Abstract

Abstract
An experimental approach to measure the temperature of in-flight particles in suspension plasma spraying
Bishoy Aziz
The temperature of in-flight particles in suspension plasma spraying (SPS) is one of the key parameters affecting the coating microstructure. Temperature measurement has been carried out before for in-flight particles in air plasma spray (APS) and other thermal spraying processes. Suspension plasma spray (SPS) is an emerging coating deposition technology that permits the deposition of nanostructured coatings with unique structural characteristics. The particles size in SPS is smaller than the one that is commonly used is APS and other spray processes leading to specific challenges for determining its temperature.
The aim of this work is to assess the feasibility of two-color pyrometer for in-flight particles in suspension plasma spraying. To do so, spectroscopic analysis in the visible to near infrared range was carried out on the jet stream when suspension of 20 wt. % YSZ particles in pure ethanol was sprayed. The analysis takes into account the radiation scattered by the particles (Mie scattering) as well as the radiation directly detected from the plasma in the jet stream, and it was found that the effect of the scattered radiation by the particles on temperature measurement is negligible along the center axis of spraying at the melting point of Zirconia.
Moreover, the main and dominant source of error on temperature measurement is the plasma radiation, the vapors and the free electrons in the background of the continuum. One the other hand, it was found that going for a longer wavelength from 1 μm to 2.5 μm is not a promising wavelength range for temperature measurement. Finally, the measurements carried out in this thesis favors future development for the current configuration of a commercial diagnostic sensor to have a better
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precision for the value of temperature measurement, as it was found that the error because of the current configuration can reach 540 ° C degrees.