The improvement of wear and corrosion resistance of nickel-graphite coating with modified graphite phase size

Abstract

The corrosion resistance, friction and wear properties of an abradable seal coating are highly dependent on the size and distribution of lubrication phase. In this work, nickel-graphite (Ni-G) coatings were fabricated by a supersonic atmospheric plasma spraying system (SAPS) and a standard atmospheric plasma spraying system (APS), respectively. The effect of size and distribution of graphite phase on the performance of Ni-G coatings was investigated. The results suggested that the SAPS coating had an average single graphite phase area of 35.4 ± 5.1 μm2, which is approximately 35.4 % less than that of the APS coating, while the average graphite phase width and length in SAPS coating decreased by 22.2 % and 16.7 % compared to the APS coating. The fine distributed graphite phase improved the formation of structure with a small cathode and a large anode, which effectively increased the corrosion resistance of SAPS coating. The reciprocating sliding friction facilitated the creation of a uniform and uninterrupted lubricant layer, attributed to the finely dispersed graphite phase of SAPS coating. In comparison to the as-sprayed and subsequent corroded APS coatings, the friction coefficients of the SAPS coating exhibited a reduction of approximately 9.1 % and 13.3 %, respectively. The aforementioned findings showed that the small-sized graphite phase was conductive to the improvement of corrosion resistance, friction and wear properties of Ni-G abradable coatings.