SINTERED BODY FROM ALPHA-ALUMINA FOR PRODUCING SAPPHIRE SINGLE CRYSTAL Russian patent published in 2016 - IPC C30B29/20 C01F7/02 C04B35/10 C04B35/64 

FIELD: metallurgy.

SUBSTANCE: invention relates to a technique for producing a sintered body from α-alumina as a raw material for further production of sapphire single crystals. Method comprises following steps: mixing 100 parts by weight α-alumina with 1-20 parts by weight α-alumina precursor to obtain a mixture, molding a compact from mixture and firing said compact to obtain a sintered body of α-alumina, wherein α-alumina has a specific surface area equal to 1-20 m²/g, a moisture content less than 0.5 %, purity of 99.99 wt.% or more and content of each of Si, Na, Ca, Fe, Cu and Mg, equal to 10 ppm or less, α-alumina precursor has a specific surface area of 50 m²/g or more, moisture content of 0.5 % or more, purity of 99.99 wt.% or more and content of each of Si, Na, Ca, Fe, Cu and Mg, equal to 10 ppm or less, at a pressing pressure of 20-400 MPa, firing is conducted at a temperature of 1,200-1,700 °C for 0.5-24 hours and rate of temperature rise of 30-500 °C/h. Invention enables to obtain a body having a relative density of 60 % or more, a closed porosity of 10 % or less, purity of 99.99 wt.% or more, content of each of Si, Na, Ca, Fe, Cu and Mg equal to 10 ppm or less, and volume of 1 cm³ or more.

EFFECT: bodies with said characteristics have high mechanical strength and allow easy production of a high quality sapphire single crystal with less coloring and cracking and high volumetric efficiency.

6 cl, 1 dwg, 4 tbl, 3 ex