Elastomer erosive wear

Erosion studies have shown that the softness and resilience of elastomers handle wear better in a number of cases than hard metals (Ephithite, 1985). In dry applications, the heat dissipation is poor and can result in rapid degradation of the elastomer. However, in slurry applications the lubrication of the water changes the friction resistance greatly. 

An elastomer with a low modulus will often have far better erosive wear than material with a higher modulus. An abrasive wear test (such as the DIN abrader) will show a poor result for a soft elastomer. This is also shown in field applications such as tire wear. When the application is changed from abrasive to erosive wear, the softer elastomer will wear very well. The reason for this is that the low modulus of the soft elastomer allows the stresses from each impact to be dissipated more readily than for hard polyurethanes. The soft material will stretch further and then snap back before damage is done. Any microcracks formed will have a slower growth rate and hence less erosion will occur. 

Studies of the properties of polyurethanes, both physical and physicochemical, showed only that resilience had some direct relationship to wear. A relationship of (1- resilience)1-4, where resilience is expressed as a fraction, has been shown (Hutchings, 1987). No other relationship has been found for other properties for erosive wear between 30° and 90° (Hutchings, 1987). External factors that affect the erosive wear of the elastomers include ... 

The rate and amount (flux rate) of material impinging on the elastomer have an effect on the wear rate of the elastomer (Arnold and Hutchings, 1989). With flux rates of between 500 and 5000 kg nr2 sec-1, the erosive wear decreased with flux rate at low velocities and low angles of incidence. At higher flux rates (1000 to 10000 kg nr2 sec-1), the wear rate decreased when the velocity was lower and the angle of impact was more normal to the surface. 

Arnold, A.C. and I.M. Hutchings. "Flux Rate Effects in the Erosive Wear of Elastomers." Journal of Materials Science 24 (1989) 833-839. 

Li, J. and I.M. Hutchings. "Resistance of Cast Polyurethane Elastomers to Solid Particle Erosion." Wear 135 (1990) 293-303. 

The evaluation of erosive wear of elastomers has not been standardized, and most industries test the erosive wear by using methods designed to simulate conditions relevant to their operations. 

The most important considerations when specifying the pipeline are that the pipe material should be able to withstand the applied pressure and that the pipe material should be wear-resistant. Erosive wear is likely to be a problem for transporting abrasive particles at higher velocities (>3m/s). Based on these considerations, pipe materials generally fall into the broad categories of hardened metals, elastomers (rubbers and urethanes), and ceramics. 

This elastomer offers exceptional resistance to oils and many chemicals at elevated temperature, but limited resistance to erosion wear. 

Refractory lining wear in blast furnaces is monitored by radioactive tracers. Sources of Co are embedded in refractory bricks during lining. The y rays of Co are monitored from outside the furnace and erosion of the bricks is detected as the extinction of the y rays. Tritiated water ( H20) provides a very sensitive way of testing watertightness of pieces connected with elastomer joints. 

Plastics and elastomers are frequently used for wheels for a variety of consumer products. Everything from in-line skates to barbecue grills, to strollers, use plastic wheels. How do various plastics resist abrasion from contact with concrete pavement Erosion of plastics is a factor in dishwashers, plumbing systems, fans, and pumps. Most domestic sump pumps are now made from plastics and in use they are required to carry sand-filled water from basement drain crocks. How do various plastics resist this type of wear ... 

---