Erosion-Corrosion behavior of NiCrAlY coatings deposited on 446 stainless steel samples by flame thermal spraying was performed in this research. The hardness of uncoated and coated sample is measured, using HVS-1000 Digital Micro hardness Tester. The results of hardness show that the coated samples have higher hardness than uncoated samples. Microstructure and phase analysis of the coating layer was observed by using optical microscope, X-ray diffraction (XRD), and SEM respectively. Erosion –Corrosion test was performed in different period of time (6, 12, and 18 hr.) using the erosion-corrosion system. The result shows that because of uniform distribution and homogeneous of coating layer, weight loss was very low and approximately equal in all period of testing time.

Valve trays play an important role in the productivity of crude oil distillation towers. The performance efficiency of these valves depends on their erosion-corrosion and fouling corrosion. In this research, NiCrAlY powder with constituents of different ratios of Molybdenum (Mo) was used as a deposited coating layer on the surface of 446 stainless steel. The scanning electron microscope and XRD were used to study the microstructure of the coating layer. Microhardness test was carried out to evaluate coating layer hardness. Erosion – corrosion test was performed to evaluate the performance of the coating layer under an aggressive medium of glass sand and a mixture of sulphuric acid and hydrochloric acid. Contact angle test was carried out to evaluate the contact angle of coated and uncoated samples. Taguchi / ANOVA technique was used to tabulate data and to optimize the results. The results showed that the coating layer containing 4% Mo exhibit high erosion-corrosion resistance and good contact angle, which improving the fouling resistance of the samples under working conditions.

Valve trays play an important role in the refinery crude oil distillation process. Valve trays are covered by lift able caps. The lifting cap positions vapor to flow horizontally into the liquid which providing better vapor/liquid contact and better separation at each tray. Corrosion and wear resistance are the most important properties should be found in the valve trays and caps. This research deals with increasing corrosion and wear resistance of valve trays and caps using thermal spray technique. (Ni Al Cr) powder was used to apply coating layer on the substrate surface. Some mechanical properties are evaluated for the coating layer. Oxidation test was performed using oxidation system. Data and results revealed that the coating layer with the thickness of 100 µm has slightly resistance against oxidation, while the thickness of 200 µm has excellent oxidation resistance and good peeling resistance. Thickness of 300 µm has excellent oxidation resistance but has poor peeling resistance.