METHOD OF OBTAINING CONSTRUCTION ALUMOOXIDE CERAMICS Russian patent published in 2014 - IPC C04B35/111 C04B35/626 

FIELD: chemistry.

SUBSTANCE: invention can be used for manufacturing products, combining high indices of porosity and strength with low thermal conductivity (heat insulation, filters for purification of liquid and gaseous media, elements of combined shock-proof protection, and matrices for obtaining composite materials by a method of impregnation). An initial aluminium alloy, which contains 0.6-10 wt % of magnesium, is processed with a NaOH water solution. Mother liquor is subjected to hydrolysis by addition of water at a temperature of 80-95°C with simultaneous ultrasound impact (22-45 kHz, 10-35 sec); a sediment is separated, washed at pH=7.5-10, dried and thermally processed in air at a temperature of 1380-1400°C for 60-90 minutes. The obtained product is used to prepare a charge, crude products are pressed under 50-200 MPa. Sintering of the crude products is carried out in air at a rate of 300-400°C/hour to a temperature of 1410-1420°C, then to a temperature of 1510-1550°C at a rate of 80-100°C/hour with further isothermal exposure for 30-50 minutes. Ceramics of a composition α-Al₂O₃ (80-94 vol.%) and Al₂MgO₄ (6-20 vol.%) has the total porosity 37-50%, the open porosity 30-38%, flexural strength 15-60 MPa, coefficient of thermal conductivity in air at 1000°C 2.0-2.5 W/m·K.

EFFECT: increase of the open material porosity with preservation of sufficient strength.

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