Cryo-Engineered Alumina–PTFE Composite Venturis for Enhanced Wear Resistance in Powder Coating Systems

Background/Objectives: Venturi components in powder coating systems are high velocity powder – air flow continuously operating wear sensitive parts. Currently, venturis are made of virgin polytetrafluoroethylene (PTFE) suffer progressive wear at the throat, which compromises suction performance, powder flow and uniformity of coating. Method: Based on earlier optimization trials involving alumina addition in the range of 0.5–5 wt.%, 1.5 wt.% Al₂O₃ was identified as the optimum composition. Cryogenic treatment (CT) was performed on virgin PTFE and 1.5 wt.% alumina–PTFE composite samples for 8, 12, and 16 h to optimize the soaking duration. The optimum treatment durations were found to be 12 h for virgin PTFE and 16 h for the alumina–PTFE composite. Accordingly, PTFE + 1.5 wt.% alumina composite venturis were fabricated. Both market-available virgin PTFE venturis and developed PTFE–1.5 wt.% Al₂O₃ composite venturis were subjected to CT for these optimized conditions and further evaluated through industrial trials. Findings: The optimum PTFE–1.5 wt.% Al₂O₃ composite exhibited a 21.4% lower wear rate than virgin PTFE during laboratory-scale abrasive wear testing. CT further reduced the wear rate by 23.1% for virgin PTFE and 17.3% for the PTFE–1.5 wt.% Al₂O₃ composite under their respective optimum soaking durations. Industrial trials demonstrated that the cryo-treated PTFE–1.5 wt.% Al₂O₃ venturi exhibited the lowest wear rate of 27.6 mm³/N-m, corresponding to an overall wear reduction of approximately 22.3% compared with the untreated commercial PTFE venturi. The improvement is attributed to enhanced load-bearing capability provided by nano-alumina reinforcement together with stress relaxation, structural stabilization, and improved resistance to powder-induced erosive-abrasive wear after CT. Novelty: Previous studies have primarily focused on laboratory-scale tribological evaluation of PTFE composites or CT of polymeric materials independently. In contrast, the present work integrates alumina-reinforcement optimization, CT optimization and validation under actual industrial powder-coating conditions using fabricated venturi components. The study therefore bridges the gap between laboratory-scale material development and industrial implementation of wear-resistant PTFE venturis. The developed cryo-engineered alumina-PTFE venturi offers a practical solution for improving component service life, reducing replacement costs, reducing the frequency of maintenance and improving the long-term reliability of industrial powder coating systems. Keywords: PTFE, Alumina, Venturi, Powder coating, Cryogenic treatment, Wear resistance