An investigation on the effect of chromizing parameters on hot corrosion behaviour of In-738 Lc at 850 'deg'

One of the most effective method used in protecting gas turbine blade against hot corrosion and oxidation is the employment of enriched chromium coatings. The effect of processing parameters such as time and chemical compositions of coating on its structure and hot corrosion resistance were evaluated in this work. Pack cementation method was used at 1100 degfor various time. Structure of coating was examined using the light and electron microscopy to evaluate hot corrosion resistance of the coated specimens, that were subjected to hot corrosion test at 850 'deg' for 528 hr s along with an uncoated sample. The corroded surfaces of the samples were studied using light and electron microscopes as well as XRD analysis. The results show that by increasing both the amount of chromium in the pack and time of operation, hot corrosion resistance of coating increases. However, the mechanical properties of the coated samples were adversely affected by increasing the surface concentration of chromium and/or thickness of coating more than a certain amount. Therefore, it is essential to optimize the time and chromium concentration in order to obtain the best mechanical and hot corrosion properties