The investigation of microstructure and mechanical properties of austenitic stainless steels seramic coated with thermal spray coating method

In this thesis, the AISI 304 and AISI 316L austenitic stainless steels were coated from substrate of oxide powder of Al2O3-13TiO2 ceramic aluminum alloy at different quantities (0-100µ/ 100-200µ/ 200-300µ) using the plasma spray method. The used powders were the ones whose chemical compositions were Al2O3-13TiO2, TiO2 99%, and ZrO2 8Y2O3. The thicknesses of the coating varying between 180 and 300 µm were obtained in the coatings made on the surface of the aluminum alloy. This difference in these coating thicknesses was revealed to identify how the corrosion and wear resistance changed depending the thickness of the coating. The samples were subjected to metallographic processes after the coating (bakelite, sandpaper, polishing, etching) and were made suitable for mechanical and microstructure analysis. The microstructure and phase composition of the coated samples were examined using an optical microscope (OM), x-ray energy dispersive spectrometry (EDS), and x-ray diffraction (XRD) in the study. Abrasion test of the substrate and the coatings was performed using pin-on disc method in a CSM tribometer. The Reference 3000potentiostat/galvanostat/ZRA corrosion system was used to measure corrosion. The general averages of the coatings varied between 300 HV and 900 HV. The arithmetic average of the hardness value of the substrate was around 250 HV. In hardness measurement taken at the joint point of the coating, the hardness value of the AISI 316 L stainless steel was 50–80 HV lower than the AISI 304 L stainless steel. It was found that the A12O3 ceramic coating performed using the plasma spray coating method increased wear resistance of AISI 304 and 316 L stainless steels. The results of the corrosion experiments ultimately revealed that the corrosion resistance of the AISI 316 L austenitic stainless steel among coated steels was higher than AISI 304 L austenitic stainless steel.