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.

Relationship between single and bulk mechanical properties for zeolite ZSM5 spray-dried particles

In this work typical mechanical properties for a catalyst support material, ZSM5 （a spray-dried granular zeolite）, have been measured in order to relate the bulk behaviour of the powder material to the single particle mechanical properties. Particle shape and size distribution of the powders, determined by laser diffraction and scanning electron microscopy （SEM）, confirmed the spherical shape of the spray-dried particles. The excellent flowability of the material was assessed by typical methods such as the Hausner ratio and the Cart index, This was confirmed by bulk measurements of the particle-particle internal friction parameter and flow function using a Schulze shear cell, which also illustrated the low compressibility of the material. Single particle compression was used to characterize single particle mechanical properties such as reduced elastic modulus and strength from Hertz contact mechanics theory. Comparison with surface properties obtained from nanoindentation suggests heterogeneity, the surface being harder than the core. In order to evaluate the relationship between single particle mechanical properties and bulk compression behaviour, uniaxial confined compression was carried out. It was determined that the Adams model was suitable for describing the bulk compression and furthermore that the Adams model parameter, apparent strength of single particles, was in good agreement with the single particle strength determined from single particle compression test.

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.