High Temperature Oxidation and Corrosion

In past, a number of materials such as T 11, T 12, T 22, GrA1, SS 347 etc. have been employed for the application in boilers. The research work is continuously being done, in order to improve the performance of these materials, by coating techniques or by introducing new materials for such applications. In recent past, a new material T 91 also known as Nine chrome moly (9Cr 1Mo), which have been used in US fossil boilers, was employed for superheater tubes at Guru Nanak Dev Thermal Power Plant, Bathinda, Punjab (India). But, the performance of the material was not found satisfactory. Therefore, the study of behaviour of T 91 at high temperature, became an important aspect. Also it was important to study, if the performance of T 91 could be improved by coating. The present study is an attempt to evaluate the high temperature corrosion behaviour of uncoated and HVOF sprayed Cr3C2 NiCr coated T 91 boiler steel. The tests were planned to be carried out in air and in salt mixture of Na2SO4 60% V2O5 reported to be most aggressive environment at an elevated temperature of 900 0C for 50 cycles