Advanced Materials Research Vols. 160-162

Abstract: To improve the wear property of magnesium alloys, Zr-based amorphous composite coatings have been fabricated on AZ91D magnesium alloy by laser cladding using mixed powders Zr55Al10Ni5Cu30/SiC. The microstructure of the coating was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The wear resistance of the coatings was evaluated under dry sliding wear test condition at room temperature. The results show that the coatings mainly consist of amorphous and different crystalline phases. The coatings exhibit excellent wear resistance due to the recombination action of amorphous and different crystalline phases. The main wear mechanism of the coatings and the AZ91D sample are different, the former is abrasive wear and the latter is adhesive wear.

Abstract: In this paper, Cu nano-powder was used to reduce CuO nano-powder by hydrogen reduction process, which was prepared by hydrothermal decomposition method taken CuSO4•5H2O and NaOH as raw materials. The reaction conditions of CuO nano-stick were that concentration of CuSO4 liquor was 0.1mol•L-1, concentration of NaOH liquor was 5mol•L-1, dropping speed was 50ml•min-1, pH value of reacting terminal was 12, stirring speed was 1200 r•min-1, reacting temperature was 60°C, reacting time was 30min. The CuO stick longness was 200nm, diameter was 30nm. The reaction conditions of CuO nano-boll were that dropping speed was 50ml•min-1, pH value of reacting terminal was 7, stirring speed 100 r•min-1, reacting temperature was 80°C, reacting time 30min. The diameter of CuO nano-ball was 50~100 nm. The Cu powder was prepared with materials CuO tick by hydrogen reduction in closed circular system. The higher the temperature, the reaction speed is faster. Hydrogen reduction time was 400s in reacting temperature 240°C. The Cu powder’ size was less than 100nm.

Abstract: The Ni(OH)2-Ag2O powders were prepared with materials NaOH, NiNO3•6H2O and AgNO3 by chemical co-precipitation method. The reaction conditions were that Ni2+ solution concentration 0.0943mol•L-1 and Ag+ solution concentration 0.0943mol•L-1 in the Ni2+-Ag+ composite solution concentration, the NaOH solution concentration 4mol•L-1, dropping speed of the NaOH solution 50ml•min-1, the pH value of reacting terminal 13, the stirring speed 1200r•min-1, the reacting temperature 25°C, the reacting time 60min. Ni(OH)2-Ag2O composite powders’ size was 2-50nm. Ni-Ag composite powders were prepared with materials Ni(OH)2-Ag2O composite powders by hydrogen reduction in closed circular system. Ni-Ag composite powders’ size was 2-40 nm.

Abstract: Aircraft is a complex product, and the Supply-Chain System of Aircraft Manufacturing has many characters which containing hierarchy structure, wide contents in each level, complex relationship between providers etc. So it has a great significance to do research on this. After studying the Kleinberg model and analyzing the characters of providers’ data in Aircraft Manufacturing industry, advanced changes of the Kleinberg model are made, and also the data of Supply-Chain of Aircraft Manufacturing is projected to circle structure, base on these two factors a advanced hierarchical navigable Kleinberg model is proposed, it is more suitable for the Aircraft Manufacturing Supply Chain and its structure is corresponding with the structure of Aircraft Manufacturing Supply Chain. From this advanced model we can do easier research on Supply-Chain System of Aircraft Manufacturing than Kleinberg model.

Abstract: Mg72.5Zn26Y1.5 (at.%) quasicrystal alloys were investigated under different solidification conditions. The cooling curves were gathered by the multi-channel temperature acquiring system and the corresponding microstructures were analyzed. The morphology, microhardness and volume fraction of quasicrystals were detailedly studied. The effects of cooling rate on the above three aspects were also studied and the relation schema among them were exhibited. The results show that the quasicrystal size tend to smaller, its microhardness and volume fraction gradually increased, and the quasicrystal morphology changed from bulk polygon to petal-like and finally changed to plat X-shape with the elevated cooling rate from 2.3K/s to 181.2K/s. However, the quasicrystal nucleation will be restrained and amorphous matter will be created if the cooling rate exceed the critical point which make against the formation of quasicrystals with high performance.

Abstract: Three critical technologies of simulation analysis on thermal-loads of radome in flight are selected to study in this paper. Section 2 analyzes the first critical technology, which is modeling of the radome and the antenna. And the computational fluid dynamics software FLUENT is used to analyse the radome, so as to calculate the temperature distribution of its outer surface. Section 3 analyzes the second critical technology, which is to establish the multi-cavity thermal radiation model of the radome so that to get the temperature distribution of the inner surface. A kind of interpolation method, which is the third critical technology, is used to transfer the temperature of flow field and the space heat radiation to the corresponding thermal-stress analysis model of radome.

Abstract: Ni-Cu-P coatings were prepared by electroless deposition method on carbon steel. The pH value and concentrations of cupric sulfate were studied to character the deposition rate, corrosion resistance of Ni-Cu-P coatings in 3.5% NaCl solution. From the results, it was shown that the deposition rate of Ni-Cu-P coatings increased with the increasing of pH value. The deposition rate speeds up until the deposition rate keeps stable when the pH value is about 8.0-9.0. When pH value was 7.5, the coatings showed good corrosion resistance. In the same conditions of solution compositions and technological conditions, the concentration of cupric sulfate must be lower than 2g/L if the copper and nickel altogether co-deposited. The minimal corrosion current and excellent surface state for the coatings can be obtained when the concentration of cupric sulfate was about 0.8 g/L.

Abstract: The nano-sized Mn0.5Zn0.5Fe2O4 spinel-type ferrite was synthesized by sol-gel auto-combustion method using citric acid as the chelating agents. The analysis methods of FT-IR, XRD, wave-guide were used to character the gel and the products after calcining. From the results, it was shown that the homogeneous organic complex base salts were formed in the process of gelation formation. The crystalline sizes of as-synthesis powders, calcined at 700°C for 2h and calcined at 1000°C for 2h were 15nm, 21nm and 25nm, respectively. The nanocrystalline had both dielectric loss and magnetic loss in the frequency range of measurement. The electron transportation of Fe2+↔Fe3+ can make the resistivity reduce to result in a certain amount of dielectric loss.

Abstract: The effect of hot rolling parameters including different hot rolling reduction, soaking time of ingots and chemical composition on cold rolling texture by TSCR process was studied. The result indicates that α fibers and γ fiber texture were affected by hot rolling reduction, and oriented density αfibers texture increases with hot rolling reduction rate increasing, and the texture components is same in the surface and different in the center. The strength of γ fiber texture, from {111}<110>to {111}<112>, is decreasing trendency for ingot soaked for 10min and 20min. however, changing trendency from {111}<110>to {111}<112> in 1/8 thickness and 1/4 thickness of cold rolling strip for ingot soaked for 30min. The volume fraction of {111}<112> is rising with the ingot soaked time and the maxium is 3.5 percent, and the volume fraction of {111}<112> is higher in every layer of cold rolling strip whose chemical composition includes Sn than without Sn, the volume fraction of {111}<112> is higher in 1/8 and 1/4 layers than the surface and center layers.

Abstract: C-grade steel has been widely used for parts of train wheel, train hook and other main parts with its predominant performance. That was mostly produced under high temperature and plastic deformation. In this paper, lots of experiments on the thermo-mechanical simulator Gleeble are operated, and the strain-stress curves under different deforming conditions are obtained. By the analysis of flow stresses under different conditions, the relationship among flow stress, temperature and strain rate as Sellers-Tegart equation is found, and the math model of C-grade steel at high temperature is established. The FEM code DEFORM has been used to simulate the forging process of train wheels. The numerical simulation results show that the first-stage forging parameters have quite important influence on the material distribution and the forge figuration of train wheel. It is necessary to determine the parameters in the pre-forming process reasonably. While, the influencing factors on the forming load are analyzed. The research shows that the heat parameters and the forging speed have influence on the forming load. Lower value of heat transfer coefficient and environment temperature, and lower speed at the ending stage could reduce the forming load significantly in the forging process of train wheels.