Applied Mechanics and Materials Vol. 751

Abstract: Effects on characteristics and mechanical properties of oil palm frond fiber (OPFF) as a reinforced element in poly vinyl alcohol (PVA) were investigated in this study. Series of different loading of OPFF were prepared by the following compositions: 5, 10, 15, 20 and 25 part per resin (phr). Glycerol at 35 phr was also compounded using twin-screw extruder to decrease degree of crystallinity and to reduce shear force of PVA to improve the processability. Injection molding was used to produce specimen for testing. The results indicated that the OPFF has an impact on mechanical properties of the composite material. Different scanning calorimeter (DSC) showed that the melting temperature (Tm) of OPFF reinforced PVA blended with glycerol was shifted to having decrease when compared to the pure PVA. Different loading contents of OPFF indicated that the compressive strength and morphological properties performed by a similar fashion. A highest compressive strength and the modulus of OPFF-reinforced PVA at 25 phr were achieved. Scanning electron microscope (SEM) indicated that OPFF-reinforced PVA at 25 phr yielded no accumulation of OPFF fibers but showed the dispersion in the matrix phase. In conclusion, the OPFF derived from oil palm industry can be used as reinforcement for manufacturing of plant pot in the future stage

Abstract: The aim of this paper is to research the influence of a different heat treatment of duplex austenitic-ferritic stainless steel to a microstructure. First, the initial data for numerical simulation were obtained by tensile test. Numerical simulation serves to determine the state of the workpiece during open die forging. The second stage focused on the evaluation of the microstructure in state after dwell time at forging temperature (7-and 10-hour) and cooling (water, air). Metallographic analysis observed the influence on precipitation of secondary phase especially.

Abstract: Determination of fatigue crack growth characteristics under shear-mode loading is a rather complicated problem. To increase an efficiency and precision of such testing, special specimens enabling simultaneous propagation of shear cracks under II, III and II+III loading modes started to be used rather recently. However, a description of crack growth rate in terms of appropriate fracture mechanics quantities demands a precise assessment of plastic zone size under various shear-mode loading levels. This contribution is focused on the numerical elasto-plastic analysis of stress-strain field at the crack tip in specimens made of a pure polycrystalline (ARMCO) iron loaded by mixed mode II+III. The dependence of plastic zone size on the J-integral value described the wide region of loading. The results reveal that formixed mode II+III the small scale yielding conditions are fulfilled in the region where plastic zone size is smaller than 1/10 of the total crack length.

Abstract: Three side-chain liquid crystalline ionomers (SLCIs) with sulfonic group (SLCI-S), quaternary ammonium salt group (SLCI-N), and carboxylic group (SLCI-C) were synthesized by graft copolymerization upon polymethylhydrosiloxane, respectively. The SLCIs were used to blend with poly (butylene terephthalate) (PBT) and polypropylene (PP). The morphological structure and mechanical properties of the blends were investigated by scanning electron microscopy (SEM). SEM results indicated that the addition of SLCIs lead to finer and better dispersion of PP polymer in the blends relative to the blends with no SLCIs added. The compatibilization of SLCIs in the blends were in the increasing order of SLCI-S> SLCI-N> SLCI-C, which was due to the specify interaction between SLCIs and PBT increased with the increasing order of SLCI-S>SLCI-N>SLCI-C. The mechanical properties were improved when the proper amount of SLCI was added, which enabled improve adhesion at the interface. The mechanical property of PBT/PP/SLCI-S was higher than that of PBT/PP/SLCI-N, which was higher than that of PBT/PP/SLCI-C.

Abstract: QPQ salt bath treatment of a certain type aviation piston engine ring was conducted by nitriding (570°C, 180 min), followed by the post-oxidation process (400°C, 20 min), polishing, the second post-oxidation (370°C, 20 min). Characterization of modified surface layers was made by means of optical microscopy, micro-hardness test, corrosion and wear resistance test. The results showed the formation of a very thin oxide layer during post-oxidation on the top of the black nitrides compound layer formed during nitriding. The maximum micro-hardness value of 592 HV was obtained after nitriding at 570°C for 180 min, which was nearly twice higher than that of the untreated sample. The wear resistance of ring could be significantly improved by QPQ complex salt bath treatment, which is almost 5 times higher than that of the untreated sample.

Abstract: Trisilanolisobutyl polyhedral oligomeric silsesquioxane (TSI-POSS) with the humping semi-enclosed cage structure, was incorporated in concentrations of 7, 13 and 22 wt% into 4,4’-methylenebis (phenyl isocyanate) (MDI) and glycerol propoxylate to prepare TSI-POSS/PU hybrid composites, respectively. The polymer chain characteristics of these composites were investigated by wide angle X-ray scattering (WAXS) and molecular dynamics simulation approach. The results indicate that with TSI-POSS concentration increasing up to 22 wt% in hybrid composites, due to the humping semi-enclosed cage structure, distinct crystallite clusters are formed which lead to the micro-phase separation in composites. Meanwhile, the mobility of TSI-POSS cores and backbones in PU composites has been evaluated by the mean square displacement, which confirms that as the concentration of TSI-POSS increasing, the mobility of polymer chains are restricted apparently. Furthermore, it also indicates that the incorporation of TSI-POSS is as the rigid core in hybrid composites.

Abstract: Baogang Group imported large quantities of Mongolian iron ore to solve the shortage of ironmaking raw materials. But the basic parameters of Mongolian iron ore in pellets production are deficient. In this paper, orthogonal experimental method was used in the optimization of roasting production process of Mongolian iron ore pellets. The results show that when the content of Mongolian iron ore is 55%, the factors affecting the expansion rate of pellets in order of decrease is bentonite proportion, roasting temperature, roasting time and preheating temperature. For pellets containing 55% Mongolian iron ore, the optimum roasting schemes are as follows: bentonite proportion at 3.3%, roasting temperature at 700°C, roasting time at 14 minutes and preheating temperature at 1280°C. Under this roasting scheme, the expansion rate of pellets is 13.41%, and the compression strength reaches 2275N, which meets the technological requires of large blast furnace. The main phase of the Mongolian iron ore pellets is hematite, with a porosity of 25%-30%. And the content of gangue and liquid phase is relatively low, which is beneficial to the reduction process of pellets in blast furnace.

Abstract: Mongolia ore is introduced in order to reduce pellet production costs in Baotou steel because of the increasing prices of iron concentrate year by year. But the production experience for pellets containing Mongolian ore is in short, and the basic characteristics of the pellets need to be analyzed. Previous analysis show that the particle size of Mongolia concentrate is relatively small, which could not be used alone but could be used with coarse grain size home-made concentrate ^[1,2]. The ballability index of Mongolia ore concentrate is 0.35. The Crystal stock characteristics of Mongolia mine is poor, which lead to the average strength of the pellets drop to 942.7N. With home-made concentrate mixed with Mongolian mine ratio increases, the intensity of the crystal stock also shows a downward trend, while the ratio more than 65% of Mongolia mine later, even crystal stock level dropped significantly.

Abstract: Several kinds of spherical cysteine grafted cobalt/manganese imprinted crosslinking chitosan spheres were synthesized for Mn²⁺ and Co²⁺ removal, in which Mn²⁺ and Co²⁺ were used separately or together as imprinting ions. Structures of the adsorbents were analyzed utilizing the techniques of SEM and FTIR. The effects of initial pH, contact time, presence of other cations, initial Mn²⁺ and Co²⁺ concentration on adsorption were investigated. Furthermore, adsorption kinetics and isotherm were studied, which showed sorption data fitted to pseudo-second-order and Langmuir models for both Mn²⁺ and Co²⁺. The overall results indicated the possibility of using Cys–Co/Mn–CCTS–2 for efficient removal of Mn²⁺ and Co²⁺ from dilute low-level radioactive liquid waste.