GOALI: Functional Superelastic Interlayers for Control of Friction and Wear In Hard-Coated Components

GOALI：用于控制硬涂层部件摩擦和磨损的功能性超弹性中间层

• 批准号: 0510294
• 负责人: David Grummon
• 金额: $ 35.5万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-15 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0510294&HistoricalAwards=false
• 关键词: GOALI; Functional; Superelastic; Interlayers; Control

Abstract 0510294In a collaborative project between Michigan State University, the University of Michigan, and General Motors Corporation, the investigators are developing an adaptive functional multilayer tribological coating system having dramatically improved adhesion, extremely high wear resistance, and excellent resistance to damage from overload, thermal cycling, and high-cycle fatigue. The work is motivated by the fact that although the use of metal-oxy/nitride/carbon hard coatings is well-established for application to tool materials, much less progress has been made on efficient wear-coating systems for use in machine components. The functionality of machine parts often dictates the use of soft and compliant materials such as Mg, Ti, Zn, Al, Cu, Ag, or Au. These all have poor elastic/plastic support properties, and entail large compliance and CTE mismatches to potential hard coating materials. Transformational superelasticity is an isothermal form of the shape-memory effect. It is what gives NiTi eyeglass frames ('Flexon') their extremely high resilience. Applied as vacuum-deposited thermo-functional interlayers, NiTi thin films increase resilience, accommodate large mismatch strains, moderate contact stresses, reduce friction, and limit damage accumulation during large, high-cycle strain reversals in both processing and service. Some of the same mechanisms also limit the interfacial stresses that degrade adhesion, potentially allowing use of much thicker hard coatings (10 microns) than has previously been thought possible. Measurements of tribological response by dry sliding wear, bend adhesion, scratch loading, and nanoindentation are being made under conditions of constant surface-chemistry and contact morphology. CrN, which is a low-cost coating having medium-high hardness, high stiffness, and very low thermal expansion, is being used as a model material for sliding contact against a hardened carbide ball. Aluminum alloy 6061-T6 is being used as a model substrate material. Experimental variables are the relative NiTiX/CrN layer thicknesses and topography, interlayer processing, load, and temperature. Tribological probes are augmented by many other techniques. Their various mechanical and tribological properties will be investigated. The solid mechanics thrust is focused on numerical modeling of interfacial shear, bearing, and compatibility stresses resulting from both processing and sliding contact loading. The emphasis is on predicting plastic strains in the substrate and strain distributions in the superelastic interlayer. The educational component involves undergraduates in the proposed work via summer internships and independent study projects. This continues our historically successful efforts to (1) challenge students from diverse groups with hands-on research, and (2) provide opportunity for advanced undergraduates to contribute to the literature, and to become competitive for NSF graduate research fellowships.

在密歇根州立大学、密歇根大学和通用汽车公司的合作项目中，研究人员正在开发一种自适应功能的多层摩擦学涂层系统，该系统具有显著改善的附着力、极高的耐磨性和优异的抗过载、热循环和高周疲劳损伤的能力。这项工作的动机是，尽管金属氧化物/氮化物/碳硬质涂层在工具材料上的应用已经很成熟，但在用于机械部件的高效耐磨涂层系统方面取得的进展要少得多。机械零件的功能通常要求使用柔软和顺应的材料，如镁、钛、锌、铝、铜、银或金。所有这些都具有较差的弹性/塑料支承性能，并且与潜在的硬涂层材料存在很大的顺应性和CTE不匹配。变形超弹性是形状记忆效应的一种等温形式。这就是为什么镍钛眼镜框(Flexon)具有极高的弹性。作为真空沉积的热功能中间层，NiTi薄膜在加工和使用过程中，在大的高循环应变反转过程中增加了弹性，适应了大的失配应变，适中的接触应力，减少了摩擦，限制了损伤积累。一些相同的机制也限制了降低附着力的界面应力，潜在地允许使用比以前认为可能的更厚的硬涂层(10微米)。在恒定的表面化学和接触形态条件下，测量了干滑动磨损、弯曲粘着、划痕载荷和纳米压痕的摩擦学响应。CrN是一种低成本涂层，具有中高硬度、高硬度和极低的热膨胀，正被用作与硬化硬质合金球滑动接触的模型材料。采用6061-T6铝合金作为模型基板材料。实验变量为NiTiX/CrN层的相对厚度和表面形貌、层间处理、载荷和温度。摩擦学探头还增加了许多其他技术。我们将研究它们的各种机械和摩擦学性能。固体力学推力集中于加工和滑动接触载荷引起的界面剪切应力、轴承应力和协调应力的数值模拟。重点是预测衬底的塑性应变和超弹性夹层中的应变分布。教育部分让本科生通过暑期实习和独立学习项目参与拟议的工作。这延续了我们历来成功的努力：(1)通过实践研究挑战来自不同群体的学生，(2)为高级本科生提供为文学做出贡献的机会，并成为NSF研究生研究奖学金的竞争对手。