Advanced Materials Research Vols. 129-131

Abstract: Tungsten heavy alloys are particle composites; they occupy a unique position in materials because of their combination of high density, strength and ductility. The main focus of this study was to examine the effect of sintering conditions (temperature and time) on the microstructural parameters of tungsten heavy alloys. Alloys composed of 88%, 93% and 95% wt. of tungsten and either Ni: Fe (in the ratio of 7:3) or Ni: Co (in the ratio of 7:3) were consolidated into green compacts. Samples of each of the six resulting alloys were sintered in hydrogen atmosphere at different temperatures for different sintering holding times. The microstructural parameters of both types were found to be roughly similar at each temperature and holding time. At higher sintering temperature and longer sintering holding times there was a matrix gradient and the formation of FeNi intermetallic phases at tungsten matrix interfaces. The microstructural parameters showed that the W-Ni-Co alloys may have some advantage as a result of their small tungsten grains and the lower contiguity.

Abstract: The plywood was prepared using the UF resin modified with isocyanate blocked by sodium bisulfate in this paper. And the effects of the ratio of UF resin and blocked isocyanate, hybrid method and the additive on the properties of the plywood were also studied. The results showed that under the condition of BPI / UF =5%, the order of urea-formaldehyde resin mixed mode curing agent, additive and finally joined the BPI , the bonding strength of the plywood was improved obviously and the formaldehyde release of the plywood could achieve the demand for the national standard.

Abstract: The paper adopted a direct approach of putting melamine inside to modify the UF resin, tested the physical properties of UF adhesive and used DSC method to study the solidifying temperature. The results show that when the molar ratio (F / U) is 1.05 or 1.15 and the addition of melamine is 4% or 8%, the viscosity, solidifying temperature, solidifying time, as well as the application period of modified UF adhesive are suitable for the production of high quality particleboard. When the molar ratio (F / U) is 1.05, the addition of melamine is 4%, particleboard density is 0.80g/cm3, the thickness of particleboard is 12mm and the addition of waterproofing agent is 1%, the performances of particleboard achieve or exceed the standard value.

Abstract: Vacuum pump plays an important role in vacuum applications. The rotor and stator profile is one of the key factors for improving pump performance. In this paper, the traditional trochoidal vacuum pump that the rotor and stator profile both are trochoidal equation was introduced. The profile of trochoidal vacuum pump with two angle rotor was studied. In order to simply the design and manufacture, the rotor profile was substituted by the arc curve. The design parameter and performance was deducted on slenderness ratio. The slenderness ratio should larger than 4, otherwise the down part of the stator profile would be dent to upper. When slenderness ratio is 4, the utilization ratio of volume would be getting the maximum value, 0.5851942. The utilization ratio of volume was decreased with the slenderness ratio increased.

Abstract: This paper points out the difficulties because of the direct measurement of elasticity coefficients of brittle materials, presents the composite measurement method, and describes the data processing procedure. A new method is introduced which is more precise for measuring the elasticity coefficients, and C program is compiled on the basis of the method.

Abstract: The 3D physical model of the electrical water heater was built. The water-heater performance was resolved by computer fluid dynamics simulation (CFD). The heater performance is characterized by a new method rather than that the discharge efficiency, extraction efficiency and fraction of heat recoverable. The new method is based on the constant discharge water temperature and rate for end user, 5L/min and 43°C that include the hot water from EWH and cold water from outside EWH. But the water discharge rate from EWH was variable as the water temperature discharge from EWH was variable. Compared with the traditional method, it is more close to the user using reality condition.

Abstract: A chrome-free chemical conversion coating was prepared using stannous sulfate as the main salt. The morphology of the chemical conversion surface layer was observed by scanning electron microscopy (SEM). Coating composition and the microcosmic phase structure were characterized using energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) respectively. Electrochemical method and dropping test were used to study the coatings corrosion resistance. The results indicated that the tin salts conversion coating is a crystal structure material that composites with Sn-F-O-Al et al., the surface appears as a accumulation of spherical particles, the crystallinity of conversion coating is better than uncoated sample obviously, the corrosion resistance has improved too.

Abstract: Priority has been giving to smart garment materials in modern textile clothing industries. The definition of smart garment material can be described as the material which has the sensory capacity to the stimulation of the surroundings or the environmental elements and can make responses accordingly and meanwhile, maintain the typical features and garment functions. Sensory capacity, feedback and response are the three main elements of the smart garment material. Five relative mature and widely used smart materials, including shape memory materials, waterproof and moisture permeable materials, temperature adaptable materials, photo chromic and thermo chromic materials, and electronic materials, were thoroughly reviewed in terms of concept, theory and up-to-date applications. The aim was to give an overview to national garment designers and manufacturers in China and to explore the potential of developing smart garments for the national market.

Abstract: We report the preparation of quasi-arrays of aluminum nitride nanocones via chemical vapor deposition on nitriding treated titanium substrate at 800 °C through the reaction between AlCl3 vapor and NH3/N2 gas. The field emission measurement exhibits a fine electron emission with the turn-on field of 10.7 V/mm, which is quite smaller than the turn-on field of 41.3 V/μm for aluminum nitride nanocones deposited on silicon wafer in our previous works. The reduction of turn-on field is attributed to the formation of a layer of conductive tiannium nitride on titanium substrate during the nitriding treatment.

Abstract: Taking the 7075 aluminum alloy as an example, this paper did some simulation work on temperature, flow field and shrinkage porosity distribution in the rheocasting process using the simulation casting software PROCAST. Effects of the casting temperature and filling speed on casting quality as well as segregation phenomenon of solid and liquid phases were discussed in this paper. Proper ranges of casting temperature and filling speed were obtained by the simulation. Good quality parts without shrinkage porosity were obtained in validation test using the casting temperature of 622~625°C and filling speed of 40mm/s. Rheocasting was an important forming method using semi-solid melt to manufacture metal parts directly. It was a promising trend of semi-solid forming industry which had shorter process, higher efficiency and lower energy consumption compared to SIMA method [1-4]. Rheocasting was generally applied to casting aluminum alloy but seldom to wrought aluminum alloys. The 7xxx series aluminum was generally manufactured though wrought or rolling technique to obtain dense parts with high strength. But few of them were produced directly through casting method without casting flaws[5-6].To process the 7xxx series aluminum by rheocasting method would further expand the application of wrought aluminum alloy, so it is essential to do some research on the rheocasting technique for wrought aluminum alloy. Taking the 7075 aluminum alloy as an example, this paper did some simulation work on temperature, flow field and shrinkage porosity distribution in the rheocasting process using the simulation casting software PROCAST. The effects of casting temperature and filling speed on the casting quality as well as the segregation phenomenon of solid and liquid phases were discussed in this paper. Proper ranges of casting temperature and filling speed were obtained by the simulation.