The industrial application of the spheroidization process using high-temperature plasma is regarded as a good method for the conversion of irregularly shaped particles into a spherica shape. High temperature and controlled plasma conditions are required to obtain satisfactory results. Given this, a 3D model was used to simulate heat transfer from a source term to titanium-alloy particles using ANSYS Fluent software. Such models consider the effects of particle treatment on thermodynamic and transport properties of the plasma. This present study aims to investigate the impact of heat transfer on the particles and the effect of radiation energy loss on the particles, using numerical analysis. The results showed that the operating condition such mass flow was inversely proportional to the rate of heat transfer between plasma particles and the characteristics of the plasma gas, which was due to significant variation in radiation energy losses.

Plasma Spraying is one of the most sophisticated and versatile thermal spray techniques. In Plasma Spraying, powdered material is injected into a plasma jet, which is generated from a plasma torch. Upon contact with the plasma jet, the particles are melted and propelled forward onto a substrate to form an adherent coating which modifies the properties of the substrate. The modifications to the substrate can, for example, increase its resistance to other extreme operating conditions such as wear, abrasion, and corrosion. However, the phenomena governing the formation of the plasma jet inside the plasma torch and its subsequent interaction with injected particles are not fully understood. This paper provides a detailed report on steps taken for the development of a comprehensive numerical model to simulate plasma jet development inside a direct current plasma torch. The heat flow and mass exchange of ionized gas with injected solid particles were followed in three dimensions by using a Computational Fluid Dynamics (CFD) method. A cylindrical energy source term which was defined as an increasing linear function dependent on time as a variable, was included to reproduce the effects of an electric arc on the gas flow. For optimization purposes, it was sought to investigate the effects of the particles’ injection angle and inlet velocity, as well as the effects of particle size distribution on the particle temperature and velocity histories.

Copper alloys are typically produced by conventional casting processes, including spark plasma sintering (SPS), which often produce inhomogeneous mixtures of Cu or Al precipitates and unwanted intermetallic phases in solid products. Induction melting should provide good mixing, controlled heating and melt stirring, potentially improving homogeneity. Homogeneous melts should produce homogeneous powders, giving better properties in additive manufacturing (AM). To ascertain homogeneity, a density test was developed. After comminution, homogeneous powders can be used to produce high quality components. To manufacture dense AM components, spheroidised powders are needed because they increase particle packing and powder flow. An Al-50Cu (at.%) button was produced by high-frequency (HF) induction melting, to give better mixing and hence phase distributions. To identify the phases and their distributions, the as-cast sample was studied using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD), as well as absolute density using helium pycnometry. Results indicated inhomogeneity in the samples, due to Al loss, complex solidification and the densest phase settling at the bottom of the button.