Mechanical, electrochemical and tribological properties of nanocrystalline surface of brass produced by sandblasting and annealing
By Xing, Y.F.; Li, S.F.Y.; Lau, A.K.H. & O’Shea, S.J.
Published in Surface and Coatings Technology
2003
Abstract
Mechanical, electrochemical and tribological properties of nanocrystalline surfaces of a brass alloy (70–30) produced by sandblasting and annealing were investigated. The grain size of a nanocrystalline surface was determined by means of optical microscopy and transmission electron microscopy. The relationships between the grain size of a surface and its properties were investigated using nano-/micro-indentation, micro-scratch, electrochemical scratch and polarization techniques. It was demonstrated that the surface hardness and elastic behavior were improved as the grain size decreased, leading to markedly enhanced wear resistance. The efficiency of hardening by reduction of grain size became lower in the nanocrystalline region, compared to that in the microcrystalline region. The potentiodynamic polarization test indicated that the nanocrystalline surface had higher resistance to corrosion. Nano-indentation and micro-scratch test with in situ monitoring changes in contact electrical resistance demonstrated that the nanocrystallization was significantly beneficial to the mechanical behavior of the passive film. Mechanisms responsible for the beneficial effects of nanocrystallization on properties of brass and its passive films are briefly discussed.