A Study of Parameters Affecting Wear Resistance of Alumina and Yttria Stabilized Zirconia Composite Coatings on Al-6061 Substrate

N Krishnamurthy,H P Raju,M S Prashanthareddy,H S Manohar

doi:10.5402/2012/585892

Abstract

In this investigation, a composite coating of alumina and yttria stabilized zirconia in equal proportion was developed on Al-6061 substrate using Atmospheric Plasma Spraying technique. Two commercially available powders of chemical composition Al 25Fe7Cr5Ni and Al2O330(Ni 20Al) were used as bond coats. The coating samples were subjected to abrasive wear test as per ASTM G99. From the results it was found that wear rate and coefficient of friction depend on various parameters such as microstructure, surface roughness, porosity, coating thickness, and hardness. It was also found that the mechanism of wear is mainly due to abrasion and once the bond coat is exposed to the disc, it loses material by adhesion. As the coating systems possess α-Al2O3 and ZrO2, they can be used for wear and heat resistant applications such as cylinder liner of internal combustion engines.

Highlights

Ceramic materials applied as thermal barrier coatings (TBC) have been extensively studied and developed since the 1960s
Thermal barrier coatings made of zirconia are applied to combustion system components such as pistons, valves, and liners, piston fire decks in diesel engines [1,2,3]
Since zirconia-based ceramics have been used in engines and gas turbines as thermal barrier coatings, plasma spraying of these materials onto cylinder liners is found to enhance

Summary

Introduction

Ceramic materials applied as thermal barrier coatings (TBC) have been extensively studied and developed since the 1960s. Since zirconia-based ceramics have been used in engines and gas turbines as thermal barrier coatings, plasma spraying of these materials onto cylinder liners is found to enhance. The effect of mixture gives higher thermal resistance in the transverse direction when heat flux is perpendicular to the coating surface This leads to the development of thickness and high functionality thermal barrier coatings. As we know that alumina has a greater hardness and zirconia has low thermal conductivity, the mixture of these two powders can produce a good wear and heat resistant coating. It is required to select bond coat materials carefully In this context, an attempt has been made to develop plasma sprayed wear and heat resistant coatings using the mixture of Al2O3 and ZrO28Y2O3 (in the ratio of 50 : 50) with the careful selection of bond coat materials. An abrasive wear test is conducted on coated samples to provide an experimental data of the wear rates, wear mechanisms, friction coefficients under different load conditions, and dry environment using coated pin on abrasive disc method

Experimental Details

Characteristics of Coatings

Results and Discussion

Abrasive Wear Test Results

Conclusions