Design and optimization of the “TiO2-Al” interfacial layer in B4C/Al composites by adding TiO2 nanoparticles to improve their electrochemical corrosion resistance

Abstract

In most aluminum matrix composites, the galvanic effects at the reinforcement/matrix interface aggravate local corrosion, thereby limiting their application in various environments. This paper presents a method to reduce the driving force of electrochemical (micro-galvanic) corrosion by introducing an interfacial layer composed of nanoparticles. In general, this layer enhanced the corrosion resistance by improving the interfacial bonding and inhibiting the formation of interfacial reaction products. Moreover, the TiO2 nanoparticles and the Al matrix had similar electron work functions; hence, no additional electrochemical corrosion occurred between them. The influence of TiO₂ content (0.0, 1.0, 2.0, and 2.5 vol.%) on the corrosion resistance of B₄C/Al composite was investigated in a corrosive Cl⁻ ion environment. The corrosion resistance was affected by changes in the “TiO₂-Al” interfacial layer and the grain size of the Al matrix caused by variations in the TiO₂ content. According to the potentiodynamic polarization analysis, the TiO₂@B₄C/Al composite with 2.0 vol.% TiO₂ nanoparticle content demonstrated the best corrosion resistance because of the dense passive film on its surface, which weakened the micro-galvanic corrosion. The thick, dense passive film acted as a barrier and prevented interactions between corrosive Cl⁻ ions and the composite. Moreover, the “TiO₂-Al” interfacial layer relieved the residual stress, consequently decreasing the Volta potential difference between the reinforcement and the Al matrix, which drives micro-galvanic corrosion. Owing to its excellent corrosion resistance, the B₄C/Al composite demonstrates broad prospects in marine and neutron shielding applications.