US-Sweden Planning Visit: Laser/Waterjet Processing of Cubic and Wurtzite Boron Nitride to Exceed the Hardness of Diamond

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This project will initiate a new international collaboration between researchers at Iowa State University, USA and Lund University, Sweden to design micro-structured materials that are harder than diamond and also more chemically stable. Such materials are likely to have numerous industrial applications, especially in machining tools. Single and polycrystalline diamonds are the hardest known materials; however, at high temperatures, diamond loses its chemical inertness and thermal stability. In contrast, cubic boron nitride (cBN) has exceptional chemical and thermal stability but has much lower hardness. Increasing the hardness of BN to the level of diamond is expected to allow BN materials to outperform diamond-based tool materials in corrosive and high temperature environments. The development and cost-effective processing of ultra-hard synthetic BN has the potential to revolutionize the manufacturing industry because of the superior chemical and thermal stability of BN materials compared to current state-of-art diamond tools. For example, ultra-precision machining of hardened steel dies and molds using the hardest BN tool could produce optical quality surfaces and ultra-fine tolerances, allowing expensive polishing operations to be eliminated while improving form accuracy. This planning visit will explore the effects of a novel laser/waterjet process on two phase cubic boron nitride/wurtzite boron nitride materials (cBN/wBN) to determine if the treatment leads to BN that exceeds the hardness of diamond. The laser/waterjet process was developed at Iowa State University in collaboration with researchers at Lund University who are leading experts in synthesis and characterization of cubic/wurtzite Boron Nitride. The planning visit is expected to initiate work on a number of different research directions, including designing processing conditions that result in desired microstructures for hardness enhancement, understanding the effects of laser heating and waterjet quenching on microstructures in cBN/wBN, assessing the influence of ultra-hard BN tool materials on high speed machining of ferrous alloys, and determining how the BN microstructures influence the chemical and mechanical properties of cBN/wBN. Overall this collaborative research effort will enable greater understanding of structure-property correlations in ultra-hard materials.The grant will support a planning visit by the PI, Shrotriya, and a US graduate student. The graduate student will spend approximately a month in Sweden performing proof of concept research that is likely to result in developing larger research proposals to the NSF division of Civil, Mechanical and Manufacturing Innovation in the Engineering directorate as well as the Division of Materials Research in the Math and Physical Sciences Directorate.