| Intermetallic compounds have lots of advantages such as light weight,high strength and hardness,excellent mechanical properties under high temperature,etc.These advantages make intermetallic compounds,which are draw worldwide attention,possible to be used in the hazardous or foul environment.Recently,the wide applications of aluminum intermetallic compounds are popularized,for example using aluminum intermetallic compounds as basic material the coating of aerospace engine's blades.At present,the preparations of aluminum intermetallic mainly include physical vapor deposition,low-energy ductile mechanical alloying,magnetron sputtering,electric arc furnace smelting,extrusion deformation and thermal diffusion,multivariate preparation,etc.The material properties are related to the way of preparation.With the development of science and technology,though the preparations are innovating,the defects still existed in choosing pure metal as raw material,oxidation,difficulty of deformation,etc.Based on this,the study of the preparing Al3Zr and Al3Ti was carried out.Based on this,the study were carried out that the Al3Zr and Al3Ti in Al-Zr and Al-Ti alloys prepared by electrolysis were leached out.Al-Zr alloy was prepared by electrolysis and it was used for the antioxidant coating of graphite anode.The result showed that there was extremely uneven Zr element composition distribution in the Al-Zr alloy prepared in the electrolyte 2.6NaFˇAlF3-5wt%CaF2-5wt%ZrO2-Al.Furthermore,the upper Zr element content was 1.77wt%and the lower was 11.2wt%.It showed that segregation of Zr caused by the combined influences of gravity and electromagnetic field.During the electrolysis,the reverse electromotive force increased with the increase of current density and then increased and kept still due to the formation of the electrolyte skull.The Al3Zr was mainly in form of needle and square.Using Al-Zr alloy as the coating of graphite anode has great anti-oxidation properties and good wettability to graphite.The lower part of Al-Zr alloy mentioned was sampled for alkaline leaching to get Al3Zr.Studying on analysis found that the inner reaction of alkaline leaching was reaction between aluminum and sodium hydroxide,its product was Al(OH)4-,and there was no reaction among Al3Zr,alkaline and acid solution.Using 5mol/L sodium hydroxide solution to leach Al-Zr alloy(5h and 75?water bath)can mainly get Al3Zr.After ultrasonic washing,the Al3Zr powder was purified and fining.Studying on effects of electrolytic processes(molecular ratio,current density and cooling)can find that the increase of Al3Zr in alloy can be raised by the increase of the solubility of Zr in electrolyte caused by the increase of molecular ratio,the increase of current density and ways of cooling can change the appearance of crystal grain.Eventually,the average size of Al3Zr crystal grains was 32.75?m.Based on the experiments above,the Al-Ti alloy and Al3Ti was expected to get in the same way.Experiments showed that the solubility of TiO2 in Cryolite electrolyte was changed with different molecular ratio.When the molecular ratio was 4.5 and the electrolyte was alkaline at the temperature of 960?,the solubility of TiO2 can up to 5.1wt%.And after the molten salt was cooled,there was no cryolite sub-phase existed.In this electrolyte,because of the poor wettability,the alloy was easy to be separated with electrolyte and graphite crucible.Comparing to the Al-Zr alloy,the Al-Ti alloy's homogeneity was improved.The form of Al3Ti in alloy was needle and irregular block shape.The crystal particles' thickness was about 10?m and average size was 64.73?m. |
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