Advanced Materials Research Vols. 634-638

Abstract: The hot dip Al-Zn alloy coated steel sheet was passivated with chromium-free passivation solution which adopted the molybdate and acrylic resin as the main film-forming substances. The surface morphology and corrosion performance of the coating were studied experimentally by using glow discharge optical emission spectroscopy(GD-OES), scanning electron microscopy(SEM) and energy-dispersive X-ray spectroscopy(EDS), polarization curves and the neutral salt spray test. The GD-OES and SEM results show that the molybdate-containing thin organic coating is deposited on the substrate compactly and homogeneously without obvious tiny cracks. The test results of corrosion performance show that the corrosion potential and current density of the passive films decrease obviously in comparison with those of the substrate, and the corrosion resistance of the coating is comparable with that of the chromate passivation coating.

Abstract: The corrosion property of three currently used hot dipped alloys (Al-8Si, Zn-0.6Ni and 55Al-Zn-Si) immersed in 3.5% NaCl solution were studied by analyzing the open circuit potential variation with time and electrochemical impedance spectroscopy (EIS) tests. The open circuit potential of the Al-8Si alloy is 100mV higher than the potential of Zn-0.6Ni and 55Al-Zn-Si, and the potential of Zn-0.6Ni is approach to the 55Al-Zn-Si alloy. The phase angles of the Al-8Si, 55Al-Zn-Si and Zn-0.6Ni are close to -80°,-70°,-60°, and the high impedance values at low frequencies are 105,104,103 Ω cm2, respectively. The EIS spectra of the alloys indicated two relaxation time constants. An “equivalent circuit” with the circuit elements representing the electrochemical properties was proposed to simulate the EIS spectra, and the simulated dates were in a good agreement with the experiment dates. The polarization resistance (Rp) of Al-8Si, 55Al-Zn-Si and Zn-0.6Ni are 18000, 2010, 251 Ω•cm-2, respectively. The results showed that the corrosion property of Al-8Si is well than the other alloys in the test solution.

Abstract: The thesis shows the impact of the epoxy resin system crosslink density on the coating’s methanol resistance. The oil absorption method critical pigment volume concentration (CPVC ) value and the dry film density method CPVC value were compared for the single pigment. The mixed pigments coating’s CPVC was calculated from the single pigment CPVC and compared with the experiment data. The methanol resistance of different relative PVC (λ) coatings was compared. The result showed that the coating with λ less and close to 1 revealed the best methanol resistance.

Abstract: Hysteresis effect of contact angle has an important impact on liquid bridges between sphere particles. This effect is not limited to increasing liquid volume of fixed particles. The hysteresis effect of contact angle is expressed by fixed liquid volume while the two sphere particles are in relative movement. The hysteresis effect of contact angle on the liquid bridge is also significant. In this paper, the hysteresis effect of contact angle on capillary forces of liquid bridges is analyzed when the two sphere particles are in relative movement. Results indicate that contact angle hysteresis effects on capillary force are significant.

Abstract: Silica abrasive plays an important role in chemical mechanical planarization (CMP) of copper. In this paper, effect of different silica abrasive concentrations on copper removal rate and planarization performance of copper was investigated. The results show that the copper removal rate was increased as the concentration of silica abrasive increase. However, excessive abrasive will lead to a decreased copper removal rate. The initial step height values of the multilayer copper wafers were all about 2500Å, and after being polished for 30s, the remaining values of step height of slurry A, B, C and D were 717 Å, 906 Å, 1222 Å and 1493 Å. It indicates that alkaline copper slurries with different abrasive concentrations all had a good planarization performance on copper patterned wafer CMP. As the abrasive concentration increased, the planarization capability was enhanced.

Abstract: The fine grains and strain-induced martensite were fabricated in the surface layer of AISI 304 austenitic stainless steel by shot peening treatment. The shot peening effects on the microstructure evolution and nitrogen diffusion kinetics in the plasma nitriding process were investigated by optical microscopy and X-ray diffraction. The results indicated that when nitriding treatments carried out at 450°C for times ranging from 0 to 36h, the strain-induced martensite transformed to supersaturated nitrogen solid solution (expanded austenite), and slip bands and grain boundaries induced by shot peening in the surface layer lowered the activation energy for nitrogen diffusion and evidently enhanced the nitriding efficiency of austenitic stainless steel.

Abstract: A superhydrophobic HDPE coating was obtained by a facile but yet effective way. The water contact angle and sliding angle of the superhydrophobic HDPE coating were 156±1.9ºand 3±1.6º, respectively. The HDPE coating was still superhydrophobic contacting with acid, alkali, salt aqueous solutions.

Abstract: To develop environmentally friendly antifouling coatings, based on fluoro-modified polyurethane emulsion, eight coatings were prepared in which the content of nano-ZnO powder is respectively 0%, 0.2%,0.4%,0.6%,0.8%,1.0%,1.2% and 1.4 wt% in mass. Based on the measurement of mechanical and optical properties, surface roughness, morphological observation of coatings by Scanning Electron Microscopy (SEM), the influence of nano-ZnO was investigated on impact resistance, hardness, adhesive and flexibility, gloss, hydrophobicity, morphology and roughness of the coatings. The results showed that adding some nano-ZnO powder in paint did not affect the mechanical properties of the coatings, but it influenced obviously the surface topography and characteristics. The gloss reduces and the roughness increases with the content of nano-ZnO. The water contact angle is only 76.5° for the coating without nano-ZnO. The coating changed from hydrophilic to hydrophobic when nano-ZnO content increases up to 0.8 wt%, water contact angle excesses 90°, max water contact angle is up to 97.8° for coating with 1.4 wt % nano-ZnO powder.

Abstract: In this work, the anti-icing properties of different poly (vinyl chloride) coatings with different wettabilities were investigated in a climatic chamber with a working temperature of −10 °C. Compared with smooth poly (vinyl chloride) coating, the superhydrophobic poly (vinyl chloride) coating with high sliding angle did not show obvious anti-icing property. However, the superhydrophobic poly (vinyl chloride) coating with low sliding angle can largely prevent ice formation on the surface, showing excellent anti-icing property.

Abstract: Intermetallic compound Al3Ti-based IMC coatings were formed on AA6063 aluminum alloy by laser cladding. The microstructure and corrosion characteristics in 3.5% NaCl solution were investigated. The results show that, the laser cladding coating is made up of Al3Ti dendrites, interdendritic α-Al and uniform distribution of TiC which hardly melted during laser irradiation, and shows good bonding to the substrate. The cross distribution of Al3Ti and α-Al helps to avoid the generation of cracks in the coating. The corrosion resistance of the laser cladding coatings is greatly increased as compared with the substrate, which owes mainly to the existence of hard Al3Ti and TiC. And with the increasing of TiC content in the coating, the corrosion resistance is improved simultaneously.