Nanocrystalline Thin Films of New Ultra-Hard Borides for Microelectromechanical Systems (MEMS) and Tooling Applications

这项资助的目的是发展对合成具有可预测性和可重复性的超硬硼化物纳米晶体薄膜的基本理解。联合首席研究员最近发现的超硬硼化物是地球上第二硬的新材料，预计制造成本约为金刚石和立方氮化硼成本的10%。研究将重点发展一种新的Ti：蓝宝石飞秒脉冲激光沉积（PLD）技术，用于在硅和硬质合金衬底上制备超硬硼化物薄膜，分别用于微机电系统（MEMS）和硬车削应用。该薄膜将与传统的纳秒（ns） PLD沉积的薄膜进行比较。本研究将探讨激光与硼化物的相互作用随脉冲宽度的变化，以及等离子体与衬底表面的相互作用对薄膜结构、组成和生长的影响。纳米压痕和划痕测试将用于机械特性，包括硬度，杨氏模量和粘附性。将探讨硬涂层在工具和MEMS中的应用。这项研究有可能产生巨大的回报。这项开创性的工作将为新型硼化物材料的快速创新发展奠定基础，并作为催化剂，用于许多工具和硬涂层应用，包括大块切削工具，硬质和耐侵蚀涂层，耐磨电气开关触点和MEMS导电薄膜。此外，这些涂层可以作为高温固体润滑剂。实验和分析相结合的方法有望将下一代硬材料和先进的激光加工技术转化为工业，并为制造业提供高质量的产品。机械工程和材料科学与工程专业的研究生和本科生将受益于纳米晶硼化物的制备，薄膜的先进激光沉积，先进加工和MEMS制造的实践研究经验。

The objective of this grant is to develop a fundamental understanding of synthesizing nanocrystalline thin films of ultra-hard borides with predictability and reproducibility. Ultra-hard borides, recently discovered by the co-Principal Investigator, are the new, second hardest materials on earth with a projected cost of manufacture approximately 10% of the cost of diamond and cubic BN. Research will focus on the development of a novel Ti:Sapphire femtosecond (fs) pulsed laser deposition (PLD) technique for preparing ultra-hard boride thin films on silicon and cemented carbide substrates for Microelectromechanical Systems (MEMS) and hard turning applications respectively. The films will be compared to those deposited by conventional nanosecond (ns) PLD. The research will investigate the laser-boride interactions as a function of pulse width and the interactions of plasma with the surface of substrate that affect the evolution of structure, composition, and growth of films. Nanoindentation and scratch tests will be used for mechanical characterization that includes hardness, Young's modulus, and adherence. Hard coating applications in tools and MEMS will be explored.The research has potential for enormous payoffs. This pioneering work will set the stage and serve as a catalyst for rapid and innovative advances in the new boride materials for numerous tool and hard coating applications including bulk cutting tools, hard and erosion resistant coatings, wear-resistant electrical switch contacts, and conductive thin films for MEMS. In addition, these coatings can serve as high-temperature solid lubricants. The integrated experimental and analytical approach is expected to transfer the next-generation hard material as well as advanced laser process technology to industry and supply high-quality products to manufacturing industries. Graduate and undergraduate students from both Mechanical Engineering and Materials Science and Engineering will benefit from hands-on research experience in preparation of nanocrystalline borides, advanced laser deposition of thin films, advanced machining, and MEMS fabrication.