A novel erosion-corrosion approach, that expands the assessment of damage occurring on engineering materials subjected to a submerged impingement jet, has been developed. This new analytical method yields quantitative data that facilitates a substantially improved understanding of the material degradation mechanisms that take place in different regions of the surface of a material when exposed to aqueous saline solutions and solid particles. The validation of this methodology involved a medium carbon steel and an austenitic stainless steel, where the stainless steel exhibited almost two-fold erosion-corrosion resistance. The application of this new evaluation technique was extended to white cast irons to enhance the understanding of interaction of the chromium carbides and the metallic matrix on the erosion-corrosion behaviour of these multi-phase materials. For this reason, two stainless steels that mimic the ferrous matrix were also investigated. The free erosion-corrosion results showed that there is no difference among the two cast irons and the stainless steels but the cathodic protection unravelled the advantages of the martensitic based alloys compared with austenitic based alloys. Sintered and HVOF coatings WC-based cermets of similar chemical composition were studied to elucidate the influence of the manufacturing process on their erosion-corrosion response of the cermets. The manufacturing process effect resulted to be significant as the sintered cermets displayed greater erosion-corrosion performance than the HVOF coatings due to the lack of process defects. By incorporating both WC-Co and WC-Ni cermets in this testing phase, the role of the binder type on the erosion-corrosion behaviour of cermets was also examined, showing the superiority of the Ni binder compared to the Co binder. The research findings enabled the formation of a material matrix, where the relative erosion-corrosion performance of the materials is evaluated, and it comprises a substantial contribution on the material selection process for critical pump components.
|Date of Award||28 Sep 2016|
- University Of Strathclyde
|Sponsors||Weir Group plc (The)|
|Supervisor||Alexander Galloway (Supervisor) & James Wood (Supervisor)|