Title

Experimental diagnostics and modeling of thermal spray deposition processes of nano-structured wear resistant and thermal barrier coatings

Date of Completion

January 2002

Keywords

Engineering, Mechanical

Degree

Ph.D.

Abstract

This study deals with comprehensive experimental, analytical, and numerical investigations of the thermal spray processes, using DC-arc plasma torch and -gas detonation deposition process. The work was concentrated on nano-structured ceramic powder utilization in thermal spray process. Plasma jet temperature and velocity fields were measured for different spraying conditions and simple engineering correlations to predict time-averaged plasma jet temperature and velocity fields were formulated. Particle velocity and size distributions were acquired at the standoff distance for nominal plasma spray conditions. Analytical solutions of the particle acceleration and heat up in the plasma jet were developed based on measured plasma jet velocity and temperature profiles. A unique system for particle spreading visualization during the plasma spray process was designed and utilized to capture the dynamic of the particle deformation after impact. Computation of single particle impact on flat and cured surfaces was done by application of a commercial fluid dynamics code FLUENT. A simple detonation gun for testing deposition of ceramic materials and generating conventional and nano-structured coatings was designed and utilized. ^