METHOD OF HARDENING WORKPIECES FROM CORUNDUM-QUARTZ CERAMICS Russian patent published in 2020 - IPC C04B35/111 C04B35/18 

FIELD: ceramics.

SUBSTANCE: invention relates to industrial production of corundum ceramics, modified with inorganic binding agents, and can be used, mainly, for production of large-size ceramic articles operating under high temperatures. Method of hardening articles from corundum-quartz ceramics involves preparing an aqueous corundum-quartz suspension, where the amount of quartz glass is 0.1–0.3 wt % to total weight of system "electrocorundum-quartz glass", and suspension stabilization. Hardening of the workpieces is carried out using an aluminum-chromium-phosphate binder having the following composition, wt %: 9–13 Al₂O₃; 31–38 P₂O₅; 4–7 Cr₂O₃; up to 1.5 CrO₃; 40.5–56 H₂O in amount of 2–7 % of the weight of the initial suspension, which is added to the suspension at the end of the stabilization step. Then, ceramic blanks are formed by a method of slip casting in gypsum molds with further thermal treatment. Heat treatment is carried out according to a mode which includes heating in range of 20–200 °C at a rate of not more than 1.5 °C/min; in range of 200–300 °C – not more than 2 °C/min; in range of 300–700 °C – not more than 3 °C/min. Finally, workpieces are held at 700 °C for 1 hour.

EFFECT: technical result consists in ensuring bending strength of articles at least 300 MPa without using high temperature roasting while maintaining fire resistance, strength and heat resistance of material.

1 cl, 3 ex, 1 tbl