Advanced Materials Research Vols. 189-193

Abstract: The cloud points of blends epoxy/polyetherimide-siloxane (PEI-Siloxane) without or with curing agent methyl tetrahydrophthalic anhydride (Me-THPA) after different curing time (1min, 2min, 3min) at 150oC were determined by optical microscope. The cloud point curve for uncured and cured after different time was then obtained from the experimental results with different composition. The effects of molecular weight of epoxy on phase diagram were discussed. The miscibility of blends will be taken into account in the toughing of epoxy resins by thermoplastic PEI-Siloxane copolymer later.

Abstract: After testing on T-type rubber bearing under tensile, compression and shear mechanical properties under different temperature in this paper. Obtained load deflection curve and destructive mode under different loading conditions at -40 and normal temperature of rubber components. Analysis the impact of temperature and the loading conditions that effect on load-elongation and destructive mode of T-type damping rubber structure. It showed that T-end rubber bearing has different kinds of deformation under different force-giving methods. Under compression, the stress pattern of the rubber bearing is three-dimensional and middle rubber bear the greatest force. Under tensile loading, the middle part of the rubber contract and the side with smaller lateral section has greater shrinkage; moreover, damage occurred in the area with stress concentration and weak strength. Under shearing action, extrude faces appeared with crinkle and damage occurred in the middle part of extrude faces. At the low temperature-40 , rubber support still has great elastic properties. The low temperature has a big effect on tensile properties and has little effect on damage properties.

Abstract: This paper considers for transformation behavior of Nb microalloyed steels, experiments had demonstrated the effect of Nb was obvious: lowered start temperature of ferrite transformation remarkably and forming more refined ferrite grain size. In this study, computer simulation of Nb-containing steels transformation during continuous cooling was carried out by adopting a classical nucleation and growth theory, the model was derived based on the theories and the experimental results, and the calculated start temperatures of ferrite transformation were compared with the results of experimental.

Abstract: In this paper，electroless Ni-P plating on copper substrate at 50 °C in ultrasonic field was carried out. The frequency of ultrasonic waves was 40 kHz. The effect of ultrasonic on the composition, plating rate and morphology of Ni-P deposite was investigated at the ultrasonic power of 40, 70 and 100 W. The experimental results showed Ni-P deposit could not be obtained without ultrasonic field at 50 °C. The content of nickel and the thickness of Ni-P deposit increased with the ultrasonic waves power increase. Ultrasonic irradiation power remarkably refines the nodule size of Ni-P particles. The collapse of cavities in solution seems to suppress the Z-direction growth of the nodule.

Abstract: We adjusted the pearlite content of ductile iron matrixin by normalizing, finding that the microstructures of laser hardened ductile iron with different pearlite content and distribution were quite different. According to their microstructure characteristics, there are three types: ⑴pearlite transformation type; ⑵ pearlite and ferrite transformation type; ⑶ferrite transformation type. We also studied the microhardness of different ductile iron laser hardened layers and the phase around the graphite ball. The results showed that under the appropriate laser treatment process (laser output power of 1kw, spot diameter of 5.2mm, scan speed of 16mm / s), ledeburite shell, with the hardness up to HV0.11070, formed around the graphite ball in the surface layer of ductile iron hardened layer. Outside the ledeburite was the carbon diffusion zone with hardness of HV0.1850. It was composed by the plate martensite of large needle and large amount of residual austenite. In the hardened layer of ferrite transformation type, martensite formed out around the ledeburite shell or graphite ball.

Abstract: For the hydration of magnesia-calcia refractory, this paper uses a new hydration-resistance technology. Namely using chemical methods, through surface and CO₂ occurring chemical reaction which generates CaCO₃ layer. The surface of magnesia-calcia firebricks are modified so that closed or stability, playing a role in hydration-resistance, and significantly improves the hydration-resistance. By SEM energy spectrum analysis and hydration resistance test, we obtained optimal technological parameters: reaction temperature is 700 °C for 4-5 hours, suitable water vapour temperature is 40°C, and the appropriate CO₂ flow is in the 4-4.5L•min^－1.

Abstract: In this paper the influence of carbon nanotubes (CNTs) on anticorrosion properties was discussed. KMnO4 modified carbon nanotubes were added into Waterborne PolyUrethane, then galvanized steel sheets were dipped into this composites to get a thin film and dried at 120 °C for 60 seconds. SEM observation show the film thickness was 3 µm and CNTs were dispersed in the polymer matrix. XRD demonstrated that some KMnO4 decomposed into K2MnO4 and MnO2. Polarization curves demonstrated the film exhibited excellent anticorrosion when the amount of KMnO4 modified CNTs was 6%.

Abstract: After the processes of crushing, screening and grinding, abandoned mortar powder can be used as a mineral admixture to replace cement. Physical-activating, alkali-activating and compound-activating have been used to stimulate the activity of abandoned mortar power. To get the mechanical properties and microstructure, compressive strength, flexural strength, XRD, TG-DTA and SEM were used. The results show that: Mechanical grinding and activator can greatly improve the activity of mortar power. Stimulating effect of compound activator was better than signal activator and it could promote further hydration of cement. The mortar which is stimulated by compound activator had higher strength than mortar by single activator. It can be seen from micro-test that the mortar with compound activator had more ettringite and other hydration products, and with compact structure.

Abstract: ZnS nanoparticles with Mn²⁺ doping (0–2.5%) were prepared through a simple chemical method. The nanostructures of the prepared undoped ZnS and Mn²⁺-doped ZnS:Mn nanoparticles had been characterized by X-ray power diffraction (XRD), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), photoluminescence spectra (PL) and UV–vis absorption spectra. The mean size of the particles was found to be approximately 3-5 nm through XRD measurements, TEM and the UV–vis absorption spectra. It was found that the Mn^{2+ 4}T₁→⁶A₁ emission intensity of ZnS:Mn nanoparticles was significantly enhanced with the increase of Mn²⁺ concentration, which arrived a maximum value when Mn²⁺ initial doping concentration was 1.5%. Continue increasing the Mn²⁺ concentration, namely more than 1.5%, the Mn^{2+ 4}T₁→⁶A₁ emission intensity became weakened. And the resultant ZnS:Mn nanoparticles exhibited high efficiency for degrading methylene blue under UV light irradiation.

Abstract: Hadfield steel matrix composite, reinforced by high-chromium (Cr) cast iron bars, was fabricated by inserting high-Cr alloy flux-cored welding wires into Hadfield steel molten at 1500 °C. The characteristics for water-quenched composite were investigated and compared with those of reference Hadfield steel. The results show that flux-cored welding wires could be melted by heat capacity of Hadfield steel molten and transformed into high-Cr cast iron bar reinforcements after solidification. The reinforcements of water-quenched composite consist of martensite, eutectic M7C3 carbides and residual austenite. With the increasing of impact energy, the impact wear rate of the composite firstly decreases, and then increases slightly, therefore, the composite is more available to the conditions of low and medium impact energy. The reason is it can combine fully advantages of the outstanding toughness of Hadfield steel, and high hardness of high-Cr cast iron.