Advanced Materials Research Vols. 199-200

Abstract: Combined Weighting Model (CWM), a new model combining entropy method, analytic hierarchy process (AHP) and back propagation network (BPN) is discussed to determine the weights(the key parameter of comprehensive evaluation) of evaluation indices(properties) for engineering materials in this paper. Taking the selection of bearing materials as an example, the combined weights of nine kinds of evaluation indices for ten kinds of candidate materials were calculated using CWM. According to these weights, candidate bearing materials were evaluated using Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). The result shows that the optimal bearing material is agreed with engineering application, which means the weights obtained from CWM are reasonable and reliable, and CWM is an effective method to determine the weights of evaluation indices for engineering materials.

Abstract: With the increasing competition in the construction market, particularly in the present situation of financial crisis, how to win the bid of the project and gain some profit becomes decisive for the bidder while the tender offer is the key factor to win the bid. Based on the analysis of the method of how the bidder determine the tender offer, the paper summarizes the ways of considerably enhance the bid success probability, including attaching importance to the working scheme, properly determining the “cost” of the engineering project and the requirements for the expected payoff, and tender-making upon the study of the competitors. Conclusion references are provided for the bidder’ tender-making.

Abstract: Through-Silicon Vias (TSVs) technology, which is widely used in three-dimensional (3D) Microsystems packaging, has been investigated by using a strain gradient finite element method (FEM). A thermomechanical strain gradient constitutive law was embedded into the commercial software ABAQUS to consider the size dependence of thermal stresses in TSVs. Our numerical results show that when both thicknesses of SiO2 dielectric layer and Si substrate are kept to a constant, for a given via depth/radius ratio, the Mises stress decreases with the decrease in the radius above 100 nm, and then it increases markedly with the further decrease in the via radius below 100 nm, which is not consistent with the results obtained by the conventional FEM. It is also shown that as the whole size of the TSV structures is scaled down proportionally, for a given via depth/radius ratio, the peak Mises stresses are almost size scale- independent above 100 nm and exhibit a strong size scale effect below 100 nm.

Abstract: The scheme for cold extrusion process of Seven-speed sleeve is determined according to the experiences and analysis by DEFORM-3D software, the extrusion procedure has been numerical simulation analyzed; The part technology and parameters of die structure has been optimized by orthogonal test. The optimized process parameters are as following: friction factor is 0.10, blank height is 31.4mm, extrusion speed is 200mm/s; The optimized parameters of die structure are as following: 1st step convex fillet is 1.5mm, 1st step concave rounded is 2.0mm, 2nd step convex fillet is 2.0mm, 2nd step concave rounded is 1.0mm, 1st step die-entrance angle is 35°, 2nd step die-entrance angle is 60°.The qualified products are obtained using the optimized process parameters in the production practice.

Abstract: The samples were prepared using Cr₂O₃ micropowder, TiO₂ micropowder and m-ZrO₂ micropowder as main starting material, polyvinyl alcohol as binder, by a series of processes such as pulping, spraying granulation, machine moulding and cold isostatic pressing, and sintering at 1 500°С for 3 h in nitrogen protected atmosphere furnace (oxygen partial pressure was 10 Pa). Then thermal shock resistance of the samples was tested by wind quenching. Effect of m-ZrO₂ (2%-5% in mass) on sintering behavior and thermal shock resistance of Cr₂O₃ material was investigated. The results show that m-ZrO₂ can accelerate the sintering of Cr₂O₃ material, but excess 2 wt% m-ZrO₂ doesn’t work; m-ZrO₂ can obviously improve thermal shock resistance of Cr₂O₃ material, sample containing 3 wt% m-ZrO₂ has 34 wind quenching cycles from 1 150°С to room temperature, and sample without m-ZrO₂ only has 11 cycles.

Abstract: In order to control the print-through, the value of print-through resistance (PTR for short) was put forward to predict the print-through of lithograph. For 5 given paper samples, the relationships between their PTR and print-through (expressed with ΔEab*) was explored under three sets of printing condition in this paper. The results showed that the PTR increase could lead to decrease of the print-through value. In particular, no matter what kind of conditions, the print-through value was almost smaller than 4NBS when the PTR of those paper samples was larger than 73%, which seems to be the absence of print-through phenomenon.

Abstract: CuInS₂ thin films were prepared on heated glass substrates by ultrasonic spray pyrolysis method. Structure, surface morphology and properties of films with different Cu/In ratios have been investigated. X-ray diffraction (XRD) analysis demonstrated that as-prepared CuInS₂ thin films with chalcopyrite structure have a preferential orientation along the (112) direction. SEM study shows films are relatively dense and smooth, but the much bigger grains and the large coherent agglomerates appear in films (Cu/In>1.25) due to the appearance of phase Cu₂S. CuInS₂ thin film (Cu/In=1.25) has a strong visible absorption and its energy band gap comes up to 1.45eV.

Abstract: The sintering behavior, physical properties and heat processing changes of bauxite-based homogenized grogs prepared by homogenization process and high temperature sintering using bauxite as starting material were investigated. Results show that the bauxite-based mullite can be synthesized by the method, sintering temperature with and without MgO/CeO₂ sintering aids are 1600°C and 1700°C separately, the mullite with apparent porosity of＜1.0% and 2.5%, bulk density of ≥2.87g•cm^-3 and 2.75g•cm^-3, Refracteriness-Under-Load(RUL) 1600°C and 1620С; changes in the heat processing is divided into three stages: dehydration stage(400°С~900°С ), primary mullitization stage(1000°С ~1200°С) and secondary mullitization stage(>1200°С).

Abstract: Flow stress of hot deformation about 00Cr12Ti stainless steel was experimentally studied by A Gleeble1500 thermo-mechanical simulator. The effects of deformed temperature, strain rate and strain to flow stress were analyzed .multiple Non-linear regression mathematical models of flow stress were proposed. 00Cr12Ti flow stress varies with temperature more slowly through 00Cr12Ti compared with 0Cr13Mn.

Abstract: Aluminum coatings were developed by arc spray on mild carbon steel Q235. Scanning electron microscopy detection shows that the coatings have good bonding with the substrate and have low porosity. The corrosion behaviors of the coatings in splash zone were studied. The results show that free corrosion potentials of aluminum coatings are much lower than that of Q235. Potentiodynamic polarization measurements reveal that the curves of aluminum coatings have activity anodic dissolution zone, passivation zone and super-passivation zone. Corrosion morphology and energy dispersive spectrometers show that Cl^- can penetrate into the coatings and some of the substrate has been corroded. The arc spray Al-coating develops a film of corrosion products on the coating surface, which tend to seal the pores in the coatings. Arc spray aluminum coatings can protect the substrate from corrosion in splash zone.