SBIR-STTR Award

This Small Business Technology Transfer (STTR) Phase I project will develop prototypes of two novel, fast deposition rate sensors that will enable implementation of real-time deposition rate control for plasma spray. Plasma spray is currently run open loop with respect to the actual particle states and is characterized by large variations which affect yield and quality. Preliminary research reveals that currently available sensors, which measure average particle temperature and velocity, are not well correlated to deposition rate. The new sensor concepts measure particle flux using a high speed CCD array and molten flux using spectral deconvolution, both of which have been shown to correlate well to deposition rate. These new high speed sensors will provide the basis for implementing real time control that can significantly reduce coating thickness variation, a primary plasma spray performance metric. Plasma spray is a high-throughput, economical, low environmental impact process that can be used to custom engineer coating microstructure to meet specific performance requirements. It is used extensively to coat turbine components with thermal barrier coatings (world wide market of $2.5 B where US has a 35% market share) as well as emerging applications such as the electrolyte coating for fuel cells. The sensor technology proposed in this project, enabling real-time control, will enhance the process capability of plasma spray to achieve greater than 2 sigma capability, enhancing coating quality, reliability and relieving some of the cost pressures faced by domestic manufacturers

This Small Business Technology Transfer (STTR) Phase II research project will develop a robust, commercial ready sensor that enables the first viable implementation of real-time control for plasma spray, reducing the cost for existing spray applications and enabling advanced coating applications that require tighter tolerances. The sensing scheme, based on a high speed solid state array, is superior to existing sensors because it can sense individual particles across the entire plume and can filter out non-molten particles that don't contribute to the coating. For the first time, a sensor will provide the basis for real-time, closed loop control for coating thickness of plasma sprayed parts. The Phase II research will develop production models of the sensor and the related closed loop control module, as well as establish proof of concept for advanced versions of the sensor. Plasma spray is a high-throughput, economical, low environmental impact process that can be used to custom engineer coating microstructures to meet specific performance requirements, primarily in the form of thermal barrier coatings for gas turbines used in power generation and aircraft engine applications as well as emerging applications such as the electrolyte coating for fuel cells. Currently, the plasma spray process is run open-loop with respect to the critical deposition physics that determine coating quality and is characterized by large variations in coating thickness and structure.