Coatings based on NiCrAlC intermetallic based alloy were applied on AISI 316L stainless steel substrates using a high velocity oxygen fuel torch. The influence of the spray parameters on friction and abrasive wear resistance were investigated using an instrumented rubber wheel abrasion test, able to measure the friction forces. The corrosion behaviour of the coatings were studied with electrochemical techniques and compared with the corrosion resistance of the substrate material. Specimens prepared using lower O 2 /C 3 H 8 ratios showed smaller porosity values. The abrasion wear rate of the NiCrAlC coatings was much smaller than that described in the literature for bulk as cast materials with similar composition and one order of magnitude higher than bulk cast and heat treated (aged) NiCrAlC alloy. All coatings showed higher corrosion resistance than the AISI 316L substrate in HCl (5%) aqueous solution at 40uC.

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This paper presents the results of a three-body abrasive wear and friction study of two different coatings on steel substrates. An instrumented rubber wheel abrasion test (RWAT) was used. One coating was thermally-sprayed WC-12 %Co, using the high-velocity oxygen fuel (HVOF) process, and the other coating was applied as electroplated hard chrome. Unlike current RWAT equipment, the apparatus described here has computer control of load and speed as well as instrumentation to measure specimen temperature and friction force. The instrument was calibrated using quenched and tempered D2 tool steel, per ASTM G 65-94. Tests of the thermally-sprayed coating were performed with loads of 65 or 130 N, and tests of the hard chrome plating used Procedure E of the standard. The wear resistance of the thermally-sprayed coating was dependent on substrate (52100 or 1020 steel) and it was in general superior to that for the hard chrome. The friction coefficients ranged between about 0.4 and 0.6 for the coatings against flowing sand. The tests performed with an applied load of 130 N did not meet the recommendation of ASTM on the coefficient of variation, and probably low loads should be considered in the standard to determine the wear resistance of coatings.

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