Advanced Materials Research Vols. 328-330

Abstract: From a physical and mechanical point of view, concrete cracking is hard to avoid. So, it is meaningful to study the influence of crack depths on chloride transport in cracked self-compacting concrete. Following the NT BUILD 492 chloride migration test method, water soluble chloride conetnt, acid soluble chloride content and penetration depth were determined on cracked concrete samples which were prepared by artificial crack method. Afterwards, the migration coefficients were obtained by curve fitting on water soluble chloride contents and penetration depths seperately. The results show that the influence of crack depth on chloride concentration of concrete is significant for the concrete zone deeper than 20 mm from the surface. Secondly, the influential zone caused by the crack is limited to a distance of 10 mm at both sides from the crack. Thirdly, the existing equation of chloride transport is not applicable to concrete with different crack depths.

Abstract: Two halogen-free flame retardant epoxy resins were prepared by diglycidyl ether of bisphenol A (DGEBA) epoxy with two compound hardeners. The aryl phosphinate dianhydride BPAODOPE was used as a hardener and flame retardant when coupled with two curing agents, such as methylhexahydrophthalic anhydride (MeHHPA) and maleic anhydride (MA). The effect of the BPAODOPE contents on the fire resistance, thermal properties and mechanical properties of halogen-free flame-retardant epoxy resins were investigated in detail. The results showed that the phosphorus-containing epoxy resin composites had a higher UL-94 grade and char yield, furthermore, the flame retardation and the char yield of the cured epoxy resins increased with an increase of the phosphorus content, the phosphorus content of 1.75% was enough to achieve UL-94 V-1 grade and the best combination properties for the two composites with different hardeners.

Abstract: Ti film on AISI 201 was prepared by plasma. The film was characterized and analyzed by using XRD. it was found that of Ti film has a different microstructure in different condition. With negative bias increased from 15V to 260V, the diffraction peaks of Ti films changed from planes (111) to planes (200). With power increased from 8W to 145W, the diffraction peaks of Ti films decrease at planes (002), the diffraction peaks of Ti films decrease at planes (102) and (103). The result suggests that negative bias and power contributed to form an different phase throughout the films. The vacuum, distance and time have no effect to crystal of Ti film.

Abstract: In this paper, the influence of sintering temperature on the output rate of the mullite which was formed from andalusite ore of Mei County Shaanxi at different constant temperature 1350°C, 1450°C, 1550°C and the mechanism which mullite was transformed were studied. The morphology of mullite formed at 1450°C was obtained by SEM, and the phase composition of andalusite ore sintered at different temperature was analyzed by XRD. The results shows that the mullitization effect of andalusite ore of Mei County Shaanxi is excellent, and the yield of mullite mineral can reach the desired results of 100% after andalusite mineral of Mei County Shaanxi is kept warming for 3 hours at the sintering temperature of 1450°C and cooled naturally with box-type resistance furnace. The mullite phase synthesized by andalusite ore of Mei County Shaanxi depends on not only the decomposition of andalusite, but also the secondary mullitization and the dissolution mechanism.

Abstract: The content of free MgCl₂ is one of the key indicators of deliquescence, dehalogenation and efflorescence for Magnesium Oxychloride Cement (MOC). A range of possible techniques for assessing the free MgCl₂ content of MOC have been investigated. The techniques are based on mixing powdered samples with absolute ethyl alcohol and measuring the amount of MgCl₂ passing into solution. The influence of temperature of solvent, extraction time, fineness, agitation and liquid to solid ratio (L/S) are discussed. The results of recovery tests ranged 96.37% or above. The method is successfully applied to leaching and detecting free MgCl₂ in commercial magnesium oxychloride cement fireproof board.

Abstract: Basalt fiber has the advantages of non-pollution and omnipotence, and will be widely used in the 21st Century. Therefore, more and more attention is paid on experimental research on the basalt fiber in the world. First,according to the requirements of the fibers used in the cement-based materials, the contrast testing of the plastic shrinkage between fiber cement mortar and pure mortar was made. The experimental results showed that basalt fiber , polypropylene fiber and polyacrylonitrile fiber can be preliminarily chosen as reinforced fibers in cement-based materials. Finally, taking both characteristics of basalt fiber and the increase of cement-based materials costs into account, it can be drawn that top priority should be given to the basalt fiber rather than to other fibers for cement-based materials.

Abstract: Nano-Cu₂O has wide application prospects in the fields of chemical industry and engineering due to its special optical, electrical and catalytic properties. The nano-particles with different morphological structure and particle size have different physical-chemical properties and different application fields. Therefore, this article reviewed the preparation methods of Nano-Cu₂O at high/room temperature and the key point of its morphology control.

Abstract: The utilization of pure waterjet for Incremental Sheet Metal Forming (ISMF) is growing. However, the fatigue of pure waterjet nozzle is not fully clear. In the current study, based on the computational fluid dynamics (CFD) and finite element analysis (FEA), the fatigue failure of pure waterjet nozzle was simulated and analyzed. The influence of uneven equivalent stress distribution and generation of cavitation on nozzle fatigue failure was discussed. The results obtained from two simulations (velocity, pressure) show a good agreement with the theoretical predictions, which indicates that the approach based on CFD and FEA is absolutely feasible. Due to the uneven equivalent stress distribution, there is the first failure point inside the nozzle, which reduces the whole life of the nozzle. The unreasonable nozzle structure is one of main causes of cavitation generation; cavitation damage is reduced by optimizing the structure to improve the overall life of the nozzle.

Abstract: Cobalt ferrites were prepared by citrate sol-gel method, chemical co-precipitation, mechanical grinding, respectively. The grain size, morphology, and the size of crystal particles were studied by x-ray diffraction (XRD) and scanning electron microscope (SEM). Cobalt ferrite showed different morphologys when prepared by different methods, It was tapered corners which prepared by sol-gel method; It was tetrahedral which prepared by mechanical grinding method; It was sphere which prepared by chemical co-precipitation method. The average grain size of cobalt ferrite was less than 100nm, while particles prepared by chemical precipitation method were the smallest. The size of Cobalt ferrite prepared by sol-gel method was decreased with the cobalt content increased.

Abstract: At present work, to make cushioning packaging material from the bamboo fibers. Change the time of the surface treatment and the component contents of foaming agents, adhesives, plasticizers, cross-linking agents, etc. to analyze the effects on the foam density, foaming rate, elasticity, and bubble diameter. The best reagent and the optimal ratio of the various components have been identified. Determined the parameter of foaming techniques based on the high efficiency and no polluting foaming mechanism. Experiment with the impact testing machine to obtain the maximum acceleration - static stress curve, dynamic stress - strain curves, dynamic buffer factor - stress curve, Analyzed the dynamic buffer performance on the of changing the drop height and compared with other cushioning material. we know that: at height of 450mm, the product had lower peak acceleration value than EPE and EPS during the stress area of 2.8-5.4kpa, which means the cushioning property of the bamboo pulp product is better at that time.