High-Performance Al2O3 Coating by Hybrid-LVOF (Low-Velocity Oxyfuel) Process

Plasma spraying is now a standard coating process to deposit ceramic coatings for applications in automotive, aviation, medical and health care and others. This study deals with a hybrid thermal spray technique to deposit ceramic coatings. This technique named "hybrid-LVOF" (low-velocity oxyfuel) makes it possible to deposit uniform thin or thick ceramic coatings on metallic or ceramic substrates. In this work, the microstructural and mechanical properties of Al2O3 coating deposited by hybrid-LVOF were compared with those of Al2O3 coating deposited by the conventional plasma spray technique. The Rietveld refinement of XRD patterns was used to quantify the alpha-Al2O3 and gamma-Al2O3 coating content. Hybrid-LVOF as-sprayed coatings have a smoother surface, lower porosity (2-3%), higher hardness and better adhesion strength than conventional plasma-sprayed coatings. The hybrid-LVOF coatings also exhibit better fracture toughness probably because of a high inter-splat bonding and low porosity.