Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/06—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of metallic material

Definitions

• Aluminum is plated on a substrate by contacting the substrate with aluminum hydride and a decomposition catalyst.
• the decomposition catalyst is a compound of a metal of Group IVb or Vb of the Periodic Table or mixtures thereof.
• This invention relates to a non-electrolytic process for the plating of aluminum on various substrates and more particularly relates to a relatively low temperature process for the plating of metallic aluminum from an aluminum hydride.
• metallic aluminum may be plated from aluminum hydrides by contacting such hydrides with a substrate at or above the decomposition temperature of the aluminum hydride.
• Such a process usually requires a relatively high temperature to cause decomposition of the aluminum hydride and therefore cannot be used to plate aluminum onto many heat sensitive substrates. It would be highly desirable, therefore, to have a process which would permit the plating of aluminum at relatively low temperatures.
• plating processes are general in nature and cause plating over the entire exposed surface of the substrate and it would be highly desirable to be able to plate only selected areas of a substrate in order to produce patterns or lettering.
• most knovm aluminum plating processes do not give a coating of uniform thickness on irregularly shaped objects and such a uniform coating would often be highly advantageous.
• An additional object is to provide a relatively low temperature process for the plating of aluminum from aluminum hydrides which permits the plating of heat sensitive substrates.
• Another object is to provide a process for coating predetermined portions of a substrate to provide designs, patterns or letters thereon.
• a further object is to provide a process whereby an irregularly shaped substrate is coated relatively uniformly with metallic aluminum.
• aluminum hydrides may be used to produce plating of metallic aluminum at temperatures substantially below the usual decomposition temperature of such hydrides.
• the use of such catalysts permits the deposition of a uniform, adherent plate or coating of metallic aluminum, usually in the form of a bright plate, on substantially any substrate at relatively low temperatures and therefore provides the art with a novel and relatively inexpensive process for aluminum plating of even those materials, such as organic polymers, which are heat sensitive.
• Substantially any normally solid material is suitable as a substrate herein.
• metals such as iron, magnesium, brass and copper, polymers such as polyolefins, polyamides and polymeric fiuorocarbons, glass, paper, cloth, carbon and graphite, wood, ceramics and the "ice like are all plated with aluminum by the process of this invention.
• the nature of the surface being plated determines to a large extend the brightness of the aluminum plate.
• the use of a smooth, non-porous surface such as found on most metals and some polymer films produces a brighter plate than a relatively porous surface such as those encountered with paper or cloth.
• aluminum hydride is used herein in its broad sense and is meant to include any hydride compound which contains at least one aluminum atom to which at least one hydrogen atom is directly bonded and includes both the solvated and non-solvated forms of those aluminum hydrides occurring in both forms. Included, therefore, are aluminum trihydride, the substituted aluminum hydrides such as those having the empirical formula AlH X wherein X is a halogen, an OR group or an R group (wherein R is an alkyl, substituted alkyl, aryl or substituted aryl group) and n has a numerical value equal to or less than 3.
• complex aluminum hydrides such as LiAlH NaAlH Mg(AlH and the like and complex substituted aluminum hydrides such as those having the empirical formula M(AlH X wherein X has the definition given above, m has a numerical value equal to or less than 4 and M is a metal or mixture of metals, preferably an alkali or alkaline earth metal and a has a numerical value equal to the valence of M.
• X has the definition given above
• M is a metal or mixture of metals, preferably an alkali or alkaline earth metal and a has a numerical value equal to the valence of M.
• the relatively simple aluminum hydrides containing at least two hydrogen atoms attached to the aluminimum e.g. AlH AIH CI, AlH Br, LiAlH and the like. Mixtures of the various aluminum hydrides may also be employed.
• solvate or form complexes with the aluminum hydrides include ethers and other oxygen-containing organic compounds, and compounds containing a functional group such as a divalent sulfur atom, or trivalent nitrogen or trivalent phosphorous atom which is capable of allowing the solvation of an aluminum hydride with such compound. It is usually preferred that the solvate be an etherate and a wide variety of ethers containing from about 2 to about 20 carbon atoms are suitable.
• the lower aliphatic ethers such as ethyl, propyl, or butyl ethers are employed but those containing an aromatic group such as methylphenyl ether, ethylphenyl ethers, propylphenyl ether or the alicyclic ethers such as tetrahydrofuran and the like may be employed.
• any solvent or mixture of solvents or suspending agents for the aluminum hydride may be employed whcih will not react with the aluminum hydride beyond the formation of a complex or solvate.
• Suitable solvents include aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as hexane, ethers, tertiary amines and the like.
• such aluminum hydrides may be prepared in situ simultaneously with the plating step by employing aluminum hydride-forming reactants such as mixtures of lithium aluminum hydride and aluminum chloride, or sodium aluminum hydride and aluminum bromide, or the like.
• aluminum hydride-forming reactants such as mixtures of lithium aluminum hydride and aluminum chloride, or sodium aluminum hydride and aluminum bromide, or the like.
• a metal halide such as LiCl, MgCl or AlCl together with the aluminum hydride is not detrimental to the plating reaction.
• Transition metal decomposition catalysts useful herein are compounds of the metals occurring in Groups IVb and Vb of the Periodic Table. In instances where the catalyst is applied to the substrate in a solvent, it is preferable that the metal be in the form of a compound which is soluble to the extent of at least 1X 10* weight percent of the solvent employed.
• transition metal catalysts defined herein have a more pronounced effect than others in lowering the decomposition temperature of the aluminum hydride.
• the chlorides, bromides and oxychlorides of titanium, niobium, vanadium and Zirconium generally seem to be more efiective than the other compounds of Group IV]; and Vb transition metals and TiCl has been found particularly effective in achieving lower temperature decomposition of the aluminum hydrides and plating of the aluminum thus produced.
• the defined catalysts are not employed, undesirably high temperatures are required to produce decomposition of the aluminum hydride. At such elevated temperatures, even when decomposition is achieved, there is usually no aluminum coating or plate formed thereby.
• the transition metal decomposition catalyst is preferably applied to the substrate prior to contact with the aluminum hydride.
• Such decomposition catalyst may be applied to the substrate directly as a finely divided solid, as a liquid solution or suspension or, where the nature of the catalyst and the substrate permit, deposited by vapor deposition.
• the substrate is contacted with a sufi'icient quantity of a relatively dilute solution of the catalyst to wet the surface of the substrate.
• the solvent for the catalyst is then removed, e.g. by evaporation, leaving the catalyst substantially uniformly dispersed over the surface to be plated.
• Catalyst solutions at least about 1 l0- weight percent in decomposition catalyst, and preferably in concentrations of from about 5 lO- to about 100 weight percent of catalyst when applied to the substrate provide sufficient catalyst to achieve plating of aluminum from an aluminum hydride at a significantly lower temperature than is possible where no catalyst is employed. It has been found that uniformity of distribution of the catalyst on the substrate has a significant effect on both the uniformity and thickness of the aluminum plate. It is, therefore, desirable to apply the catalyst to the substrate in a manner which will assure relatively uniform distribution.
• Suitable wetting agents include, for example, stearates such as sodium or aluminum stearate or aluminum alkoxides such as aluminum isopropoxide.
• Solvents for the transition metal decomposition catalysts are those normally liquid materials in which the catalyst is soluble to at least the extent of 1X 16- weight percent, which will not adversely affect the substrate and which will not change the anion of the catalyst sufficiently to render it insoluble.
• Suitable solvents include non 4.- reactive solvents such as benzene, hexane, and halogenated hydrocarbons, reactive solvents such as alcohols, aldehydes, ketones, mercaptans, carboxylic acids and mineral acids, and coordinating solvents such as ethers, nitriles, amides and amines.
• transition metal decomposition catalyst By application of the transition metal decomposition catalyst to only selected areas of the substrate, it is possible to form an aluminum plate only on such selected areas. In this manner, ornamental designs, outlines, printed circuits and the like may be produced. Likewise, all or a portion of a selected substrate may be coated or plated with aluminum to enhance the ability of such surface to adhere to other materials. Of particular utility is the aluminum coating of glass, ceramic, metal or polymer surfaces to enhance their bonding to adhesive polymers and copolymers such as the copolymers of ethylene and acrylic acid.
• the catalyzed substrate surface is contacted with a suitable form of aluminum hydride.
• a suitable form of aluminum hydride In general, it is desirable to apply the aluminum hydride as a solution or suspension containing at least 1x10 Weight percent, preferably from 0.1 molar to 1.0 molar or more, aluminum hydride which may be applied by dipping, spraying or other suitable means.
• good results are also achieved by contacting the catalyzed substrate surface with a finely divided solid aluminum hydride.
• a vapor phase deposition of aluminum may be achieved at below usual decomposition temperatures by heating an aluminum hydride in close proximity to a catalyzed substrate surface. With or without the use of reduced pressure, a coating of metallic aluminum will form on the catalyzed surface.
• the catalysts defined herein will produce plating from the aluminum hydride at room temperature in a period of time from a few minutes to a few hours. More rapid decomposition of the catalyzed aluminum hydride to cause plating of the aluminum on a substrate may be achieved, however, by the application of sufiicient energy thereto to initiate the deposition.
• the aluminum hydride and catalyst may be applied to a substrate which is heated to the required temperature, or a catalyzed substrate may be contacted with a heated bath containing aluminum hydride.
• actinic light such as cold ultraviolet light may be employed or high energy radiation such as electron bombardment may be used to produce relatively rapid aluminum plating at low temperatures, e.g. room temperature.
• combinations of such forms of energy may be used.
• the decomposition of the catalyzed aluminum hydride is initiated, it will be self-sustaining and will form a continuous plate without supplying additional energy.
• the deposition temperature of aluminum catalyzed by the transition metal catalysts defined herein will vary depending on the particular aluminum hydride employed, upon the catalyst used, to some extent, upon the catalyst concentration and upon the type of energy'used to initiate the decomposition of the aluminum hydride. Such deposition temperature-s will, however, be substantially lower than those required where no catalyst is present.
• Example 1 An aluminum hydride solution was prepared in a dry nitrogen atmosphere by admixing 49 ml. of 1.0 molar lithium aluminum hydride, 18.5 ml. of 0.98 molar aluminum chloride and 156 ml. of diethyl ether. After stirring,
• Example 2 aluminum coat Polyamide film (Mylar) Mirror Cellophane film Mirror Saran film Mirror Polyethylene film (surface treated by electric discharge) Mirror Glass plate Mirror Fiberglass cloth Shiny Polyvinyl chloride film Mirror POrous paper sheet Dull Brass strip Mirror
• Example 2 In a manner similar to that of Example 1, a 0.3 molar solution of aluminum hydride in ether was prepared and several strips of Mylar film were coated with TiCl in hexane and dried. To this solution were added 3 cc. increments of a 1.2 molar AlCl solution in diethyl ether. After each addition, one of the above catalyzed Mylar strips was immersed in the aluminum hydride solution. Upon exposure to an ultraviolet sun lamp, decorative, aluminum film was deposited on the film. Each film was evaluated as to the effect of excess AlCl on the decorative nature of the plate.
• Example 3 In a manner similar to that of Example 2, strips of Mylar, Saran, polyethylene and glass were dipped into a 0.046 molar solution of TiCL; in benzene. The catalyzed films were then dried and immersed in an 0.30 molar aluminum hydride solution in ether. After removal from the ether solution, the substrates were placed in a convective oven heated to 110 C. A mirror-like, uniform, adhesive coating of aluminum was produced in from 2 to 3 seconds.
• substrates of the same materials not treated with TiCl were immersed in the 0.3 molar aluminum hydride solution and also placed in the convective furnace.
• the furnace was slowly heated from 110 C. to 250 C. over a period of one hour.
• the organic substrates melted and gave no evidence of aluminum deposition on their surfaces.
• the glass substrate showed no evidence of aluminum deposition even at 250 C.
• Example 4 In a dry nitrogen atmosphere, two strips of Mylar having a thickness of 0.002 inch were immersed in a 0.046 molar solution of TiCL; in diethyl ether, dried at room temperature, immersed in a diethyl ether solution of 0.266 molar solution in aluminum hydride and 0.005 molar in aluminum isopropoxide. The films were dried at room temperature and one film was exposed at ambient temperature to one megarad of high energy electron flow. A mirror-like aluminum plate was formed extremely rapidly on this substrate.
• the second strip of Mylar film used as control, and
• Example 5 In a manner similar to that of Example 1, a strip of Mylar film having a thickness of 0.002 inch was immersed into a 0.05 molar solution niobium pentachloride (NbCl in diethyl ether for about 5 seconds, dried, immersed in a diethyl other solution 0.3 molar in aluminum hydride and about 0.005 molar in aluminum isopropoxide for about 5 seconds and dried again. The treated film was then heated to about C. A uniform aluminum coating having a mirror-like appearance was almost immediately formed on the Mylar film.
• niobium pentachloride NbCl in diethyl ether for about 5 seconds
• an aluminum plating was formed on Mylar film by immersing the film in a 0.05 molar solution of zirconium tetrachloride in diethyl ether, drying the treated film, immersing the film in the aluminum hydride solution as above, drying the film and heating to a temperature of 80 C.
• Example 6 A strip of Mylar was coated with a thin layer of TICL; by exposing it to vapors of TiCl Immersion of the film thus treated in 0.2 molar aluminum hydride solution and subsequent heating of the film to 80 C. with infrared light yielded a shiny, adherent aluminum plate.
• solid TiOCl was suspended in mineral oil and applied to one side of an 0.002 inch thick Mylar film by brushing.
• Immersion of the film in 0.2 molar aluminum hydride solution in diethyl ether followed by exposure to infrared light yielded a mirror-like aluminum plate on the side of the film to which the catalyst had been applied.
• the uncatalyzed surface of the film was not plated with aluminum.
• Example 7 A design was drawn on a strip of Mylar film with a glass rod dipped in a 0.046 molar solution of TiCl in benzene. After evaporation of the benzene, the film was immersed in a diethyl ether solution 0.2 molar in aluminum hydride and 0.001 molar in aluminum isopropoxide. The film was then removed from the ether solution and heated to about 80 C. under an infrared lamp for 2 minutes. At the end of this time, aluminum was found to have plated only the area of the design originally made with the TiCl solution.
• Example 8 In a manner similar to that of Example 3, a strip of Mylar film having a thickness of 0.002 inch was immersed in a 0.3 molar aluminum hydride solution. The
• Example 9 In a dry nitrogen atmosphere, a strip of Mylar film 0.002 inch in thickness was dipped into a 0.046 molar solution of TiCl in n-hexane. The treated strip of film was dried under an infrared heat lamp and then dipped into a 0.3 molar solution of aluminum dihydride isopropoxide [AlH2(l-OC3H7)], in diethyl ether. The film was held under an infrared heat lamp for several minutes to produce a temperature of about 80 C. on the surface of the substrate. A uniform coating of aluminum was ob tained on the Mylar.
• Example 10 In a dry nitrogen atmosphere, a strip of Mylar film was immersed in a 0.046 molar solution of TiCL; in benzene and dried at about 80 C. A glass microscope slide was immersed in an 0.3 molar solution of aluminum hydride.
• Example 11 In a nitrogen filled dry box strips of various substrates were immersed in a solution of TiCl for about 1 second, dried, immersed in a solution of aluminum hydride in ether and then dried under various conditions. The following table shows the solvents and concentrations employed and the results obtained.
• Example 12 In a nitrogen filled dry box a strip of sanded magnesium metal was immersed in a benzene solution 0.4 molar in TiCL, for approximately 30-60 seconds, The above solution contained about 0.006 weight percent of sodium stearate.
• the catalyzed magnesium strip was dried, dipped in an 0.4 molar solution of aluminum hydride in diethyl ether and briefly dried on a hot plate at 150 C. A light coat of metallic aluminum was deposited on the treated magnesium surface in a few seconds.
• Example 13 In a dry nitrogen atmosphere, a strip of Mylar film was immersed in a 0.9 molar solution of TiCl in hexane to which 20 volume percent mineral oil had been added to increase the viscosity. This catalyst solution, due to its viscosity, deposited a heavier concentration of catalyst on the substrate than the less viscous catalyst solutions. The treated film was dried, immersed in a 0.3 molar solution of aluminum hydride in diethyl ether and heated to 80 C. An unusually heavy mirror coating of aluminum was produced on the surface of the substrate.
• Example 14 A strip of Mylar film was immersed in a 0.046 molar solution of TiCl in diethyl ether and dried. The catalyzed surface of the film was dusted with a fine powder of solid aluminum trihydride etherate and then heated to about 80 C. with an infrared lamp. A mirror-like adherent coat of metallic aluminum was substantially uniformly deposited on the catalyzed surface of the film.
• a process for the plating of aluminum from an aluminum hydride onto a substrate which comprises: contacting an aluminum hydride and a decomposition catalyst, in the presence of each other, with a substrate for a time sufiicient to deposit metallic aluminum onto said substrate, said decomposition catalyst being selected from the group consisting of compounds of the metals of Groups IVb and Vb of the Periodic Table and mixtures thereof.
• aluminum hydride contains two hydrogen atoms bonded directly to the aluminum.
• the decomposition catalyst is a member selected from the group consisting of ZrCl NbCl VOCl V001 TiCl -2[(C H O], TiCl TiBr V01 Ti(OC H Cl TiCl (i-OC H TiCl -2[(C H O], Ti(BH -2[(C H O] and mixtures thereof.
• a process for the plating of aluminum from an aluminum hydride onto a substrate which comprises applying to a substrate a decomposition catalyst selected from the compounds of the metals of Groups Nb and Vb of the Periodic Table and mixtures thereof subsequently contacting the catalyst-containing substrate with a solution of an aluminum hydride and maintaining contact between the aluminum hydride and the catalyst-containing substrate for a period suflicient to deposit metallic aluminum thereon.
• a decomposition catalyst selected from the compounds of the metals of Groups Nb and Vb of the Periodic Table and mixtures thereof subsequently contacting the catalyst-containing substrate with a solution of an aluminum hydride and maintaining contact between the aluminum hydride and the catalyst-containing substrate for a period suflicient to deposit metallic aluminum thereon.
• the decomposition catalyst is a member selected from the group consisting Of ZI'C14, NbCl VOClg, VOC13, TiCl TiBr V01 Ti(OC H Cl TiCl (i-OC H TiCl -2[(C H O], Ti(BH -2[(C H O] and mixtures thereof.
• a process for the plating of aluminum from an aluminum hydride onto a substrate which comprises (a) contacting a substrate with a solution containing at least 1X10- weight percent of a catalyst selected from the group consisting of compounds of the metals of Groups IVb and Vb of the Periodic Table and mixtures thereof,
• the aluminum hydride is LiAlH 42.
• the decomposition catalyst is a member selected from the group consisting of ZI'C14, NbCl VOC12, VOC13, 2 (C2H5 TiCl TiBr VCl Ti(OC H Cl TiCl (i-OC H 2 2 5)2 4)a 2 5)2 m xtures thereof.

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• 1966
  • 1966-06-20 US US558583A patent/US3462288A/en not_active Expired - Lifetime
• 1967
  • 1967-05-26 DE DE1967D0053175 patent/DE1621227B2/de active Granted
  • 1967-06-09 NL NL676708057A patent/NL146222B/xx unknown
  • 1967-06-14 GB GB27503/67A patent/GB1122359A/en not_active Expired
  • 1967-06-16 LU LU53900D patent/LU53900A1/xx unknown
  • 1967-06-19 BE BE700145D patent/BE700145A/xx unknown
  • 1967-06-19 CH CH866167A patent/CH496104A/de not_active IP Right Cessation

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