Mechanical and corrosion performance of multilayer ceramic coatings deposited on an austenitic stainless steel using plasma spray

Abstract

This research investigated consecutive multilayer thermal barrier coatings, including Ni 3 Al-Al 2 O 3-Al 2 O 3 /MgO, produced by plasma spray with outer layer thicknesses of 50, 100 and 150 μm deposited on an AISI 316 stainless steel. X-ray diffraction, scanning electron microscopy, Rockwell-B hardness measurements, pin-on-disk wear test and potentiodynamic polarization test were performed to evaluate the specimens. The results revealed that the structure of the produced coatings was completely crystalline. An increase in the coating thickness formed a smooth surface and a low degree of roughness and promoted grain growth. According to the Hall-Petch equation, the degree of hardness decreased from 99 to 92 HRB, and the friction coefficient decreased from 1.25 to 0.6 because of low surface roughness. An adherence test performed with a Brinell hardness test showed that an increase in the layer thickness improved the coating adherence coefficient (d p/dr) from 0.083 to 0.118 kg μm −1. The corrosion test results indicated that the increase in the coating thickness caused a decrease in corrosion current density from 1.1 to 0.008 mA cm −2 .

Wear and corrosion resistance of Al2O3 and TiC deposition on steel substrate using self- propagating high temperature synthesis method

“…As the coating thickness increased, the increased deposits on the surface of Ni 3 Al-Al 2 O 3 -Al 2 O 3 /MgO composition coated over AISI 316 stainless steel led to the creation of a uniform layer. As a result, the coating was little penetrated by Cl -, increasing corrosion resistance [14].…”