Investigation of wear mechanisms in multi‐scale short carbon fiber reinforced PTFE composites for blade rotor volumetric pumps in variable lubrications

Abstract To address bearing material damage in the Blade Rotor Volumetric Pump, We proposed a preparation method for multi‐scale short carbon fibers (SCFs) reinforced PTFE composites, which exhibited excellent tribological properties under water lubrication. However, its performance under other lubrication conditions remains insufficiently explored. Therefore, this study investigates the tribological behavior of h‐BN/5 wt% SSCFs/10 wt% LSCFs/80 wt% PTFE composites under diverse lubrication conditions (dry friction, deionized water, and seawater) with varying loads (2–4 MPa) and velocities (0.25–0.75 m/s). The composite demonstrates exceptional wear resistance across all conditions, achieving specific wear rates within the 10 ⁻⁶ mm ³ /(N•m) range. The results reveal superior performance under water lubrication with the lowest specific wear rate (1.21 ± 0.28 × 10 ⁻⁶ mm ³ /(N•m)), contrasting with seawater lubrication's maximum value (4.55 ± 0.72 × 10 ⁻⁶ mm ³ /(N•m)). Notably, the composite maintains a remarkably low friction coefficient of 0.036 under seawater lubrication at 3 MPa‐0.25 m/s. Distinct wear mechanisms emerge across conditions: Dry friction induces thermal softening of the composite matrix and interfacial weakening between SSCFs and PTFE, reducing the direct contact area by forming a transfer film on the duplex stainless steel disc. Water lubrication facilitates self‐reconstruction of SSCFs, achieving greater than 20% surface coverage through self‐directed and enriched short carbon fibers, synergizing with interfacial water films to establish boundary/fluid lubrication states. Seawater conditions introduce dual effects‐while maintaining water lubrication benefits, precipitated inorganic salts (primarily NaCl) generate abrasive wear, causing plowing marks on the friction surface, though salt films provide supplementary lubrication. The chemical reaction of seawater elements on DSS surfaces, together with inorganic salt particles, causes fluctuations in the friction coefficient. Temporal evolution analysis shows load/speed‐dependent friction trends: dry friction exhibits friction coefficient increases with ascending speed/load, water lubrication demonstrates initial reduction followed by increase, while seawater maintains stable coefficients across speed variations. All lubrication conditions involve SSCFs self‐reconstructing, which achieves alignment and enrichment of SSCFs along the sliding direction on the friction surface of the pin, thereby improving the wear resistance of composites. Highlights The multi‐scale SCFs hybrid strategy is effective and reliable. Excellent wear resistance is observed under various lubrication conditions. SSCFs' self‐reconstruction during friction enhances wear resistance. Seawater lubrication causes abrasive wear due to salt particle precipitation.