CHAPTER 1

1.0 INTRODUCTION

The general purpose of coating is to protect the substrate and to be decorative, enhancing the appearance of substrate in terms of gloss, colour, adhesion and wetability. Consequently, in addition, surface properties such as resistance to wear, indentation, and scratching are critical to retain the basic functions [1, 2]. Polymers are common materials which are widely used in industry. Polymer coating acts as a protective covering in corrosive environments. The properties of polymers depend largely on the structures of individual polymer molecules, molecule shape and size as well as how molecules are arranged to form a polymer structure. Polymer molecules are characterised by their very large size – a feature that distinguished them from other most organic chemical compositions.

The wear rate for an advanced polymer materials varies depending on the applied normal load and the sliding speed which is affected by size, shape, the matrix composition and the test conditions [3]. As the load decreases the contact becomes elastic with consequent changes in mechanism of friction.

Epoxy resin are characterized by the presence of three- member cyclic ether group commonly referred to as an epoxy group, epoxies cross-link when a catalyzing agent (hardener) is added, forming a three-dimensional molecular network. Because of their outstanding bonding strength, epoxy resins are used to make coatings, adhesives, composite laminates and have important applications in the aerospace industry. Epoxy powder coating is still widely used today, especially as a functional and tough coating where flexibility, adhesion, toughness and corrosion resistance are needed. Epoxy coatings are based on epoxy resin; they are manufactured in a way which enables the possibility of coating to a certain thickness without defect in the coating after curing [14, 16]. Epoxy power coatings get a good adhesion to aluminium or steel surfaces, and provide a good corrosion protection layer (for indoor use). Most outstanding with powder finish is the excellent resistance against other chemicals. Epoxy powder coatings are suitable especially in aggressive environments. However, they are not suitable for external use where they become discoloured as the pigments are broken down by ultra violet rays when exposed to sunlight. They consequently become chalky and actually decreased in thickness as they are washed away [15].

1.1 AIM

The main aim of this project is to determine the effect of sliding speeds on the wear rate of an advanced Polymer coating.

1.2 RESEARCH OBJECTIVES

The objective of this project is to investigate the wear rate of an advanced powder coating using a reciprocating linear ball-on-flat sliding machine. Due to the nature of the resources required to run the experiments, this investigation included the careful attention taken for wear testing especially in areas of the ball-on-flat sliding machine, data acquisition and wear rate calculation.

The technical approach for the investigation will involved preparing different test specimens cured at temperatures of 140oC, 160oC, 180oC, and 200oC respectively. These test specimens would then be tested for one hour at sliding speeds of 0.02 m/s, 0.03 m/s and 0.04 m/s on a fixed normal load of 0.76 kg. Data from the wear testing would be acquired at once as electrical signals through with the help of electronic data acquisition devices. Also this would involve investigating and analysing the microstructure of the all the tested coated sample to see the level of damage done to it at the above temperatures and sliding speeds.

CHAPTER 2

2.0 LITERATURE REVIEW

2.1 POLYMERS

Modern scientific tools revolutionized the processing of polymers thus available synthetic polymers like useful plastics, rubbers and fibre materials says (Satish V. Kailas) [38]. As with other engineering materials (metals and ceramics), the properties of polymers are related their c