Advanced Materials Research Vols. 152-153

Abstract: The paper built electro-hydraulic position closed-loop sampling control system based on PLC, established mathematical model of this system by applying theory of sampling control and determines the range of the sampling period T under the stability of the system according to system stability theory. Then carried out simulation analysis and experimental verification in the range of T, provided with the method determined the range of sampling period. The results showed that simulation results of this model were consistent with the actual operation of the system , the method and sampling period be chosen have some practical significance.

Abstract: A novel template-free method, which was based on heating the mixture of InCl3•4H2O and thiourea in air from room temperature to 200 or 250 °C, coupled with a subsequent washing treatment using distilled water and ethanol, was proposed for the synthesis of In2S3 hierarchical nanostructure. X-ray diffraction and field emission scanning electronic microscopy demonstrated that the obtained products were pure cubic phase In2S3 urchin-like clusters built up by mainly nanoflakes (about 12–47 nm thick). UV-vis absorption spectra disclosed that the as-prepared In2S3 urchins had optical band gaps in the range of about 2.18–2.26 eV.

Abstract: Spherical α-Fe2O3/Ag core/shell nanoparticles were prepared by reducing Ag(NH3)2+ with formaldehyde using the seeding method. 3- Aminopropyltriethoxysilane (APS) acts as a “bridge” to link between α-Fe2O3 core and Ag shell. The obtained nanoparticles were characterized by XRD, TEM, SEM, EDS, and Roman. The results show thatα-Fe2O3 cores are coated by Ag shell completely. The average size of α-Fe2O3/Ag nanoparticles is 95 nm and the thicknesses of Ag shell are 15nm in 3.7% HCHO and 1.0M AgNO3. The thickness of Ag shell can be tunable by changing reaction conditions, such as the concentration of AgNO3, reduction reaction rate. The surface-enhanced Raman scattering (SERS) effect of the core/shell particles are measured with Pyridine (Py) as molecule probe. SERS indicate that the Raman signals of Py adsorbed on α-Fe2O3/Ag nanoparticles exhibit large enhancement at 1010 and 1038 cm-1 respectively. And the intensity of signals is enhanced with the increase of the thickness of Ag shell. The uniform and rough surface of α-Fe2O3/Ag particles exhibits strong SERS activity in 3.7% HCHO and 1.0M AgNO3. The spherical α-Fe2O3/Ag core/shell nanoparticles exhibit SERS activity.

Abstract: Damage initiation and propagation in unidirectional glass fibre reinforced epoxy matrix composites under tension load were simulated in this study. Cell models with either single fibre or multiple fibres were modelled by extended finite element method (XFEM). The damage progress in the cells was investigated and then the nominal stress-strain curves as well as stress distributions in the fibre and matrix were obtained. Results presented here indicate that the extended finite element method is an effective modelling technique to study the initiation and propagation of a crack along an arbitrary, mesh-independent, solution-dependent path.

Abstract: A near-infrared spectroscopy (NIR) technique has been applied for rapid and nondestructive quality determination of glass/epoxy prepreg. Abundant information related with resin and volatile was observed in the NIR spectra of the prepreg cloth. The partial least square (PLS) regression was used to develop the calibration models by utilizing several spectral pretreatments combined with different spectra ranges. Some unknown samples were analyzed by the NIR method. The mean absolute predicted errors were 0.32% and 0.214% for the resin content and the volatile content respectively. The results of the paired t-test revealed that there was no significant difference between the NIR method and standard method. The NIR method can be used to predict the resin and volatile content simultaneously within 30s. The study indicates that the NIR method is sufficiently for quality determination of glass/epoxy prepreg cloth.

Abstract: The homogeneous multiferroic BiFeO3 nanoparticles with average particle size of 85 nm have been successfully synthesized by a simple sol-gel route. The prepared sample was characterized by a variety of techniques, such as X-ray diffractometry, thermogravimetric analysis and differential thermal analysis, differential scanning calorimeter analysis, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The obtained results shows that rapid sintering and subsequently quenching to room temperature are the two vital important factors for the preparation of pure BiFeO3. The magnetic phase transition (TN = 369 °C) and the ferroelectric phase transition (TC = 824.5 °C) were determined, revealing the antiferromagnetic and ferroelectric nature of the as-prepared BiFeO3 nanoparticles. The optical properties of the nanopowders were investigated. The strong band-gap absorption at 486 nm (2.55 eV) of the BiFeO3 nanoparticles may bring some novel applications.

Abstract: To reduce weight and improve strength in the aerospace industry, composite structure connected by glue has gained popularity as a replacement for conventional materials and structures. However, the adhesive bonding process is more susceptible to quality variations during manufacturing than traditional joining methods. The integrality, strength and rigidity of product would be broken by disbonding. Investigate the sensitivity and accuracy of the testing method was more impotent to ensure the product quality and testing efficiency. This paper presents a study of detecting sensitivity of sheargoraphy methods when it is used for inspecting disbondinging on honeycomb structures. The potential of shearography method is also outlined.

Abstract: Friction material in the future will be towards the low-noise, low wear debris, no poisoning and environment-friendly trends and direction. This paper describes the friction material formulation filtering and evaluation, and proposes design of the basic idea of friction material formulations. Then the article optimizes design of friction material formulations by means of golden section method and the gray correlation coefficients means. Experimental results show that the method gave by this paper is an effective way to study friction material formulation.

Abstract: Stable nano-silver colloids with highly pure silver were synthesized by using polyethylene glycol as solvent, stabilizer and reducing agent. The colloidal nanoparticles need not be separated from the solution and the silver sol can be directly used in antibacterial fields. Tannic acid and ascorbic acid were used as co-reducing agents to improve conversion rate of silver ion. Transmission electron microscopy (TEM) analysis showed that stable spherical metal particles 3-50 nm in diameter with a well-crystallized structure were obtained by using tannic acid as co-reducing agent,15-20 nm in diameter were obtained by using ascorbic acid as co-reducing agent. The X-ray diffraction (XRD) study revealed the formation of metallic silver particles crystallized in the face centered cubic (fcc) structure. The antimicrobial test results illustrated that the nano-silver colloids have excellent antimicrobial effects against E.coli and Streptomyces.

Abstract: The tube spread around strong cooling technology is new technology of the making semisolid slurry and semisolid billet in Semi-Solid Processing. The technologic parameter of its on the A356 Alloy is researched in the article. It is showed by the result of the experimentation: that the fine and form verge on rotundity crystal grain is made at 180L/h and at 640-650°C. It has met all the conditions in the semi-solid processing on semisolid billet. Semi-solid forming technology has been called the "new metal processing technology in the 21st century", which in foreign countries has certain industrial applications. In 1996 in the United States the sales of semi-solid casting was up to 1 billion dollars. But the industrial application in China is almost empty, one of the most important reasons is: the preparation of slurry or billet is too complicated or cost of production is too high, so that semi-solid forming technology in China has suffered serious setbacks on the road of industrialization. According to this situation, we have done a little attempts on manufacturing slurry and billet of semi-solid forming and have developed a new technology of spread around strong cooling whose intellectual property rights belong to us, equipment production is simple and the process is easy to control and the semi-solid slurry is east to prepare continuously. It will be discussed in this paper that process parameters of the single-tube strong cooling impacts on the microstructure of semi-solid