• National Research Institute Of Mechanical Engineering

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    Heat treatment of an arc spray NiCr alloy coating after sealing with aluminum phosphate.

    Abstract: The paper presents our study on the influence of heat treatment on the properties of an electric-arc thermal spray NiCr20 coating after sealing with aluminum phosphate. The applied annealing temperature was varied in a range of 400-1000oC. Obtained result shows that the porosity of coatings tends to considerably decrease with the increase of the annealing temperature. After treatment at 800-1000oC, over 90% of initial pores in the coating was successfully filled with the sealant. The phase analysis by XRD revealed a formation of different crystalline compounds and an interaction between the coating and the sealant. The filling with the sealant then followed by the heat treatment allowed to increase the wear resistance of the coating by more than 12 times in comparison with the coating without treatment. The ability to increase the resistance of the NiCr20 alloy coatings against corrosion in H2SO4 solution by sealing with aluminum phosphate was also investigated. The results indicated the ability of the sealed coating to bring a better protection than the unsealed one in this case.