Research Of Preparation Of ?-Al₂O₃ Powder By Sol-Gel Method

With the advent of 5G era,the demand of high purity?-Al₂O₃ ceramics in the circuit substrate and electrode co-firing is increasing day by day.The preparation temperature of?-Al₂O₃ powder is very high,generally above 1100?,which will cause the agglomeration of the powder.The agglomeration reduces the sintering activity of the powder,and makes the sintering temperature of?-Al₂O₃ ceramics very high.So it is very important to lower the synthesis temperature of?-Al₂O₃ powder.In this paper,?-Al₂O₃ powder is prepared through sol-gel method by using different aluminum sources and ammonia as raw materials.The effects of?-Al₂O₃ seed,Al F₃,aging time,ball mill and drying methods on the preparation temperature of?-Al₂O₃ powder were studied.The influnce of different ball milling methods on particle size distribution and sintering properties of?-Al₂O₃ powder were investigated.X-ray diffraction(XRD),infrared absorption spectroscopy(FT-IR),thermogravimetric-differential scanning calorimetry(TG-DSC),scanning electron microscope(SEM)and solid-state nuclear magnetic resonance(NMR)were used to characterize precursor,?-Al₂O₃ powders and ceramics.The main research results are as follows:(1)Due to?-Al₂O₃ seeds and Al F₃mineralizer treatment,preparation temperature of?-Al₂O₃ powder was lowered by about 150°C.Precursor was dried by ordinary drying box,then milled and preheated at 400°C,?-Al₂O₃ powder with an alpha phase of 99%can be obtained by calcining at 925?for 15min.The powder by cacining precursor at 1050?for2h was grinded by planetary ball mill,the ceramic sintered at 1400?only reached the maximum relative density of 88%.The powder by cacining precursor at 925?for 1h was grinded by stirring mill,the ceramic sintered at 1550?reached the maximum relative density of 95%.(2)?-Al₂O₃ powder with an alpha phase of 98%can be obtained by calcining precursor which was dried by freeze drying method at 975?for 2h.Precursor was dried by freeze drying,then milled and preheated at 400°C,?-Al₂O₃ powder with an alpha phase of 98%can be obtained by calcining at 850?for 15min.The powder by calcining precursor at 975?for 2h was grinded by planetary ball mill,the ceramic sintered at1400?reached the maximum relative density of 94%.The powder by calcining precursor at 850?for 1h was grinded by stirring mill,the ceramic sintered at 1550?reached the maximum relative density of 94%.(3)?-Al₂O₃ powder with an alpha phase of 98%can be obtained by calcining precursor which was dried by microwave drying method at 975?/2h.Precursor was dried by microwave drying,then milled,?-Al₂O₃ powder with an alpha phase of 97%can be obtained by calcining at 850?for 15min.The powder by calcining precursor at 975?for2h was grinded by planetary ball mill,the ceramic sintered at 1400?reached the maximum relative density of 92%.The powder by calcining precursor at 850?for 1h was grinded by stirring mill,the ceramic sintered at 1550?reached the maximum relative density of 97%.