A Study on Using Glass Micro-Spheres in Erosion Resistant Coatings and Polymer Composites

Abstract

The present work reports the performance of a new class of glass micro-sphere based coatings and glass micro-sphere filled polymer composites with emphasis on the general trends observed in their properties and erosion wear behavior. A wealth of property data has been generated by conducting various tests under controlled laboratory conditions and the analysis of the test results is presented in the thesis.

The quality of coating in terms of mechanical, micro-structural and functional characteristics depends on a large number of variables that include both materials as well as operational parameters. While the composition of coating material and the substrate play an important role in determining the coating quality, the influence of plasma torch input power is also equally important; this
is reflected in the research findings of the present investigation. This work suggests that glass micro-spheres are coatable and deposition of such coatings
on metallic substrates using plasma spraying route is possible. The variations of different coating characteristics such as coating adhesion strength,deposition efficiency, coating thickness and micro-hardness with the plasma torch input power are evident in the illustrations presented in this thesis. These coatings possess desirable characteristics such as good adhesion strength, hardness etc.Pre-mixing of micro-sized Al2O3 or TiO2 particles improves the coatability of glass micro-spheres. Such coatings also exhibit improved interfacial adhesion strength. The strength is greatly affected by the plasma torch input power.

Glass micro-sphere possesses ample reinforcing potential to be used as a functional filler in both thermoset and thermoplastic polymers. Successful fabrication of epoxy composites reinforced with glass micro-spheres is possible by simple hand-lay-up technique. Similarly, glass micro-sphere filled polypropylene composites can be fabricated by injection/compression molding routes. These glass micro-sphere filled composites possess very low amount of ix porosity (maximum ≈ 2%) and improved micro-hardness. They also exhibit improved impact strength as compared to that of the neat polymers. The tensile and flexural strength of the composites are affected, though marginally, by the weight fraction of glass micro-spheres in the composites. With improved hardness, these composites have the potential to be used in wear related
applications.

Solid particle erosion wear characteristics of glass micro-sphere coatings and glass micro-sphere filled polymer composites have been successfully analyzed
using Taguchi technique. Significant factors affecting the erosion rate of these coatings and composites are identified through successful implementation of
signal-to-noise response approach. Two predictive models; one based on artificial neural networks (ANN) approach and the other on Taguchi approach are proposed in this work. It is demonstrated that these models well reflect the effects of various factors on the wear loss and their predictive results are consistent with the experimental observations. Neural computation is successfully applied in this investigation to predict and simulate the wear
response of these coatings and composites under various test conditions within and beyond the experimental domain.