Advanced Materials Research Vols. 341-342

Abstract: Hydroxyapatite (HA, Ca₁₀(PO₄)₆(OH)₂) powder along with other additives such as P₂O₅, Na₂Co₃ and KH₂PO₄ are used for biocompatible coating of Ti-6Al-4V through sol-gel method. An in-house dip coating machine was developed to control dipping and withdrawal rates of the substrate. After passivating of the samples in nitric acid, coating of HA gel was performed followed by sintering in a vacuum furnace. Characterization of the coating layer was evaluated by the XRD and SEM. Imagej software was used for analysis of the data. It was found that increasing the sintering temperature decreases the pore size, resulting in a denser structure of hydroxyapatite and decrease in surface roughness of the coating. High sintering temperatures produced cracked surface of HA due to the α to β transition temperature of Ti and its alloys. HA with coating thickness of about 100 µm free cracks was obtained for sintering temperatures lower than 800 °C.

Abstract: Based on partial least-squares multinomial regression, this paper had a prediction on carbonization depth of conctete. Taking water-cement ratio (i.e. water-ash ratio), cement content (i.e. application amount of cement material), and exposure time of concrete as independent variables , and carbonization depth of conctete as dependent variable , the forecast model of carbonization depth of conctete was obtained. It was found that, Press residual value decreased with the increase of number of latent variables, and the number of latent variables were three by Press residual value versus number of latent variables. The normal regression coefficient of exposure time of concrete was the largest wiithin three influence factors, this indicated that the influence of exposure time of concrete was largest to conctete carbonization depth; The determination coefficient of forecast model obtained in this paper was 0.9940, the error of forecast model was . The following conclusion can be drawn that, the model is accurate and credible, and the partial least-squares multinomial regression is a eximious non-linear method, and it is worthy to spread its application in the forecast analysis of conctete carbonization depth.

Abstract: Based on BP neural network, this paper had a prediction analysis on concrete strength at the 28th day. Taking the influences of application amount of cement, application amount of scoria, application amount of fly-ash, water-ash ratio into account, the prediction model of concrete strength at the 28th day based on BP neural network was obtained. It was found that, the average value of absolute value for the relative error of fitting value of concrete strength at the 28th day compared with the observed value for 43 groups of independent variables training BP neural network model was 0.64372%; And the relative error of prediction value of concrete strength at the 28th day was -2.0392%~0.964668% compared with the observed value for 5 groups of independent variables validating BP neural network model, and the average value of absolute value for the relative error was 0.95467%. The following conclusion can be drawn that, the prediction model is accurate and credible, and the BP neural network is a excellent method, and it is worthy to spread its application in the prediction analysis of concrete strength at the 28th day.

Abstract: Sol-gel combustion synthesis method was adopted to prepare nano-sized CoFe₂O₄ using urea as fuel. The as-synthesized CoFe₂O₄ powders were characterized through such experimental means as Fourier transform infrared spectroscopy (FTIR), TG (thermogravimetric)–DSC (differential scanning calorimetry), X-ray diffraction (XRD), field-scanning electron microscopy (FSEM). FTIR analysis and XRD analysis revealed that the dried CoFe₂O₄ gel was formed by the coordination of metal with O, and consisted of various phases through the hydrolysis of urea and metal nitrates along with the coordination of the various groups produced. And then, TG-DSC analysis of the dried CoFe₂O₄ gel under air atmosphere indicated that there are two remarkable exothermic reactions occurring, related to the redox reactions between urea and nitrates used, and as-synthesized CoFe₂O₄ was porous due to the emission of large amount of gases during preparation. Finally, three cycles of temperature-programmed reduction (TPR) coupled with temperature-programmed oxidization (TPO) tests were conducted on the AutoChem 2920 system to show the good reaction and sintering-resistance performance for the synthesized CoFe₂O₄.

Abstract: This paper develops a computational model for predicting the failure probability of multilayered packages fabricated using anisotropic conductive film (ACF). The ACF and NCA are stacked layers by layers, and spaced with each other. The analyzed pads array 10x10 combined with specified geometry parameters in the IC/ Substrate are used to analyze the failure probability. The computational results indicate that the multilayered analysis developed in this study can provide lower failure probability by means of reducing bridging effects for improving the ACF packaging yield.

Abstract: We have fabricated site-controlled InAs quantum wires (QWRs) on the cleaved surface (110) of AlGaAs/GaAs superlattices (SLs) structures by using Ga-assisted deoxidation method. In the surface of SLs regions, InAs QWRs were nucleated on GaAs in stead of AlGaAs. In the (110) surface without superlattices(SLs) structures, QDs with a large size were obtained, which is considered hard to realize. To understand the different InAs growth phenomena in the regions with and without superlattices structures, we suggest that indium adatoms have an apparent trend to migrate to the SLs area.

Abstract: The purpose of this study was to understand damping and anti-slip properties of the Reebok and the Huakang shoes, evaluate the mechanical effect of those aerobics sports shoes as well. From the biomechanical test, almost all mean pressure, average impulse and average pressure of the Reebok and the Huakang was less than the bare foot condition on "shoes - ground", but the average pressure, average impulse and average pressure of the Reebok shoes was slightly higher than the Huakang shoes. Meanwhile, the damping mechanics indexes do not exist significant differences (P＞0.05). It’s friction coefficient tests show that dynamic or static friction coefficient of the Reebok is superior than the Huakang, and dynamic or static friction coefficient does exist significant differences (P＜0.05).

Abstract: In order to improve the dimensional stability, mechanical properties and fire resistance of the wood from Cryptomeria fortunei, the melamine-urea-formaldehyde (MUF) resin and the mixture of MUF/boric acid/borax (MBB) were prepared and used as the wood modification solution. Results show that both the MUF resin and the MBB solutions exhibit good permeability to wood. Under the same treatment conditions, the weight percent gains (WPG) of treated wood increases with the increasing concentration of modification solutions. MUF and MBB modification solutions can effectively enhance the dimensional stability, MOR, MOE and fire resistance of wood. Compared with MBB treated wood, MUF treated wood exhibits higher MOR and dimensional stability. The MBB treated wood has higher MOE and fire resistance than MUF treated wood.

Abstract: Various Ti oxides formation potential was analysised by thermodynamics during solidification of steel. It was found that Ti₃O₅ is the most stable one among all the types of Ti oxides. The effect of Mn element on the structure of Ti oxide was analysised by some experiments. The structure of Ti oxide without Mn is Ti₃O₅, and the inclusion, which contains some content of Mn, is Ti₂O₃ with rhombohedra structure. It is assumed that, [Ti] and [O] in liquid steel precipitated in form of Ti₃O₅. During the cooling process of solid steel, Ti₃O₅ reacted with [Mn], and exsited in form of Ti₂O₃ and MnO complex inclusion, which is advantageous for the nucleation of IGF.

Abstract: In order to conform to the dimensional tolerances of wax pattern die-profile for turbine blade in investment casting process, an optimization method of geometric parameter for turbine blades based on inverse adjustment was proposed. The geometric parameters for optimizing were extracted, and the bending and torsional deformation can be compensation. Therefore the nonlinear deformation compensation during solidification and cooling procedure can be efficiently realized. This method finally exhibits its advantage over the traditional linear scaling method. It set the theoretical foundation on optimization method of die-cavity for turbine blade. The die-profile optimization system which was developed in this paper proves better effect for the die-cavity design.