WEAR REDUCTION SYSTEMS FOR COAL-FUELED DIESEL-ENGINES .1. THE BASICS OF POWDER LUBRICATION

The objective of this investigation is to resolve the problem of severe wear occurring in systems using coal-water particulates as fuels or as a process material. The approach discussed herein consists of replacing conventional oil lubrication with a powder lubrication system that uses the process particles, either alone or in combination with another powder. Unlike previous work in this field, this approach is based on the postulate of the quasi-hydrodynamic nature of powder lubrication. This postulate is deduced from past observation and present verification that there are a number of basic features of powder flow in narrow interfaces that have the characteristic behavior of fluid film lubrication. In addition to corroborating the basic mechanism of powder lubrication, the conceptual and experimental work performed in this investigation provide guidelines for selection of the proper geometries, materials, and powders suitable for this tribological process. The present investigation describes the fundamentals of quasi-hydrodynamic powder lubrication and defines the rationale underlying the design of the test facility. A follow-up paper dealing with the performance and the results of the experimental investigation presents conclusions reached regarding design requirements as well as the formulation of a proper model of quasi-hydrodynamic powder lubrication.