Sliding wear

Types of Wear. There are several distinct types of wear that can be divided into three main categories abrasive wear, sliding wear, and erosive wear. The type of wear encountered in a particular appHcation is an important factor influencing the selection of a wear-resistant material. 

Sliding wear is perhaps the most complex in the way different materials respond to sliding conditions. The metallic materials that perform best... 

Lead addition improves machinability and sliding-wear properties of bearings. It is usually less than 2% of the bronze composition. 

Figure 8.13 Materials selection chart of dry sliding wear rate constant [Eq. (8.21)] versus hardness. Reprinted, by permission, from M. F. Ashby, Materials Selection in Mechanical Design, 2nd ed., p. 60. Copyright 1999 by Michael F. Ashby.

The wear resistance is better than most plastics, except for UHMWPEin sliding wear applications such as chutes. Polyurethanes can be made in thick-sectioned intricate shapes. This makes them a very good choice in wear-resistant applications. 

Bailey WF, Rice SL, Albert RJ, Temin SC Influence of contact stress, sliding velocity, and surface roughness on the sliding wear of a composite restorative. J Dent Res 1981 60 914-918. 

Rice SL, Bailey WF, Wayne SF, Burns JA Comparative in vitro sliding-wear study of conventional, microfilled and light cured composite resin and glass ionomer cement. J Dent Res 1984 63 1173-1175. 

Surfaces in contact and moving parallel to each other exhibit phenomena that are encountered incessantly in our everyday life. These phenomena include friction, slide, wear, and lubrication (the process used to modify friction). We could not walk without controlled friction, nor could the internal combustion engine operate without the lubrication of its moving parts. The name tribology (from the Greek tribein—to rub) is given to phenomena that involve surfaces in relative motion. 

P. J. Blau and C.D. Olson. Application of thermal wave microscopy to research on the sliding wear break-in behavior of tarnished Cu - 15 wt % Zn alloy. Wear of Materials, Proc. ASME Conf., ASME, New York, 1985, pp. 425-431. 

Wang, A., A Unified Theory of Wear of UHMWPE in Multi-Directional Sliding, Wear, 248, 38-47, 2001. 

The wear situation is likely to be aggravated should hard additives of a coarser grain fraction be embedded in a softer matrix, such as clay, as the result of an upstream kneading process. This may lead to grain sliding wear (besides a two-body and even a proper three-body abrasive wear), which could, in the absence of an intermediate lubricating medium, have drastic consequences. Similarly, lack of an intermediate medium will favour any likely adhesive wear. 

C. Zantner, A.M. Kielbassa, P. Martins, K.H. Knnzelmann, Sliding wear of 19 commercially available composites and compomers. Dent. Mater. 20 (2004) 277-285. 

As with other mechanical properties there are standard tests to measure wear resistance. The main method is described in ASTM G99, which uses a pin-on-disk apparatus. This test is used to measure sliding wear of ceranucs and ceramic coatings. 

J. Tong, M. Yunhai, J. Man, Effects of the wollastonite fiber modification on the sliding wear behavior of the UHMWPE composites. Wear 255, 734—741 (2003)... 

Limited data is available on the wear rate of CVD diamond [90,91]. A recent study has been conducted in order to investigate the basic tribological properties of bulk and thin-film CVD diamond. The sliding wear characteristics of a number CVD diamond materials have been evaluated using a modified Denison T62 abrasion [92] pin-on-disc test rig, operated in dry and lubricated sliding wear conditions, and compared with a typical hardened steel which is often used for wear part components. 

The coefficient of friction determinations have been made at specific times into the sliding wear tests. These have an associated uncertainty of approximately 10%, predominantly from the (unsteady) change in friction coefficient with time as the sample surface is modified by wear and vibration/noise associated with the friction monitoring transducer. 

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