RU2535894C1 - Method of producing thin-film light-reflecting element for optical systems - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method includes preliminary chemical-mechanical treatment of the surface of irregularly shaped components and forming a metal-coated reflecting layer after the preliminary chemical-mechanical treatment, successively depositing a chemical zinc sublayer and a nickel-phosphorus layer with thickness of up to 200 mcm, which is polished to 6-8 E to obtain a duplicated matrix surface which is passivated in potassium dichromate solution and forming a reflecting gold layer in a citrate electrolyte of the following composition, g/l: potassium dicyano-(1)aurate 8-12 (on Au), potassium citrate 30-80, citric acid 15-40, with current density of 0.5 A/dm², temperature 55-60°C for 15-20 minutes, and a galvanic nickel bearing layer, after which the obtained metal-coated replica is removed from the matrix by thermal shock to form a thin-film light-reflecting element for subsequent installation into an optical system.

EFFECT: improved optical and geometrical properties and mechanical strength of the metal-coated reflecting layer.

1 ex, 1 dwg

Description

The invention relates to the field of manufacturing technology of reflective elements of complex shape (spherical or conical shape) for optical systems and can be used to obtain high-precision reflective optical elements of astronomical mirrors.

Known from the prior art, a method of manufacturing reflective elements of optical systems (RF patent No. 02156487, IPC G02B 26/02, publ. 09/20/2000), according to which a pre-prepared polished substrate (matrix) is coated with a metal-dielectric coating and a layer of highly reflective metal (silver or gold) with a thickness of 0.03-0.06 microns, which provides high reflective properties of the finished mirror.

A known method of producing reflective elements for optical systems by thermal gas-phase decomposition of gold and platinum compounds (RF patent No. 01840420, IPC C23C 14/00, publ. March 20, 2007), which is carried out in a mixed gas stream, is known metal is carried out at a substrate temperature of 190 ÷ 250 ° C with the simultaneous removal of organic decomposition products from the reaction zone, which ensures an increase in the reflection coefficient of the finished product coating, adhesion, purity and resistance to mechanical stress.

The disadvantages of analogues include the difficulty of manufacturing parts with a high degree of accuracy of the complex profile profile reproduced in a replica in a replica and meeting the requirements for clean surface treatment and minimizing the weight of finished products.

The objective of the inventors is to develop a method for manufacturing a thin-film reflective element of a complex profile for optical systems, providing high optical (light reflectance) and geometric parameters (thickness and accuracy of reproduction of the matrix profile in a removable metallized replica), specified adhesion parameters of the coating to the matrix and mechanical strength, sufficient for the implementation of the stages of high-intensity machining of the matrix and subsequent removal of the replica.

A new technical result provided by using the present invention is to provide an increase in optical (light reflectance) and geometric parameters (equal thickness and duplication of the matrix profile in a removable metallized replica), indicators of adhesion of the nickel-phosphorus coating to the matrix and its mechanical strength sufficient to conduct high-intensity machining of the coated matrix, and subsequent removal of the replica.

These tasks and a new technical result are ensured by the fact that in the known method of manufacturing a thin-film reflective element for optical systems, including preliminary chemical-mechanical treatment of the surface of the parts, the formation of a metallized reflective layer, according to the invention, the formation of a metallized reflective layer is carried out after preliminary chemical-mechanical processing, application successively a sublayer of chemical zinc, applying a nickel-phosphorus layer of thicknesses up to 200 μm, which is subjected to heat treatment up to 400 ° C and high-intensity polishing up to 6-8 Å to obtain a duplicate matrix surface, after degreasing an additional surface passivation of the matrix surface in a solution of potassium dichromate, followed by the formation of a successively reflecting gold layer on the matrix surface in citrate electrolyte the following composition (g / l):

dicyano- (1) potassium aurate 8-12 (by Au) potassium citrate 30-80 citric acid 15-40

at a current density of 0.5 A / dm ² , a temperature of 55-60 ° C for 15-20 minutes and then a supporting layer of galvanic nickel, after which the obtained metallized replica is removed from the matrix by thermal shock with the formation of a thin-film reflective element for its subsequent installation in optical system.

The proposed method is illustrated as follows.

Initially, the surface of the workpiece (matrix of a given geometric profile) is prepared for complex parts by traditional methods of chemical-mechanical processing, degreasing, etching. The etching process is carried out in a solution of the composition (g / l): nitric acid, hydrofluoric acid; water in a ratio of 1: 1: 10, respectively, after which all products of surface etching are washed off with water.

Then, an intermediate zinc layer is applied to the prepared surfaces of the blanks of complex-shaped parts by chemical deposition from a multicomponent zinc-containing solution, followed by removal of this layer, which is necessary to activate the surface of the coated complex-shaped parts (matrix) and increase the adhesion of subsequently applied nickel-phosphorus coating to them.

Next, re-applying the zinc film by a similar method.

After that, by chemical reduction from a solution of a mixture of multicomponent compounds of nickel and phosphorus in a single step at a temperature of 80-90 ° C, a nickel-phosphorus layer with a thickness of up to 200 μm is applied, heat treated in the temperature range up to 400 ° C, which contributes to an increase in the adhesive-mechanical strength indicators obtained coatings and provides the ability to conduct high-intensity machining of the matrix to a purity of 6-8 Å. Such a high degree of surface finish is necessary for accurate subsequent duplication of the geometry of the matrix in the subsequently created layered removable replica.

The matrix obtained in this way is made with a surface corresponding to the profile of the finished product.

After degreasing and washing with water, the matrix is passivated with coated layers in a solution of potassium dichromate to reduce the adhesion of the thin-film element to the surface of the matrix.

A thin-film reflecting element with a thickness of 280-300 μm is obtained by gilding on the nickel-phosphorus layer of the matrix in a citrate electrolyte composition (g / l):

dicyano- (1) potassium aurate 8-12 (by Au) potassium citrate 30-80 citric acid 15-40

at a current density of 0.5 A / dm ² , a temperature of 55-60 ° C for 15-20 minutes and the subsequent deposition of a nickel layer by the galvanic method of a sulfamine electrolyte composition (g / l):

nickel sulfamic 300-400 nickel dichloride 12-15 boric acid 25-40 sodium lauryl sulfate 0.01-0.1 saccharin 0.008

at a current density of 2.5 A / dm ² , a temperature of 55-60 ° C for 8 hours.

After the next washing with water and drying of the workpiece, the thin-film replica is removed from the gold-nickel layers by thermal shock, the obtained samples of the thin-film reflective element are subjected to control tests for optical and mechanical parameters.

Thus, when using the proposed method for manufacturing a thin-film reflective element for optical systems, an increase in optical (reflectance) is achieved due to the exact duplication of geometric indicators (thickness and reproduction of the matrix profile in a removable metallized replica), adhesion indicators of the final nickel-phosphorus coating to the matrix and mechanical strength sufficient for high-intensity machining of the matrix and subsequent removal of tiles.

The possibility of industrial implementation of the invention is confirmed by the following implementation example.

Example 1. The proposed method was implemented in laboratory conditions on billets of aluminum alloy AmG6 coated with a nickel-phosphorus coating and polished to 6-8 Å. The method included the following operations:

- degreasing in a solution of the composition (g / l): - trisodium phosphate 45-55;

- soda ash 45-55;

at a temperature of 50-60 ° C for 10 minutes;

- washing in hot water;

- washing in cold water;

- passivation in a solution of potassium dichromate (2 g / l) at room temperature for 3 minutes.

- washing in cold water;

- gilding in a citrate electrolyte composition (g / l):

dicyano- (1) potassium aurate 8-12 (by Au) potassium citrate 30-80 citric acid 15-40

at a current density of 0.5 A / dm ² , a temperature of 55-60 ° C for 15-20 minutes;

- washing in hot water;

- Nickel plating in a sulfamine electrolyte composition (g / l):

nickel sulfamic 300-400 nickel dichloride 12-15 boric acid 25-40 sodium lauryl sulfate 0.01-0.1 saccharin 0.008

at a current density of 2.5 A / dm ² , a temperature of 55-60 ° C for 8 hours.

- washing in hot water;

- washing in cold water;

- removal of a replica.

Figure 1 presents a view of a nickel replica with a gold reflective layer made by electroplating.

As the experiments showed, when using the proposed method, an increase in optical parameters (light reflectance) is achieved due to the exact duplication of geometric (thickness and reproduction of the matrix shape in a removable metallized replica) indicators, indicators of nickel-phosphorus coating adhesion to the matrix, and mechanical strength sufficient to conduct high-intensity machining the matrix and then removing the replica.

Claims (1)

A method of manufacturing a thin-film reflective element for optical systems, including preliminary chemical-mechanical surface treatment of complex parts and the formation of a metallized reflective layer, characterized in that the formation of a metallized reflective layer is carried out after preliminary chemical-mechanical processing, successive deposition of a layer of chemical zinc, deposition of nickel-phosphorus layer thickness up to 200 μm, which is subjected to high-intensity polishing up to 6-8 Å s Acquiring duplicated matrix surface, a surface which is passivated in potassium dichromate solution, followed by forming a reflective layer of gold on the surface of the matrix in citrate electrolyte of the following composition, g / l:
dicyano- (1) potassium aurate 8-12 (by Au) potassium citrate 30-80 citric acid 15-40,
at a current density of 0.5 A / dm ² , a temperature of 55-60 ° C for 15-20 minutes, and a supporting layer of galvanic nickel, after which the obtained metallized replica is removed from the matrix by thermal shock with the formation of a thin-film reflective element.

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