Precursor Plasma Spraying (PPS) using Radio Frequency (RF) induction plasma spray is a new process used to synthesize functional materials. RF plasma spray has the advantages of stability, cleanness, high temperature and high chemical reactivity. In this paper, a two-dimensional numerical model has been developed to investigate the induction electromagnetic (EM) field and the thermo-fluid field in a radio frequency inductively coupled plasma (RF-ICP). In flight particle interaction with the plasma jet will be investigated. The traditional micron-size powder particles, e.g. zirconia (PSZ), are injected with carrier gas such as argon. During their interaction with the RF plasma, the powder particles experience acceleration, heating, melting and evaporation and particle heat transfer is considered coupled with the thermo-fluid flow of the RF plasma. A generalized particle model is developed and applied to the precursor plasma spray process operated in a vacuum chamber. The effects of power input, standoff distance and powder size on the RF plasma and particle in flight characteristics are investigated.

Inside diameter (ID) spraying with a two-wire gun for thermal spraying has become an established practice. While the simplicity of the two-wire arc process is tempting, there is a marked difference between the coating microstructures obtained with standard two-wire arc and two-wire arc ID systems. In conventional two-wire arc spraying, the arc is partially surrounded by the nozzle, which leads to the fused tips being enveloped by the atomizing gas flow. In comparison, the right-angled arc is unprotected if the airflow hits the arc at 90 degree. In this paper, the particle formation process is investigated using diagnostic tools such as Laser Strobe Vision (Control Vision) and DPV2000. Although the data collected may not fully encompass the breadth of the phenomena associated with two-wire arc spraying, a comparison was made between the 0 degree and 90 degree spray processes. Paper includes a German-language abstract.

Two sets of plasma spray processing conditions were utilized in the investigation of graded layers, consisting of NiCrAlY and PSZ. Following the optimization of the plasma spray parameters and particle characteristics, the deposition efficiencies (DEs) of various powder species was examined. Selection of the best suited powders for coating production were selected based on the DE results. The base DEs were corrected by conducting the analyses using pre-deposited substrates as targets. Individual mixed coating layers were prepared and their compositions confirmed by image analysis. The effects of standoff distance and substrate temperature were also seen to have an effect on the DE and thus the coating formation. It is suggested that two-feeder, single injector plasma processing may not be the optimal method for the formation of FGMs.