Cr对原位自生TiC/Ni基复合材料宽温域摩擦学性能的影响

The influence of Cr on the tribological properties of in-situ TiC/Ni composites in wide temperature range

  • 摘要: 为探究Cr对原位自生TiC/Ni基复合材料宽温域摩擦学性能的影响,本研究采用无压反应烧结工艺制备了Cr含量为0wt.%与15wt.%的TiC/Ni复合材料,系统分析其物相组成、显微组织、硬度及常温至 800℃的摩擦学性能,其中,摩擦工况为与Al2O3球对磨,载荷10 N,时间30 min。结果表明,TiC/Ni复合材料主要由TiC与Ni组成,引入15wt.% Cr后生成Cr7C3与Cr23C6相,二者发挥晶界钉扎效应细化TiC颗粒,使材料硬度由623.8 HV提升至996.8 HV。常温下,含有15wt.% Cr的复合材料因高硬度呈现负磨损特征,磨损机制主要为磨粒磨损和轻微的氧化磨损。600~800℃时,添加15wt.%Cr使复合材料表面形成连续且微裂纹较少的摩擦膜,主要由NiO,TiO2,NiTiO3,SiO2和Cr2O3组成。在800℃下,引入15wt.% Cr使复合材料的磨损率由14.03×10−6 mm3/(N·m)降低至7.19×10−6 mm3/(N·m)。因此,添加适量的Cr可提升TiC/Ni基复合材料的宽温域摩擦学性能,延长其服役寿命。

     

    Abstract: To investigate the influence of Cr on the tribological properties of in-situ TiC/Ni-based composites in a wide-temperature, the study prepared TiC/Ni composites with Cr contents of 0wt.% and 15wt.% by pressureless reaction sintering. The phase composition, microstructure, hardness and tribological properties from room temperature to 800℃ were systematically analyzed. The friction test condition is grinded by Al2O3 ball under 10 N load for 30 min. It was found that the TiC/Ni composites mainly consist of TiC and Ni. The introduction of 15wt.% Cr promotes the formation of Cr7C3 and Cr23C6 phases in the composites, which refines the TiC particles through the grain boundary pinning effect, thereby increasing the hardness of the composites from 623.8 HV to 996.8 HV. At room temperature, the composite with 15wt.% Cr exhibits negative wear rate due to the higher hardness, and the primary wear mechanism is abrasive wear and slight oxidative wear. At 600~800℃, the addition of 15wt.% Cr enables the formation of continuous tribolayer with microcracks on the composite surface, which is made up of NiO, TiO2, NiTiO3, SiO2 and Cr2O3. The wear rate at 800℃ reduces from 14.03×10−6 mm3/(N·m) to 7.19×10−6 mm3/(N·m) by adding 15wt.% Cr. Therefore, the addition of suitable content of Cr can enhance the wide temperature range tribological properties of TiC/Ni composites and improve their service life.

     

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