Wear is too divers to neglect the subdivision.
The principle difference between adhesive and abrasive wear is the absence of ploughing action by hard particles or rough surfaces in the case of adhesive wear. Adhesive wear arises from the adhesive forces between atoms in close contact. During sliding there is a possibility these contacts will not break at the original interface. Surface fatigue represents the formation of (sub)surface cracks due the repeated loading and unloading (ball bearings). Tribo oxidation occurs when sliding action wears protective films away in a corrosive environment. In this way the surface becomes extra susceptible to (continuous) corrosion.
Major wear systems:
| fretting |
| erosion |
| cavitation erosion |
| impact |
| adhesive wear |
| abrasive wear |
| surface fatigue wear |
| tribo oxidation |
Wear mechanisms can follow pathways as displayed below:
Adhesive wear:
Adhesive wear is generally the most important type of wear for most clean non-lubricated moving parts, or moving parts which operate in partly lubricated conditions. Cold-welding or galling describes the formation of small bonds which disrupt during translation. These disruptions leave small malformations in the surface. The most important measurements to prevent adhesive wear without lubrication are:
- selecting materials with softer oxides ( 'oxide lubrication', so not aluminum. Also tribo-oxidation related)
- raising the hardness (mostly of one side) and so preventing 'micro plastic' distortion of the surface
- excluding cubic/planar (Nickel, Aluminum or Austenitic steel) or homogeneously arranged metals
- selecting highly incompatible material pairs (such as silver on cobalt)
- selecting materials with low surface energy
- selecting nonmetal-(non)metal pairs
Adhesive wear comparison diagram:
Conditions: non-lubricated / free of abrasive medium / no inert gas.
Speed: 0,7 m/sec
Ambient temperature: 30 °C
First record: Ring ( the adhesive counterpart, no measurement. For example the 1.2379 steel record at the first bar )
Second record: Pin ( measurement of volume-decrease. The bronze record at he the first bar )
Attention: some material pairs of pin and ring have also been tested in reversed order.
In this way, information has been collected about the material that shows the highest wear rate in a translating material pair.
Lunac 1 and 2+, 1.2379 ( regular tooling steel) and ASP 60 were all hardened.
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