The erosion of ductile metals by solid particles
Erosion is a wear process, in which surface damage is caused by the repeated application of high localised stresses. Erosion by solid particle impact is a problem of great practical significance which can result in component failures in, for example, turbines and energy conversion systems.
This dissertation describes experiments in which ductile metal surfaces were eroded with abrasive particles (size range 40 - 600nm) under controlled conditions. Damage to the surface was characterised by weight loss measurements, and also by microscopical examination. Surface and subsurface damage was studied using optical microscopy and also scanning electron microscopy.
As a result of this experimental work a new model of the erosion process, for ductile metals eroded by spherical particles at normal impingement, is proposed. Analytical techniques were used to investigate the observed surface deformations, and also the energy requirements of the proposed model.
Further experiments were conducted to investigate the effect of erodent particle shape on the erosion of mild steel. A literature survey was completed, which identifies methods which may prove useful in quantifying the shapes of abrasive particles.
A study of the effect of nitrogen ion implantation on the erosion resistance of mild steel was completed. An investigation of indentation parameters provided an explanation for the minimal effects recorded.
The technique of cross correlation has been applied to. the problem of measuring the velocity of the erodent particles. A device has been developed to measure the time of flight of particles over a known djstance . Data from this device was analysed on a micro-computer.