Aluminium alloys are commonly used as lightweight materials in the automotive industry. This non-ferrous family of metallic alloys offers a high versatility of properties and designs. To reduce weight and improve safety, high strength-to-weight ratio alloys (e.g. 6XXX and 7XXX), are increasingly implemented in vehicles. However, these alloys exhibit low formability and experience considerable springback during cold forming, and are therefore hot formed. During forming, severe adhesion (i.e. galling) of aluminium onto the die surface takes place. This phenomenon has a detrimental effect on the surface properties, geometrical tolerances of the formed parts and maintenance of the dies. The effect of surface engineering as well as lubricant chemistry on galling has not been sufficiently investigated. Diamond-like carbon (DLC) and CrN physical vapour deposition (PVD) coated steel have been studied to reduce aluminium transfer. However, the interaction between lubricants and PVD coatings during hot forming of aluminium alloys is not yet fully understood. The present study thus aims to characterise the high temperature tribological behaviour of selected PVD coatings and lubricants during sliding against aluminium alloy. The objectives are to first select promising lubricant-coating combinations and then to study their tribological response in a high-temperature reciprocating friction and wear tester. Dry and lubricated tests were carried out at 300 °C using a commercial polymer lubricant. Tests using DLC, CrN, CrTiN, and CrAlN coated tool steel were compared to uncoated tool steel reference tests. The initial and worn test specimen surfaces were analysed with a 3-dimensional (3D) optical profiler, scanning electron microscope (SEM) and energy dispersive X-ray spectroscope (EDS) as to understand the wear mechanisms. The results showed formation of tribolayers in the contact zone, reducing both friction and wear. The stability of these layers highly depends on both the coatings’ roughness and chemical affinity towards aluminium. The DLC and CrN coatings combined with the polymer lubricant were the most effective in reducing aluminium transfer.

铝合金在汽车工业中通常用作轻质材料。该有色金属合金家族具有很高的性能和设计多功能性。为了减轻重量并提高安全性，在车辆中越来越多地采用高强度重量比的合金（例如6XXX和7XXX）。然而，这些合金表现出低的成形性并且在冷成形期间经历相当大的回弹，因此是热成形的。在成型过程中，铝在模具表面上发生了严重的粘附（即擦伤）。这种现象对表面性能，成形零件的几何公差和模具的维护有不利影响。表面工程以及润滑剂化学对磨损的影响尚未得到充分研究。研究了类金刚石碳（DLC）和CrN物理气相沉积（PVD）涂层钢，以减少铝的转移。然而，尚未完全了解铝合金热成型过程中润滑剂与PVD涂层之间的相互作用。因此，本研究旨在表征所选的PVD涂层和润滑剂在铝合金滑动过程中的高温摩擦学行为。目的是首先选择有希望的润滑剂涂层组合，然后在高温往复式摩擦磨损测试仪中研究其摩擦学响应。使用商用聚合物润滑剂在300°C进行干式和润滑测试。使用DLC，CrN，CrTiN和CrAlN涂层的工具钢进行的测试与未涂层的工具钢参考测试进行了比较。使用3维（3D）光学轮廓仪，扫描电子显微镜（SEM）和能量色散X射线光谱仪（EDS）对初始和磨损的试样表面进行了分析，以了解其磨损机理。结果表明在接触区形成了摩擦层，减少了摩擦和磨损。这些层的稳定性高度取决于涂层的粗糙度和对铝的化学亲和力。DLC和CrN涂层与聚合物润滑剂的结合在减少铝转移方面最有效。这些层的稳定性高度取决于涂层的粗糙度和对铝的化学亲和力。DLC和CrN涂层与聚合物润滑剂的结合在减少铝转移方面最有效。这些层的稳定性高度取决于涂层的粗糙度和对铝的化学亲和力。DLC和CrN涂层与聚合物润滑剂的结合在减少铝转移方面最有效。