Thermal Cycling Tribological Behavior and Its Evolution of hBN-Reinforced Ni/WC/CeO2 Cladding Layers from 25 to 600 °C

Enhancing the high-temperature tribological performance of protective claddings is crucial for demanding industrial applications. This study focuses on developing hexagonal boron nitride (hBN)-reinforced Ni-based composite claddings to improve wear resistance over a wide temperature range. Ni/WC/CeO2 cladding layers with varying hBN contents (0.25 wt% and 0.75 wt%) were fabricated on 45 steel substrates via vacuum cladding. Their microstructure, mechanical properties, and tribological behavior under thermal cycling (25–600 °C) were systematically evaluated. Results reveal that the in situ formation of a hard Cr2B phase, coupled with hBN addition, was key to achieving optimal overall properties. The composite with 0.25 wt% hBN (NWB25) demonstrated optimal overall properties, featuring the lowest porosity (0.1813%) and the highest H/E ratio (0.0405), leading to the best overall tribological performance. A distinct transition from mild to severe wear was observed during the 300 °C-2 stage, resulting from the fracture of a high-temperature tribo-oxidative layer. An hBN content of 0.25 wt% is identified as optimal for balancing solid lubrication and matrix cohesion, thereby achieving superior thermal cycling wear resistance. Higher hBN concentrations promote grain coarsening and increased porosity, which degrade performance.