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Method for preparing silicon carbide reflecting mirror material and CVI forming device thereof

A reflective mirror and silicon carbide technology, applied in metal material coating technology, mirrors, gaseous chemical plating, etc., can solve the problems of easy cracks in the substrate and coating, low overall density of the material, and low preparation cost, and achieve thermal The effect of consistent performance, shortened time, and short production cycle

Inactive Publication Date: 2008-08-13
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a new preparation method of SiC mirror material, which solves the problem that cracks are easily generated between the substrate and the coating, and the method has short production cycle, low preparation cost, and low overall density of the material

Method used

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  • Method for preparing silicon carbide reflecting mirror material and CVI forming device thereof
  • Method for preparing silicon carbide reflecting mirror material and CVI forming device thereof
  • Method for preparing silicon carbide reflecting mirror material and CVI forming device thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0021] The CVI forming device is formed by adding a graphite chamber to a conventional CVI deposition furnace. The graphite cavity 2 is composed of two semi-cylinders and two upper and lower gas-conducting graphite gaskets 4. In order to facilitate demoulding, the contact surface is covered with graphite paper 5, and the graphite cavity 2 is tightened by the graphite outer mold sleeve 1. Between the SiC powder 3 and the inner wall of the graphite cavity 2 is a layer of graphite paper 5 to prevent the SiC powder 3 from adhering to the inner wall of the graphite cavity 2 during the CVI process. Since the pore diameter of the gas-conducting graphite gasket 4 is larger than that of the SiC powder, the SiC powder may be carried out by the air flow during the CVI process. There is a layer of carbon fiber mesh tire 7 between the SiC powder 3 and the gas-conducting graphite gasket 4, also for the convenience of Demoulding, the carbon fiber net tire 7 and the gas-conducting graphite ga...

Embodiment 2

[0023] A SiC mirror material with a size of φ150×20mm is prepared. The preparation process and related parameters are as follows: (1) β-SiC powder with a particle size of 50 mesh is loaded into a graphite cavity. (2) CVI deposited SiC densification at 1100°C to form SiC powder. The process parameters are: MTS: H 2 =1:12, the Ar gas flow rate is 200ml / min, the deposition pressure is 300Pa, and the deposition time is 50h; (3) After removing the graphite cavity, CVI is densified again for 50h; (4) SiC blank is processed on a diamond grinding machine Preliminary mechanical processing to increase the surface porosity and make the green body have a certain flatness; (5) Repeat CVI deposition SiC densification twice, each deposition time is 50h, deposition temperature is 1300°C, MTS:H 2 =1:8, the Ar flow rate is 300ml / min, the deposition pressure is controlled at about 5kPa, and the surface of the green body needs to be machined before each densification; (6) Deposit a layer of CVD...

Embodiment 3

[0028] SiC mirror materials made of SiC powders of different particle sizes and the same CVI deposition process were prepared, and the sample size was φ50×15mm. The preparation process and related parameters are as follows: (1) SiC powder with a particle size of 50 mesh and 200 mesh is loaded into a graphite cavity. (2) SiC densification by CVI deposition at 1100°C to shape the matrix additive. The process parameters are: MTS: H 2 =1:12, the Ar flow rate is 200ml / min, the deposition pressure is 300Pa, and the deposition time is 50h; (3) After removing the graphite cavity, CVI is densified again for 50h; Mechanical processing to increase the surface porosity and make the green body have a certain flatness; (5) Repeat the densification twice, each deposition time is 50h, the deposition temperature is 1300°C, MTS:H 2 =1:8, the Ar flow rate is 300ml / min, the deposition pressure is controlled at about 5kPa, and the surface of the green body needs to be machined before each densif...

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Abstract

The invention discloses a preparing method for SiC reflector material and a CVI forming device for the preparing method. The method is: using 50 to 200 mesh Sic power as raw material put in the graphite cavity of the CVI forming device, methyltrichlorosilane as Sic gas source, H2 as eluant gas and diluent gas, Ar as protective gas, under a temperature of 1000 to 1300 DEG C, depositing SiC to form a blank by CVI method; after shucking off the graphite cavity, repeatedly CVI depositing SiC to intensify the blank and mechanically processing for several times; and preparing SiC reflecting layer on the surface of the SiC blank by CVD method. For reflector material prepared by the invention, crackle is not easy to appear, since the base and coating have same heat performance, the production period is greatly reduced, the production cost is lowered, and multiple workpieces can be deposited at the same time.

Description

technical field [0001] The invention relates to a method for preparing a SiC mirror material and a CVI forming device used in the method. Background technique [0002] At present, SiC mirrors are widely used in large space telescopes, large ground telescopes, early warning satellites, detection satellites, reconnaissance satellites, meteorological satellites, high-energy laser weapons, lidar systems, vacuum ultraviolet telescopes and high-resolution space cameras and other fields. The methods for preparing SiC mirror materials at home and abroad mainly include hot isostatic pressing (Hot Isostatic Pressing, HIP), reaction sintering (ReactionBoned, RB) and chemical vapor infiltration / chemical vapor deposition (Chemical VaporInfiltration / Chemical Vapor Deposition, CVI / CVD). Among them, SiC materials prepared by HIP and RB methods are not dense and have low optical processing precision. The material prepared by CVI / CVD method has the advantages of high density, good optical p...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C16/32C23C16/44C23C16/52G02B1/00G02B5/08
Inventor 肖鹏熊翔邓清
Owner CENT SOUTH UNIV
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