Doctoral Dissertations

Date of Award

12-1999

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Metallurgical Engineering

Major Professor

Narendra B. Dahotre

Committee Members

Mary Helen McCay, Peter Liaw, Thomas Meek

Abstract

The aim of the present study was to identify and develop an unique combination of coating technique and material, which could target its properties similar to that of an "ideal coating". In the present study, Nd:YAG laser was used as a tool to deposit ultrahard TiB2 ceramic on AISI 1010 steel within a fixed envelope of processing parameters such as laser power and traverse speed. The thrust of the present study is on the material properties and behavior of the TiB2 coating within the fixed envelope of these processing parameters. A uniform, continuous and crack free coating with metallurgically sound interface is obtained. Coating is “composite” in nature, comprising TiB2 particles and the Fe from steel trapped in the laser melt zone. Such coating has been evaluated for various properties such as mechanical (hardness, elastic modulus,interfacial energy, fracture toughness and fracture morphology), chemical and structural(x-ray diffraction, SEM, TEM and HRTEM) and high temperature oxidation and corrosion properties. Coating is hard and tough in nature. A semi-quantitative model has been developed to estimate the elastic modulus of TiB2 coating using nanoindentation technique. It also has been concluded that TiB2 coating has a high interfacial energy suggesting a stronger and adherent interface. Composite TiB2 coating has a significant oxidation resistance up to 800°C. Also, it has shown improved high temperature corrosion resistance against liquid aluminum. Such features contribute significantly towards the goal of achieving an ideal coating.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS