| 摘要 |
<p>The present method for preparing synthetic sellaite (magnesium fluoride) aims at obtaining optical material and can find its application in the technology for producing semi-finished products of optical ceramic intended for use in input windows, lenses and other optical elements for the infrared band of the spectrum. The inventive method permits obtention of uniphase transparent polycrystaline sellaite characterized by a transparency area with no selective absorption band and an increased mechanical resistance. The method consists in precipitating the magnesium fluoride from an aqueous magnesium carbonate suspension using hydrofluoric acid, in maintaining the pH of the stock solution equal to 4,2-5,0 by introducing an aqueous monomolecular ammonium fluoride solution, in separating the precipitate, drying the obtained powder, submitting it to a thermo-treatment in the open air, sintering it at a maximum pressure of 20 MPa, heating the agglomerate under vacuum at a temperature of 200 °C to 380 °C during a period not exceed ing 30 minutes, with a temperature rise of 20-40 °C/min, and hot pressing it by submitting same to a pressure of 148 to 196 MPa, at a temperature of 760 to 800 °C.</p> |
