RU2522448C1 - Coating for space mirror workpiece - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: disclosed is a coating for a space mirror workpiece, which is glass of the following composition, wt %: SiO₂ - 44-61; B₂O₃ - 8-20; Al₂O₃ - 5-19; CaO - 3-12; Sb₂O₃ - 0,3-0,7; V₂O₅ - 2-11; Nb₂O₅ - 1-7; MoO₃ - 0.2-4 and F - 1.5-6.

EFFECT: composition of the material enables to obtain a high-quality optical surface directly on substrates made of silicon carbide materials.

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Description

The invention relates to structural coatings of blanks of space mirrors, in particular to enable high-quality optical surfaces on the substrate of the mirrors.

From the field of production of space mirrors, it is known that previously metal - beryllium, a very toxic material, was used as the substrate material. To create an optical surface on a substrate of this material, vitrification was used with specially designed glass, which was then polished and a reflective coating was applied.

Subsequently, a multilayer reflective coating (mirror) is sprayed onto the substrate on which the optical surface is formed, then a protective coating.

Currently, it is of interest to use blanks for space mirrors made of silicon carbide, which has the best ratio of elastic modulus and density among known materials.

The purpose of the glass is as follows: the surface of silicon carbide is defective, because in volume, this material is not uniform as glass, i.e. it cannot be polished to optical surface quality. For this, a material that can be polished to optical quality, i.e. glass. Then a multilayer reflective coating (mirror) is sprayed onto the glass, on which a protective coating is then applied.

In the patent of the Russian Federation No. 2025749, published on 12/30/1984 according to the IPC index G02B 5/08, it is stated “Mirror and method of forming its protective coating”, intended for mirrors operating under conditions of increased exposure to aggressive environments.

The inventive mirror contains a substrate, a reflecting metal layer and a protective coating made of nitride and silicon carbide in the following ratio of components: silicon carbide 2-27 wt.%; silicon nitride - the rest. The invention relates to optics, in particular to mirrors intended for domestic needs and various technical purposes, operating under conditions of increased exposure to aggressive media (moisture vapor, corrosive media, temperature extremes, etc.).

In the RF patent No. 2304557, published on 08/20/2007 according to the indices MPK В82В 1/00 and H01Q 17/00, the “Protective coating of electronic components” is stated, where the technical result is to create a protective coating that is highly resistant to ionizing radiation at low specific gravity of the structure. The protective coating is made in the form of a small specific gravity of the structure. The protective coating is made in the form of a nanostructure, which includes a set of rare-earth atoms introduced into the structure of a reinforcing atomic-molecular metal matrix. The nanostructure can be an integral part of the protected structure or a protective layer of the structure.

These designs are distant analogues and are not suitable for creating an optical surface on silicon carbide blanks.

It is known in the prior art to solder-vitrify a tungsten substrate. (M.P. Alekseenko. Cohesion and adhesion of hot glass. Edited by Professor K.S. Evstropiev. M.: Mechanical Engineering, 1969, p.136). This source lists the composition of the optical glass - Brand 3058 III (Supermax), which is taken as a prototype of a new invention. Data on the prototype in Table 1.

Table 1 Component Wt% SiO ₂ 55.3 B ₂ O ₃ 7.4 Al ₂ O ₃ 22.9 CaO 4.7 MgO 8.5 K ₂ O 0.38 Na ₂ O 0.6 Fe ₂ O ₃ 0.13 As ₂ O ₃ 0.5 Material characteristics Value The coefficient of thermal expansion (10 ^-7 deg. ^-1 ). 33 Temperature corresponding to glass viscosity 10 ^13.3 Poise (Tg) 738 The temperature corresponding to the viscosity of the glass 10 ¹² Poise (T _Eb ) 775 Appointment For tungsten soldering

The objective of the new invention is to create a new composition of the material, providing the possibility of obtaining high-quality optical surfaces directly on substrates of silicon carbide materials.

The technical result is achieved due to the possibility of using silicon carbide as a structural material of the substrate, its vitrification, for use in optical devices where a combination of low weight and high strength parameters, in particular in space instrument engineering, is required.

The problem is solved by creating a glass material, including components SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ and CaO, which, unlike the prototype, additionally contains Sb ₂ O ₃ , V ₂ O ₅ , Nb ₂ O ₅ , MoO ₃ and F in the following ratio of components, wt.%: SiO ₂ -44-61; B ₂ O ₃ -8-20; Al ₂ O ₃ -5-19; CaO-3-12; Sb ₂ O ₃ -0.3-0.7; V ₂ O ₅ -2-11; Nb ₂ O ₅ -1-7; MoO ₃ -0.2-4 and F-1.5-6.

The presented composition of glass provides vitrification of substrates from silicon carbide materials with obtaining high characteristics in strength and optical parameters.

table 2 The specific compositions of the claimed glass material in wt.%. Component one 2 3 four SiO ₂ 44 61 fifty 57 B ₂ O ₃ 8 twenty 14.5 12 Al ₂ O ₃ 15.6 5 19 eleven CaO 12 3 3 7 Sb ₂ O ₃ 0.7 0.3 0.5 0.4 V ₂ O ₅ eleven 2 four 3,1 Nb ₂ O ₅ 7 1.7 2 one Moo ₃ 0.2 2 four 2,5 F 1,5 0.5 3 6 KTR (10 ^-7 deg. ^-1 ). 28 thirty 25 27 Adhesion of glass to a silicon carbide substrate. there is there is there is there is Glass melting temperature (° C). 1540 1500 1550 1530

A method of manufacturing the material is glass melting according to the technology adopted for technical glasses in the Russian Federation.

Depending on the task - the volume of production, the size of the workpieces, the type of processing equipment installed at the plant, the cooking mode may vary.

Optical and technical glasses are produced (boiled) in bathrooms and pot furnaces. In continuous continuous bath furnaces, it is advisable to make glass of mass grades, which is required in large quantities, for example sheet metal. Therefore, for the production of a large number of brands of optical and technical glasses, glass melting is used in pot furnaces. It is possible to use flame or electric furnaces.

The technological process of cooking optical and technical glass of various compositions in pot furnaces consists of the following stages (Physicochemical principles of the production of optical glass. Edited by Doctor of Technical Sciences L.I. Demkina. L .: Chemistry, 1976. 456 p. , Chapter XVI "Optical Glass Cooking", p.330-349.):

- preparation of a glass pot and stirrer;

- filling and boiling of the mixture;

- clarification of the melt;

- cooling of glass;

- cutting.

For each stage of glass melting, a temperature-time regime is determined, which is determined by the composition of the glass and takes into account the particular production (Glass technology. Edited by II Kitaigorodsky. M .: Gosstroyizdat, 1961, 624 p.).

A method of manufacturing the material is glass melting according to the technology adopted for technical glasses in the Russian Federation. The cooking mode for glass should be specially designed taking into account the particular production.

Experiments were performed on sintering glass with samples of silicon carbide with a billet diameter of 60 mm, after which the glass was polished. The glass is sintered with the silicon carbide substrate material without breaking. On the glass surface, an optical surface was obtained that satisfies the task.

Claims (1)

A coating for the preparation of a space mirror, which is a glass composition comprising SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ and CaO, characterized in that it further comprises Sb ₂ O ₃ , V ₂ O ₅ , Nb ₂ O ₅ , MoO ₃ and F in the following ratio of components, wt.%:
SiO ₂ 44-61 B ₂ O ₃ 8-20 Al ₂ O ₃ 5-19 CaO 3-12 Sb ₂ O ₃ 0.3-0.7 V ₂ O ₅ 2-11 Nb ₂ O ₅ 1-7 Moo ₃ 0.2-4 F 1,5-6