Improved Process Controls of Combustion Sprayed Clearance Control Coatings Through Sensor Diagnostic Technology

Abstract

Abstract Sensor technology is becoming more of a production tool to help improve production quality, reliability and reduce manufacturing costs. Combustion sprayed abradable seal products are a family of materials where this technology will be helpful to the applicator and end user. Although these materials have been used for over forty years with wide success in the aerospace and industrial gas turbine industries they can be sensitive to spray process variables. Changes in spray processing conditions during spraying will change the desired microstructure and coating properties. This paper looks at a commercially available combustion powder and how process parameters such as gas flows and powder feed rates affect output process variables such as particle velocity and temperature. This paper will also discuss the importance of understanding the influences that particle temperature and velocity have on coating properties such as hardness, erosion and coating strength. Deposit efficiency of these combustion powders is also measured as a function of particle temperature and velocity. Based on particle temperature and velocity, sensor diagnostic tools can provide warnings about process changes resulting in fast corrective action. The benefits of this sensor technology are the potential for less inspection requirements, improved microstructure control, reduced in-service failures, and less time and labour required for stripping coated components that may not meet specification standards.