Precision Cast Turbine Airfoil Cooling Technology

The reduction to practice of advanced material and process technologies are often the key to realization of significant improvements in turbine blade airfoil performance. Today they can be gained by developing a casting process capable of far greater degrees of accuracy, precision, and thinness than currently possible. The development of a plastic pattern material with superior dimensional control and unique in-process inspection features is the key. Infiltration of this pattern by a ceramic compound supplants the core placement step and assures improved dimensional control. Three resin systems will be evaluated. Trial injections of simple shapes leads to subsequent critical testing for dimensional characteristics, compatibility between the plastic materials and the ceramic compounds, and ease of the pattern removal. Ceramic injection materials will be evaluated for flow and fill characteristics and more tests for compatibility with the selected plastic pattern material, the critical characteristics of the ceramic material include the ability to fill small (less than 20 mils) cooling passages, smooth surfaces, no included voids, and strong and stable enough to survive pattern removal as well as the casting process. This project will define and demonstrate for the USAF the capability of a plastic pattern and ceramic core injection concept to meet the increased dimensional accuracy demands of precision cast, higher performance turbine airfoils. To improve the in-process inspectability, significantly improve the process yield for precision cast thin-walled airfoils, and thus dramatically lower component costs.