Adaptive High-Temperature Lubrication through Nanopore Channels

这项研究工作的重点是高温自润滑的新方法，使用耐磨纳米多孔涂层。关键思想是控制和引导易于剪切的固体润滑剂内含物通过复合涂层硬基体内的纳米孔通道流向其滑动接触面。可以设想，润滑剂的流动可以通过以下方式来控制：(i)原始的润滑剂团聚体大小，（ii）通道宽度，以及（iii）仅在磨损表明润滑剂耗尽的地方允许扩散的薄屏障层。与各向同性或多层自适应复合涂层相比，这种方法的主要优点是，在开始向表面提供额外润滑剂时，所需的磨损量要小得多，从而减少磨粒磨损碎片，从而大大提高了涂层的使用寿命。虽然在氮化铬纳米孔基体中专门探索了银固体润滑剂包裹体，但这种新策略适用于一系列涂层系统，并有可能成为一项真正的突破性技术，因为它可以在各种环境和从0到~1000°C的多个温度循环中提供低摩擦表面。应用领域包括用于节油喷气发动机和燃气轮机高温轴承的硬质耐磨润滑涂层，用于空间应用的循环空气真空环境中的固体润滑，以及用于燃料电池和储氢装置的气体压缩机中的无油空气箔轴承。这项研究工作还将为一名研究生提供通过完成博士学位的论文经验，以及为几名参与研究实验室的本科生提供开阔眼界的经验。最后，每年将有200多名机械工程本科学生在其初级机械系统实验室课程中进行涉及含固体润滑剂材料的实际摩擦和磨损滑动测试，为他们提供直接接触工程多功能自适应材料领域的机会。

This research effort focuses on a new approach to high-temperature self-lubrication, using wear-resistant nanoporous coatings. The key idea is to control and guide the flow of easily-sheared solid lubricant inclusions through nanopore channels within the hard matrix of a composite coating towards its sliding contact surface. It is envisioned that the lubricant flow can be controlled by (i) the original lubricant agglomerate size, (ii) the channel width, and (iii) a thin barrier-layer that allows diffusion only exactly where wear indicates lubricant depletion. The primary advantage of this approach over isotropic or multilayered adaptive composite coatings is the much smaller amount of wear that is required to initiate the supply of additional lubricant to the surface, resulting in less abrasive wear debris and, in turn, greatly enhanced coating life-time.While specifically exploring silver solid lubricant inclusions within a chromium nitride nanoporous matrix, this new strategy is applicable to a range of coating systems and has the potential to become a true breakthrough technology by providing low friction surfaces in various environments and during multiple temperature cycles ranging from 0 to ~1000°C. Applications include hard wear-resistant lubricious coatings for high-temperature bearings in fuel-efficient jet-engines and gas-turbines, solid-lubrication in cyclic air-vacuum environments for space applications, and oil-free air-foil bearings in gas compressors for fuel cells and hydrogen storage. The research effort will also provide the dissertation experience of one graduate student through completion of the doctoral degree, as well as a mind-broadening experience for several undergraduate students to also be involved in the research laboratories. Finally, a hands-on friction and wear sliding test involving solid lubricant-containing materials will be performed by over 200 mechanical engineering undergraduate students per year in their required junior-level Mechanical Systems Laboratory course, providing them direct exposure to the field of engineered multi-functional adaptive materials.