Evaluation of vegetable and petroleum based diesel fuels in the aspect of lubricity in steel-aluminium association

The paper presents the results of a study on wear resistance of elements of injection system operating in steel-aluminium friction system with relation to the kind of fuel used. The fuels used in the study included regular petroleum-based diesel fuel, esters of colza oil, and their mixtures. The study, of a laboratory character, was done using a friction machine with a roller-ring friction couple. Such a combination allows to obtain the border friction which is based on the rule of transition from friction on the material surface to friction on the surface of adsorbed polar compounds. The persistence of lubricating film was evaluated as ability to counteract the wear of a sample made of aluminium. On the basis of the research it was found that a small supplement of RME to diesel fuel causes a sudden increase of sample wear. The highest wear value was obtained with a 20% supplement of RME. The smallest value of wear of aluminium sample was obtained with the use of pure diesel fuel.