A kind of foam Si mirror and preparation method thereof
Technical field
The present invention relates to a kind of catoptron and preparation method thereof, particularly relate to a kind of foam Si mirror and preparation method thereof.
Background technology
Along with the aggravation of space field competition, the each power in the world all drops into a large amount of human and material resources and develops correlation technique.One of Main Function of spacecraft is collection information, therefore the performance of Space Optical System is launched to research significant.Space telescope normally adopts reflective structure design, and wherein principal reflection mirror is the core component of whole optical system.The trend of space telescope principal reflection mirror design is large area, low-gravity, requires reflecting mirror material to have excellent mechanical property and thermophysical property simultaneously.
The Chinese invention patent that publication number is 1576902 a kind of high reflection mirror is provided.This high reflection mirror has high reflectance in visible region, the excellent in te pins of durability of moisture-proof and resistance to salt water etc., and incident angle-dependent little (incident angle of light is difficult to cause the variation of reflectivity).It is on substrate, order with silverskin, low refractive index film, high refractive index film is carried out the high reflection mirror that lamination forms, it is characterized in that, in the contrary side of the substrate of silverskin, form to adhere to and improve film, the extinction coefficient of low-refraction and high refractive index film is all less than or equal to 0.01, and it is that oxidation film Bees Wax is less than or equal to 0.1 that adhesion improves film.
Publication number is that the Chinese invention patent of 102119304A discloses a kind of catoptron.This mirror assembly comprises catoptron and in the face of panel, at catoptron with in the face of between panel, has sealing gas space.Catoptron can be: the catoptron that comprises glass substrate, silver coating and at least one dope layer; Or comprise the catoptron that is bonded to on-chip organic mirror coating.The in the situation that of glass reflector, at least one dope layer is in the face of sealing gas space, and in the case of the catoptron that comprises organic mirror coating, mirror coating is in the face of sealing gas space.
Although can be a lot of for the candidate material of manufacturing optical mirror, consider the severity of space environment, what practical application was many is the materials such as metallic aluminium, metallic beryllium, metallic nickel, optical glass, silicon and silit.For meeting application demand, spacing reflection mirror is towards the trend development of heavy caliber, long-focus, high optical property, Si and SiC material rely on its comprehensive advantage at aspects such as physical characteristics, mechanical property, thermal behaviors, and instead of glass and metal become the main representative of third generation spacing reflection mirror blank of material.
Summary of the invention
The present invention, mainly for Space Optical System, provides a kind of foam Si mirror and preparation method thereof.The density of Si is 2.33, and thermal conductivity is 130, and elastic modulus reaches 155GPa, and the thermal expansivity of room temperature to 1000 ℃ is only 3.1, and more easily processes than SiC, is a kind of elite clone that is suitable for making catoptron.
A kind of foam Si mirror, the fine and close Si coating that it is characterized in that comprising foam silicon idiosome He be attached to idiosome surface.Described foam silicon idiosome is a kind of take carbon foam as substrate, and surface attachment has the open celled foam of Si film, and wherein, the thickness of Si film is 50nm~2 μ m.Foam inside presents tridimensional network, by irregular holes not of uniform size, is cross-linked and is formed, and has large specific surface area, can fill the many kinds of substance of solid, liquid, gas state.In idiosome surface attachment, have fine and close Si coating, coating thickness is 0.5~3mm.
The minute surface of above-mentioned catoptron can be plane, can be also curved surface.
A preparation method for foam Si mirror, is characterized in that comprising the step of following order:
(1), by isocyanurate foam pyrolysis, make carbon foam;
(2) by one or more surfaces mirror surface structure that becomes to need of the carbon Foam machining making;
(3) prepare Si film: finished carbon foam is put into CVI stove, pass into SiCl
4and H
2, control temperature and time, at open celled foam inwall, adhere to certain thickness Si film, finally obtain foam silicon;
(4) preparation of surperficial Si coating: take out foam silicon from CVI stove, put into silication stove, pass into H
2and SiCl
4, SiCl
4at 1100~1300 ℃, pyrolytic goes out Si, and the Si crystal grain decompositing is deposited on foam silicon face, and sedimentation time is 4~20 hours, finally at foam silicon face, adheres to the Si coating of one deck densification;
(5) surface attachment there is is the foam silicon of dense coating take out from silication stove, be finish-machined to needed minute surface with adamas, finally obtain a kind of foam silicon transmitting mirror.
According to above-mentioned preparation method, carbon foam is by isocyanurate foam, to heat carbonization to obtain, and concrete technological process is carried out in two steps: first in air, isocyanurate foam is heated at 200~255 ℃; Then in inert atmosphere, carbonization at 700~900 ℃.
Major advantage of the present invention is: 1. foam silicon structure provides high specific strength, thermal conductivity and very light quality, when maintaining a quite low surface density, can make the optical property of catoptron exceed the transmitting mirror of current glass, pottery and metal; 2. surperficial Si coating is completely fine and close, isotropy, and easily Precision Machining becomes smooth minute surface, and high reflectivity is provided; 3. this mirror structure is simple, easy to prepare, does not need complicated positioning system, has reduced cost; 4. the foam texture of porous can absorb energy, buffering distortion, makes this catoptron have excellent thermal stability and minimum metamorphopsic distortion.
Embodiment
Below in conjunction with specific embodiment, further illustrate the present invention, should understand these embodiment is only not used in and limits the scope of the invention for the present invention is described, after having read the present invention, those skilled in the art all fall within the application's claims to the modification of the various equivalent form of values of the present invention and limit.
Embodiment 1
(1) isocyanurate foam is heated in air atmosphere to 200 ℃, organic substance volatilization, then puts into high-purity argon gas atmosphere and is heated to 800 ℃, and skeleton carbonization obtains carbon foam;
(2) by one or more surfaces mirror surface structure that becomes to need of the carbon Foam machining making;
(3) prepare Si film: finished carbon foam is put into CVI stove, pass into SiCl
4and H
2, control temperature and time, at open celled foam inwall, adhere to the Si film of 100nm thickness, finally obtain foam silicon;
(4) preparation of surperficial Si coating: take out silicon foam from CVI stove, put into silication stove, pass into H
2and SiCl
4, at 1135 ℃, pyrolytic goes out Si, and Si crystal grain is deposited on foam silicon face, controls temperature and time, makes surface obtain the fine and close Si coating that thickness is 1mm.
(5) surface attachment there is is the foam silicon of dense coating take out from silication stove, be finish-machined to needed minute surface with adamas, finally obtain a kind of foam silicon transmitting mirror.
Said method obtains a kind of foam Si mirror, and this catoptron comprises foam silicon idiosome and is attached to the fine and close Si coating on idiosome surface.The porous foam structure of this catoptron inside can absorb energy, buffering distortion, make this catoptron there is excellent thermal stability and minimum metamorphopsic distortion, simultaneously, the easy isotropy of fine and close Si coating on surface, easily processing, when keeping mirror surface density extremely low, reflectivity can increase substantially.
Embodiment 2
(1) isocyanurate foam is heated in air atmosphere to 250 ℃, organic substance volatilization, then puts into high-purity argon gas atmosphere and is heated to 900 ℃, and skeleton carbonization obtains carbon foam;
(2) by one or more surfaces mirror surface structure that becomes to need of the carbon Foam machining making;
(3) prepare Si film: finished carbon foam is put into CVI stove, pass into SiCl
4and H
2, control temperature and time, at open celled foam inwall, adhere to the Si film of 1 μ m thickness, finally obtain foam silicon;
(4) preparation of surperficial Si coating: take out silicon foam from CVI stove, put into silication stove, pass into H
2and SiCl
4, at 1200 ℃, pyrolytic goes out Si, and Si crystal grain is deposited on foam silicon face, controls temperature and time, makes surface obtain the fine and close Si coating that thickness is 2mm.
(5) surface attachment there is is the foam silicon of dense coating take out from silication stove, be finish-machined to needed minute surface with adamas, finally obtain a kind of foam silicon transmitting mirror.
Said method obtains a kind of foam Si mirror, and this catoptron comprises foam silicon idiosome and is attached to the fine and close Si coating on idiosome surface.The porous foam structure of this catoptron inside can absorb energy, buffering distortion, make this catoptron there is excellent thermal stability and minimum metamorphopsic distortion, simultaneously, the easy isotropy of fine and close Si coating on surface, easily processing, when keeping mirror surface density extremely low, reflectivity can increase substantially.
Above are only two embodiments of the present invention, but design concept of the present invention is not limited to this, allly utilizes this design to carry out the change of unsubstantiality to the present invention, all should belong to the behavior of invading the scope of protection of the invention.In every case be the content that does not depart from technical solution of the present invention, any type of simple modification, equivalent variations and the remodeling above embodiment done according to technical spirit of the present invention, still belong to the protection domain of technical solution of the present invention.