Development of coatings using the TriplexPro 200 plasma gun has provided an ideal means for implementing process maps due to the large operating window in terms of particle velocity and particle temperature, as well as the flexibility to use multiple plasma gasses to tailor the coating process. Process mapping enables tracking of coating characteristics, such as hardness, and relating those characteristics to the conditions of the particle that are induced upon the particle by the process parameters. Work performed to date has provided new insights into conditions of the powder particle that result in specific characteristics in the coating. An example is the ability to determine the critical particle energy state that affects coating stress. This work affords an understanding of general theory behind coating characteristics that result from the conditions of the particle. This paper describes the parameter impact in controlling coating stresses and determining optimum particle conditions to produce a desired, or set of desired, coating characteristics.

Process mapping is an ideal method for tracking coating characteristics in the thermal spray process. With the increased utilization of in-flight particle diagnostic tools in recent years it is now possible to quickly and effectively characterize inflight powder particle properties. With industries' increasing understanding of the relationship of these properties and coating characteristics, it is now possible to rapidly understand the implications of in-process changes with respect to coating performance. This paper is an exploratory exercise that describes the utilization of process mapping of in-flight particle velocity and temperature characteristics to optimize tungsten carbide (WC) coatings sprayed with a High Velocity Plasma torch (HVP). Key performance factors of WC coatings include high inherent hardness, low porosity and neutral to compressive stress conditions. The combination of these factors all contribute to the coatings' overall success in it's intended application and elude to its toughness, wear resistance, corrosion resistance and general ability to protect the required components. Presently, the High Velocity Oxygen Fuel (HVOF) and High Velocity Liquid Fuel (HVLF) combustion processes are the favored method of applying dependable and commercially viable WC coatings that meet all of these criteria.

The use of computational fluid dynamics (CFD) to model the operation of thermal spray processes has gained interest in the thermal spray community, able to provide an understanding as to how a process functions, and better yet how to make a process work better. Advancements to the science of modeling now permits the ability to create a comprehensive model of a plasma gun that not only simulates the dynamics of the gas but also the mechanics of arcs (plasma), thermodynamics, and entrained particulates to form a nearly complete model of a working thermal spray process. Work presented includes the methods and procedures used to validate the model to a Sulzer Metco TriplexPro 200 plasma gun and exploration of the operating regime to give an in depth and insightful look into the physics behind the operation of a triple arc cascaded plasma gun.

Utilization of a comprehensive validated computer model of a thermal spray process enables an ability to improve, optimize, and fine tune the performance of that thermal spray process. A validated model of the Sulzer Metco TriplexPro 200 plasma gun has been used to improve the performance of the actual gun in terms of enhancing gas flow dynamics, thermal management, and overall performance in terms of a robust design. Internal changes to the gun geometry using the model have extended the life of the hardware beyond any current plasma gun. In addition the model has permitted the investigation of the fundamental operation of the gun, specific to the behavior and path of the arcs, as well as the ability to operate the plasma gun, under simulation, in operating regimes that currently cannot be supported by the physical hardware. The model has been run at gas pressures above 14 bar and/or voltages above 300V that currently cannot be obtained with the physical hardware due to equipment limitations to evaluate the potential to extend the operating window of the Sulzer Metco TriplexPro 200 gun beyond current levels in terms of particle velocity and temperature. The end result is an improved process tool for applying thermal spray coatings from high temperature ceramics to relatively colder and faster carbides and alloys.