Abrasive wear elevated temperature

In the extreme case where the load is supported entirely by solid-solid contact, frictional wear will be at a maximum. However, the transport of slurry under the wafer will be poor, resulting in a limited amount of chemical activity and little lubrication effect. Under such conditions elevated temperatures would be expected and mechanical abrasion would dominate. As a consequence, the polished surface is likely to be severely damaged. 

A prime example of where polyamide-imides enjoy prominence is in friction and wear applications. This means not only in a system where the polymer components are meant to operate with low-friction and low-wear characteristics, but also in new applications such as brake pads and abrasion wheels, where the operating conditions require low wear with high friction, a truly demanding scenario. Polyamide-imides can achieve this due to their high softening temperature and retention of strength, stiffness, and compression properties at elevated temperatures. 

Alloy Cast Irons. Alloying elements beyond the levels mentioned above are added to cast irons almost exclusively to enhance resistance to abrasive wear or chemical corrosion, or to extend their stability for application at elevated temperature. The function of the alloying elements is essentially the same as in steels. Table 3.1-81 lists the groups of grades with typical compositions and the microstmctural constituents present in the as-cast state. 

Tungsten (W). Tungsten is one of the most important alloying elements of tool steels, particularly because it imparts a hot hardness, foat is, the resistance of the steel to the softening effect of elevated temperature, and it forms hard and abrasion-resistant tungsten carbides (e.g., WC and W C), thus improving the wear properties of tool steels. 

Silicon carbide has long been recognized as an ideal ceramic material for applications where high hardness and stiffness, mechanical strength at elevated temperatures, high thermal conductivity, low coefficient of thermal expansion, and resistance to wear and abrasion are of primary importance. Moreover, because of its low density it offers greater advantages compared to other ceramics. 

The variation in the wear rates, which were calculated from the slope of Figure 7 in the unit of g/m, are presented in Figure 10 as a function of test temperature. The addition of Mg to A1 matrix resulted with an improvement of the wear resistance of the composites. Thus, the high strength composite exhibited high resistance to abrasion at ambient and elevated temperature. 

Various types of sliding wear, erosive wear and abrasive wear test rigs are discussed in this section. These test rigs are designed primarily for testing at elevated temperature. 

Liu et al. [9] designed a low stress elevated temperature abrasion testing equipment. Their setup is shown in Figs 6.3c and 6.3d. It consists of a symmetric 7t-shaped specimen holder which is rotated in a stainless steel tank filled with abrasive sand. The setup is held inside an electric furnace to heat the sand and the sample to a maximum temperature of 923 K. The samples are rotated at a speed of 200 rpm corresponding to linear speed of 1.36 m/s. The abrasive wear rate is determined by interrupting the test after an interval of 20 h and measuring the volume loss as a function of time. 

Important features of elevated temperature abrasive wear... 

Significant developments in high temperature tribology have been reported recently. However, most of these developments are confined to sliding wear and erosive wear only. As mentioned previously, the literature on elevated temperature abrasive wear is rather limited. Consequently, no effort is made here to highlight recent developments in high temperature abrasive wear. 

It is stated that formation of various types of layers such as transfer layer, mechanically mixed layers, composite layer, etc., having characteristic composition and surface roughness governs the elevated temperature wear behaviour of metallic materials. Similarly during elevated temperature erosion, metallic erosion, erosion from the composite layer and erosion on the oxide scale are reported. The reported literature on abrasive wear at high temperature is much sparser and hence such layers are not yet found in the literature. The... 

Study of the elevated temperature abrasive wear of metallic materials is far from satisfactory. Certainly this area needs sustained attention from investigators. 

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