Influence of Plasma Gas Mixture On Particle In-flight Properties For The Axial III Plus Plasma System

Gas mixtures of Argon, Hydrogen and Nitrogen are typically used for plasma forming gasses with the Axial III Plus plasma torch, leading to a more complex set-up than a conventional plasma system. The three gasses may also be utilised over a large range of gas ratios, from nitrogen to argon rich; with a total gas flow can variation up to 300%. This produces a large processing window within which, vastly different material treatment conditions can be achieved. However, it can be difficult to select appropriate parameters for coating development due to the process window size.

This work will present the impact of the plasma gases on in-flight particle properties to understand how parameters may be optimised in the Axial III plasma system. Experimentally the plasma gas mixtures were varied across a range of settings. Plasma system outputs in the form of voltage, gross power and net power were recorded. The influence of plasma conditions was measured on the in-flight particle properties with an Accuraspray system, using a model thermal spray material (yttria stabilised zirconia). The results show the relative effects plasma operating parameters have on particle properties and give an insight on how to select appropriate plasma start conditions.