Effect Of Alloy Element On Dissolve Properties Of Al-Based Alloy

Dissolvable materials have been widely used in packaging and biology fields because of its special performance. Comprising with plastic and polymeric materials, alloy dissolvable materials have tremendous application potentiality in oil-gas fracturing owing to their outstanding mechanical properties. Among the kinds of alloy dissolvable materials, Al-based dissolvable material attracts the most attention due to its excellent properties, such as ability of reaction with water, low density, low cost and good mechanical properties. In fact, Al will not react with water directly because a thin layer of Al oxides forms on Al surfaces in spite of high chemical activity of Al.In this paper, on account of the electrochemical activation principle, the elements of Mg, Sn and Ga were added into alloy to improve the dissolve properties of aluminum alloy. The micro structures and phases of alloys with different contents of Mg, Sn and Ga are investigated by scanning electron microscope with energy dispersive spectrometer and X-ray diffraction. The effects of Mg, Sn and Ga additions on the dissolving properties of alloy were measured by weight loss tests. The electrochemical performance of the as-prepared alloy was tested by the Electrochemistry workstation. The electrochemical performances of alloy with different contents of Mg, Sn and Ga were analyzed by the open circuit potential. At last, the mechanism of alloy reacting with water was proposed.The results showed that the element Mg, Sn and Ga could enhance the dissolving properties of aluminum alloy. The second phase of Mg2Sn could be found when Sn was added to the alloy, the amount of which increased with the increase of Sn. With the open circuit potential turn negative, the activity of alloy increased, and the dissolving properties are improved. With the increase of Mg contents, the dissolution rate of alloy increased at first and then decreased, at the same time, the open circuit potential turned negative and then moved to postitive. That is because when the Mg content is low, the Mg2Sn phase increased with the increment of Mg content, but when the Mg content is high enough, the Al3Mg2 phase turned up in alloy. When the Mg content is 3 wt.%, the dissolution rate reached the maximum value. The effects of Ga on the dissolving properties and the open circuit potential of alloy are same with that of Sn. With the increasing of Ga content, the open circuit potential turned negative, the activity of alloy increased, and the dissolving properties raised.Considering the analysis mentioned above, the Mg2Sn phase can de produced by the metal elements Mg and Sn. Due to the potential difference between Mg2Sn phase and aluminum matrix, primary cell can be formed and cause micro-galvanic corrosion which improve the dissolution of alloys. The addition of Ga could destroy the thin layers of Al oxides formed on alloy surfaces and result in the continuous dissolution of alloy.