SBIR-STTR Award

Mikro Systems Inc. (Mikro) has developed an advanced manufacturing platform called Tomo Lithographic Molding (TOMO). The platform has been successfully applied to produce highly engineered products, including turbine airfoils for power generation and aviation flight. Specifically, TOMO is currently being used to produce ceramic cores for investment casting of advanced turbine blades and vanes. This has enabled the production of internal cooling geometries that are beyond the current state-of-the-art, thus providing potential fuel savings for next generation turbines. Mikro now proposes to extend the use of TOMO within the investment casting process through the development of engineered ceramic filters for metal casting. Current state casting filters are not sophisticated from a design perspective and no specific filters have been engineered for single crystal (SX) casting. Our proposal will focus on developing ceramic filters that will optimize filtration performance while enabling directional flow of molten alloy during the SX casting process. These performance advantages will be enabled through the geometric design of the filter. Another anticipated benefit is the ability to design part-specific filtration schemes for advanced airfoil castings. This performance optimization could significantly improve casting yields, lowering the cost and thereby removing a primary obstacle to more wide spread use of SX casting for industrial gas turbines and other critical investment cast products. The market potential for this technology is significant because the ceramic filters can be used for land based and aviation turbine applications as well as any other investment cast parts using SX techniques.

Modern gas turbines must operate at higher temperatures in order to achieve better fuel efficiency and reduce emissions. To achieve maximum performance, components must be made of Nickel super-alloys and must be cast as single crystals. Although single crystal casting yields have improved, they have not improved sufficiently to enable wide-spread use of single crystal super-alloys in industrial gas turbines (IGT), primarily due to low yields. Innovative approaches to increase the yield are needed. Mikro Systems proposes to apply its patented Tomo Lithographic Molding (TOMO) process to produce superior ceramic filters that are used to remove the impurities during the molten metal pouring step in the casting process. Improved filtration will increase the yield and ultimately lower the cost of these critical and costly high technology parts. A 1% improvement in casting yield could lead to annual savings over $10 million in the U.S. alone. During Phase I Mikro demonstrated the technical feasibility of producing advanced designs for pour cup and inline filters using TOMO. Until now, these designs could not be produced due to limitations in current manufacturing methods. Flow tests of Mikro filters demonstrated much lower variability in flow rate and pressure drop from filter-to- filter compared with off-the-shelf filters. Flow rates during single crystal casting are critically linked to the metal solidification process, which is directly tied to production yield for turbine blades. The primary Phase II objectives are to optimize materials and filter designs to be ready for industry standard single crystal casting. This will include extensive testing and modeling, and will conclude with foundry casting of an advanced turbine blade to evaluate and compare the new filter performance with current filters. Commercial Applications and Other

Benefits:
Advanced filters have application in investment casting of turbine components for IGT as well as the much larger aero turbine markets. This will improve the yield and lower costs for single crystal casting and can be expanded to other casting processes and products. Investment casting is a multi-billion dollar global market.