STTR Phase II: Nano-Layered Composites as High-Temperature Hard Coatings

Applied Thin Films Inc, Skokie IL

Investigators

Abstract

This Small Business Technology Transfer (STTR) Phase II Project aims to develop novel nano-layered coatings for high-temperature tribological applications, specifically cutting-tool coatings that perform well at elevated temperatures (up to 1000 degrees C). There is a high level of interest in these coatings because of the desire to cut at higher rates and due to increasing environmental concerns over the use of coolants during machining. Traditional coating materials do not perform well under these conditions, primarily because their hardnesses decrease rapidly as temperature rises. Research in Phase I developed a new class of coatings, combining many alternating nanometer-thick layers of metals and nitrides, which show substantial hardness enhancements. Hardnesses up to 44 gigapascals (GPa) were maintained after high temperature annealing, demonstrating the feasibility of these new materials as high-temperature stable coatings. Strong dislocation confinement in nano-layers is likely to yield higher high-temperature hardness than in monolithic coatings, providing improved wear resistance. In Phase II, nano-layered coatings will be developed that optimize key properties including hardness, thermal expansion match with the substrate, stability against dissolution into different workpieces, and oxidation resistance. Nano-layered coated cutting tools have the potential to make dry-cutting a practical alternative, and to improve wet-machining performance.