Advanced Materials Research Vols. 194-196

Abstract: Keratins from wool were reduced by the optimize method(PH 7.0, NaHSO₃ 50wt%, Urea 200wt% and SDS 15wt%), wool 5g, distilled water100mL, shaken at 80°C inconstant temperature water-bath for 24h, filtered through different nylon screens with 50-300 aperture using decompression filtering, dialyzed against distilled water afford a colorless and clear solution. The keratins main molecular weight was 35,000-45,000 Daltons; a clear film is readily prepared from a keratin solution containing glycerol or PEG on the basic of SMS nonwovens; the films moisture content was changed while glycerol concentration changed from 5% to 25%; the film was insoluble in water and organic solvents. The films were tested by SEM, Ultraviolet and FTIR.

Abstract: Effects of wood powder (WP) on mechanical properties of PP/WP composites were studied, and interfacial compatibility between polypropylene (PP) and WP was investigated with SEM. All PP/WP composites were compounded in a parallel twin-screw extruder. Mechanical properties of composites were characterized by tensile, hardness, and impact testing. The result showed that interfacial compatibility in PP/WP composite was ameliorated efficiently by PP-g-(MAH-St) compatilizer, mechanical properties of PP/WP composites were improved by pre-treating WP with alkali and coupling agent. They were also influenced by WP size and WP amount, which were the best at the size of 60-mesh and the amount of 40 wt%.

Abstract: The Si-Fe (≤0.043 mm) fine powder was added to the Al₂O₃-ZrO₂-C slide gate, and the influences of adding different Si-Fe contents (2wt%, 4wt%, 6wt%, 8wt%) are studied. Two different firing ways of nitridation and carbonazation atmosphere were used. The experimental results indicated that the addition of Si-Fe improve the physical and chemical properties of the slide gate, the performance is the best when the addition of Si-Fe is 6wt% and the properties of slide gate sintering in N₂-flowing atmosphere is better than that in CO-flowing atmosphere. Si-Fe will react with nitrogen and generate Si₃N₄ in the N₂-flowing atmosphere, while it will react with C or CO to produce SiC in CO atmosphere.

Abstract: Excellent Fe₃Si-Si₃N₄-SiC composites were successfully prepared with FeSi₇₅ and SiC as main starting materials by nitridation reaction(at 1300°C for 8Hrs). The effect of ferrosilicon alloy addition amount on material properties was studied; the ferrosilicon nitridation mechanism was analyzed through chemical thermodynamics; phase composition, microstructure, alkali resistance of products were also investigated. The results show that when ferrosilicon addition amount is 12wt%, the comprehensive property of Fe₃Si-Si₃N₄-SiC is the best. The nitridation products are fiber-like α-Si₃N₄ and rod-like β-Si₃N₄, which makes better mechanical behavior due to fiber reinforcement; a great deal of Fe₃Si intermetallic compounds uniformly distribute in matrix, which is one of the products of Fe-Si nitridation and as a plastic phase forming in grain boundary optimizes the performance of products. Chemical thermodynamic analysis shows that the fiber-like α-Si₃N₄ is formed by SiO(g) and N₂(g) reaction which also increases the rate of nitridation. Fe₃Si-Si₃N₄-SiC material has good performance. Now it has been successfully applied to one 2000M³ domestic steel plant, the blast furnace operation goes well.

Abstract: Multiwalled carbon nanotubes filled ABS (ABS/MWCNTs) composites were prepared via a method combined solution-blending with hot-press forming. Fractured cross-sectional surfaces of the ABS/MWCNTs composites were analyzed by scanning electron microscopy showing that MWCNTs were dispersed homogeneously in the ABS matrix. The volume resistivity of these composites was also analyzed and the percolation threshold was obtained at low filler loadings about 1–3 wt%. The Electromagnetic interference (EMI) shielding effectiveness (SE) of ABS/MWCNTs composites was investigated in 100–1500 MHz. It was found that SE of the prepared composites strongly depended on MWCNT loading. The highest EMI SE reaching 36 dB was observed for ABS/MWCNT composites containing 15 wt% of MWCNTs at 760 MHz.

Abstract: General materials can satisfy the structure strength requirement of space effective payload easily. But it can hardly satisfy the structure stiffness requirement of space payload. Carbon fiber composite has many excellent properties, such as high relative strength, high relative stiffness, small expansion coefficient, good fatigue resistance and excellent vibration resistance. It can be used to make space products. Firstly, this paper discussed the properties of carbon fiber composite material. Compared with common materials, such as aluminum alloy and titanium alloy, carbon fiber composite material is more suitable for applications of space instruments. Secondly, the metal part embedded technique of carbon fiber composite structure was studied. According to the carbon fiber composite structure of a space camera frame, a few structure forms of embedded part ware studied. A space camera frame of carbon fiber composite was designed and manufactured. Finally, finite element analysis and mechanical tests on the space camera frame was carried out. The results reveal that the characteristic frequency of carbon fiber composite frame is up to 104Hz.The space camera frame is of high stiffness and dimensional stability.

Abstract: Si-Si₃N₄-SiC composites was prepared by firing at 1450°C for 8hrs in air atmosphere with SiC, Si₃N₄, Si as principal raw materials. Si-Si₃N₄-SiC composites has good performance and its services life is 5~7 times than that of oxides sagger. This paper also studies the material attack mechanism and observes the microstructure of Si-Si₃N₄-SiC composites which has been used 15 cycles.

Abstract: A deformation-processed Cu-10Fe-3Ag in situ composite was made by consumable arc melting and casting followed by extensive deformation. A superior combination of mechanical strength and electrical/thermal conductivity was achieved with the composite since Fe filaments existed in the copper matrix. The effects of sliding speed and electrical current on sliding wear behavior and microstructure of the composite were investigated on wear tester. Worn surfaces of the Cu-10Fe-3Ag in situ composite were analyzed by scanning electron microscopy (SEM). Within the studied range of electrical current and sliding speed, the wear rate increased with the increasing electrical current and the sliding speed. Compared with Cu-10Fe in situ composite under the same conditions, the Cu-10Fe-3Ag in situ composite had much better wear resistance. Adhesive wear, abrasive wear and arc erosion were the dominant mechanisms during the electrical sliding processes.

Abstract: The polypropylene/aluminum nitride (PP/AlN) thermal conductivity composites were prepared by compression moulding method. Results revealed that the thermal conductivity of the composites were increased with the increasing AlN, and the thermal conductivity of composites was 1.84W/mk filled with 50vol% modified AlN. Both the tensile and impact strength of the composites increased firstly, but decreased with excessive addition of AlN. For given AlN loading, the surface modification of AlN exhibited a positive effect on the thermal conductivity. Meantime, the grafting of PP could increase the thermal conductivity of the composites compared with pure PP. And the addition of AlN did not change the crystal form of PP, but decrease the crystallinity of the composites.

Abstract: Progressive damage method is adopted to predict the static mechanics properties of FRP composite laminates with central hole. Progressive damage models with three different 3D failure criteria and material degradation models are established and analyzed via a user defined subroutine embedded into the general FEA package. Numerical results indicate that all the three 3D failure criteria can simulate the failure process of FRP laminates with central hole, but the final failure load is different. Degradation coefficient and the finite element mesh have significant effect on the numerical results.