A. S. Khanna, S. Kumari, Indian Institute of Technology Bombay, Mumbai, India
Fireside corrosion and erosion of heat exchanger tubes is a serious problem. One of the methods to combat this is by applying corrosion and erosion resistant coatings. Tungston carbide in a matrix of Ni-Cr was used for this application. High Cr concentration takes care of oxidation and sulphidation, while tungston carbide will take care of erosion from flyash. Various compositions comprising of Ni-Cr with 15, 35, 60 and 100% WC were made using thermal spray grade powders. These were then coated on the steel substrate by HVOF method. After detailed charaterization of the coatings, their performance was checked using oxidation, sulphidation, aqueous corrosion, wear and abrasion tests. It was found that Ni-Cr ( 35% WC) gave the optimum results.
Summary: Fire side corrosion and erosion of heat exchanger tubes is a serious problem. One of the methods to combat this is by appyling corrosion and erosion resistant coatings. Tungston carbide in a matrix of Ni-Cr was used for this application. High Cr concentration takes care of oxidation and sulphidation, while tungston carbide will take care of erosion from flyash. Various compositions comprising of Ni-Cr with 15, 35, 60 and 100% WC were made using thermal spray grade powders. These were then coated on steel substrate by HVOF method. After detailed characterization of the coatings, their performance was checked using oxidation, sulphidation, aqueous corrosion, wear and abrasion. It was found that Ni-Cr ( 35% WC) gave the optimum results.
