Advanced Materials Research Vols. 250-253

Abstract: The affecting law of nickel on structure and properties of ferro superalloy, which was cast by intermediate frequency induction furnace, were studied by orthogonal experimental method. The tensile strength and oxidation weight gain rate at 1000°C were tested. The matrix microstructure and scale morphologies and composition were studied using scanning electron microscope (SEM) and X-ray diffraction (XRD) respectively. It was found that the high temperature tensile strength went up with the increase of nickel by the forming of high temperature strengthening phase of γ’. After 100 hours aging at 1000°C, γ’ phase separated in blocks. Certain content of nickel improved the high temperature oxidation resistance of test alloys, but excess of it caused the higher oxidation weight gain rate and loose structure oxide scales with holes and exfoliating. In considering of high temperature tensile strength and oxidation resistance, the ideal content of nickel in ferro superalloy should be 9wt.%, with which at 1000°C the tensile strength of test alloys mostly exceeded 70MPa, and the average oxidation weight gain rate was only 0.55g.m^-2.h^-1, reaching the strong oxidation resistance. Such scale was compounded by Cr₂O₃ and Fe(Ni)Cr₂O₄ with compact structure, fine and even oxide grains.

Abstract: By processing waste into recycled aggregate concrete, and producing recycled concrete aggregate with 50 percent of it replacing natural gravel, we make a study of different curing conditions on the carbonation of recycled concrete as well as the resistance capacity of steel corrosion. The experiment results indicate that the depth of carbonation of recycled concrete increases sharply with the standard curing period lowering. The recycled concrete steel corrosion resistance rate decreases as standard maintenance ages. The recycled concrete steel corrosion rate is much lower than the general concrete steel. The steel corrosion weight loss rate of general concrete is less than 0.3%, with no rusting of the steel. The steel corrosion weight loss rate of recycled concrete is mostly more than 0.3%, with apparent rusting.

Abstract: Composite materials have excellent mechanical properties and can be mechanically tailor designed, so the composite materials are widely used in civil engineering and structural system such as aerospace and shipbuilding industry. Numerous studies show that the damage of joints is main reason which results in composite structure failure. In this paper, extended finite element method (XFEM) is applied to investigate the failure load prediction of bolted single-lap composite joint. The influences of geometric parameter: edge-to-diameter (E/D) on failure load is investigated.

Abstract: Through a series of tests of thermal capability to rubber concrete, we get the adiabatic temperature rise curve and hydration temperature curves with different amount rubber in concrete. It revealed the relationship between amount of rubber and thermal conductivity of rubber concrete. Large rubber pieces should be used to replace coarse aggregate in protection concrete of sluice pier and bridge pier.

Abstract: Using 6% HCSA, HEA and CSA equivalent replacement Slag Portland Cement add into the normal concrete, the compressive strength, splitting tensile strength and flexural strength at the age of 3d, 7d and 28d are researched. It is concluded that reinforcing effect of the three expensive agents are in order CSA, HEA and HCSA form the view of mechanics , expansive agents increase the bonding force between coarse aggregate and slurry, alleviate the development speed of cracks and increase the destruction deformability of concrete.

Abstract: Traditional approaches such as ocean dumping and inland deposit are unsatisfactory for the management of dredged sediments, in the context of sustainable development. The solidified sediments with fly ash and lime as road base materials are preferred to conserve land and minimize impact to environment. A series of tests, such as compaction tests, tensile strength tests and swell tests, were performed to explore mechanical and swell properties of Dunkirk dredged materials. The fly ash contributes to the considerable increase in elastic modulus and the small increase in tensile strength in the presence of lime. Then the potential of treated sediments as road base material is evaluated. After immersion in water for 4 days, the addition of fly ash can induce a remarkable increase in swell percents in contrast with the lime-based sediments.

Abstract: The obstacles met during the production and construction of High Strength Concrete (HSC) and High Performance Concrete (HPC) are analyzed, then the poly-carboxylate based admixture is studied in detail. After that, presents the trend of using Self Compacting Concrete (SCC) to improve the performance of concrete structures, i.e. its durability and reliability, because its highly flowing nature makes it suitable for placing concrete in difficult conditions and sections, especially with crowded steel reinforcement. Utilization of SCC can also reduce the time required for placing large sections in concrete structures, e.g. in the basement or substructure’s concrete pouring. SCC may also minimize the noises on the construction site that are induced by concrete vibrators. Accompanying the presentation of the performance of SCC, its applications in the recently completed Grand Wisata Cable Stayed Bridge designed by the Authors are also introduced.

Abstract: For the compressive strength of the normal concrete is high and the tensile strength is low, it is typically brittle material. The ultimate tensile elongation of it is insufficiently 1/1000. Zhongwei Wu, an academician of Chinese Academy of Engineering pointed out that compounding cementitious composites was the way to make it high-performance, and fiber reinforced was the key^[1]. Polyvinyl Alcohol Engineered Cementitious Composites has super flexural performance^[2] and stretching ability^[3],and its ultimate deflection is approximately 40 times larger than that of normal concrete when bended, similar to the multiple cracking and super toughness of uniaxial tensile test, it shows significant bending hardening behavior in the process of the test. This paper studied its flexural property by four point bending test .

Abstract: Mn-doped alumina red pigment was prepared with Mn(NO₃)₂·6H₂O and Al(NO₃)₃·9H₂O as main raw materials by Low-temperature Combustion-Calcination process. The Mn-doped alumina red pigment was tested by XRD, SEM and CIE L*a*b* colour parameter measurement. The results showed that the reaction of Mn(NO₃)₂·6H₂O, Al(NO₃)₃·9H₂O and CH₃COONH₄ with the theoretical ratio could be ignited and self-propagating at 500 °C. One kind pigment with excellent chromatic performance had been gained at the ratio about 1:40 between Mn(NO₃)₂·6H₂O and Al(NO₃)₃·9H₂O. The crystallite of the precursor obtained by Low-temperature Combustion synthesis (LCS) is imperfectly developed and the aggregation of particles is serious. The crystallite of the powder grows up more perfectly after calcined at 1000 °C for 4 hour with a corundum-like structure. The average particle size of the pigment is approximately 5 μm.

Abstract: To develop a superplastic damping device, the mechanical properties and superplastic capability of Zn-22Al alloy with a large size in the rolled samples were investigated. It is indicated that the alloy with a large size has some advantage properties, such as high ductility, low yield stress and low work hardening at room temperature, which is very useful to a seismic damper.