METHOD FOR SYNTHESIS OF THREE-DIMENSIONALLY CRYSTALLISED COMPOUNDS IN GLASS Russian patent published in 2015 - IPC B01D9/00 C30B29/22 

FIELD: chemistry.

SUBSTANCE: invention relates to techniques for producing new materials and is intended for use in crystalline and glass-ceramic materials engineering. The method comprises crystallising glass in the form of large pieces in conditions which enable fast precipitation of known phases, which correspond to the system phase diagram, and crystallising a sample in isothermic conditions at temperature corresponding to or 20-40°C higher than the maximum crystallisation temperature of glass powder on a differential thermal analysis curve; melting the crystallised glass at a temperature 50-80°C higher than liquidus temperature; holding for 15-20 minutes until complete melting and moulding large pieces in a steel mould; repeating the crystallisation-melting cycle 1-2 times, wherein at the last melting step, temperature is raised by 100-200°C to break down structural groups existing in the melt over the liquidus line, which serve as the nucleating centre for easy crystallising phases; for further melting, cleaning the quartz or corundum crucible by holding for 15-20 minutes in hydrofluoric acid, washing with distilled water and drying; annealing for several minutes at the temperature at which the glass was fused; placing the crucible inside a larger protective quartz crucible with pure quartz sand or corundum filling; fusing the large pieces that have undergone crystallisation and melting cycles in a melting furnace in the quartz or corundum crucible, and moving the protective crucible with the crucible containing fused glass in a hot state from the furnace in which fusion was carried out into an annealing furnace which is preheated to a temperature which is selected as the average temperature between the temperature of the end of the vitrification effect and the beginning of the crystallisation effect, determined preliminary differential thermal analysis of the powder of the investigated glass; removing the crucible with the fused glass from the protective crucible and transferring into an annealing furnace in a hot state, where said temperature is maintained until full crystallisation for 3-10 days; removing the crucible is removed from the furnace and cooled on air; removing the crystallised glass from the crucible; removing, from the pieces of the crystallised glass, the transition layer with thickness of 1-2 mm which is in contact with the crucible material and the layer adjoining the top surface bordering the air, wherein the inner part of the crystallised glass is three-dimensionally crystallised glass.

EFFECT: method is characterised by inhibiting surface crystallisation and use of cheap consumable material when carrying out the method.

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