Download WEAR SIMULATION OF ELECTRICAL

further classified into four subgroups, Oxidative Wear, Corrosive Wear, Solution Wear
and Diffusive Wear. Oxidation Wear occurs when oxide films are formed on the surface
during high sliding velocities. As the thickness of the oxide film increases, frictional
heating causes it to flow plastically or melt. Corrosive wear occurs when surfaces slide
against each other in a corrosive atmosphere. This results in the formation of pits.
Solution wear occurs when a solution is formed between the materials in contact
decreasing the free energy. This is an atomic level wear process in which new
compounds are formed at high temperatures. This type of wear is observed in carbide
tools during high speed cutting. Diffusive Wear occurs when there is a diffusion of
elements across the interface. It is observed in high speed tool steels.
In most practical cases, materials wear out due to the combination of the above
mentioned mechanisms. In spite of this, in order to solve the wear problem, a primary
mechanism is identified. Ragnar Holm [1938] stated that when two surfaces were brought
together, they touched at their asperities and the area of contact was related to the load
divided by the yield pressure of the material. This contact resulted in cold welding of the
asperities, particularly if the contact surfaces were clean. The force required to separate
these members, resulted in the shearing of asperities. This was the beginning of adhesion
theory of friction which was subsequently developed by Bowden and Tabor [1950]. The
first quantitative statement of wear was also given by Holm [1946].
W=Z
Ps
H
(8)
W is the wear volume, s is the sliding distance, P is the load, H is the yield pressure of the
metal and Z is a dimensionless number. P/H was called the real area of contact.
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