Advanced Materials Research Vols. 291-294

Abstract: The tensile strengths of carbon-coated and non carbon-coated SiC filament by Chemical Vapor Deposition were tested, respectively, which were analyzed according to double-parameter Weibull distribution. Various techniques including XRD and SEM were also used to study the phase composition and microstructure of SiC filament. The result shows that carbon coating plays a very important role on increasing the tensile strength.

Abstract: Nanorod-shaped zinc stannate Zn₂SnO₄ (ZTO) with great photocatalytic activity was successfully synthesized via a co-precipitation method. In this paper, a strong base (NaOH) and a weak base (Na₂CO₃) are adopted as precipitants in order to form the precursor precipitate. The titration endpoints are fixed at pH6, pH8, and pH10 in order to adjust the solution precipitant quantity. Dependent variables above were not seen in other research before. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results show that the powders synthesized were ZTO nano-particles. Photocatalytic activity of the powders was measured utilizing a photocatalytic degradation reaction with methylene blue (MB) solution. The smallest particles were obtained by utilizing NaOH as a precipitant and adjusting pH to 6. Based on TEM images, the ZTO had nano-rod particle morphology. However, when precipitant Na₂CO₃ was utilized, particles agglomerated together, reducing specific surface area. Hence, the former sample shows better photocatalytic activity than the latter one. Consequently, powders titrated to pH6 by precipitant NaOH and calcined for 1 hour will form partly nano-rod particles with slight agglomeration, increasing the specific surface area of ZTO and bringing about the best photocatalytic characteristics.

Abstract: The purpose of this study is to investigate the electrochemical properties of Fe₄₄Cr₁₆Mo₁₆C₁₈B₆ amorphous alloy coating fabricated using high velocity oxygen fuel (HVOF) technology in 2.0M HCl and NaOH solution at room temperature(25°C). Based on the potentiodynamic polarization curves and Electrochemical Impedance Spectroscopy(EIS) testing results of coating in aqueous solutions of HCl and NaOH, the corrosion resistance of Fe₄₄Cr₁₆Mo₁₆C₁₈B₆ amorphous alloy coating in HCl solution was superior to that in NaOH solution. The i_corr was 1.487×10^-5A·cm^-2 in HCl solution and 1.107×10^-4A·cm^-2 in NaOH solution, while the R_t reach to 5.789×10⁴Ω·cm² and 9780Ω·cm², respectively. On the other hand, these corrosion phenomenon could be better interpreted by R(Q(R(RQW)))(RL) and R(RL)(Q(R(CW))) equivalent circuit model, which were different from that of other Fe-based amorphous alloys in HCl and NaOH solution, respectively.

Abstract: Fe₃O₄/chitosan magnetic nanoparticles were prepared by chemical cross-linking technique, using dialdehyde starch as a crosslinker, and the adsorption performance of the adsorbent toward Hg²⁺ was investigated. The adsorption capacity of mercury ions was greatly affected by pH value, adsorption doses and adsorption time. Results indicated that optimal adsorption conditions were pH value, 6, adsorption doses, 140 mg.L^-1, adsorption time, 20 min, and the adsorption capacity was 25.12 mg.g^-1. The well-defined nanoparticles with a uniform distribution were observed.

Abstract: In mechanical manufacturing, the traditional methods adopted for finishing is not only high labor intensity, but also difficult to reach the surface roughness and requirements. The vibration grinding finishing process method is put forward, and the surface finishing experiments for spiral nozzle which is one of the important parts for aeroengine are carried. It can be seen from the experimental results that the vibration grinding process method can reach the finishing effect. Compared with the common grinding method, the vibration grinding has the features of high efficiency and high quality, etc. The vibration grinding new process method has high practical value.

Abstract: Much attention has been paid to NiTi intermetallic coating for enhancing cavitation erosion resistance property due to its shape memory effect. In this paper two processes were used to deposit NiTi intermetallic coatings. Process 1 was the deposition of NiTi intermetallic coating using warm spray process with NiTi intermetallic powder as feedstock, and solution treatment was subsequently performed. Process 2 was a mixture process of warm spray and laser treatment. Ni-Ti coating was first deposited via warm spray process with Ni-cladding Ti as feedstock, and laser-treatment was performed to realize the alloying of Ni-Ti. The microstructure and phase compositions for NiTi intermetallic coatings were characterized by means of SEM and XRD. The fundamental properties for NiTi intermetallic coatings were also analyzed.

Abstract: The ferrous sulfide (FeS) solid lubrication composite layer was prepared on the surface of CrMoCu alloy cast iron that treated by ion Nitrocarburizing, with low-temperature ion sulfurizing technique. By morphology and composition analysis, it is shown that the FeS layer has a micro-nano-hole structure, formed by nanometer sulfide particles, and the composite layer surface is mainly FeS. Also, there are a cross area and a diffusion area between the ion sulfide layer and the ion nitrocarburizing layer.

Abstract: Nanostructured WC-17Co coatings, nanostructured WC-12Co coatings, conventional WC-17Co coatings were prepared by means of High Velocity Oxygen Flame (HVOF) technique. The characteristic of powders and coatings of nanostructured WC-17Co coatings, hardness of different coatings, distribution gradient of the hardness of the nanostructured WC-17Co coatings in the depth direction, fracture toughness and interface fracture toughness of different coatings, residual stress of different coatings, different phase and distribution of WC phase in the depth direction were investigated. The results indicated that the micro-crack is spread along the phase interface where the brittle phase are more in the Co rich area , where there are more different properties in the Co rich area and W rich area, where there are more defects close to the intend end in the W rich area, even spread through the WC particles in microcosmic and the different residual stress of different phase are because of different melting point and different expansion coefficient , so the WC, W₂C produced compressed stress, the Co₆W₆C produced tensile stress. The residual stress manifested from higher to lower in the depth direction of the coatings.

Abstract: With Aspect Oriented Programming(AOP) technology, Model Driven Architecture(MDA) and ATLAS Transformation Language(ATL), this paper proposes a PIM framework of based on OOP and a PIM framework of based on AOP, also proposes a idea with ATL accept model conversion signals to model transformation.

Abstract: The main purpose of this paper is to research on the different ion nitriding temperatures of 40Cr effect on the surface hardness, wear resistance of the workpiece. With series of experiment and test of micro-hardness, ring-block wear, metallographic observation, to select the optimization temperature for the ion nitriding process of 40Cr steel.