Study Of Fabrication Of BaPbO₃/2024Al Composites And Coating Process On BaPbO₃ Particles

The aluminium matrix composites with radioprotection function were fabricated by powder metallurgy using BaPbO₃ powders and 2024Al powders. Preparation technology is studied on impacting interface reaction of composites. The microstructure and properties of the composites were investigated by XRD, SEM and tensile test. The technical parameter is researched on making BaPbO₃ coated by Al₂O₃. The effect of coatings is investigated by XRD, SEM, EDS and TG/DTA.The experimental results indicated that the tensile test shows that the tensile strength of the aluminium matrix composites is 317MPa, and the composites contain Pb, so there are reactions between BaPbO₃ and 2024Al when the composites were fabricated. When the sintering temperature is 430℃and no pressure, there is no reaction between BaPbO₃ and 2024Al, but when the pressure of hot pressing is not 0MPa, even if the temperature is 400℃, there also exit reactions between BaPbO₃ and 2024Al. And composite is unsound. So that shows us for making dense composites, interface reaction did not avoid through controlling the temperature and pressure of hot pressing.When technical parameters are that concentration of Al-sol is 0.4mol/L,Al₂O₃:BaPbO₃ (wt.%)=1:1, pH=3.5-4.1 and mixed for 30min, Al₂O₃ completely coated BaPbO₃ are produced. But PbO is found in BaPbO₃ coated by Al₂O₃.BaPbO₃ coated by Al₂O₃ are produced using chemical precipitation method. There only puting BaPbO₃ powders into Al(OH)3 liquor is suitable, and putting Al(NO3)3 liquor into BaPbO₃ suspending liquid is not suitable. The effect of coatings is better along with the Al₂O₃:BaPbO₃ (wt.%) lager. But Al₂O₃ coating is incomplete coated on BaPbO₃ surface.Al₂O₃ completely coated BaPbO₃ are produced by a humid solid state reaction at room temperature. There is Al element on BaPbO₃ coated by Al₂O₃ by EDS analysis, so this proves the coating is Al₂O₃. DTA analysis of 2024Al+ BaPbO₃ coated by Al₂O₃ shows that there is no exothermic peak and endothermic peak between 350℃and 500℃, and this proves Al₂O₃ is completely coated on BaPbO₃, so contact between BaPbO₃ and 2024Al is impossible and reaction is avoided.