Cheng Zhong

Effect of Surface Mechanical Attrition Treatment on Corrosion Behavior of 316 Stainless Steel

The nanocrystalline microstructure of the surface of 316 stainless steel (316SS) induced by surface mechanical attrition treatment (SMAT) was determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The technique of hydrogen embrittlement was first used to obtain the information of the brittleness cleavage plane. The effects of SMAT and the following annealing process on the corrosion behavior of 316SS were investigated by potentiodynamic polarization curves and potentiostatic critical pitting temperature measurements. The results demonstrated that the nanocrystalline layer with an average grain size of 19 nm was produced. However, there were lots of cracks on the surface, which led to the degradation in the corrosion resistance of 316SS after SMAT. Nevertheless, after annealing treatment, the corrosion resistance of the nanocrystalline surface had been improved greatly. The higher the annealing temperature, the better was the corrosion resistance.

Effect of Humidity on Transport Mechanism in Ag/7,7,8,8-Tetracyanoquinodimethane Bilayer Films

Ag/7,7,8,8-tetracyanoquinodimethane (TCNQ) bilayer films were prepared on glass substrates by alternate vacuum deposition of Ag and TCNQ. The metal–organic complex Ag–TCNQ was formed via transport of Ag+ in the film at a temperature of 25 °C and in atmosphere with different humidities. The transport behavior of Ag+ in the organic layer in dry and wet atmospheres was studied by measurement of optical transmittance spectra. An accelerated transport phenomenon has been observed with the increase in the relative humidity. The results showed that the transport time and relative humidity follow an inverse law. It has been found that the transport mechanism was changed from solid-state diffusion in dry atmosphere to electrochemical diffusion in wet atmospheres. A transport model based on water absorption and condensation was established to explain the effect of humidity on the transport process in the films.

Two New Methods for Characterizing the Kinetics of the Complexation of Metal/Organic Thin Films and the Oxidation of Metal Thin Films

Abstract Two new methods were developed for characterizing the kinetics of the complex and oxidation process of the thin films by using transmission spectrum and sheet resistance. Ag/TCNQ (7,7,8,8-tetracyanoquinodimethane) bilayer films and copper films were prepared on glass substrates by vacuum evaporation. The complexation kinetics of Ag/TCNQ bilayer thin films was studied via transmission spectrum. The oxidation kinetics of the copper thin films was studied via sheet resistance, which increased during the process. The results suggested that the two methods can be used to characterize the kinetics of the reaction process of thin films.