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The poisoning of three way catalysts (TWC) by the phosphorus contained in oil formulations containing zinc dialkyldithiophosphate (ZDDP) is examined. Catalysts were exposed to various types of ZDDP and detergents under conditions that were known to reduce performance through phosphorus poisoning without the blocking of sites by formation of glazing. The presence of phosphorus was detected with energy dispersive x-ray spectroscopy (EDX). In addition to analyzing the surface concentration of the phosphorus on the washcoat, the catalyst was cross cut so phosphorus that diffused into the washcoat could be mapped. The total phosphorus in the catalyst could then be calculated. The amount of total phosphorus detected correlated well with the reduced activity of the catalyst as measured by the temperature of 50% conversion.

The Cummins M-11 high soot diesel engine test is a key tool in evaluating lubricants for the new PC-7 (CH-4) performance category. M-11 rocker arms and crossheads from tests with a wide range of lubricant performance were studied by surface analytical techniques. Abrasive wear by primary soot particles is supported by the predominant appearance of parallel grooves on the worn parts with their widths matching closely the primary soot particle sizes. Soot abrasive action appears to be responsible for removing the protective antiwear film and, thus, abrades against metal parts as well. Subsequent to the removal of the antiwear film, carbide particles, graphite nodules, and other wear debris are abraded, either by soot particles or sliding metal-metal contact, from the crosshead and rocker arm metal surfaces. These particles further accelerate abrasive wear. In addition to abrasive wear, fatigue wear was evident on the engine parts.

The Cummins M-11/EGR diesel engine test is a key tool in evaluating lubricants for the new PC-9 performance category. Wear on liners, crossheads, rocker arms and top ring faces of M-11/EGR high soot test engines operated with two different test cycles was studied through analytical surface techniques. The first test cycle used in this study was an early prototype PC-9 cycle, and the second test cycle was the PC-9 test procedure. Abrasive wear was observed on liners, crossheads and top ring faces. In addition to abrasive wear, corrosive wear was also found on M-11/EGR liners. However, no corrosive wear was observed on crossheads, rocker arms or top ring faces. Soot provides the major contribution to abrasive wear, since the widths of the relatively uniform parallel grooves in the wear scars closely match the primary soot particle sizes. More importantly, soot produced by the M-11/EGR engine was found to be harder than the engine parts.

Emission requirements for all vehicles have become increasingly more stringent. Diesel engine design changes required to meet emissions requirements result in increased levels of soot in the lubricant. This increased level of soot causes increased wear when oils are not properly formulated. Recent studies have shown that the primary cause of wear in the crossheads of Cummins M-11 and M-11/EGR engines is the abrasive nature of primary soot particles. In addition, it has also been shown that oils, which form films that are thicker than the size of primary soot particles can prevent abrasive wear. Dispersants and dispersant-polymers are known to prevent wear in the presence of soot. The goal of this study is to better understand the role of dispersants and functionalized polymers on the prevention of wear by examining their ability to form films in the presence of abrasive contaminants.