Numerical simulation of the effects of the impact velocity on the particle deposition characteristics in cold gas dynamic spraying

In this study, the effects of the impact velocity on the particle deposition characteristics in cold gas dynamic spraying （CGDS） of 304 stainless steel （SS） on an interstitial free （IF） steel substrate are numerical simulated by means of a finite element analysis （FEA）. The results have illustrated that when the particle impact velocity exceeds a critical value at which adiabatic shear instability of the particle starts to occur. Meanwhile, the fatten ratio and impact crater depth （or the effective contacting area ） increase rapidly. The particle-substrate bonding and deposition mechanism can be attributed to such an adiabatic shear deformation induced by both the compressive force and the slide friction force of particle. The critical velocity can be predicted by numerical simulation, which is useful to optimize the CGDS processing parameters for various materials.

Modeling study of solid-particle erosion with consideration of particle velocity dependent model parameters

An advanced erosion model that correlates two model parameters—the energies required to remove unit mass of target material during cutting wear and deformation wear,respectively,with particle velocity,particle size and density,as well as target material properties,is proposed.This model is capable of predicting the erosion rates for a material under solid-particle impact over a specific range of particle velocity at the impingement angle between 0◦and 90◦,provided that the experimental data of erosion rate for the material at a particle velocity within this range and at impingement angles between 0◦and 90◦are available.The proposed model is applied on three distinct types of materials:aluminum,perspex and graphite,to investigate the dependence behavior of the model parameters on particle velocity for ductile and brittle materials.The predicted model parameters obtained from the model are validated by the experimental data of aluminum plate under Al2O3 particle impact.The significance and limitation of the model are discussed;possible improvements on the model are suggested.

Analytical modeling of oxide thickness variation of metals under high temperature solid-particle erosion

The paper presents a study of model development for predicting the oxide thickness on metals under high temperature solid-particle erosion.The model is created based on the theory of solid-particle erosion that characterizes the erosion damage as deformation wear and cutting wear,incorporating the effect of the oxide scale on the eroded surface under high temperature erosion.Then the instantaneous oxide thickness is the result of the synergetic effect of erosion and oxidation.The developed model is applied on a Ni-based Al-containing(Ni–Al)alloy to investigate the oxide thickness variation with erosion duration of the alloy at high temperatures.The results show that the thickness of the oxide scale on the alloy surface increases with the exposure time and temperature when the surface is not attacked by particles.However,when particles impact on the alloy surface,the oxide thickness is reduced,although oxidation is continuing.This indicates that oxidation does not benefit the erosion resistance of this alloy at high temperatures due to the low growth rate of the oxide.