Remarkable Tribological Properties of AlMgB ₁₄ Ceramic at Extreme Temperatures Enabled by In Situ Formed Environmentally Adaptive Liquid Lubricating Films

ABSTRACT Ceramics are widely regarded as ideal candidate materials for extreme high‐temperature applications (>900°C) due to their excellent high‐temperature strength and chemical stability. However, their inherent insufficient lubrication performance at high temperatures has long restricted their use in advanced tribological systems. Existing improvement strategies primarily rely on incorporating solid lubricants, but this often leads to a sharp decline in material strength, making it difficult to balance lubricity and wear resistance. This study proposes a breakthrough approach, which is that of in situ constructing a high‐temperature liquid lubricating layer at the friction interface. We found a novel high‐hardness, high boron‐fraction AlMgB 14 ceramic exhibits, for the first time, ultra‐low friction (with a friction coefficient as low as 0.09) and near‐zero wear in both air and vacuum environments at extremely high‐temperature over 900°C. This remarkable performance originates from a co‐evolved double‐layer structure formed during the friction process: a low‐shear liquid lubrication layer (partial oxidized under limited vacuum conditions) that enables very low friction, and a high‐hardness load‐bearing layer that maintains interface stability. This research provides new strategies and a theoretical basis for designing high‐performance ceramic materials for extreme environments.