Dual-Phase Nanocomposite TiB2/MoS1.7B0.3: An Excellent Ultralow Friction and Ultralow Wear Self-Lubricating Material.

Proper lubrication is essential to the reliable and efficient operation of mechanical systems ranging from the industrial to the nanoscale. Self-lubricating materials that can self-generate and sustain concurrent ultralow friction and ultralow wear in harsh environments open up a unique realm that is unattainable by traditional external lubrication mechanisms, but developing such extraordinary materials has been a long-standing grand challenge. Here, we devise an unconventional strategy to construct a dual-phase nanocomposite (DPNC) that comprises a wear-resistant phase (TiB2) and an internal lubricant source (MoS1.7B0.3). Tribological tests demonstrate simultaneous ultralow friction coefficient (∼0.03) and ultralow wear rate (∼10-10 mm3·N-1·m-1) of the synthesized DPNC specimen in ambient environments; these superb properties remain intact after the specimen has been annealed at 400 °C in air. First-principles energetic and stress-strain calculations elucidate atomistic mechanisms underpinning DPNC TiB2/MoS1.7B0.3 as an ultimate self-lubricating material. This accomplishment solves the classic lubricity-durability tradeoff dilemma, enabling advances to meet the most challenging lubrication needs.