Nanomaterials exhibit intriguing tribological performance and have received particular attention in the lubrication field. However, little research has been found that surveyed the application of nanometer Ni in lithium grease. In this study, nanometer Ni with an average size of 100 nm was synthesized by the direct reduction method and dispersed in lithium grease. The feasibility of nanometer Ni as a grease additive in different lubrication scenarios was evaluated by a four-ball friction tester and a TE77 reciprocating friction tester. The lubrication mechanism was analyzed based on the evaluated physical properties of lithium grease and the characterization of the wear surface. The tribology test results showed the tribological properties of lithium grease were enhanced after introducing nanometer Ni. When the dosage was 0.2 wt%, the friction-reducing and anti-wear properties of point-to-point contact increased by 34.8% and 35.2%, respectively, while those of the point-to-flat contact increased by 28.8% and 38.7%, respectively. Our work not only provides theoretical guidance and practical reference for the utilization of nanometer Ni in grease, but also explains several possible lubrication mechanisms of nanomaterials in grease.

With the worldwide concern of environmental protection, water-based lubricants exhibit extensive potential applications due to their advantages of energy-conservation, innocuity, and competitive price. Nonetheless, the common lubricating additives currently available in the market are mainly oil-based, while multifunctional water lubricants are rare. This paper reports a sulfur- and phosphorus-free multifunctional additive with high water-solubility, which is applicable for multitype material surfaces. Specifically, through the Mannich reaction method, a Jeffamine-triazole derivative was synthesized from olyetheramine and benzotriazole. Compared with distilled water, the derivative exhibited superior friction reduction and wear resistance properties in water, with the friction reduction rate up to 72.7% and 70.2% for steel/steel and steel/aluminum contacts, respectively, when the concentration of the JD2000 is 2 wt.%. Remarkably, the wear resistance property for steel/aluminum contact is improved by 88.2%. Moreover, the additive showed corrosion inhibition on the metal surface by 75.5%. We further revealed the lubrication and anti-rust mechanisms: the additives are adsorbed on the surfaces through nitrogen atoms, and the long-chain structure of polyether can cover the sliding surfaces, forming a stable viscoelastic film to prevent the severe damages caused by the direct contact between rough friction pairs. Concurrently, the dense protective film can resist the corrosion of environmental media on the metal surface and delay the metal rust. This research may provide a candidate for an ecofriendly multifunctional water-based lubricating additive.

China’s rapid industrial development requires more energy consumption based on non-renewable energy resources. The energy consumption caused by unnecessary friction accounts for about 4.5% of the GDP in China. Although grease effectively lubricates machines, lubrication failure may occur under severe conditions. Nanomaterials exhibit intriguing tribological performances and have received much attention regarding lubrication. In this study, oleylamine-modified Ni nanoparticles (OA-Ni) were synthesized and used as lubricant additive in four kinds of commonly used greases: lithium, calcium, composite calcium, and polyurea grease. The OA-Ni were uniformly dispersed in the greases through electromagnetic stirring, ultrasonic vibration, and three-roll grinding. The physicochemical properties and the structure of OA-Ni-doped grease were investigated, while the feasibility of OA-Ni as various grease additives at different contact modes was evaluated by a four-ball friction tester and a UMT-tribolab tester. Tribological tests results revealed that the friction-reducing and anti-wear properties of point-to-point contact were increased by 56.7% and 70.3% in lithium grease, respectively, while those of the point-to-face contact were increased by 59.5% and 68.9% in polyurea grease, respectively. The present work provides not only theoretical guidance of nano nickel modification but also a practical reference for the application of modified nanomaterials to various greases.