Numerical modeling the bonding mechanism of HVOF sprayed particles

Abstract

a b s t r a c tDuring high velocity oxy-fuel (HVOF) thermal spraying, most powder particles remain in solid state prior to the formation of coating. A finite element (FE) model is developed to study the impact of thermally sprayed solid particles on substrates and to establish the critical particle impact parameters needed for adequate bonding. The particles are given the properties of widely used WC-Co powder for HVOF thermally sprayed coatings. The numerical results indicate that in HVOF process the kinetic energy of the particle prior to impact plays the most dominant role on particle stress localization and melting of the particle/substrate interfacial region. Both the shear-instability theory and an energy-based method are used to establish the critical impact parameters for HVOF sprayed particles, and it is found that only WC-Co particles smaller than 40 lm have sufficient kinetic and thermal energy for successful bonding.

Numerical study of molten and semi-molten ceramic impingement by using coupled Eulerian and Lagrangian method

“…The thermal-physical state of an individual particle can therefore be predicted at the substrate surface which can then be relayed into a focused impingement model in order to simulate the impingement and buildup of the coating microstructure particle by particle. The most developed finite element simulations for unmelted, solid particle impingements can be found in [1,2] for copper powder deposited by cold spray, and in [3,4] for tungsten-carbide cobalt (WC-Co) powder deposited by HVOF combustion spray. By utilizing the Johnson-Cook strain hardening, temperature softening plasticity model, the deformation and stress of the solid metal particles could be captured.…”

The Influence of Powder Porosity on the Bonding Mechanism at the Impact of Thermally Sprayed Solid Particles

“…[16] The reported study on fully solid particles states that the kinetic energy prior to impact is a key factor for strong adhesion. [7] Solely judged on the value of impact velocity, porous powder should form a better coating from the HVOF process. [5] In fact, the particle microstructure influences the rate of deformation rate during impact.…”

“…However, the detailed behavior, including densification and deformation, is not understood clearly for HVOFsprayed porous powders, because adequate knowledge is lacking about the transition of particles from porous structure to dense deposition layer during impingement. In this article, the previous particle impact model [7] is developed more broadly to investigate the influence of particle porosity in deposition efficiency. The WC-Co powder is used for consistency with the previous study, whereas the particle parameters prior to impact are taken from the computational fluid dynamics (CFD) in-flight particle models reported in Reference 2.…”

Modelo de nucleación y crecimiento de capas nanoestructuradas de óxido de zinc sobre sustratos cerámicos con aplicación a materiales fotovoltaicos híbridos

“…En la etapa inicial la deformación de la superficie de contacto es evidente aumentando el tamaño del cráter en anchura y altura para acomodar a la partícula ya deformada. Así es como la partícula penetra más profundamente en el sustrato [72].…”

“…Una vez la energía cinética de las partículas se ha reducido a cero, la partícula se aplana en forma de lente, siendo esta deformación como máximo el límite de la deformación plástica que permite el material [72].…”