LUBRICATION OF SI3N4 AND STEEL ROLLING AND SLIDING CONTACTS BY DEPOSITS OF PYROLYZED CARBONACEOUS GASES

Pin-on-disk and four-ball tests with steel and silicon nitride surfaces can be lubricated by carbon deposited as a result of pyrolysis in the tribo-contacts of ethylene or other carbonaceous gases at bulk temperatures in excess of 500-degrees-C. The carbon deposits were analyzed and shown to be different for different gases. Substantial improvements could be achieved by insertion of a hot wire into the ethylene stream. This was shown to be equivalent to an admixture of a small amount of acetylene. Since carbon deposit formation from pure ethylene was enhanced by the presence of acetylene carbon, the carbon and not the gaseous acetylene was the catalyst for enhanced formation of lubricating carbon. Lubrication was also achieved with the carbon formed from a feed gas of carbon monoxide and hydrogen.