Advanced Materials Research Vols. 1030-1032

Abstract: The root shrinkage cavity (SCRT) is one special kind of high-energy welding defect which can remarkably decreases mechanical strength and induces fatigue crack, so it is of great significance to numerically study its formation mechanism. In this paper, a set of Niyama criterion program based on temperature field was developed and adopted to numerically predict it in non-penetration 2219 aluminum alloy electron beam weld. The results indicate that the formation possibility of SCRT defect decreases with the increased welding speed. In addition, the error of simulated SCRT in the weld penetration direction is 8.76%, while the error in the weld width direction is 23.46%, which shows good agreement with experimental comparison samples. All the simulation and experimental results validate the correctness and feasibility of the developed Niyama criterion program.

Abstract: Ozonation of humic acid has been conducted in the presence of hydrogen peroxide as catalyst. Besides the study of total organic carbon removal in the ozonation, ozonation by-products were investigated through the change of injected concentration of H₂O₂, initial pH of aqueous humic acid and injection time of H₂O₂. The variation of hydrogen peroxide and formaldehyde contents in the processes are mainly evaluated. The formaldehyde was formed less in ozonation with hydrogen peroxide system than without it. When initial pH in solution was changed from 3.5 to 10.5, the formaldehyde was formed with the highest concentration at pH 5. In addition, the concentration of H₂O₂ produced by ozonation was found to be increased with decreasing pH of the sample solution in this process.

Abstract: Iron-phthalocyanines (Fe-phthalocyanines) with different amounts of carboxyl groups were added into carboxymethylcellulose (CMC) cation exchange membrane to prepare the modified CMC/CS bipolar membranes (BPMs, CS: chitosan), which were characterized using electric universal testing machine, contact angle measurer and so on. Experimental results showed that the ion exchange capacity, hydrophilicity of CMC membrane and mechanical properties of the BPM notablely got better after Fe-phthalocyanines were added. Furthermore, a high charge density area formed in the interlayer of the BPM after modification, which sped up water dissociation and lowered the membrane impedance. At the current density of 60 mA cm^-2, the cell voltages of Fe₂Pc₂(COONa)₁₂-CMC/CS BPM, FePc (COONa)₈-CMC/CS BPM, FePc (COONa)₄-CMC/CS BPM and CMC/CS BPM were 5.6V, 6.2V, 6.5V and 8.9V respectively [here, Fe₂Pc₂(COONa)₁₂: planar binuclear iron (III) phthalocyanine; FePc (COONa)₈:iron (III) octocarboxyphthalocyanine; FePc (COONa)₄:iron (III) tetracarboxyphthalocyanine]. The cell voltage of Fe₂Pc₂(COONa)₁₂-CMC/CS BPM was the smallest.

Abstract: The EP/ZnO nanocomposites were prepared by using epoxy resin as matrix, nanoZnO as the modifier, polyamide as curing agent. The surface morphology of nanoZnO was observed,the average particle diameter of nanoZnO is 20nm. Their mechanics properties were studied and the experiment results were analyzed. The results indicated that the compressive stress-strain curves of the nanocomposites had obvious three phases characters, i.e., linear elastic phase, plastic yield flat phase and compact phase. Along with the nanograins content of the nanocomposites increasing, the compressive elastic modulus and compressive strength of the nanocomposites augmented. When the nanograins content is 5% and the transfiguration speed is 10mm/min, the compressive elastic modulus and compressive strength of the nanocomposites respectively improved 36.4% and 48.9% comparing with their of the pure epoxy resin. At the same nanograins content, with the transfiguration speed increasing, their compressive strength added.

Abstract: Semisolid metal forming (SSF) has been regarded as a potential process to shape the wrough Mg alloy base on the thixotropy and low deformation resistance of non-dendritic semisolid slurry. Therefore, it is necessary to develop the slurry production method of wrought Mg alloy as most current researches are focused on the cast alloy. In this paper, the AZ31 billet was refined by the self-inoculation method, and the partialy remelt method was employed to produce the non-dendritic microstructure. Results indicate that both the morphology and size of the primary Mg phase in AZ31 were refined by the grain refining treatment. When the billet were reheated under 595°C and 610°C with different holding times, the morphology of primary Mg phase undergo an evolution pattern from rosette or tiny dendritic to spherical, and with the prolonged holding time, the size of primary Mg phase increased and the shape turn to irregular. Moreover, the result show that the high holding temperature shorten the evolution time from irregular to spherical and the deteriorative grains obtained earlier compared to the low holding temperature.

Abstract: Our goal was to produce a complex inorganic polymer flocculant containing poly aluminum ferric chloride (PAFC) from blast furnace dust. The optimum reaction conditions to achieve high extraction efficiency of iron and aluminum were obtained through a series of batch experiments. PAFC was synthesized by controlling the hydrolysis conditions of iron and aluminum. Extraction efficiency of iron and aluminum oxides from blast furnace dust was affected greatly by reaction parameters such as temperature, time and hydrochloric acid consumption. The dissolution rate of iron was 67.61% and the dissolution rate of aluminum was 12.35% under the optimum reaction conditions (100 °C, 3 hours, and and the mixing ratio of the blast furnace dust to the hydrochloric acid is 1:3). To neutralize the pH and then synthesize PAFC, a solution of Al (OH)₃ was added to the dissolved blast furnace dust, and the mixture was hydrolyzed at 60~70 °C for 4 hours. The prepared complex inorganic polymer flocculant proved to be effective in removing turbidity. The turbidity removal ratio for kaolin simulative water was 99.36%.

Abstract: Solid composite propellants are extensively used for propulsion of rockets, missiles and space applications. The composite propellant is a polymeric matrix in which the oxidizer and fuel particles are embedded in a polymeric binder. Different composite propellant mixtures have been prepared using ammonium-perchlorate (ratio 70:30) as oxidant and mixture of aluminium powder (ratio 50:50) as metal component. In the present work, RDX (Cyclotrimethylene trinitramine) has been used in successive increments replacing AP (Ammonium Perchlorate) in number of batches by varying the percentage of solid loading, and studied their different properties such as viscosity build-up, mechanical and ballistic properties.

Abstract: In this experiment, we examine the impact of photoinitiator and reactive diluents for the UV curing of epoxy resin and Urethane acrylate in detail, so as to provide a theoretical basis for obtaining a satisfactory light curing system. We conducted a number of UV curing experiments, discussed the key influencing factors of the success in Synthesis experiment, explored and researched the Reaction mechanism to some certain extent. The performance was tested after curing, according to the orthogonal experiment method, we analyses the effect of different factors.

Abstract: Black ceramic membranes are made on the surface of AZ31B magnesium alloy to further study the micro-arc oxidation coloring ceramic membranes with more colors.In the system of sodium silicate - copper sulfate, black ceramic membrane with good compactness and uniform color can be made while the concentration of sodium silicate is 20g/L and the concentration of copper sulfate is 1.0g/L. Experimental results show that the chroma of the membrane varies from light color system to deep color system with the increasing content of copper aluminum compounds.

Abstract: A kind of rapid heating method which takes advantage of carbon fiber conductivity to shorten the cycle time of VARIM was designed in present paper. The processing cycle time, curing degree, glass transition temperature and mechanical properties of the laminates fabricated by carbon fiber internal resistive heating aided VARIM (R-VARIM) were studied. The results revealed that the cyle time of R-VARIM with con-water cooling process is only 450s, it is about 52% lower than that of previous study. Lower cooling rate before glass transition temperature is useful to complete cure of resin and improve the properties of the composites.