College of Engineering
Materials Engineering Department
BS in Materials Engineering
In petroleum processing, the flow of catalyst readily leads to erosion of piping in a fluid catalytic cracking unit. Advances in coating materials and processes necessitate a re-evaluation of current protection methods. Commercially available tungsten-carbide (WC) claddings and nanostructured WC-W CVD coatings were investigated as potential alternative erosion-resistant coatings. Erosion tests by solid particle impingement were conducted on 2 variations of claddings and 1 variation of WC-W coatings following ASTM standard G76. A36 steel coupons were used as reference samples. For statistical validation, 2-3 replications of the tests were performed for the claddings and WC-W coating. Testing was conducted using a sandblasting apparatus with 70 μm alumina powder at an impingement angle of 90° and 25°. Data obtained for each cladding, as well as A36 steel, was used to plot mass loss versus time, resulting in erosion rates. Average erosion values were reported as volume loss per gram of abrasive with units of mm3/g. The claddings displayed similar erosion values at 90°, but both were less resistant than bare A36 steel. Optical and electron microscopy of the cladding interface revealed coherent bonding across the interface and no obvious voids in the coating or at the interface. The microstructure of the steel substrate consisted of large regions of pearlite embedded in a ferrite matrix; therefore, improper heat treatment cannot be used to explain the superior erosion resistance. At 25°, the WC-W coating and claddings performed similarly and both resisted erosion better than A36 steel.