Influence of Sensitive Parameters and Flow Characteristics in HVOF Coating

The present work provides a review of recent researches in the field of the high-velocity oxygen-fuel (HVOF) thermal spray process. Initially the authors present the gas velocity, temperature, pressure and Mach number distributions for various locations inside and outside the gun and the influence of the process operating conditions on particle characteristics. The paper also focuses on the modeling of the HVOF thermal spray, including combustion, gas dynamics and particle in-flight behavior. To predict gas dynamic behavior in a HVOF thermal spray gun, a computational fluid dynamics (CFD) model is developed. The CFD analysis is applied to investigate axisymmetric, steady-state, turbulent, compressible, and chemically combusting flow both within the gun and in a free jet region between the gun and the substrate to be coated. The dependency of gas dynamic behavior on fuel-to-oxygen ratio and total gas flow rate are discussed. The CFD model is also used to investigate the effect of changes in combustion chamber size and geometry on gas dynamics. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Noorul Islam Centre for Higher Education