there is a lot of types of wear include abrasive wear, catastropic wear, corrosive wear, fatigue wear, cutting wear, impact wear and so on. my experiment is to test a wear on a cylinder head valve but I'm not sure what type of wear it is because there is quite similar between some of them.
Dear Syazwan Ishak, evidently, the fatigue wear is a dominant type of wear process in joint under discussion. You know that valve is contacting with counterbody at cyclic loading without abrasive particles. Then, contact fatique is developed. Best regards
Dear Syazwan,
I am afraid that the wear process is too complicated to be described by a single mechanism. The contact involves high loads at repeated contact, at high temperatures, and without any conventional lubrication. At each closing of the valve there is a relative hard impact plus a limited sliding. The wear can also differ between intake and exhaust valves in the same cylinder.
The wear rate depend also on the type of fuel that is used, and the amount of oil (including its additives) that is combusted. It has been shown that microscopic ash particles following flowing through the exhaust valve may become trapped on the sealing surfaces, becoming worked by the operating valve and eventually forming protective tribofilms, a couple of µm thick, or so.
May I recommend you to read the freely downloadable thesis of Peter Forsberg, If you want to know more on this demanding subject. The thesis also give reference to further papers. Link to download the thesis:
Dear Syazwan,
Sorry, my previous answer was obviously cut short. I did not notice.
The thesis abstract is downloadable from this link:
http://uu.diva-portal.org/smash/record.jsf?dswid=2240&faces-redirect=true&language=en&searchType=SIMPLE&query=Peter+Forsberg+thesis&af=%5B%5D&aq=%5B%5B%5D%5D&aq2=%5B%5B%5D%5D&aqe=%5B%5D&pid=diva2%3A639359&noOfRows=50&sortOrder=author_sort_asc&onlyFullText=true&sf=research
Further publications on the subject from the Ångström tribomaterials group:
[1] Elo, R. and Jacobson, S., Formation and Breakdown of Oil Residue Tribofilms Protecting the Valves of Diesel Engines, Wear 330 (2015) 193-98.
[2] Forsberg, P., Elo, R. and Jacobson, S., The Importance of Oil and Particle Flow for Exhaust Valve Wear – an Experimental Study, Tribology International 69 (2014) 176-83.
Good luck!
Staffan
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