EFFECT OF CERAMIC BASED COATINGS ON STEEL WELDS

Abstract

Cr-Mo steel has many applications which includes power plants where the material is under a very high temperature of 600-700°C which leads to the condition like corrosion and high temperature oxidation. Power plants give more efficiency under high temperature and pressure. In the present dissertation, Cr-Mo steel and Cr-Mo steel welds welded with TIG welding are coated with a simpler coating which is slurry based or dip coating with different parameters like sintering temperature, sintering time and sintering time. Further the characterization of coated sample is done by SEM analysis and measuring the hardness at the surface of based metal, interface of base and coating and at the coating. SEM analysis shows that the coating microstructure is crack free for the sintering temperature of 950°C. Measurement of coatings thickness is also done by the SEM analysis. EDAX analysis of coating shows the distribution of various elements and also shows the diffusion of elements due to high temperature sintering. Corrosion behavior is studied with the polarization which shows that the coated samples shows less corrosion as compared to uncoated sample. Further the coated sample which is sintered at a high temperature shows lesser corrosion. Oxidation behavior is checked with the weight gain test which shows that the uncoated samples more gain in weight when put in furnace at 700°C for 20 hours.