| Inclusions and pinholes in aluminum alloy melt directly affect the performance of castings, the melt cleaning focus on the melt of the exhaust purification. In this paper aim to refining agent for the current function of this single feature, so designed the new composite refining agent for the main of purify, second remove out gas. Through the rational choice and distribution the group element of the new composite refining flux, research the function of the new composite refining flux, finally determine the best group element.In addition in this paper, by X-ray diffraction (XRD) analysis of the slag phase;by scanning electron microscopy (SEM) and energy spectrum (EDS) research the refining process, description the changes in the morphology of mixed oxide;other research the relationship between mixed oxide and refining flux, in order to find new composite refining purifying flux.The results show that:1,The new composite refining flux have an great melting area can be choosed, the NCU-3 in which the melting point of 600℃, the relative impurity removal rate of 30%, the pinhole reach to 3; In the NCU-3 based on the mass ratio of 16% add fluoride prepared NCU-8-type impurity removal rate relative refining flux can be increased to 48%, the pinhole can be increased to 2.2,The Mg2N3 as an important group of the new composite refining flux, in its preparation process found that reaction of ammonia and magnesium Gibbs free energy than the reaction of nitrogen and magnesium Gibbs free energy is lower;so the ammonia nitrogen more easily than the reaction of magnesium nitride and magnesium; At the 600℃heat preservation for 1h, then heated rearch to 800℃, the ammonia flow rate 500ml/min, the nitridation time for 1h, can be prepared with high purity,uniform,high-quality nitride powder particles of magnesium powder.3,Apply to Mg2N3 compound the new composite refining flux, the NCU-10 for ADC12 purify exhaust effect is obvious, the new composite refining flux for oxide inclusions, the relative amount of the trash can as much as 81%.By GB/T7964.3-2005 to assess the pinhole rearch to 1; While it for the A356 aluminum scrap melt the impurity in terms of NCU-12 exhaust impurity effect is more than NCU-10; Thus the add content of magnesium nitride from the melt inclusions in the Al2O3 content of the decision.4,In the unrefined samples haved a large number of oxide inclusion reunite at the large pores. In the matrix was distributed on a large number of flakes, grains, and thin-film oxide floc linear inclusions, oxide inclusions in granular size of about 200um; After refining the sample does not appear in the reunion of mixed oxide, oxide inclusion particles gradually become smaller, the size of 50um or less. Reunion of dispersed inclusions of the new composite refining flux is adsorbed, dissolved and broken, In this process, along with nitrogen oxide inclusion reaction of magnesium and nitrogen adsorption Al2O3 inclusions and hydrogen in the melt away; Therefore, refining flux is a new type of adsorption and diffusion, dissolution of the Union response and the role of bubbles floating purification mechanism. |
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