Abstract: Ni/C composite particles consisting of mesophase carbon microbeads (MCMB) coated with a metal layer of nickel are produced and studied. When the new particles and their derived coating are compared with the normal ones, a great difference between them has been found. At the same time, the chemical stability of the coating is also studied by oxidation in air at 400℃ for various periods of time, as well as catalysis of nickel on the oxidation of graphite. A suitable coating can be obtained from the new spherical particles with less energy consumption and under more loose operation conditions. Hardness variation of the derived coating is kept within 30%, which is much smaller compared with the normal Ni/C coating. It is found that the maximum hardness appears after heating for 20 h, and then the hardness steps down to a steady value. During the oxidation, the increased mass of the mixture of nickel and graphite reaches its maximum, 0.25% between 25~28 h, which differs from the mass change that would occur under the assumption that nickel should have no effect on the oxidation of graphite.

Key words: Ni/C, mesophase carbon microbeads, particles, coating, hardness

摘要： 以中间相碳微球为芯材，采用水溶液加压氢气还原方法制备了镍包覆石墨(Ni/C)复合粉体材料. 对比研究了该粉体及其热喷涂涂层与以普通人造石墨为芯材的Ni/C粉体及涂层的性能差异. 通过研究球形Ni/C涂层的热稳定性能，找到了在涂层工作温度下涂层硬度和质量随时间的变化规律. 另外通过对比研究镍与石墨及其混合粉末的氧化失重，探讨了400℃下镍对石墨氧化的催化作用. 火焰喷涂实验发现，球形Ni/C粉体在较低能耗条件下即能制备出合格的涂层，且喷涂工艺参数易于控制，涂层性能更加稳定，涂层硬度的波动范围比普通Ni/C涂层缩小了70%. 在400℃的大气气氛中，涂层硬度大约在20 h左右出现最大值，然后减小并趋于稳定. 氧化实验发现，镍与石墨的混合粉末在25~28 h之间出现增重最大值(0.25%)，这与假设镍对石墨的氧化无催化作用时粉末持续增重的情况不同.

关键词: Ni/C, 中间相碳微球, 粉体, 涂层, 硬度