Advanced Materials Research Vols. 189-193

Abstract: Mn-doped ZnO (Zn_0.97Mn_0.03O) nanorods were synthesized by sol-gel method combined with subsequent heat treatment. The structure and optical property of Mn-doped ZnO nanorods were studied by x-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and fluorescence. The results of electron microscopes illuminate that the Zn_0.97Mn_0.03O nanorods are prepared at calcinations of 450 under the protection of nitrogen. The Zn_0.97Mn_0.03O nanorods are composed of small particles of size 20–30 nm. Fluorescence spectra of Zn_0.97Mn_0.03O nanorods exhibit that there are two very strong blue emission peaks at 451 nm and 461nm except a strong UV emission at 396 nm.

Abstract: ZrC coatings were prepared by CVD using ZrCl₄, C₃H₆, and H₂ as the precursors. The mechanisms responsible for the effects of deposition temperature, H₂ flow rate and inlet C/Zr ratio on the ZrC coatings were studied based on the deposition mechanism of ZrC. The results indicate that the ZrC morphologies change from a loose spherical structure to a cauliflower structure, then to a glassy structure as the deposition temperature increases from 1050°C to 1150°C, then to 1250°C. The carbon content in the ZrC coatings increases with increasing the deposition temperature. Higher inlet C/Zr ratio can lead to rough surfaces and higher carbon content. Reasonable H₂ concentration can inhibit carbon deposition, and lead to a cauliflower structure.

Abstract: Small samples of Chinese fir/TiO₂ composites were prepared by sol-gel method and MWLPD (microwave assistant liquid phase deposition) method for the first time. The surface of samples were analyzed by Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the microstructure and Ti distribution of samples was observed by scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). Results show that Ti is not only distributed on the composites surface, but also go into the inside wood. The composites surfaces are covered with pure TiO₂. Activities of composites are increased considerably for the oxygen content and number of oxygen containing groups on there surfaces are increased considerably.

Abstract: The GCr15 steel specimens were treated through laser transformation hardening technology. Influence of the laser transformation hardened layers on the bending strength and flexural deflection of the specimens was studied through three-point bend tests. Fractal dimensions of the hardened layer fracture were calculated by image processing. The results show that the bending strength and flexural deflection of the specimens are decreased obviously after the laser quenching and failure mechanism also changes, which causes the decrease of fracture toughness and the plasticity in the laser transformation hardened layers. There are relationships between laser quenching GCr15 steel bending properties and hardened layer fracture fractal dimension.

Abstract: This paper discusses the main reasons for the leakage of hydraulic cylinder, analyzes the advantages and disadvantages of polyurethane seal rings for hydraulic cylinder reciprocating sealing, compares the performance and characteristics of several commonly-used reciprocating seals, and studies the sealing mechanism, material characteristics , effects of practical applications and gives the solution of Packing PTFE combined sealing.

Abstract: Recently, Cr-Al-N coatings have received more and more attention of researchers owing to its standing-out mechanical performances and superior chemical stability. In this present work, CrAlN ternary coatings were deposited by a bipolar pulsed dual magnetron sputtering (BPDMS) method and the effects of substrate negative bias on deposition rate, structure, hardness and adhesion of the coatings were investigated. The application of appropriate negative substrate bias voltage leads to dense structure, high hardness and excellent adhesion for CrAlN coatings.

Abstract: The Al₂O₃-ZrO₂ composite ceramic coatings were prepared on 2A12 aluminum alloy by Microarc oxidation in the mixed electrolyte of 40g/L Na₂SiO₃ and 8g/L Na₂WO₄ solution containing different ZrO₂ content particles. The thickness of the coatings was measured by an eddy current thickness meter. Microstructure and phase composition were analyzed by scanning election microscopy (SEM) and X-Ray diffraction (XRD), respectively. The experimental results show that ZrO₂ in electrolyte can promote coatings growth; Al₂O₃-ZrO₂ composite ceramic coatings consist of α-Al₂O₃, t-ZrO₂, m-ZrO₂, and ZrO₂ is located in island-like discharge channels and does not destroy the integrity of composite coatings; There is scarcely any erosion on the surface of Al₂O₃-ZrO₂ composite coatings because the intermediate product Zr(OH)₄ could suppress composite coating corrosion.

Abstract: optimized mix proportion of autoclaved cement concrete by orthogonal test, and studied effect of two type fibers for the flexural strength of autoclaved cement concrete by the mix proportion of autoclaved concrete. The results showed, wollastonite and plant fiber were favorable to increasing the flexural strength of autoclaved cement concrete. Content of wollastonite was about 15% of cement mass, and increase amplitude of the flexural strength was more than 40% and the compressive strength slightly increased for autoclaved cement concrete admixed wollastonite. Content of plant fiber was about 1.5% of cement mass, increase amplitude of the flexural strength was more than 20%, but compressive strength change of autoclaved cement concrete was not significant for autoclaved cement concrete admixed plant fiber.

Abstract: Applying autocorrelation method to process laser speckle patterns, the relation between surface roughness and speckle elongation and correlation length of autocorrelation function can be obtained, and the measured surface roughness can be achieved based on this relation. One-dimension autocorrelation and two-dimension autocorrelation function are used, Moreover, surface roughness is evaluated by speckle elongation and correlation length of autocorrelation function. Aspect ratio of speckle granular represents speckle elongation ratio, which eliminates effects of speckle granular average size on measurement results compared to other methods using before. It has high reliability and efficiency in surface roughness measurement evaluation.

Abstract: In this paper, LY12 alloy was processed by Plasma Micro-arc Oxidation (MAO) technique. When the aluminum alloy was processed by MAO with positive pulses and positive-negative pulses, the latter turned on a slowly growing speed, low surface roughness and high surface micro-rigidity for the layers. The aluminum alloy was set on both anode and cathode, and was processed by MAO at the same time. The number of positive pulses and negative pulses greatly changed the layers. When four positive pulses and four negative pulses are applied, the layer grows quickly and its surface roughness decreases remarkably. Compared with mono-polar MAO, the aluminum alloy MAO ceramic layers processed by the double-polar MAO grow efficiently, and the layer performances improve at the same time.