Near-zero-wear with super-hard WB4 and a self-repairing tribo-chemical layer

Abstract

Achieving near-zero-wear remains a major challenge in mechanical engineering and material science. Current ultra-low wear materials are typically developed based on the self-consumption strategy. Here, we demonstrate a new self-repairing approach to achieve near-zero-wear. We find that the WB4-βB/WC tribo-pair has a low wear rate of 10−8 mm3 N−1 m−1 in low vacuum conditions, under a maximum Hertzian contact stress of 2.23 GPa over 1 × 105 friction cycles. Additionally, we observe an abnormal wear phenomenon after 5 × 104 friction cycles, characterized by an increase in the dimensions of the tribo-pair. This near-zero-wear mechanism is attributed to the synergistic action of the super-hard WB4-βB substrate and the self-repairing tribo-oxide layer. This research provides a new approach for advancing wear-resistant materials and enhancing material longevity. Expanding the range of ultra-low-wear material systems would benefit a number of applications. Here, near-zero-wear is reported in a WB4-βB/WC tribo-pair system, attributed to surface self-repair in a certain wear regime.