Study On Preparation Of New Type Coated TiH₂ In Aluminum Production

The method of using coated TiH2 to obtain foam aluminum aiming at the difficult point of foam aluminum production-when TiH2 as a foaming agent entering the high temperature system of melted aluminum, it quickly release hydrogen so that limiting the operation time of churning homogenize is studied on this paper. The TiH2 that coated with Al2O3, SiO2 and coated with Al2O3 and SiO2 at the same time were prepared. Using the orthogonal experiment research the best technologic parameter of the coating technology. The microstructure of coated TiH2 was observed by SEM; Using energy spectral instrument to measure the component of the surface layer; Using self-made device to measure the hydrogen releasing property of coated TiH2 powder. With the coated TiH2, the foam aluminum has been made in the laboratory. The experiment result shows: l)The best technological parameters of coating with Al2O3 are : The concentration of NaAlO2 is 0. 06mol/L,the concentration of A12(SO4)3 is 0.01mol/L,the temperature is 35 ℃.the dropping rate is 60ml/h,churn acutely, PH is 5.2)The best technological parameters of coating with SiO2 are: The concentration of Na2SiO3 is 1mol/L, the concentration of HCL is 2mol/L, the temperature is 85℃,the dropping rate is 60ml/h, churn acutely, PH is 9.3)The hydrogen-released characteristic of TiH2 changed much after coated, TiH2 coated with Al2O3 can delay hydrogen released timeup to 60 seconds, TiH2 coated with SiO2 can delay hydrogen released time up to 70 seconds, TiH2 that first coated with SiO2 and then coated with Al2O3 can delay hydrogen released time up to 75 seconds, TiH2 that first coated with Al2O3 and then coated with SiO2can delay hydrogen released time up to 90seconds .The result of delay hydrogen releasing of TiH2 that coated with SiO2 is better than that of TiH2 that coated with Al2O3 , The result of delay hydrogen releasing of TiH2 that first coated with Al2O3 and then coated with SiO2 is the best.4)The coated TiH2 can prepare even foam , in especially, TiH2 coated with double layers can prepare more even foam..5)After analyzed the coating mechanism, we can find: control the PH value at 5 or so, coated with Al2O3 in forms of core formation can be obtained; control the PH value at 9 or so, coated with SiO2 in forms of film formation can be obtained.6)Analyzed the effect of how coated TiH2 affect hydrogen releasing from three aspects.