Tribologically stressed material

For the resistance to abrasion, the so-called wear low state/high state characteristic is particularly important (see Figure 11.61 in [3]). Therefore, the wear is only low when the tribologically stressed material is harder than the attacking material. In practice, good results are achieved with a surface hardness > 50 HRC. 

The fact that wear starts at the surface of the work piece suggests that only the tribologically stressed surface should be strengthened instead of making the entire component out of wear-resistant material. It should be borne in mind that the base material has to fulfill other functions such as load-bearing as well as surface stressing (i.e., the surface that has been made wear-resistant must not interfere unduly with the component). 

The elements of such a system consist of the primary body, the counter body, the interfacial medium and surrounding medium. Wear is a result of the action of the collective stress on the structure respectively on the elements of the tribological system and manifests itself in energetic and material interactions between these elements. It is defined by the wear parameters. Basically all wear mechanisms can occur abrasion, adhesion, tribo-chemical reactions or wear caused by fatigue. In the case of the extrusion of ceramic bodies, corrosion must be considered as another harmful mechanism. When determining the elements of the tribosystem for the... 

Although LPSSiC may not be suitable as an universal tribology material like SSiC, the initial assessment of properties suggests that it will be suitable for high-stress engineering components and in many wear applications, where strength, reliability, and toughness are demanded. 

In the section under Fracture Mechanics and Crack Propagation, cracks and notches were discussed as stress concentrators. Scratches are also stress concentrators which affect the reliability. Therefore, we now need to move from the mechanics of polymer-based materials to their tribology. Tribology deals with friction, wear, scratch resistance, and design of interactive surfaces in relative motion (70). It is an imderappreciated science. Rabinowicz (71) says the following about the so-called Jost report on tribology prepared for the British Government ... 

In the contact area between part and counter part elementary friction and wear mechanisms such as adhesion, abrasion, surface fatigue, deformation, elastic hysteresis and damping, tribochemical reactions etc. may occur. These mechanisms are overlapping in the temporal and spatial undetectable real material contact area. In addition highly formulated lubricants, which are mainly used with highly stressed engine elements, exert influence on tribochemical reactions inside and outside of the tribological contact. ... 

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