Papers by Keyword: Copper-Zinc Alloy

Abstract: Powder metallurgy technique were proved successful net-shape technology which suitable for the production of steel parts characterised by good physical and mechanical properties of MMCs. The aim of this work is to study the effect of the sintering temperature with different volume ratio of natural carbon fibers reinforced copper-zinc alloy via powder metallurgy route. In this study, water hyacinth was used as a natural carbon fiber to replace tin element. The samples were mixed in different volume fraction of natural carbon fiber which is 0%, 5%, 10% and 15% in constant composition of copper alloy (70Cu/30Zn). The mixture was consolidated into rigid die compaction at 300MPa, then sintered at 400, 550 and 750°C respectively in the furnace under Argon atmospheric pressure at a flow rate of 50ml/min for 2h and cooled down naturally under Argon gas protection. Vickers hardness test were investigated. The composite were then characterized using optical microscope and scanning electron microscopy (SEM). The copper alloy composite reinforced with 10% carbon fiber at 550°C shows highest hardness strength which is about 112.0 HV.

Abstract: Mini forming is an appropriate technology to manufacture small metal parts, as these are required in many industrial products resulting from mini-technology. This paper work want to underline the fact that even in down scale there are problems regarding deviation from the required dimensions. One of the problems is scaling effects, which occur in tribological aspects such as the friction coefficient, which increases with decreasing specimen size. Simulations investigations into mini forming process were carried out and mini conical parts have been obtained with different geometries. . The main objective is to observe and quantify behaviour of the mini parts during forming process and geometry deviations that affect the final product. The material used in this analysis is copper - zinc alloy with anisotropic properties. During forming process of conical mini-parts, the material record important variation along the part length and generate important shape deviation. This phenomenon causes deviations of sidewall angle, superior diameter, inferior diameter, mini part height, and connection radius between the part bottom and sidewall. There are multiple factors that affect the geometry deviations: sidewall angle, friction coefficient, tools gap, punch radius, and punch speed. The Dynaform 5.9.1 software was used to simulate the forming process. The part obtained after each simulation was analyzed and measured to quantify the deviation from the desired geometry on the final conical mini-part. In the final part of this paper some conclusions regarding geometry deviation of conical mini-parts obtained by forming are presented.

Abstract: The aim of this study is to investigate the cyclic behavior and the fatigue life of an industrial α/β brass through mechanical tests and microstructural observations. The main obtained results are about the cyclic behavior of the alloy and the characterisation of fatigue life in connection with the evolution of the microstructure. Cyclic tensile test shows a great and rapid evolution of the isotropic hardenig during cycling.

Abstract: Effect of activating device on the property of tap water was studied by surface tensiometer and pH meter. The results showed that the surface tension of tap water activated by the device reduced and pH value increased. The variations of surface tension and pH value are connected with flow rates. The larger flow rate, the less variation of surface tension and pH value when at the same cycle time, however, the more variation of surface tension and pH value when at the same activating time. Activated by the device, 17O NMR half width of tap water reduced from 70.79Hz at the inlet to 60.87Hz at the outlet. Reduction of surface tension were caused by hydrogen bonds in water clusters which were weakened or broken by far-infrared radiation of functional ceramic ball and galvanic cell action of copper-zinc alloy. Increment of pH value were caused by H+ in water exchanging with metal cations on surface of far-infrared ceramic balls and dissolved oxygen getting electron and forming OH-1 with the function of copper-zinc alloy.

Abstract: Multiple copper-zinc alloy was used to treat water in order to restrict the formation of hard scale during heating process. Trace amounts of metal ions were dissolved from the alloy under the action of tiny battery corrosion, which took part in the crystallization of calcium carbonate crystal. The ion migration rules and its effect on the crystal structure of water scale were studied. The ICP test results show that after immersion in the water for 20 min, the zinc ion concentration increased to 0.35 mg•L-1 compared with contrast group. The simulating experiment of the scale crystal growth demonstrated that the calcium carbonate scale after treated with the alloy showed a transformation from calcite to aragonite, and the ratio of calcite to aragonite changed from 1:0.125 to 1:2.30. Meanwhile, the heat transfer efficiency was increased to 2.19%.