SBIR-STTR Award

The Phase I objective is to demonstrate the feasibility of using the Laser Engineered Net Shaping (LENS*) process as a method to fabricate an advanced trialloy compressor impeller for advanced Army turbo shaft applications. LENS* technology will be the key to the success of the project; it has the ability to bond high performance titanium alloys together to obtain unique and exceptional properties in both the parent materials and the bond region. The LENS* process uses a high power laser beam to deposit layers of metal to form a solid metal object directly from a CAD solid model in a fashion similar to rapid prototyping methods. The Rolls-Royce Allison 250-C30 impellers to be addressed by this proposal will be comprised of gamma titanium aluminide airfoil shell bonded to an orthorhombic titanium aluminide bore. The impellers will feature high impact tolerant airfoil leading edges at the inducer. This will be achieved by laser fusion of a relatively tough Ti-6242 insert on to the gamma titanium aluminide airfoil shell. The exducer portion of the flowpath shell, being gamma titanium aluminide, will exhibit excellent creep and oxidation resistance, while the orthorhombic titanium aluminide bore will have superior burst and low cycle fatigue capabilities.

Benefits:
The LENS* technology to be developed in this program will be novel and unique for gas turbine applications and will provide an enabling capability for the fabrication of high performance aerospace structures for both military and commercial propulsion systems. The technology will also have major relevance to advanced airframe components where it can be used to achieve improved fly-to-buy ratios and tailored mechanical properties for optimum performance.

The Phase II objective is to develop a fully integrated system that fabricates a trialloy structure directly from a CAD solid model and to demonstrate this capability by fabricating a trialloy compressor impeller. As described in the Phase I Proposal Abstract, this work will continue to focus on development of the Laser Engineered Net Shaping (LENS) process as a method to fabricate an advanced trialloy compressor impeller for advanced Army turbo shaft applications. Several key issues to be addressed during this Phase II effort include: developing a model to, based on performance criterion, define material location and shape to optimize performance, develop a means to use this information to drive the LENS process, develop a robust method to control powder composition in real-time, validate model predictions through material characterization, and perform critical rig tests to validate performance and durability capabilities of trialloy impellers. Overall, the Phase II effort will develop the process and component specific experience base necessary to scale and commit the technology into new centerline designs where the combination of performance and affordability characteristics are demanded by competitive pressures. This will subsequently allow Optomec to secure funding for Phase III commercialization through industrial partnerships.

Keywords:
SOLID FREEFORM FABRICATION LASER DEPOSITION METAL DEPOSITION LASER PROCESSING DIRECT FABRICATION POWDER DEPOSITION