Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/08—Mirrors
  • G02B5/0816—Multilayer mirrors, i.e. having two or more reflecting layers
  • G02B5/085—Multilayer mirrors, i.e. having two or more reflecting layers at least one of the reflecting layers comprising metal
  • G02B5/0858—Multilayer mirrors, i.e. having two or more reflecting layers at least one of the reflecting layers comprising metal the reflecting layers comprising a single metallic layer with one or more dielectric layers
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
  • C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/922—Static electricity metal bleed-off metallic stock
  • Y10S428/923—Physical dimension
  • Y10S428/924—Composite
  • Y10S428/925—Relative dimension specified
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/922—Static electricity metal bleed-off metallic stock
  • Y10S428/9335—Product by special process
  • Y10S428/938—Vapor deposition or gas diffusion
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
  • Y10T428/12583—Component contains compound of adjacent metal
  • Y10T428/1259—Oxide
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12736—Al-base component
  • Y10T428/12764—Next to Al-base component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12993—Surface feature [e.g., rough, mirror]

Definitions

• the invention relates to metal reflectors and to a method of manufacturing such reflectors.
• Metal reflectors for outdoor use and for use in damp spaces have to satisfy stringent requirements. They have to be capable of withstanding any type of climate and elevated temperatures while retaining their reflecting power.
• Materials which might be particularly suitable for such use are aluminium casting alloys consisting mainly of aluminum with magnesium and/or silicon as main alloying element or elements.
• satisfactory corrosion resistance which in some cases can be improved by the provision of an oxide film, for example by anodizing, and sufficient mechanical strength at the temperatures which may occur in practice
• the use of an aluminium casting alloy has the advantage that the reflector, which frequently has a complicated shape, can be simply manufactured by casting in sand or a permanent mold.
• the said alloys and many other alloys suffer from the disadvantage that articles manufactured from them cannot be polished so as to be highly reflecting.
• the coefficient of reflection, expressed as a percentage, of a known aluminium alloy containing 1.0% of magnesium and 5% of silicon after polishing is at most about 60%, whereas the coeflicient of reflection of pure aluminium after polishing may be from 80 to 90%.
• a further disadvantage consists in that an anodizing treatment of an aluminium alloy performed to increase the corrosion resistance reduces the coeificient of reflection by about one half, while some alloys do not form a continuous oxide film during this treatment.
• reflectors comprising a support made of a material which itself cannot be polished so as to become highly reflecting when provided with a reflecting layer consisting of pure or substantially pure aluminium coated with a protective oxide film, are particularly suitable.
• Mirrors and reflecting layers produced by deposition of pure or substantially pure aluminium from vapour are known. It is also known to anodize aluminium so as to grow an oxide film which imparts an increased corrosion resistance to the metal.
• an oxide film having a thickness which does not reduce the reflectivity to an unserviceable value that is to say, a thickness of the order of magnitude of from 5 to microns, is not capable of withstanding temperatures exceeding about 150 C. for a prolonged period of time. Above the said temperature cracks are produced in the oxide film so that the protective action preventing further oxidation is lost and the reflecting power of the mirror is decreased.
• reflectors in accordance with the invention can be heated to temperatures of up to about 300 C. for a prolonged period of time without the oxide film on the aluminium mirror losing its protective action against further oxidation and without the reflectivity deteriorating perceptibly.
• Such a support is preferably made of an aluminium casting alloy containing magnesium and/ or silicon as main alloying element or elements.
• Such alloys are 3,372,008 Patented Mar. 5, 1968 the aluminium alloys containing 3.0% of magnesium, less than 0.6% of manganese and less than 0.3% of silicon, or about 0.4% of managanese and from 12.0 to 13.5% of silicon, or 1.0% of magnesium, from 0.2 to 1.0% of manganese and 5% of silicon, and the like.
• a parabolic reflector was made by casting a molten alloy having the composition 1.0% of magnesium, 0.6% of manganese, 5.0% of silicon and the remainder aluminium, in a suitable mold and cooling in the mold, after which the inner side was polished. The coeflicient of reflection of the material expressed as a percentage was 57%. Part of the reflector was anodized until an oxide film having a thickness of 1 micron was obtained. The coefficient of reflection now was 25%.
• Another part of the reflector was degreased with the aid of an organic solvent, for example trichloroethane, and heated to a temperature of from 250 C. to 275 C., after which this part was treated in a vacuum with the aid of a glow discharge for 10 minutes. After cooling, aluminium was deposited from vapour so as to form a coating having a thickness of about 1.5 micron. This mirror had a coeflicient of reflection of 84%.
• an organic solvent for example trichloroethane
• This climate chamber test had been preceeded by a temperature test at 300 C. for 2 hours and at 250 C. for 24 hours.
• the deterioration of the light reflectivity was only 2% compared with the initial value.
• a metal reflector comprising a cast reflector body of aluminum and having alloys chosen from the group consisting of an alloy having 3.0% of magnesium, less than 0.6% of manganese, less than 3.0% of silicon and the remainder aluminum; an alloy having about 0.4% of manganese, from 12% to 13.5% of silicon and the remainder aluminum; an alloy having about 1.0% of magnesium, from 0.2% to 1.0% of manganese, about 5% of silicon, and the remainder aluminum; a reflecting layer of alumi num on said cast aluminum body and an oxide layer coating on said reflecting layer of aluminum.
• a method of manufacturing a metal reflector comprising casting a metal reflector body from an alloy chosen from the group consisting of an alloy having 3.0% of magnesium, less than 0.6% of manganese, less than 3.0% of silicon and the remainder aluminum; an alloy having about 0.4% of manganese, from 12% to 13.5% of silicon and the remainder aluminum; an alloy having about 1.0% of magnesium, from 0.2% to 1.0% of manganese, about 5% of silicon, and the remainder aluminum, polishing the surface of said body which is desired to be reflecting, degreasing said surface, treating said surface with a glow discharge in a vacuum, vapor depositing aluminum upon said surface, and anodizing said polished aluminum reflective surface whereby said reflective surface is coated With an oxide layer.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Optical Elements Other Than Lenses (AREA)
• Physical Vapour Deposition (AREA)

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Publications (1)

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ID=19753064

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Cited By (3)

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Citations (8)

• 1962
  • 1962-05-10 US US194217A patent/US3372008A/en not_active Expired - Lifetime
  • 1962-05-25 DK DK236562AA patent/DK103862C/da active
  • 1962-05-25 GB GB20212/62A patent/GB1011977A/en not_active Expired
  • 1962-05-28 CH CH647662A patent/CH439182A/de unknown

Patent Citations (8)

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