Materials Science Forum Vols. 809-810

Abstract: Ni-P-multi-walled carbon nanotubes (Ni-P-MWNTs) composite coating was successfully co-deposited on 45 steel substrate by electroless plating. The microscopic morphology of Ni-P-MWNTs composite coating was observed by SEM. The influences of CNTs concentration in plating bath on the microstructure and corrosion resistance of the composite coating were investigated. The results indicated that the deposited composite coating shows dispersed CNTs and continuous Ni-P matrix, and there are no pores and cracks and other defects at the interface between the substrate and composite coating, and the thickness of the composite coating is about 50 μm. The Ni-P-MWNTs composite coating with 0.3g/L CNTs in bath displayed the best corrosion resistance, the corrosion potential of the composite coating is-0.372V.

Abstract: In this research, micro-hardness and wear resistance of two types of electroless coatings were investigated including Ni-P and Ni-P-B₄C composite coatings. Dispersible B₄C particles and electroless Ni-P alloy were codeposited on carbon steel by electroless plating and then heat treated at 200, 400 and 600 °C for 1 h, respectively. The cross-section morphology and microstructure of the composite coatings were characterized. Meanwhile, the micro-hardness and tribological behavior of composite coatings were evaluated. The results showed that the Ni-P-B₄C composite coating presents better wear resistance in comparison with that of Ni-P coating. The Ni-P-B₄C composite coating with heat treated at 400 °C exhibits high micro-hardness and good wear resistance, which the highest hardness is 1200 HV, the minimum wear weight loss is 0.12 mg and the lowest friction coefficient is 0.2054.

Abstract: Through orthogonal test of Ni-P chemical plating process optimization to determine the optimum process recipe, the Ni-P-β-SiC composite coating were prepared by chemical plating method. The deposition rate, microhardness, composition and organization of Ni-P-β-SiC composite coating are observed and analyzed by scanning electron microscopy (SEM), vivtorinox microhardness tester, X ray diffraction (XRD) and energy spectrum analysis (EDS). The influences of β-SiC particle concentration in bath on the solution of composite coating deposition rate and microhardness. The results show that the influence of composite coating deposition rate and microhardness are NiSO₄•6H₂O, NaH₂PO₂•H₂O, C₃H₆O₃, and PH. The optimum process conditions: NiSO₄•6H₂O 25 g/L, NaH₂PO₂•H₂O 27 g/L, C₃H₆O₃ 27 ml/L, PH 5.2. It was found that the Ni-P-β-SiC composite coating with 5g/L β-SiC particles exhibited a maximum deposition rate and microhardness, the deposition rate of composite coating is 12.32μm/h, microhardness is 567.93HV_0.05.

Abstract: A new and facile method for improving the procedure of anodic aluminum oxide (AAO) film preparation was presented, which was based on an electrochemical detachment procedure. The detachment and pore-opening were performed just through one step in a solution of HClO₄ and C₂H₅OH at a voltage of 40V. The as-obtained AAO film was characterized by scanning electron microscopy (SEM) and scanning probing microscopy (SPM). The process of detachment and pore-opening was also discussed.

Abstract: Due to its high in-field superconducting performance, high irreversible magnetic field, low AC loss and high transition temperature, YBa₂Cu₃O_7-x (YBCO) has been taken as a hot research object. Well-oriented La_0.4Sr_0.6TiO₃(LSTO) thin films were prepared on the biaxially textured Ni-W alloy substrates by metal-organic deposition (MOD) method which could used for YBCO coated conductor. The homogeneous and stable precursor solution was prepared by Y, Ba and Cu acetates and deposited on LSTO/Ni-W composite structure by spin-coating method. YBCO films were obtained after heat treatment. Effect of thermal decomposition time on YBCO films was discussed,and the results showed that the proper time of organic decomposition was 3h at 400°C.

Abstract: Mullite coatings were prepared on C/C-SiC composites surface by pulse arc discharge deposition using mullite powder as source materials. Phase composites and microstructures of the as-prepared mullite coatings were characterized by XRD and SEM. Deposition kinetics and influence of pulse frequency on the phase composites and microstructures were investigated. The results indicate that the outer layer is composed of mullite phase, density and homogeneity of the mullite coatings are achieved when the pulse frequency reaches 2000 Hz. The deposition amount of the mullite coatings also increases with increasing deposition temperature. The deposition mass of the coatings and the square root of the deposition time at different deposition temperatures according to linear relationship, and the deposition activation energy is calculated to be 32.24 kJ/mol.

Abstract: A B₂O₃-modified ZrSiO₄ outer coating was prepared by Pulsed arc Discharge Deposition on the surface of SiC bonding layer coated carbon fiber reinforced carbon (C/C) composites. The phase compositions of the prepared coatings were analyzed by X-ray diffraction (XRD), the morphologies of the multi-layer coatings were observed by scanning electron microscopy (SEM). The influence of pulsed arc discharge deposition electric voltage and time on the phase composition, microstructure of the mixed coatings was particularly investigated. And the invalidation behavior of the as-prepared coating coated samples at 1273K was analyzed. XRD results show that the outer layer of the coating was mainly composed of B₂O₃ and ZrSiO₄ phase. When the deposition electric voltage was 400V, single deposition time was 8 min, total time was 32min, the structure and thickness of the outer layer was compact and uniform. The coating prepared at optimal technological conditions could effectively protect C/C composites from oxidation at 1273K in air for 600min with a weight loss of 4.063%. The failure of the coating at intermediate temperature is due to the generation of some cross-cracks in the coating and sectional volatilization of B₂O₃.

Abstract: A series of tourmaline/ZnO composite thin films were prepared by the facile route of low-temperature wet chemical method. X-ray diffraction (XRD) and Raman Spectroscopy analyses showed the hybrid spectroscopic characters of tourmaline and ZnO. With adding the different amount of tourmaline powder, ZnO tended to exhibit the different peak intensity of X-ray diffraction and Raman vibration. ZnO deposited into bending nanosheets and intersected to upstanding nanostucture on the surface of tourmaline particles in SEM images. The optical adsorption properities obtained by the UV-Vis spectra indicated that the addition of tourmaline had enhanced the maximum absorption strength, and had shifted the absorption wavelength and the absorption range of ZnO crystals.

Abstract: CaWO₄ films were prepared in saturated Ca(OH)₂ solution through constant-voltage anodization method. Influences of reaction time, voltage and temperature on the morphology, crystal structure and photoluminescence properties were studied through scanning electron microscopy (SEM), X-ray diffractometer (XRD) and photoluminescence measurements (PL). Results show that the as-prepared CaWO₄ film is of tetragonal phase, the reaction conditions affect the morphology, grain size and photoluminescence properties greatly. The CaWO₄ film anodized at 20V, 45°C for 40 min is flat, uniform and dense with stronger photoluminescence intensity. The formation process of CaWO₄ films has also been discussed.

Abstract: Here a novel technique was employed to fabricated three-dimensionally porous polystyrene (PS) films via ultrasound assisted template method. In contrast to spin-coated thin film, different morphologies appeared on the films prepared by casting PS/toluene solution on glass substrates. By varying either systematic parameters or intrinsic parameters, surface structures changed from two-dimension flat pores to three-dimension sponge pores. The influences of ultrasonic intensity, frequency, irradiation time, film thickness and toluene content in water bath on surface morphologies were extensively studied. Scanning electron microscopy and white-light confocal microscopy showed that PS casted films with thickness of 200μm have a higher porosity and lower surface roughness within micrometer range. The contact angle measurement indicated slight changes of surface hydrophilicity with toluene content in water bath. Suitable toluene content favored multilayer formation of PS film and led to monodisperse pore distribution analyzed by ImageJ.