Abstract

Suspension Plasma Spraying (SPS) has emerged as a promising coating technique for producing nano-structured, and fine-grained surfaces in the aerospace, and energy sectors. However, predicting the final coating morphology remains a challenge due to the complex interplay of parameters, such as particle velocity, temperature, injection configuration, substrate geometry, and plasma dynamics. Experiments have contributed valuable insights, but remain resource-intensive, time-consuming, and limited in scope.

This thesis presents a comprehensive numerical model, developed in MATLAB, for simulating coating buildup in SPS processes. The model is designed as a flexible computational tool to support researchers, and engineers in exploring process-structure relationships, and optimising spray parameters. It simulates particle motion, temperature-dependent flattening, spray gun motion, and surface evolution over time. The framework accommodates injection schemes, incorporates plasma jet fluctuations, and integrates a broader set of particle distribution datasets to enhance generalisation.

Compared to prior models, this work expands the design space by enabling simulations across multiple substrate geometries, and injection configurations. Model outputs include deposition coverage, and morphological growth trends that align with observed experimental behaviours, such as columnar structures, and shadowing effects. The model is used to analyse the effects of interpeak distances of asperities, particle velocity distributions, spray gun traverse velocities, and database representative times on the final coating microstructures, thus better informing users on the impact of parameters on microstructural features such as porosity, density, and column formation.

Overall, the simulation framework provides a cost-effective and scalable alternative to experimentation. It contributes to the digitalisation of SPS process development and lays the groundwork for future integration with data-driven optimisation techniques, CFD-based plasma torch simulations, and intelligent control strategies for optimisation.