Studies on Wear Response of Waste Marble Dust Based Composites and Coatings

Abstract

The research reported in the thesis is based on the characterization and wear response analysis of a new class of polymer composites and thermal spray coatings developed using waste marble dust. To attain the purpose of the study, a treasure of property data has been produced by conducting several micro-structural studies, mechanical/physical tests and wear trials on these composites and coatings under controlled laboratory conditions. The experimental findings suggest that marble dust, in spite of being a waste is quite suitable to be used as a functional particulate filler in the fabrication of polymer composites and is eminently coatable on metal substrates. This research shows that the physical and mechanical properties are greatly affected by the incorporation of micro-sized waste marble dust in polyester. Tribo-performance tests on the composites and an exhaustive analysis of the test results suggest that the wear resistance of the hardened neat polyester and glass-polyester composites improves substantially with the incorporation of marble dust in the resin. The filler content is found to be one of the most significant control factors affecting the wear rate of the composites both in the dry-sliding and erosion wear modes. This research also shows that waste marble dust is eminently coatable on metal substrates following the high-velocity oxy-fuel spraying route. The coating quality in terms of the deposition efficiency, thickness, adhesion strength and micro-hardness values is fairly good. These basic coating characteristics can be further improved by the pre-mixing of conventional spray grade powders of nickel-chrome with raw marble dust while preparing the feedstock. This work reveals that the compositional/microstructural, mechanical and tribological properties of the coatings depend greatly on the feedstock composition, substrate properties as well as on the spray parameters. The coatings are found to exhibit excellent wear resistance both in dry-sliding and erosion modes. The thesis thus essentially focuses on the value-added utilization of a waste like marble dust in the making of composites and coatings.