Application of Cascade Non-Transfer Arc Torches for Powder Plasma Spraying, Surface Treatment and Micro-Spherical Powders Production

摘要

Brief review of the potential advantages offered to spraying, surface treatment and powder processing by the implementation of cascade plasma torches (CPT) is presented. The paper provides evidence that the modular designed single cathode CPT helps eliminate the following major disadvantages of conventional torches: plasma parameters drifting, 1-5 kHz pulsing of plasma flow, as well as excessive erosion of electrodes. More stable plasma results in higher quality, homogeneity and reproducibility of plasma sprayed coatings, surface and powders treated. CPT offers an extremely wide operating window allowing better control of plasma parameters, particle dwell time and, consequently, particle temperature and velocity within a wide range by generating high enthalpy quasi-laminar plasmas, medium enthalpy transient plasmas and relatively low enthalpy turbulent plasmas. Stable operation, flexibility with plasma gases as well as wide operating window of CPT should help significantly improve the existing plasma spraying processes, and also help develop new advanced technologies.