It is well-known that the performance of the CS process is enhanced by increasing the process gas stagnation temperature, as this increases the gas velocity, and thus the particle velocity (kinetic energy). However, the influence of the initial substrate, coating, and particle impact temperatures on the CS process performance is still a topic that has barely been studied. This work focuses on establishing in a more systematic way how the initial substrate, coating, and particle impact temperatures affect the CS process performance by decoupling these three variables from the general spray parameters, namely the gas stagnation temperature. This decoupling is of crucial importance if one wants to be able to study the effect of each temperature and this approach has never been reported anywhere so far.
In this work, two feedstock powder materials are used: pure aluminum and Inconel 718. The substrate material selected is Ti-6Al-4V. Therefore, the observations provided in this thesis are valid for the deposition of aluminum-on-Ti-6Al-4V and Inconel718-on-Ti-6Al-4V. To increase and control the initial substrate and coating temperatures while ensuring proper decoupling of other spray parameters, an induction heating system is used with the CS process. To control the initial particle temperature, independently from the gas stagnation temperature, powder preheater units are used. The powder is fed in the diverging section of the nozzle to avoid the uncontrollable heating usually observed by feeding the powder in the converging section.
Single-particle impact testing and splat adhesion strength testing are carried out to evaluate the effect of the initial substrate temperature on individual particles. This is investigated using pure aluminum as the feedstock powder material. A finite element modeling is also carried out to complement the experimental results. The influence of the initial substrate temperature on the deposition process is quantified by measuring the deposition efficiency and coating porosity values. Micro-hardness testing and adhesion strength testing are used to characterized the as-sprayed coating mechanical properties.
To study the influence of the coating temperature on the CS process performance, both powders, pure aluminum and Inconel 718, are used. The role of the coating temperature on the CS process is assessed by measuring the deposition efficiency and coating porosity values for the deposition of both powders. Micro-hardness, adhesion, and tensile strength measurements of the pure aluminum coatings is carried out. For the Inconel 718 coatings, only micro-hardness testing is conducted.
To characterize the influence of the particle impact temperature on the CS process, Inconel 718 is used. The particle impact temperature is predicted using a computational fluid dynamics model. Deposition efficiency, coating porosity values, and micro-hardness testing are used to characterize the influence of the particle impact temperature on the CS process.
The results in this thesis provide a path to optimize the CS process performance based on the influence of the initial substrate, coating, and particle impact temperatures. This work also demonstrates that other variables, such as particle impact velocity and feedstock powder material hardness, must also be considered to optimize the CS process performance through the use of different temperatures.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/43906 |
| Date | 11 August 2022 |
| Creators | Ortiz Fernandez, Roberto |
| Contributors | Jodoin, Bertrand |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Attribution 4.0 International, http://creativecommons.org/licenses/by/4.0/ |
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