A NOVEL DESIGN AND OPTIMIZATION OF MULTIPOWDER HVOF THERMAL SPRAY SYSTEM FOR FUNCTIONALLY GRADED COATINGS

摘要

The high velocity oxy-fuel (HVOF) process is designed to produce dense coatings with higher hardness and bond strengths compared to any other thermal spray processes. However, this process has its drawbacks, which includes the deposition of thick deposits due to the build-up of residual stress, which may lead to interlaminar debonding and adhesion loss between the coating and the substrate. Technologies such as functionally graded coatings, whose microstracture and/or properties vary gradually from the substrate to the coating, reduce residual stress build-up within coating deposits.