Optimizing TiO2 content for balanced mechanical and corrosion properties in Cu-1 %CNT nanocomposites

Abstract

Copper-carbon nanotube (Cu-CNT) nanocomposites are increasingly explored for advanced structural and functional applications where both mechanical performance and corrosion resistance are critical. This study proposes a hybrid reinforcement strategy using titanium dioxide (TiO 2 ) nanoparticles to mitigate these issues. In this work, carbon nanotubes (1 wt.%) were employed as a fixed reinforcement to establish a structural baseline, while titanium dioxide (TiO 2 ) nanoparticles were systematically varied at 0, 3, 6, 9, and 12 wt.% to investigate their combined influence. The powders were processed by high-energy mechanical alloying at 350 rpm for 4 h and consolidated through vacuum sintering at 950 °C for 90 min. The composites underwent comprehensive microstructural, mechanical, and electrochemical characterization. The results reveal a significant mechanical enhancement with increasing TiO 2 content. The microhardness of the composite with 12 wt.% TiO 2 increased by 122.5% (from 98.7 to 219.6 HV), while the compressive strength improved by 49.9% (from 364.1 to 545.8 MPa). However, these enhancements were accompanied by a reduction in relative density from 97.7% to 89.95% and a substantial deterioration in corrosion resistance, as the corrosion rate rose from 33.127 μm/y for TiO 2 -free composites to 614.64 μm/y at 12 wt.% TiO 2 . These findings demonstrate that TiO 2 reinforcement introduces a trade-off between mechanical strengthening and corrosion resistance in Cu–CNT nanocomposites. An optimum balance was achieved at 6 wt.% TiO 2 (S6 composition), providing enhanced strength; microhardness increased by 53.8% to 151.8 HV, and compressive strength improved by 37.1% to 499.2 MPa, while maintaining acceptable corrosion performance with a corrosion rate of 419 mpy, representing only a 12.6-fold increase compared to the baseline.