceramic seals were investigated. The results show that the flake-shaped particles of graphite are uniformly distributed in the Si C ceramic matrix. The bulk density, flexural strength, elastic modulus and dry and wet frictional coefficients of the composite ceramic seals gradually decrease with the increase of graphite content. The relative density of the composite ceramic is only 90.6 %, the flexural strength decreases to 189 MPa, the elastic modulus decreases to 295 GPa, the fracture toughness decreases to 1.82 MPa·m1/2, and the Vickers hardness decreases to 19.2 GPa, and the dry and wet friction coefficient reduce to 0.14 and 0.10, respectively, when the graphite content increases to 20 %(mass fraction). It is indicated that the graphite content of 10 %–15 % is suitable for Si C ceramic seals based on the corresponding mechanical and friction properties.
引文
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[3]顾永泉.机械密封实用技术[M].北京:机械工业出版社,2001:85–109.
[4]王静,张玉军,龚红宇.无压烧结碳化硅研究进展[J].陶瓷,2008(4):17–50.WANG Jing,ZHANG Yujun,GONG Hongyu.Ceramics(in Chinese),2008(4):17–50.
[5]郭兴忠,朱潇怡,张玲洁,等.无压烧结制备纳米复合碳化硅陶瓷[J].硅酸盐学报,2010,38(2):258–264.GUO Xingzhong,ZHU Xiaoyi,ZHANG Lingjie,et al.J Chin Ceram Soc,2010,38(2):258–264.
[6]郭兴忠,杨辉,王建武.Si C/YAG复合粉体的烧结特性与力学性能[J].稀有金属材料与工程,2004,33(3):58–60.GUO Xingzhong,YANG Hui,WANG Jianwu.Rare Met Mater Eng(in Chinese),2004,33(3):58–60.
[7]SAINI I,SHARMA A,ROZRA J,et al.Modification of structural,thermal,and electrical properties of PVA by addition of silicon carbide nanocrystals[J].J Appl Polym Sci,2015,132(34):42464–42471.
[8]GUO X Z,YANG H,ZHU X Y,et al.Preparation and properties of nano-Si C-based ceramic composites containing nano-Ti N[J].Scr Mater,2013,68:281–284.
[9]KRENKEL W,HEIDENREICH B,RENZ R.C/C-Si C composites for advanced friction systems[J].Adv Eng Mater,2002,4(7):427–436.
[10]张亚妮,徐永东,楼建军,等.碳/碳化硅复合材料摩擦磨损性能分析[J].航空材料学报,2005,25(2):49–54.ZHANG Yani,XU Yongdong,LOU Jianjun,et al.J Aeronaut Mater,2005,25(2):49–54.
[11]GUO X Z,CAI X B,ZHANG J L,et al.Sintering,properties and microstructure of low friction Si C ceramic seals containing graphite fluoride[J].Adv Appl Ceram,2013,112(6):341–344.
[12]YANG H,ZHANG J L,GUO X Z,et al.Pressureless sintering of silicon carbide ceramics containing zirconium diboride[J].Ceram Int,2011,37:2031–2035.
[13]ZHANG J L,YANG H,GUO X Z,et al.Preparation and properties of silicon carbide ceramics enhanced by Ti N nanoparticles and Si C whiskers[J].Scr Mater,2011,65:186–189.
[14]KRENKEL W,BERND F,C/C-Si C composites for space applications and advanced friction systems[J].Mater Sci Eng A,2005,412(1/2):177–181.
[15]SATO S,SERIZAWA,H ARAKI H,et al.Temperature dependence of internal friction and elastic modulus of Si C/Si C composites[J].J Alloy Compd,2003,355(1/2):142–147.