Synthesis and Tribological Behavior of Metal Diboride-Nitride Coatings: Optimizing the Hard and Compliant Response

该奖项的研究目标是开发机械硬度和耐磨的摩擦学涂层，以便：(a)涂层过程提供高一致性（即在可入式形状内各处均匀的厚度）；(b)涂层在正常操作条件下提供低摩擦和低磨损；(c)在高负荷、高温等极端工况下，摩擦学性能稳定且可预测。具体来说，低温化学气相沉积用于沉积过渡金属二硼化物HfB2， CrB2和TiB2的涂层，使用单源，无杂质前驱体如Hf(BH4)4。与氮气合金化可使HfBxNy涂层具有可变弹性顺应性；采用Cr合金增强抗氧化性；并合成了多层涂层，以设计硬度与弹性响应之间的关系，从而影响摩擦性能。如果成功，这项研究的结果将产生重大影响：它将使开发不含润滑剂的先进设备成为可能，这些设备在恶劣的操作条件下具有优异的使用寿命。这些包括但不限于节能和无油压缩机以及基于微机电的传感和执行装置。工程专业的研究生和本科生通过参与研究而受益。学生们在桑迪亚国家实验室度过暑假，并与桑迪亚和艾默生气候技术公司直接互动。通过在国内和国际专业会议上的演讲、在高级同行评议的科学期刊上的发表、在大学和工业实验室举办的研讨会、以及讨论这项工作以及国家科学基金会的关键作用的新闻报道，这些结果得到了广泛的传播。

The research objective of this award is to develop mechanically hard and wear-resistant tribological coatings such that: (a) the coating process affords high conformality (i.e., uniform thickness everywhere within reentrant shapes); (b) the coating provides low friction, and low wear under normal operating conditions; and (c) the tribological performance is stable and predictable under extreme operating conditions, such as high load and high temperature. Specifically, low-temperature chemical vapor deposition is used to deposit coatings of the transition metal diborides HfB2, CrB2, and TiB2 using single-source, impurity-free precursors such as Hf(BH4)4. Alloying with nitrogen affords HfBxNy coatings that have a variable elastic compliance; alloying with Cr is used to enhance oxidation resistance; and multilayer coatings are synthesized to engineer the relationship between hardness and elastic response, which affects the tribological behavior.If successful, the results of this research will have a significant impact: it will enable the development of advanced devices that are free of lubricants and which have excellent lifetime under aggressive operating conditions. These include, but are not limited to, energy-efficient and oil-free compressors and microelectromechanical-based sensing and actuating devices. Graduate and undergraduate engineering students benefit through involvement in the research. Students spend summer time at Sandia National Laboratories, as well as have direct interaction with both Sandia and Emerson Climate Technologies. The results are broadly disseminated by presentations at domestic and international professional conferences, by publication in upper-tier peer-reviewed scientific journals, by seminars given at university and industrial laboratories, and by news stories that discuss the work as well as the critical role of the National Science Foundation.