An overview of slurry erosion control by the application of high velocity oxy fuel sprayed coatings

Slurry erosion of turbine components is a serious problem in most of the hydraulic power plants all around the world. Although some counter measures such as catchment area treatment to reduce the amount of sand particles going through the turbine components and modifying the hydraulic shape of turbine to reduce slurry erosion have been taken, still slurry erosion is responsible for heavy economic losses. Research is also in progress for improving the surface properties of the turbine components by the application of thermal sprayed coatings. Among various thermal spray processes, high-velocity oxy fuel (HVOF) spray process is a relatively industrially established and economical process. In this paper, an attempt has been made to describe HVOF thermal spray technology. Further, this paper presents a tutorial introduction, comprehensive history, and review of research work done on the use of this technique to provide protection against slurry erosion of some metals and alloys with a special emphasis on the hydraulic turbine steels.