Deposition and structural characterization of plasma sprayed Ni(5Al)-Al2O3-MoS2 composite coating

The purpose of this article of depositing and structural characterization of Ni(5Al)-Al2O3-MoS2 composite coating on the CK45 substrate by atmospheric plasma spray process. For this purpose, Powdering materials by combining the 60%Ni(5Al)-40%Al2O3, 60%Ni(5Al)-35%Al2O3-5%MoS2 and 60%Ni(5Al)-25%Al2O3-5%MoS2(wt%) were prepared by mechanical working mill. The spray dryer process was performed to increase the uniformity of density and granulation of the powder particles. Spraying operation by a plasma spray with gun equipped model PS50 at a distance of 100 mm, a current of 350 A and a voltage of 35 kV was done. The powder and coated surface were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), roughness and powder flow tests. Fluidity of powder was investigated by powder flow test according to Agglomerated powder exit from outlet of Hall flow meter. In order to investigate the substrate roughness and the effect of depositing composite coating on the average substrate roughness, roughness test with ultrasonic detector by contact method was performed. The results of the roughness test showed that with the increasing amount of MoS2, average coating roughness was reduced from 5.95 to 4.08 μm. According to the results of XRD, brittle NiAl2O4 phase in the coating without lubricant compared to lubricant coatings the more was formed. Composite powder structure and micrometer interfaces were led to the combination of Ni and S. According to the results can be expressed that depositing of Ni(5Al)-Al2O3-MoS2 composite coating with different amounts of MoS2 lubricant by APS method is possible.