METHOD OF OBTAINING TRANSPARENT PROTECTIVE NANOCOATING ON SURFACE OF PRECIOUS/SEMI-PRECIOUS, INCLUDING ARTIFICIALLY GROWN, AND GLASS STONES FOR JEWELLERY Russian patent published in 2024 - IPC C23C16/40 C30B33/00 A44C17/00 C01F7/304 C01G23/07 B82Y30/00 B82Y40/00 

FIELD: jewellery industry.

SUBSTANCE: invention relates to the jewellery industry and can be used to produce transparent protective coatings on precious and semi-precious stones, including artificially obtained, for example, on diamond, sapphire, emerald, ruby, topaz, amethyst, rock crystal, turquoise, cubic zirconia, as well as on decorative glass stones. Surface coating is obtained using atomic layer deposition (ALD) at reaction zone temperature of 150-180 °C by using ALD cycle, which consists of alternating cyclic supply into reaction zone of aluminium- or titanium-containing substance vapours and water with nitrogen purging after vapours of each of said reagents. One ALD cycle is performed in the following mode: injection of vapours of the said substance for 1 s, purging for 30 s, injection of H₂O vapours for 1 s, purging for 30 s, and repeating the ALD cycle until the required thickness of the film is obtained. To obtain a film of Al₂O₃ with thickness of 10-50 Å, the vapour of the aluminium-containing substance is trimethylaluminium (TMA) vapour. To obtain a TiO₂ film with thickness of 10 to 50 Å, the titanium-containing substance vapour is titanium tetrachloride (TiCl₄) vapour. To obtain a surface coating based on mixtures of Al₂O₃ and TiO₂, vapours of TMA or TiCl₄ and water are alternately fed into the reaction zone in the above mode, and the ALD cycles are repeated until the required thickness of the coating is achieved, which does not exceed 50 Å. Thickness of the Al₂O₃ or TiO₂ film in the composition of such coating is 10-25 Å. Said coatings enhance the degree of lustre of the stone without changing its natural colour and enable to increase its service life in jewellery due to protection against scratching and wear, increasing resistance to the appearance of chips and cracks, as well as to changes in storage and operation conditions, such as temperature and humidity.

EFFECT: atomic layer deposition technology enables to control the composition and thickness of the film at the nanometre level and obtain homogeneous films having conformity and high adhesion to both flat surfaces and surfaces with complex topography.

1 cl, 4 dwg, 3 ex