Advanced Materials Research Vols. 79-82

Abstract: In this research, powders of Y2Mo3O12 and Yb2Mo3O12 were successfully synthesized by liquid phase coprecipitation, followed with a heat treatment at 750°C for 6h. X-ray diffraction (XRD) analysis indicated that the Y2Mo3O12 and Yb2Mo3O12 were single orthorhombic structure with the space group of Pbcn. Negative thermal expansion properties of Y2Mo3O12 and Yb2Mo3O12 were studied with high temperature XRD analysis. The thermal expansion coefficients of Y2Mo3O12 and Yb2Mo3O12 were calculated to be -5.943×10-6K-1 and -6.237×10-6K-1 respectively.

Abstract: Samples of AISI 1045 carbon steel were surface hardened by micro plasma transferred arc (PTA) process. The hardened layer was characterized using both light optical and scanning electron microscopy and microhardness techniques. The tribological properties of the surface hardened layer and untreated substrate were investigated using a block-on-ring tribometer sliding against GCr15 steel under unlubricated condition. The worn surface morphologies and dominant wear mechanisms were identified using microscopy techniques. Results show that the surface hardened layer consists mainly of martensite and retained austensite with fine and dense structure, the microhardness of hardened layer increases from approximately HV 200 to HV 600. The wear volume loss of plasma hardened layer was 81.86×10-11m3 much better than that of untreated AISI 1045 carbon steel (743.44×10-11m3). Wear of untreated AISI 1045 carbon steel occurred by combined mechanisms of adhesion, abrasion and plastic deformation. While the worn surface of surface hardened layer is quite better with slight track and thin oxides on the worn surfaces. Plasma surface hardening has essentially changed the wear mechanism of the AISI 1045 carbon steel to slight abrasion and oxidation wear.

Abstract: A series of novel highly branched poly(urethane-imide)s (PUIs) were first successfully prep- ared by a two-step method with toluene-2,4-diisocyanate (TDI), pentaerythritol (PAT) and dianhydrides, including pyromellitic dianhydride (PMDA), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-oxydiphthalic anhydride (ODPA). It was found that the prepolymerization of PAT and TDI at 40 °C was ascertained to be 40 minutes. And the imidization of the prepolymer and PMDA was successfuly carried out after 120 °C for 2 hours. The XRD demonstrated that the obtained highly branched PUIs pre- sented semicrystalline aggregation structure which had clear crystal phase with the d-spacing around 0.39 nm. TGA curves exhibited that these highly branched PUIs had obviously two steps of weight loss attributed to the urethane chain segment and imide chain segment, respectively. The solubility testing indicated that the highly branched PUIs exhibited desirable solubility in various polar aprotic solvents, and were also resistant to dilute acid corrosion.

Abstract: SiCp reinforced copper matrix composites with the reinforcement content of 30-50vol. % were fabricated by hot pressing using Cu-coated and uncoated SiC powder. And the microstructure and electrical conductivity of the composites were also studied. The results showed that with the increasing of SiCp particle size, the electrical conductivity of the composites also increased. And the oxides in the composites can decrease the electrical conductivity of the composites obviously. The electrical conducting property of the composites can be improved by the copper coating layer and suitable annealing treatment. It provided important data for the application of SiCp/Cu composites as electronic packaging materials.

Abstract: This research was aimed to study the electrospinning of natural rubber (NR)-acrylonitrile butadiene styrene (ABS) blend. The NR used in this research was compounded in a torque rheometor, with stearic acid, wingstay-L, dibenzothiazoledisulfide (MBTS), tetramethylthiuram disulfide (TMTD) and sulfur, respectively. The compounded NR was blended with ABS by dissolving them in tetrahydrofuran (THF), concentration of solution included 5, 10, and 15 w/w%. The ratio of NR/ABS was varied by varying the content of ABS of 20, 30, 40 and 50 wt%. Then NR/ABS electrospun membrane was built up by electrospinning technique with high voltage 15 kV, flow rate 30 ml/h, collector distance 15, 20 and 25 cm and collected the electrospun fiber on rotating circular at 1000 rpm. The morphology of electrospun fibers were characterized by scanning electron microscope (SEM). SEM images showed that NR/ABS membranes had higher porosity with decreasing ABS contents. Decreasing ABS contents, decreasing solution concentration and increasing collector distance decreased fiber diameter of electrospun NR/ABS.

Abstract: Foam glass insulation materials were made by using titania-bearing blast furnace slag. Heat treatment process including foaming temperature, foaming time and heating rate were studied and their parameters were determined. First of all, heat treatment process parameter was determined by single factor experiment. Second, optimum process parameters of heat treatment process were obtained by the optimization of orthogonalization procedure. The results showed that foaming temperature has a remarkable effect on sample pore structure ；Foaming time has a less effect on pore distribution but its effect on the diameter of the pore is obvious; Heating rate has a less effect on the diameter of the pore. The magtitude of impact of heat treatment on glass properties arrange in an order of foaming temperature, foaming time and heating rate. The Optimal parameters of heat treatment are that heating rate ,foaming temperature and foaming time are 12°C/min，900°C, 15min respectively ; After preheating, sintering, foaming and foam stability and annealing heat treatment process, an amorphous foam glass with uniform pore size was obtained. Its thermal conductivity coefficient, the bulk density, compressive strength and average diameter are 0.131w / m ∙ k, 445.8 kg/m3, 2.8MPa, 4.78mm respectively. This kind of material can be widely used in building, chemical and shipbuilding industry as thermal insulation, sound absorption, corrosion-resistant and floating materials. Titania-bearing blast furnace slag is solid waste generated from vanadium-titanium magnetite by the blast furnace smelting, which is accumulated without being utilized. At present, Titania-bearing blast furnace slag is mainly used for cement concrete admixture, preparation of photocatalytic materials, extraction of titanium dioxide etc [1-2].Foam glass has been playing a more important role in low-temperature thermal insulation and moisture-proof anticorrosive projects field, and getting more economic benefits in energy saving and technology field. At present, the stuff for preparing foam glass is solid waste including waste glass, fly ash, slag, or natural minerals such as ash, mica, perlite etc. Foaming agent is usually selected from Carbon and carbonate [3-6]. In this paper, foam glass insulation materials were made by using titania-bearing blast furnace slag-based stuff. The effect of heat treatment process on foam glass performance was studied in a bid to find a new way to utilize titania-bearing blast furnace.

Abstract: The study on bisphenol A epoxy resin (EP)/4,4'-Diaminodiphenylmethane (DDM) system modified with poly(aryl ether ketone) (PEK-C) by the method of melt blending process is reported. The microscopic phase structure and morphology of impact fractured surface were observed by SEM, the phenomenon of microscopic phase separation and heat resistance property were studied by DMA. The results showed that PEK-C can disperse in the blends in the form of nanometer size (<100nm) particles or in the form of molecular size when the content of PEK-C lower than 10%, and the nano-particles are uniformly dispersed in the blends. The rough region of impact fractured surface with PEK-C modified sample is larger and more obvious, which indicated that toughness of the blends has been improved. The modified system has microscopic phase separation characteristics with higher content of PEK-C, as the same observed result of SEM, the glass transition temperature (Tg) of the blends moves towards higher temperature with the increasing content of PEK-C and the property of heat resistance has been improved.

Abstract: Semi-Interpenetrating networks (SIPN) hydrogel composed of poly (acrylic acid) (PAA) and poly (vinyl alcohol) (PVA) was prepared by free radical solution polymerization. The SIPN was characterized by Fourier transform infrared spectroscopy (FTIR). The electric stimuli responsive characteristics were investigated. The hydrogel bent toward the anode initially, altered the bending direction for two times and bent toward the anode ultimately when it was placed in a 0.1 M NaCl aqueous solution under non-contact DC field. For interpreting the special deformation the osmotic pressure curves according to Shiga’ osmotic pressure model were simulated and the pH gradient theory was applied to explain the final direction.

Abstract: The mechanical properties of CFRP without epoxy resin were tested by the monotonic load method, and the corresponding stress-strain relationship curve was established. The probability model and the parameter fitting based on Weibull distribution theory were applied, and the characteristic strength parameter and the shape parameter of CFRP were obtained. Three large scale RC short columns were constructed, the specimen not retrofitted, specimen strengthen retrofitted by CFRP and specimen repaired by CFRP which has been damaged by earthquake were simulated respectively. Quasi-static testing was carried out. The hysteretic-loop curve and average framework curve were obtained, furthermore, the performance of ductility and strength were analyzed and compared. The calculational results approximately agree with the experimental results, which prove the validity of OpenSees. The short columns retrofitted by CFRP have superior ductility so as to enhance the seismic performances effectively. The residual seismic behavior of short columns can also meet the requirement of seismic code. The research provides reference to seismic analysis and engineering design of retrofitted reinforcement concrete structures.

Abstract: MnCO3, CuO, NiO and Fe2O3 doped SrTiO3 multifunction ceramics were fabricated firstly. The microstructure and electrical properties were investigated. The results show that MnCO3 doped ceramic and CuO doped ceramic possess relative higher resistivity (ρ),nonlinear coefficient (α), varistor voltage (V1mA) and relative lower dielectric constant (ε),dielectric loss (tgδ) in contrast with NiO doped ceramic and Fe2O3 doped ceramic with the same contents under the same sintering conditions. The electrical properties among the ceramics doped are different due to the different behaviors of Mn,Cu,Ni and Fe acceptor dopants during the sintering course.