Wang Guixiang

Preparation and Properties of Electroless Plating Wear- resistant and Antifriction Composite Coatings Ni-P-SiC- WS2

Abstract The functional coating with high microhardness, high wear resistance and low friction coefficient on metal surface can reduce friction power consumption effectively and prolong the service life of mechanical equipments. In this study, Ni-P-SiC-WS2 composite coating was deposited on the stainless steel substrate by electroless composite plating. The surface morphology, microstructure, the composition, the microhardness, the tribological properties and the corrosion resistance of the coating were tested and analyzed. The results indicate that the surface of Ni-P-SiC-WS2 coating is compact. Extrinsic insoluble SiC and WS2 are entrenched in the coating and dispersed uniformly. Compared with other nickel coatings obtained under the same experiment condition such as Ni-P-SiC and Ni-P-SiC-MoS2, the tribological properties and the corrosion resistance of Ni-P-SiC-WS2 are improved effectively due to hard-particle-dispersion-strengthening and soft-particle-lubrication of SiC and WS2 in the composite coating.

Corrosion Properties of the Polypyrrole-molybdate Film Electro-polymerized on the AZ31 Mg Alloy

Abstract The polypyrrole (PPy) coating and polypyrrole-molybdate (PPy-MoO 4 2− ) coating were electro-polymerized in sodium salicylate solution by cyclic voltammetry (CV) on the AZ31 Mg alloy surface. Surface morphology of PPy coating and PPy-MoO 4 2− coating on Mg alloy surface before and after being corrupted was observed by scanning electron microscopy (SEM). Attenuated total reflection-infrared (ATR-IR) spectra showed the characteristic ring stretching peaks of the PPy coating and PPy-MoO 4 2− coating, and also revealed the influence of MoO 4 2− on the characteristic ring stretching peaks on PPy. The surface resistance was measured by four-point probe method. The open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization analyzed the corrosion resistance performance of PPy coating and PPy-MoO 4 2− coating on the Mg alloy surface in 3.5% NaCl solution immersing for 12 h. The results show that the surface morphology of PPy-MoO 4 2− coating is compact. And the corrosion current density of PPy-MoO 4 2− coating is lower three orders than that of the PPy coating. The PPy-MoO 4 2− coating on the Mg alloy surface has better corrosion resistance and smaller surface resistance than the PPy coating because of the existence of the molybdate ion.

Effect of SiO2 Sol Sealing on Corrosion Resistance of Anodic Films of AZ31 Mg Alloy

Abstract Silica sol was used to seal the pores of anodic oxide film of AZ31 magnesium alloy. The effect of the immersion time, the calcinating temperature and the immersion times on morphology and corrosion resistance of the film was discussed. Scanning electron microscope (SEM) was employed to characterize the surface morphology of the composite film, and potentiodynamic polarization curves were used to analyze the corrosion behaviors. The surface composition of the sealed anodic films was studied by energy dispersion spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). It has been found that the corrosion resistance of anodic film is improved by sealing by silica sol. When the dipping time is 1.5 min and the calcination temperature is 350 °C, the corrosion resistance of the film is the best. Times of dipping and calcination have a greater influence on the performance of the film. When the dipping-calcination is 7 times, the film has a good corrosion resistance. After sealing, silica sol is adsorbed on inner pores and outside pores of the anodic oxidation film.

Synthesis and characterization of nanostructured Fe-Ni alloy whisker

The nanocrystalline γ - (Fe, Ni) alloy whiskers have been prepared by chemical reduction of Fe2+ and Ni2+ ions with potassium borohydride under the function of a dispersant agent PE followed by heat treatment at 600 °C under the protection of nitrogen. Conditions, such as quantity of NaOH, concentration of salts, and species of surfactants, of preparation of Fe - Ni alloy have been discussed. X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) characterized the synthesized Fe-Ni alloy. Character, capability and use of the materials have been summarized.