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INVENTION
Russian Federation Patent RU2162456
METHOD FOR PRODUCING SYNTHETIC MATERIAL STRUCTURE OF PRECIOUS OPAL
The applicant's name: Limited Liability Company "Agency of marketing of scientific research"
Name of the inventor: Samoylovich MI .; Samoylovich SM
The name of the patentee: Limited Liability Company "Agency of marketing of scientific research"
Address for correspondence: 111250, Moscow, ul. Aviamotor 53, JSC "Patent Attorney" Andrushchak GN
Starting date of the patent: 2000.03.17
The invention relates to synthetic minerals industry and can be used to obtain a synthetic material with a noble opal structure, particularly during subsequent processing analog noble natural opal used, for example, in the jewelry industry. The inventive synthetic material with a structure of precious opal are made by preparing a monodisperse suspension of globules of amorphous silica with a size of 140-600 nm. Then, the precipitate is precipitated in layers. The resulting precipitate was dried, first at 100-150 ° C for 10-30 hours and then further reduced in pressure to 10.1 Pa. After drying, the precipitate was subjected to annealing at pneumatolytic 15-45 MPa and 350-400 ° C in the presence of water vapor and tetraethoxysilane, and then impregnated with a silica sol is heat treated at 400-600 ° C for 1-2 h INVENTION Technical Problem -. Obtaining a synthetic material with structure of precious opal, approaching the maximum in their jewelry to the natural characteristics of disgrace.
DESCRIPTION OF THE INVENTION
The invention relates to synthetic minerals industry and can be used to obtain a synthetic material with a noble opal structure - in particular, in the subsequent processing of natural analogue noble opal used, for example, in the jewelry industry.
Natural precious opal is one of the most expensive and beautiful stones. The chemical composition - it is water-containing silica globular structure. silica globules have a size of 150-450 nm. The refractive index of a natural opal 1,41-1,46, microhardness - 4.5-6.0 units. on the Mohs scale. Noble opal is different iridescent play of colors (iridescence), the cause of which is the diffraction of light by a spatial lattice formed by regularly spaced monospaced globules of amorphous silica, the space between which is partially or completely filled vitreous silica, the refractive index of which differs only slightly from the refractive index of the globules themselves.
Iridescence color determined by the diameter of the globules: at 150-200 nm - purple, up to 400 nm - green, above - the red, and the color intensity of the game depends on the degree of ordering of the structure, composition and structure of matter, filling the space between the globules.
A method of obtaining precious opal by preparing monodisperse suspension containing globules with dimensions of 150-450 nm, packaging particles by centrifugation or sedimentation in an ordered structure, sludge dehydration in air first at 100 o C, and then at 400-900 o C (US N 3497367 , cl. C 04 35 / 14.1970).
The closest to the proposed invention as to technical essence and attainable result is a method for producing a synthetic opal, comprising preparing a slurry of spherical granules of amorphous silica, sludge deposition layering to form each successive layer from a slurry containing globules that differ in size from the previous 10-15% , drying at 100-150 o C for 10-30 hours, pneumatolytic annealing in the presence of water vapor at 350-400 o C for 2-10 hours the precipitate silica sol impregnation and heat treatment at 400-600 o C for 1-2 h (RU N 2051864, cl. C 01 B 33/113, 1996).
A drawback of known methods is that obtained by the above methods is not sufficient opal monodisperstnosti silica spheres, uniformity, clarity and microhardness making such opal sufficiently different from the natural opal.
An object of the invention is to provide a synthetic material with a structure of precious opal, most approaching for the jewelry to the natural characteristics of disgrace.
The stated technical problem is achieved by the method for producing noble synthetic opal comprising preparing monodisperse suspension containing spherical globules of amorphous silica, sludge layer-deposition, drying at 100-150 o C for 10-30 hours, pneumatolytic annealing in the presence of water vapor for 2-10 hours at 350-400 o C, the precipitate silica sol impregnation, heat treatment at 400 to 600 o C for 1-2 hours, the suspension was prepared with amorphous silica globules the size of 140-600 nm, before annealing is performed additional sludge drying under reduced 1-10 Pa pressure, and annealing was carried out at 15-45 MPa in the additional presence of tetraethoxysilane vapor.
The following are specific examples of the described method.
example 1
Suspension is prepared by hydrolysis of tetraethoxysilane (TEOS) in spirtoammiachnoy environment. To this was mixed with 100 ml of 2 H 5 OH with 2.2 ml of 30% aqueous ammonia and 4 ml of TEOS mixture was put on a shaker for 30 min AVU-type 6c, and then allowed to stand for 1.5-2 h at rest . A suspension of a spherical amorphous silica globules size of 300 nm, it is poured into a test tube and centrifuged for 1 h. The hydrolyzate was decanted opalovidny precipitate remains wet at the bottom of the tube. The test tube is filled a new batch of slurry, wherein the mixing ratio is changed 100 ml of C 2 H 5 OH, 2.5 ml of 30% NH 4 OH and 4 ml of TEOS (particle size of 335 nm, i.e. 12% greater than in the first case), and again centrifuged to obtain the 2nd layer opalovidnogo precipitate. Similarly deposited layers 3 and 4, while at the same proportions of TEOS and alcohol charge accordingly - 3.0 and 3.5 ml of ammonia. particle size becomes 375 and 420 nm. The wet precipitate is dried first at room temperature and then dried in an oven at 120 o C for 20 hours. After subsequent cooling to room temperature, the samples were dried under a reduced pressure of 1.5 Pa, followed by subjecting to annealing in the autoclave pneumatolytic at 40 MPa, 400 o C in the presence of TEOS and water vapor for 5 hours. After cooling the autoclave the samples are removed silica sol to impregnate them. These samples have a high uniformity and monodisperstnost silica spheres. Microhardness Mohs 5-6 pcs., A density of 2 g / cm 3, the translucent microstructure of polygonal globules arranged in a cubic lattice.
example 2
opal to obtain the same operation as in Example 1, but an additional drying is carried out at a pressure of 9 Pa and the size of the globules - 400 nm. Results similar to Example 1 was formed by a synthetic material with a structure inherent in natural noble opal: silica globules firmly interconnected to have a contact area segments.
According to the physical and chemical characteristics of the resulting synthetic material with a structure of precious opal after impregnation identical to natural opals: chemical composition - SiO 2 · n H 2 O, micro-hardness of 5-6 units. Mohs, iridescence and the block includes two or more colors of the visible spectrum, the microstructure (by electron microscopy data) - densest hexagonal or cubic packaging, 1,43-1,45 refractive index, density, g / cm 2.0-2.1 3.
CLAIM
A method for producing a synthetic material with a structure of noble opal comprising preparing monodisperse suspension containing spherical globules amorphous silica layerwise deposition of sediment, drying at 100 - 150 o C for 10 - 30 hours, pneumatolytic annealing in the presence of water vapor for 2 - 10 h at 350 - 400 o C, impregnating precipitate silica sol, a heat treatment at 400 - 600 o C for 1 - 2 h, wherein the prepared slurry globules amorphous silica size of 140 - 600 nm prior to annealing is carried further drying the precipitate under reduced pressure 1 - 10 Pa and the annealing was carried out at 15 - 45 MPa in the additional presence of tetraethoxysilane vapor.
print version
Publication date 03.01.2007gg
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