GLASS STRENGTHENING METHOD Russian patent published in 2025 - IPC C03C21/00 C03C23/00 

FIELD: glass.

SUBSTANCE: invention relates to a thermochemical method for ionic hardening of glass and can be used in making high-strength glass. Glass hardening is carried out by immersing it in a bath filled with a mixture of molten chemically pure potassium nitrate with salts of regenerating additives, represented by fluoroborate salt, silicophosphorus-antimony salt, potassium antimonate. Said mixture is used in the following ratio of components, wt.%: potassium nitrate – 70–93, potassium fluoroborate salt – 5.0–28.0, silicophosphorus-antimony salt – 0.5–1.0, pyroacetic potassium antimonate – 1.0–2.0. Before immersing the glass, the salt melt is preliminarily held at temperature of 520 °C for 8 to 11 hours. Glass prior to immersion into bath is heated to working temperature from 380 °C to 520 °C. Before immersing the glass, the salt melt temperature is brought to a temperature higher than the operating temperature of 40 °C to 50°C. Glass is held at said temperature for 24–25 hours. After that, the glass is removed from the bath and held for 4 to 8 hours in a cooling chamber with operating temperature and with further reduction of temperature at a cooling rate of 4 °C to 7 °C per minute.

EFFECT: high strength of glass while maintaining high optical properties and high efficiency of the process, as well as low toxicity of production.

1 cl, 4 tbl, 3 ex