Principal investigator: Paul Salvador, Gregory Rohrer, Aharon Inspektor
University: Carnegie Mellon University
Industry partners: Kennametal, Inc.
A collaboration between Kennametal and Carnegie Mellon University (CMU) researchers is proposed to develop a high-throughput methodology to accelerate the discovery of processing routes for the fabrication of important coatings used to improve metal-cutting tools in advanced manufacturing. Corundum alpha-Al2O3 and cubic (AlxTi1-x)N, with ultrahigh Al contents near x=0.9, are among the most important coatings for the cutting tools industry, but neither can be commercially prepared on the majority of the cutting tools used in the market, so-called sharp-edged round tools like drills and endmills. This is because they are successfully formed only using high temperature processes that result in high tensile stresses, which sharp edge tools cannot support. Therefore, successful deposition of these two phases at lower temperatures with appropriate stress states for sharp edge tools will constitute major advance in cutting tool fabrication for advanced manufacturing, and will yield a competitive advantage for PA industry.
We propose to develop a method that can identify buffer layers that epitaxially stabilize the targeted crystalline phases at low-temperatures using commercial deposition methods. We propose to apply and develop a high-throughput analysis method to accelerate the identification of appropriate buffers to support growth of the targeted phases. CMU researchers have already developed such a methodology called combinatorial substrate epitaxy (CSE), wherein the local epitaxial growth on a large number of micro-crystalline substrates can be investigated using standard electron back-scatter diffraction (EBSD). Commercial coatings often have columnar grains that are only a few hundreds of nanometers wide, and standard EBSD cannot be used. Together, CMU and Kennametal researchers will use traditional micro-scale CSE to screen specific buffer layer possibilities and will develop a novel nano-scale CSE method, using transmission EBSD (called TKD) with nano-scale resolution appropriate for characterizing nano-scale grains, for identifying buffer layer / coating phase relationships in commercial coatings.