Advanced Materials Research Vols. 430-432

Abstract: A novel modified phenolic (PF) resin with high performance was developed, which was prepared by hybranched phenyl polysiloxane (HPSi) synthesized by our research group with PF resin. The effect of the incorporation of HPSi into PF resin on typical performance of HPSi/PF resins were systemically discussed. Results show that the incorporation of HPSi can not only effectively promote the thermal properties, but also improve the flame retardancy. For example, in the case of the modified PF resin with 10wt% HPSi, initial decompose temperature (Tdi) of HPSi is at about 405°C, which is 18°C more than that of neat PF resin at the heating rate of 10°C/min; its char yield at 800°C increases from 68.9% to 76.2% at the heating rate of 10°C/min. What’s more, HPSi10/PF resin has the maximum LOI value, which is 14.6% more than that of neat PF resin. The novel modified PF resin with improving integrated properties exhibits great potential to be used for many cutting-edges fields.

Abstract: By way of alloying, a sort of low-chromium heat-resistant ductile iron material was developed. Through the observation of microstructure, testing of mechanical properties and process performance, heat-resistant test, the microstructure and properties of heat resistant ductile iron of low chromium was studied. The results show that microstructure of the developed heat-resistant ductile iron is spherical graphite distributed regularly on matrix of pearlite and a small amount of ferrite; mechanical properties, processing performance and high-temperature heat resistance of samples of different chrome composition are preferable, but 1.6% of chromium component possess the best performance.

Abstract: The fiber reinforced concrete with flexible fiber and rigid fiber respectively added into C30 plain concrete, curing under standard condition for 28 days, was used for impact resistance performance experiment. The flexible fiber is American Dura fiber and Chinese nylon fiber. The rigid fiber is Chinese steel fiber. The impact resistance property was evaluated by initial cracking times, final cracking times and impact toughness. The result shows that the impact toughness of steel fiber concrete, Dura fiber concrete and nylon fiber concrete is respectively 15.1, 3.4 and 2.7 times of the plain concrete. The fiber reinforced concrete improves the impact resistance property compared with the plain concrete. The impact resistance of rigid steel fiber reinforced concrete is increased greatly.

Abstract: The curing rate of epoxy/Versamid 125 (V125) by heating curing, room-temperature curing and microwave curing was compared. It is founded that applying microwave technology could effectively improve the curing rate and the curing time is only 3-4minutes. 140W microwave could cure the epoxy system in good condition, but 280W and 420W were easy to make the materials coking. The impact of diluent on mechnical properties of curing product were studied and it is showed that the impact strength increases and the impact ductility will be improved with the content of diluent increases, while the compressing strength, bending strength and tensile strength decrease.

Abstract: The microstructure, mechanical properties and damage morphology of as-cast and as-extruded AZ31 Mg alloy under different annealing treatments were investigated. The result of three-point bending test showed that the as-extruded magnesium alloy after annealing treatment followed by 300°C×30min can obtain a good mechanical properties and fine uniform grains. There are clear surface macro-cracks and emboss, the micro-cracks and cavities generated in the vicinity of the main crack, the main cracks of as-extruded samples arises from the maximum compressive stress position ,but as-cast samples arises from the maximum tensile stress position. The main crack of magnesium alloys is extended from the edge to the center of the specimen. This is because the crack propagates along grain boundaries or twin boundaries, and the cracking process will be obstructed by dislocation and/or the second phase particles

Abstract: Heterogeneous acid catalyst, H4SiW6Mo6O40/SiO2 was synthesized by a sol-gel technique. Catalytic application of the catalyst for synthesis of acetals and ketals were tested. The variation of different reaction parameters on the yield of acetals and ketals were also studied. The yields of acetals and ketals can reach 80.0%~96.9% at the optimized conditions. The high activity and stability of the catalyst is well retained after 4 runs. The results reveal that the H4SiW6Mo6O40/SiO2 catalysis is a novel, effective and reusable catalyst for synthesizing actetals and ketals.

Abstract: Extending extrusion process of semisolid AA2017 alloy was achieved. Metal flow during the process was analyzed by the finite element simulation. It was shown that alloy flow velocity decreases gradually from the center part to the sides of the mould, sometimes a transitional turbulence region appears in the middle. A smaller declining angle θ and without step d is suggested in the design mould. Alloy flow velocity at the center of the forming region decreases linearly with increases of the extending ratio s1/s0.

Abstract: Polyurethane/poly (methylacrylate-butylmethacrylate-2-Hydroxyethylmethacrylate) Interpenetrating polymernetworks (IPNs) were prepared by sequential polymerization. Their glass transition performance was measured by using differential scanning calorimetry (DSC). DSC results revealed there are three glass transition temperatures (Tg) for both IPNs samples. Their damping properties were evaluated according to ASTM E756-05. Their loss factor (tan δ>0.3) from 10-1300Hz displays a wide temperature range of 94°C.

Abstract: Rheological properties of blend spinning solution of sodium alginate and TiO2 nanoparticles (SA/nano-TiO2) were investigated. The rheological parameters, structural viscosity index (Δη) and flow activation energy (Eη) of spinning solutions were calculated. The results reported that the blend spinning solutions were non-newtonian fluids. The apparent viscosity, consistency index (k) and Eη increased with increasing nano-TiO2 content in SA spinning solution, but the degradation degree of apparent viscosity decreased, flow behavior index (n) only slightly decreased and the Δη had no significantly change. The apparent viscosity (ηa) of spinning solutions could be regulated by changing temperature under 50oC. Blend spinning solution had good stability and practical applicability.

Abstract: In this paper, a new non-lead machinable austenitic stainless steel was investigated. The metallurgical properties, machinability and mechanical properties of the developed alloy were compared with those of the conventional austenitic stainless steel 321. The results have shown that the presence of machinable additives, such as sulfur, copper and bismuth, etc. contributes to the improvement of the machinability of austenitic stainless steel, because the inclusions are something like internal notches causing crack nucleation and facilitating rupture. Bismuth has a distinct advantage over lead. The machinability of the austenitic stainless steels with free-cutting additives is much better than that of austenitic stainless steel 321. The mechanical properties of the free cutting austenitic stainless steel are similar to those of 321 although the former are slightly lower than those of the latter.