Microstructure, Thermal Transport, and Dry‐Sliding Tribology of Powder‐Metallurgy Al7075 Composites Reinforced With Sol–Gel‐Derived ZnO–rGO Hybrid Nanoparticles

Al7075 hybrid nanocomposites reinforced with sol–gel‐derived ZnO–rGO nanoparticles were fabricated by powder metallurgy to examine whether a single hybrid architecture can simultaneously improve hardness, thermal transport, and dry‐sliding behavior. ZnO–rGO hybrids containing 1–10 wt.% rGO were synthesized, blended with Al7075 at a fixed total reinforcement loading of 15 wt.%, compacted at 60 MPa, and sintered at 550°C under Ar. X‐ray diffraction, Fourier‐transform infrared spectroscopy, scanning electron microscopy (SEM), field‐emission scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy confirmed the retention of wurtzite ZnO and reduced graphitic carbon, uniform hybrid dispersion, and limited interfacial ZnAl 2 O 4 formation. Relative to unreinforced PM Al7075, the best‐performing hybrid increased hardness from 65 ± 4 to 107 ± 5 HV30 and effective thermal conductivity from 7.84 to 13.27 W m −1 K −1 , while reducing the mean coefficient of friction from 0.506 to 0.231 and wear loss from 90.4 to 56.1 mg under 10 N, 50 mm s −1 , and 1000 m. The improvement is attributed to a complementary hybrid mechanism in which ZnO provides load‐bearing support and dispersion strengthening, whereas rGO contributes low‐shear lamellar sliding, interfacial strengthening, and improved heat spreading. These results identify rGO‐rich Al7075–ZnO–rGO composites as promising lightweight materials for dry‐sliding components requiring enhanced durability and heat dissipation.