Adaptive High-Temperature Lubrication through Nanopore Channels

这项研究工作的重点是一种新的方法，高温自润滑，使用耐磨纳米多孔涂层。其关键思想是控制和引导易剪切的固体润滑剂夹杂物通过复合涂层的硬基质内的纳米孔通道流向其滑动接触表面。可以设想的是，润滑剂流可以通过（i）原始润滑剂聚集体尺寸、（ii）通道宽度和（iii）仅在磨损指示润滑剂耗尽的地方允许扩散的薄阻挡层来控制。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，开始向表面供应额外润滑剂所需的磨损量要小得多，从而产生更少的磨料磨损碎片，进而大大提高了涂层寿命。这种新的策略适用于一系列涂层系统，并有可能成为一种真正的突破性技术，在各种环境中和在0至~1000°C的多个温度循环期间提供低摩擦表面。应用包括用于燃料效率高的喷气发动机和燃气轮机中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氢存储的气体压缩机中的无油翼型轴承。 研究工作还将通过完成博士学位提供一名研究生的论文经验，以及为几名本科生也参与研究实验室提供开阔思路的经验。 最后，每年将有200多名机械工程本科生在其所需的初级机械系统实验室课程中进行涉及固体含润滑剂材料的实际摩擦和磨损滑动测试，使他们直接接触工程多功能自适应材料领域。

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.