In wear test of pin on disc apparatus i found that mass loss of pin when i used Aluminum disc is higher than when i used Steel disc under the same conditions ,pressure, velocity and contact time can anyone explain this behavior to me and give me the reason ?
Answer
Sometimes, when you have a soft material like aluminum, and a brittle material like asbestos, in a pin/disk configuration, particles of asbestos break off and become embedded in the aluminum. And now you have created a very abrasive disk (a bit like diamond particles in phosphor bronze), and you will wear the pin much more rapidly while apparently protecting the aluminum.
See for example Pamuk et al
From the introduction:
Abrasive wear is the most common type of wear that causes failure of machine elements. Examinations of abraded surfaces revealed presence of embeded particles and grooves elongated along the sliding direction. This indicates that, there are two sequential stages of an abrasion process. In the first stage, asperities on the hard surface and/or hard abrasive grains penetrate into the soft material surface and then in the second stage, they grind the surface in the sliding direction.
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