Wear mechanisms in polymer matrix composites abraded by bulk solids

doi:10.1016/S0043-1648(00)00365-3

Wear

Volume 240, Issues 1–2, May 2000, Pages 207-214

https://doi.org/10.1016/S0043-1648(00)00365-3 Get rights and content

Abstract

An experimental study of the wear of polymer matrix composite materials subjected to abrasion from bulk materials has been conducted. Three examples of vinyl ester resin systems were considered: (a) unreinforced, (b) reinforced with glass fibres, and (c) reinforced with particles of ultra high molecular weight polyethylene (UHWMPE). Soft and hard bulk materials used for abrasion were granular forms of coal and the mineral ignimbrite. The bulk material was presented to the wear surface on a conveyor belt in a novel wear tester. While UHWMPE reinforcement enhanced the wear resistance to both hard and soft abrasives, the situation for fibre reinforcement was more complicated. With coal as the abrasive, it was found that glass fibre reinforcement reduced the wear rate, whereas in the case of the harder ignimbrite, fibre reinforcement increased the wear rate. Microscopy indicated significant differences in the mechanism of wear in each surface/abrasive combination. Wear textures, consistent with both two and three-body wear, were observed with, respectively, soft and hard abrasive particles.

Introduction

Polymer matrix composites are being increasingly used in industry because of their unique combination of mechanical, electrical, and thermal properties. Typically they have high specific strength and modulus, excellent fracture toughness and fatigue properties, and good corrosion, thermal and electrical resistance properties. This combination of properties, particularly their high strength/stiffness to weight ratio, make them very attractive materials for transport applications where there is commercial advantage in minimising vehicle weight. One such application is in the transport and handling of bulk solids. However, their use in this application is limited by an incomplete understanding of their abrasion wear resistance and the means by which this can be controlled and improved. The aim of the work described in this paper was to provide further understanding of the wear of polymer matrix composite materials when subjected to abrasive wear from bulk solids.

In addition to transport applications, there has also been growing interest in their abrasive wear performance in applications such as chutes in mining and agricultural equipment [1]. A number of studies on polymer matrix composites subjected to sliding and abrasive wear indicate that wear resistance depends on the detailed properties of the material as well as the external wear conditions such as applied pressure and contact velocity [2], [3], [4], [5]. Furthermore, fibre addition to polymers does not necessarily improve their wear resistance [6].

Abrasive wear can occur as two-body abrasion, three-body abrasion, or a combination thereof [2]. In two-body abrasion, the two surfaces in contact are constrained to move in two dimensions and as such wear occurs through abrasive material on one surface sliding over the other surface. During three-body abrasion however, the abrasive material is trapped between the two constraining surfaces and is free to roll as well as to slide. Typically, wear rates obtained under two-body conditions are much higher than those actually observed in three-body wear, sometimes by as much as an order of magnitude [7] and the mechanisms of one cannot be modeled accurately from the other [8]. In reality, because of the complexity of the abrasion process, no single mechanism can completely account for all of the material loss.

This paper reports a study of the wear performance of three different surfaces with and without reinforcement during abrasion by both hard and soft bulk solids. The bulk solid abrasives were applied to the surface of the test surfaces under conditions common in industry in which there was limited constraint of the transport of the bulk solid particles. As such, both two and three-body wear was possible, depending on the abrasive/surface interaction. The purpose of this study was to shed light on the transition between these mechanisms, and to characterise wear damage arising from these mechanisms as a function of relative hardness and other properties of the wear system. The effects of the reinforcement and the wear media on the wear mechanisms involved were investigated through scanning electron microscopy (SEM) and weight loss measurements.

Section snippets

Experimental details

The abrasive wear of a relatively hard wear medium (ignimbrite) and a relatively soft wear medium (coal) on three different composite surfaces (vinyl ester resin, glass fibre reinforced plastic (GFRP), and ultra high molecular weight polyethylene (UHMWPE) particle reinforced resin) have been investigated. The choice of the two different wear media was dictated by intention to evaluate the effects of wear media hardness upon the wear rates of different materials. Coal mined from Bulga Colliery

Results and discussion

The particle size distributions of the wear media were measured to monitor the particle degradation during the testing in accordance with Australian Standard 1141.11-Particle Size Distribution by Dry Sieving. Particle size distributions of the wear media before and after the wear experiments are given in Fig. 2, Fig. 3 for the ignimbrite and coal particles, respectively. These images show that while the ignimbrite does not show any significant degradation, the coal particles degrade gradually

Conclusions

Specimens of three different composite materials, vinyl ester resin, glass fibre reinforced resin, and UHWMPE particle reinforced resin, have been abraded using hard (ignimbrite) and relatively soft (coal) bulk solids. In general terms, lower wear rates were obtained for surfaces abraded by coal than for surfaces abraded by ignimbrite. These lower wear rates, in the case of coal, were a consequence of both lower particle hardness and decreasing particle size during abrasion.

The abrasion

Acknowledgements

This work was carried out as part of the CRC-ACS and the Centre for Bulk Solids and Particulate Technologies research programmes. The authors wish to thank A. Whitton, who performed the experiments involving coal.

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¹: Current address: A. Goninan and Company, Newcastle, Australia.

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Wear mechanisms in polymer matrix composites abraded by bulk solids

Abstract

Introduction

Section snippets

Experimental details

Results and discussion

Conclusions

Acknowledgements

Tribol. Int.

Wear

Wear

Composites

Powder Technol.

Wear

Tribol. Int.