TRIBOLOGICAL STUDIES OF PRECISE FRICTION PAIRS UNDER OPERATING-CONDITIONS IN A DIESEL-ENGINE

The subject of the present study was the precise plunger friction pair s of a fuel pump in a diesel engine. The problem is solved using the f ollowing strategy: (a) identification of the causes of failure of prec ise plunger pairs and the causes of the high wear of their surfaces in contact; (b) development of design, technological, and operating meth ods for control of the processes of wear. The results obtained from th e study show that the process which determines the seizures of plunger pairs is hot seizure (type II seizure) with the formation of metallic bonds and thin layers with various degrees of oxidation. The followin g methods were used to investigate the conditions after 500 working ho urs: surface microphotography, profilography of the surfaces in contac t, metallographic analysis, measurement of the microhardness of the su rface layer, electron microscopy, scanning microscopy, X-ray analysis, and chemical analysis. The conclusions are as follows: (a) chemical e tching can prevent the seizure of friction pairs after 500 working hou rs; (b) dust and water in the diesel fuel, when in large quantities, l ead to the formation of corrosive spots on the surfaces in contact of the plunger pairs when they are not chemically treated. Double filtrat ion is recommended in these cases.