Advanced Materials Research Vols. 512-515

Abstract: This paper details the preparation of one kind of PEG/MMT solid-solid phase change materials. With polyethylene glycol (PEG) as the phase change materials, montmorillonite (MMT) as skeletons, through the graft copolymerization method, prepare PEG/MMT solid-solid phase change energy storage materials. The structure, the phase transition behavior and thermal stability of PEG/MMT phase change materials were analyzed and studied by infrared spectroscopy (FTIR), thermogravimetry (TG) and differential scanning calorimetry (DSC), and studied the influence of different molecular weight PEG on the capability and structure of the material, polymer phase change energy storage behavior and crystallization behavior. Finally, The PEG/MMT solid-solid phase change material could improve enthalpy value and thermal stability.

Abstract: Currently, there are many unresolved issues to produce high quality phenolic molding compounds (PMC), which are widely used in many industry sectors. In this paper, we design a new approach to resolve some issues, and produce high quality PMC from phenolic resins, fillers, curing agents, and modified fiberglass by silane coupling agents. The preparation processes and the mechanical properties of the newly prepared PMC are studied extensively, and typical composite properties are: volume resistivity of 2.4×10¹³Ω.cm, surface resistivity of 3.9×10¹³Ω.cm, impact strength of 2.65KJ/m², bending strength of 95.9MPa, electric strength of 12.28mv, heat deflection temperature of 240°C, fluidity of 0.26mm, electric strength of 12.28mv, specific gravity of 1.661g/mL. Compared with currently used approaches, our approach can produce PMC with better overall performance and lower costs. This paper has two contributions, one is to propose and test a new approach for producing high quality PMC, and another is that we made a high quality PMC material with low costs.

Abstract: Nowadays, human society is facing three major issues: environment, resource and population, among which environmental issue is especially outstanding. With the rapid development of global economy and science and technology, more and more people begin to pay attention to the deteriorating environment, in particular, limited resource and unsustainable environment are realized by more countries. Western countries proposed application of environmental protection concept to modern human industrial activities very early. Based on this, research and development of environmental clothes began in 1930s, when western countries started to study environmental clothes for the purpose of security and strategy. It becomes consumers’ rational demand to choose environmental clothes.

Abstract: Al-doped ZnO thin films（ZnO:Al）were prepared by sol-gel process, the influence of preparation parameters on micro-structure was studied by XRD. The results showed that the solution concentration of 0.65mol/L was multi-axis orientation and when the concentration reached 0.8mol/L the film showed c-axis preferred growth; when film was too thin, showing amorphous, with the film thickness increased, ZnO:Al film turned multi-axis orientation to (002) plane preferential growth; the grain could not get enough energy to move to the right place for crystal when annealing temperature was too low, with the annealing temperature increased, ZnO:Al turned from multi-axis orientation to c-axis preferred orientation.

Abstract: In this paper, the coal ash /refractory samples were sintered in the furnace at certain temperature for 20h. Then three tests were made by visual observation method, XRD analysis of the coal ash and electromagnetic vibration of the coal ash/ refractory samples respectively in this paper to determine the critical temperature of three coal ashes on the corundum based refractories. Finally, the result shows that the electromagnetic vibration test is the most effective method with a better discriminabiltity on slagging intensity to determine the critical temperature of the coal ash slagging on the refractory. And furthermore, it advances a new and reliable method to determine the critical temperature on the refractories.

Abstract: The fretting wear behavior of Inconel 690 for steam generator tube in a nuclear power plant against Inconel 600 (Cr plating) for anti-vibration bar was investigated in a plain cylinder/plane contact configuration under ambient conditions. The fretting wear tests were conducted under various applied normal loads of 20-100 N, slip amplitudes of 20-100 μm and frequency of 2 Hz. Observation of worn surface and corresponding chemical composition analysis were performed to clarify the fretting wear mechanism. It is found that the friction coefficient value increases firstly and then tends to stabilize with decrease in normal loads and increase in slip amplitudes. In addition, the fretting regime is identified to be gross slip regime, indicating that the fretting damage mechanism of Inconel 690 tube against Inconel 600 (Cr plating) bar is wear. The corresponding fretting wear mechanisms are dominant by delamination wear, abrasive wear and friction oxidation.

Abstract: Numerical simulation study on the rheology or foam fluid was carried through by treating inner phase as granular fluid with mixture model. The simulation results show that the gas phase is well distributed on cross-section. Besides, the higher the foam quality, the higher the velocity gradient near the wall. For turbulent properties, the turbulent kinetic energy and viscosity increase as the foam quality increases. With the same foam quality, the bigger the bubble diameter, the higher the turbulent viscosity and turbulent kinetic energy. What’s more, the foam quality 63% is a catastrophe point at which the rheology of foam fracturing fluid changes sharply. The change trend of turbulent viscosity along radial direction is different between the regions where the foam quality is below and over catastrophe point, and in the latter the change trend is flatter. From the simulation results it can be seen that the mixture model is more applicable and effective to the region where foam quality is over 63%.

Abstract: Polyparaphenylene/Zn_0.925Co_0.075O(PPP/Zn_0.925Co_0.075O) nanocomposites were synthesized by using a sol-gel method and their thermal conductivity properties were measured. The XRD pattern of Zn_0.925Co_0.075O shows the single phase wurtzite structure. The SEM images show that the lighter-contrast area is PPP and the dark-contrast area is the polycrystalline of Zn_0.925Co_0.075O. The increase in the band edge is a clear indication for the incorporation of Co inside the ZnO lattice. The observation of three additional absorption peaks provided evidence that the 3d⁷ high-spin configuration of Co²⁺ under the tetrahedral crystal field was probably formed by neighboring O^2- ions. With the increase of the PPP content, the thermal conductivity of nanocomposite samples is smaller than those of pure Zn_0.925Co_0.075O. Due to the high density of interfaces and grain boundaries present in the nanocomposites, the scattering of phonon across a broad wavelength spectrum was enhanced. This suppressed the lattice thermal conductivity of the nanocomposites significantly.

Abstract: Synthesis conditions for generating high quality zeolite type Na-P1, A, and X from a South African coal fly ash were identified in this study. XRF, XRD, FTIR and SEM analytical techniques were used to characterize the starting fly ash feedstock and the resulting synthesis product. Synthesis of these high quality zeolites types is expected to provide a competitive alternative for recycling the ever increasing quantity of fly ash produced in the South African coal-fired power plants. This approach will not only be environment friendly but could also be attractive from an economic point of view since the cost of disposal of fly ash could be offset by the income generated from the sale of the synthesized zeolitic materials.

Abstract: The composites of ZnO/multi-wall carbon nanotubes (ZnO/MWCNTs) were efficiently synthesized via a simple hydrothermal method, and their capacitive properties were evaluated by cyclic voltammetry (CV) and galvanostatical charge/discharge tests, respectively. The resulting ZnO/ MWCNTs composite displayed net-like combined structure, in which the flower-like ZnO particles assembled by ZnO nanorods were entangled by the MWCNTs, Electrochemical investigation exhibited that the highest specific capacitance of 310 F g^-1 was obtained when the content of MWCNTs reached to 20%, compared to the ZnO (55 F g^-1) and MWCNTs electrode (17 F g^-1), showing the synergistic effect of ZnO and MWCNTs. The excellent net-like hybrid structure and the good conductivity of MWCNTs were considered to be responsible for its preferable electrochemical performances.