Tailoring Ta(Zr)B2 film for superior high-temperature lubrication

Effective lubrication is essential for mitigating friction and wear in mechanical systems, particularly in high-temperature, oxygen-containing environments where friction-induced energy dissipation and material degradation critically affect operational efficiency and safety. Traditional low-shear strength materials often suffer severe wear or even failure under such harsh conditions, making robust high-temperature lubrication a pressing need and key challenge in materials research. Here, we present recent advances in tailoring Ta(Zr)B 2 films for superior high-temperature lubrication, guided by an unconventional design principle: first constructing materials with exceptional strength to withstand wear at elevated temperatures, and subsequently creating lubricity via operando tribochemical reactions at the contacting surface. Magnetron-sputtered Ta(Zr)B 2 solid solution films exhibit enhanced mechanical and chemical stability compared with the recently deposited high-strength TaB 2 film, exhibiting outstanding anti-wear ability with low wear rates of 1.0 × 10 –5 –1.7 × 10 –5 mm 3 /Nm. Moreover, tribochemically generated weak-shear products (B 2 O 3 and Ta 2 O 5 ) provide effective lubrication, yielding low friction coefficients (0.2–0.3) at 773 K. These findings offer a roadmap for solving the classic lubricity-durability tradeoff and developing a new class of transition-metal diboride protective films for demanding applications under high-temperature and oxygen-containing conditions.