Formation of wear particles in polishing of brittle solids and grinding of metals

Ling Lu, Purdue University

Abstract

An experimental study has been made of the polishing of brittle solids with diamond and alumina abrasives. Polished surfaces of soda-lime glass, several ceramic polycrystals, and single crystals of magnesium oxide and spinel were prepared using special methods. Polishing wear particles (chips) and polished surfaces were examined using optical and electron microscopy, electron diffraction, surface profilometry and atomic force microscopy. The effect of polishing process parameters on surface finish and material removal has been investigated. These observations indicate that material was removed during polishing by a plastic cutting process involving the action of the abrasive particles. The cutting process was essentially the same as that occurring in the machining of metals with single point, cutting tools. The roughness (Ra) of the polished surface changed considerably in the initial stages of polishing but asymptotically reached a steady state value which was almost 50-100 times smaller than the abrasive particle size. Furthermore, this steady state roughness value was negligibly influenced by the initial surface roughness of the specimen. A study has also been made of the morphology of spherical wear particles generated during the grinding of steels and pure metals in air and argon. The morphologies were found to be characteristic of particles forming from a molten state. The evidence presented strongly suggests that at least some of the wear particles have formed by melting due to energy transfer along the wheel-specimen interface alone. Two possible mechanisms are outlined.

Degree

Ph.D.

Advisors

Chandrasekar, Purdue University.

Subject Area

Mechanical engineering|Industrial engineering|Materials science

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