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A laboratory method has been developed to rank the scuff resistance of piston ring coatings. This method employs a standard wear test apparatus with a specially designed sample holder. Scuff resistance of electrolytic chrome, thermal spray and physical vapor deposition (PVD) face coatings have been examined. Based on this method, examined PVD coatings produced the highest scuff resistance of all the tested face coatings.

This paper examines the feasibility of using the boundary element method (BEM) and the Rayleigh integral to assess the sound radiation from engine components such as oil pans. Two oil pans, one cast aluminum and the other stamped steel, are used in the study. All numerical results are compared to running engine data obtained for each of these oil pans on a Cummins engine. Measured running-engine surface velocity data are used as input to the BEM calculations. The BEM models of the oil pains are baffled in various ways to determine the feasibility of analyzing the sound radiated from the oil pan in isolation of the engine. Two baffling conditions are considered: an infinite baffle in which the edge of the oil pan are attached to an infinite, flat surface; and a closed baffle in which the edge of the oil pan is sealed with a rigid structure. It is shown that either of these methods gives satisfactory results when compared to experiment.

High Velocity Oxygen Fuel sprayed face coatings have shown great promise for piston rings used for High Power Density Diesel Engines. Various coatings have been tested on both wear test rigs and in engines. A highly dense HVOF cermet coating was developed with reasonable crack resistance during service. The HVOF coated piston rings wore three to six times lower than chrome plating. Cylinder liner (counter face) wear was found to be one to three times higher than chrome. However, engine oil consumption and blow by were within normal values. The HVOF coating is considered to be an excellent replacement for chrome plating. The coating process is more environmentally friendly than the chrome plating process. Also, the coating has potentially lower or equivalent production cost when compared to chrome.

A number of wear resistant coatings has been developed using physical vapor deposition(PVD) process. However this coating process has not yet been widely used in the automotive industry. The purpose of this work was to evaluate thin PVD coatings such as diamond like carbon doped with tungsten (W-DLC), molybdenum-disulfide doped with aluminum (MoS2-Al), and chrome nitride (CrN). Some of these coatings were previously found to have low friction, high wear resistance, or both when tested in unlubricated conditions. In the present work, the experiments were conducted using a Cameron-Plint apparatus in lubricated conditions. The ring counterfaces used were Cr-plated and gas-nitrided compression rings. Our data also indicated that some PVD coatings with thicknesses in the same order of magnitude as the surface roughness of the liners did show some improvement in liner wear resistance. The suitability of thin coatings for liner applications needs additional study.