Effects of electroless nickel -coating on tribological and corrosion behaviour of TMT steel rebar with multi-walled carbon-nanotube and titanium dioxide nanoparticles

Abstract

This study incorporated Multi-walled carbon nanotube particles (MWCNTs) and Titanium Dioxide Nanoparticles (TiO2) into a metal matrix composite in Ni–P coated substrate using an Electroless technique. This study significantly improves the tribological properties, enhances corrosion resistance, increases durability and extends the service life of coated rebar. Coated rebar helps make infrastructure more sustainable by extending the life of buildings and lowering their material consumption, trash output, and ecological footprint. The tribological behaviour of steel rebar has been studied by using a variety of characterization techniques, like X-ray diffraction, Atomic Force Microscopy, Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (EDX) including the corrosion test and the hardness test. The topographical roughness of the bare specimen, Ni–P coated specimen, CNT coated specimen and TiO2 coated specimen are 67.4 nm, 112 nm, 201 nm, and 162 nm respectively. The microhardness of the bare substrate, Ni–P coated, CNT doped coated, and TiO2 dopped coated specimens was done using Vicker's Hardness tester and the mean values were 455 HV, 580 HV, 810 HV, and 680 HV respectively. Resistance to corrosion of TMT steel rebar of Fe500 was examined using the polarisation method and Electrochemical-Impedance-Spectroscope (EIS) method. These techniques were examined in 3.5 wt% aqueous medium of NaCl and analysed the Ecorr (corrosion potential) and Icorr (Corrosion current density) of the bare substrate, Ni–P coated, Ni–P/CNT and Ni–P/TiO2 substrate. The corrosion inhabitation efficiency of the Ni–P-CNT doped was 22.5% more than the Bare substrate, and the TiO2 doped coated specimen was 10.63% more than the bare substrate. Resistance to corrosion of the CNT-coated substrate is better than Ni–P/TiO2 and Ni–P-coated specimens.