<title>Erosion of aerospace materials by solid-particle impact</title>

Abstract

The degradation of various aerospace window materials by the action of solid particle impact is investigated. Laboratory simulations of high velocity sand, dust and hail impacts have been carried out, and the damage assessed in terms of the reductions in optical and mechanical performance. A new erosion rig has been designed to cover the broad size and velocity range of airborne particulates encountered by moving craft, and an ice-firing gas-gun was used to simulate hail impacts. IR-transmitting materials studied include CVD diamond, sapphire and coated zinc sulphide. A radar-dome composite material was compared with polymethylmethacylate (PMMA) for hail impact. Nylon spheres were assessed as a convenient simulation for ice and were found to cause very similar damage over parts of the velocity range studied. The different damage mechanisms observed in these materials are discussed and the extent of degradation by multi-particle erosion related to the particle size and impact velocity.