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
  • C23C16/56—After-treatment
• • 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
  • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
  • C23C10/18—Solid state diffusion of only metal elements or silicon into metallic material surfaces using liquids, e.g. salt baths, liquid suspensions
  • C23C10/20—Solid state diffusion of only metal elements or silicon into metallic material surfaces using liquids, e.g. salt baths, liquid suspensions only one element being diffused
• • 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
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
  • C23C2/12—Aluminium or alloys based thereon
• • 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
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/02—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using non-aqueous solutions

Definitions

• This invention relates to an aluminum plating process and more particularly it concerns a process for forming an excellent aluminum film on a substrate by contacting a heated substrate with an alkyl aluminum compound to cause thermal decomposition of said alkyl aluminum compound.
• a substrate covered with aluminum means a substrate which has been covered with aluminum produced by thermal decomposition of an alkyl aluminum compound caused by contact of a heated substrate with alkyl aluminum compound, but which has not yet been taken out into the air.
• K. Ziegler et al. invented a method for plating a substrate with aluminum by contacting a heated substrate with a liquid alkyl aluminum compound or with vapor of an alkyl aluminum compound to cause thermal decomposition of said alkyl aluminum.
• a liquid alkyl aluminum compound or with vapor of an alkyl aluminum compound to cause thermal decomposition of said alkyl aluminum.
• the inventors have found a method where said drawbacks of the conventional aluminum film are eliminated.
• the object of this invention is to provide a method for plating a substrate with aluminum to obtain an aluminum film having no cracks and pinholes, a uniform thickness and an excellent surface luster by contacting the substrate covered with aluminum with a small amount of a surface treating agent selected from active hydrogen-containing compounds, oxygen and halogens and thereafter taking out thus treated substrate into the Other objects will be apparent from the following descriptions.
• Alkyl aluminum compounds used in this invention include any alkyl aluminum compounds capable of depositing aluminum by thermal decomposition. Among them, the following are preferable because they are easily thermally decomposed and are economical. That is, di-
• alkyl aluminum hydrides trialkyl aluminums having alkyl groups containing 2-20 carbon atoms such as triethyl aluminum, diethyl aluminum hydride, trinormalpropyl aluminum, triisopropyl aluminum, trinormalbutyl aluminum, dinormalbutyl aluminum hydride, triisobutyl alumium, diisobutyl aluminum hydride, trinormalbenzyl aluminum, trinormalhexyl aluminum, trinormaloctyl aluminum, tri-2-ethylhexyl aluminum hydride and tridecyl aluminum, or mixtures thereof.
• triethyl aluminum diethyl aluminum hydride
• trinormalpropyl aluminum triisopropyl aluminum
• trinormalbutyl aluminum dinormalbutyl aluminum hydride
• triisobutyl alumium diisobutyl aluminum hydride
• trinormalbenzyl aluminum trinormalhexyl aluminum
• trinormaloctyl aluminum tri-2-ethylhexy
• alkyl aluminum compound may be used together with compounds such as alkali metal compounds, ethers, tertiary amines, quaternary ammonium salts, etc. which are capable of producing a complex compound with the alkyl aluminum compound and which are mentioned in U.S. Pats. 3,154,407 and 3,273,996.
• the alkyl aluminum compound may be used in admixture with inert organic solvents, such as hexane, heptane, octane, cyclopentane, cyclohexane, benzene, toluene, xylene, petroleum, paraffin, alkyl benzene, diphenyl, etc.
• inert organic solvents such as hexane, heptane, octane, cyclopentane, cyclohexane, benzene, toluene, xylene, petroleum, paraffin, alkyl benzene, diphenyl, etc.
• Substrates to be plated are, for example, metals such as iron, steel, aluminum, copper brass, pottery, glass, or-
• the substrate is preferably cleaned prior to formation of aluminum film.
• the substrate is heated to a temperature higher than the thermal decomposition temperature of alkyl aluminum compound, preferably of 300-600 C. and is contacted with a plating solution or plating vapor.
• the substrate may be heated by known methods and resistance heating, induction heating, etc. may be employed depending upon kind and shape of the substrate.
• the induction heating is preferable for continuous heating of especially thin metal sheet.
• a method which comprises contacting a heated substrate with a liquid alkyl aluminum compound or a method which comprises contacting a heated substrate with vapor of alkyl aluminum compound may be used. Election of one of these methods is determined depending upon 'kind and shape of the substrate to be plated.
• the substrate may be covered with aluminum by thermal decomposition of an alkyl aluminum compound on a substrate by one time heating or by intermittent thermal decomposition due to two or more beatings. The latter is especially preferable.
• the thermal decomposition may be carried out in the presence of a compound capable of accelerating the thermal decomposition such as titanium chloride, titanium bromide, vanadium chloride, iron chloride, copper chloride, etc. which are mentioned in US. Pat. 3,306,732. Addition of such compounds is useful especially for plating a substrate of low heat stability.
• the thermal decomposition is required to be carried out in an inert atmosphere, but no critical limitation is present in pressure for operation.
• Examples of the surface treating agent to be contacted with substrate covered with aluminum in this invention are oxygen, halogens such as chlorine, fluorine and bromine and active hydrogen-containing compounds having at least one substitutable hydrogen such as water; ammonia; primary or secondary amine compounds such as dimethyl amine, monobutyl amine, etc.; sulfides such as hydrogen sulfide, ethyl thioalcohol, dodecyl thioalcohol, etc.; monoor polyhydric alcohols such as methanol, ethanol, isopropyl-alcohol, butanol, ethylene glycol, propylene glycol, glycerine, etc.; carboxylic acids such as acetic acid, naphthenic acid, stearic acid, adipic acid, maleic acid, phthalic acid, etc.; and inorganic acids such as hydrogen chloride, hydrogen fluoride, hydrogen bromide, nitric acid, etc.
• Said active hydrogen-containing compounds are used as a solution which contains 1'010,000 p.p.m., preferably IUD-1,000 p.p.m. (weight basis) of said active hydrogencontaining compound dissolved in aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene, alkylbenzenes, etc., aliphatic hydrocarbons such as pentane, hexane, octane, decene, etc. and mixtures thereof or as an atmosphere of the active hydrogen-containing compound of 0.01-20 mm. Hg, preferably 01-10 mm. Hg. In case of the latter method, the atmosphere is usually diluted with an inert gas and the method is operated under normal pressure or higher pressure. When the amount of the active hydrogen-containing compound is less than or more than the above range, the surface of aluminum film is not effectively improved.
• aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene,
• Oxygen is used as a solution which contains 10,000 p.p.m. (weight basis), preferably IOU-1,000 ppm. of oxygen dissolved in aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene, alkyl benzenes, etc., aliphatic hydrocarbons such as pentane, hexane, octane, decene, etc. and mixtures thereof or as an atmosphere containing oxygen of 001-100 mm. Hg, preferably 0.1- 80 mm. Hg.
• aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene, alkyl benzenes, etc.
• aliphatic hydrocarbons such as pentane, hexane, octane, decene, etc. and mixtures thereof or as an atmosphere containing oxygen of 001-100 mm. Hg, preferably 0.1- 80
• Halogens are used as an atmosphere of halogen gas of 001-20 mm. Hg, preferably 01-10 mm. Hg or as a solution containing l02,000 p.p.m (weight basis) dissolved in a suitable solvent such as paraffins.
• the surface treating agent When the surface treating agent is contacted in vapor phase, it is preferable to contact the substrate covered with aluminum with the surface treating agent diluted with an inert gas under normal pressure or higher pressure, instead of using the gas of the surface active agent as it is.
• ISaid treatment is generally carried out at 0-300 (3., preferably of 200 C.
• the method of this invention provides the following advantages as compared with the conventional method according to which a substrate covered with aluminum is taken out into the air without treatments of this method. That is, since oxidation which occurs when the substrate covered with aluminum is taken out into the air without treatments of this method can be prevented, aluminum film formed on the substrate has no cracks and pin-holes on its surface, has a uniform thickness and exhibits excellent surface luster.
• the substrate plated with aluminum in accordance with this invention has high corrosion resistance and oxidation resistance at a high temperature and excellent electric characteristics.
• the substrate can be subjected to metal surface treatment, such as sealing treatment, stabilization treatment and alumite finishing. Because of these excellent characteristics of the aluminum film, the industrial value is extremely great.
• EXAMPLE 1 A steel sheet of 50 mm. x 50 mm. x 0.6 mm. was dipped in a 0.5 weight percent aqueous hydrofluoric acid solution at room temperature for 15 seconds, then was washed with water and subsequently with alcohol and then dried. Thus treated steel sheet was used as a specimen.
• Said specimen was heated to 400 C. in argon atmosphere and thereafter was dipped in 500 cc. of an alkyl aluminum solution comprising 81% by weight of diisobutyl aluminum hydride, 11% by weight of diethyl aluminum hydride, 5% by weight of triisobutyl. aluminum and 3% by weight of triethyl aluminum at C. After lapse of one minute, the specimen was withdrawn from the solution and maintained in argon atmosphere at C. for 10 minutes to wash away the deposited alkyl aluminum. Said treatment was repeated further 3 times to form aluminum film on the steel sheet.
• the specimens were treated with hexane containing 0.01% by weight of ethanol, hexane containing 0.02% by weight of acetic acid, hexane containing 0.04% by weight of monobutyl amine, and hexane containing 0.08% by weight of dodecyl thioalcohol, respectively and were taken out into the air.
• Each steel sheet having aluminum film had excellent luster of silver white color and good surface properties.
• Acid resistance test was also efiected to these specimens to observe no generation of bubbles even after lapse of 40 minutes and no change in the surface of the film.
• EXAMPLE 2 The same specimen as in Example 1, which was washed in the same manner as in Example 1 was used used in this example.
• the specimen was pre-heated to 500 C. and was dipped in an alkyl aluminum solution having the same compositions as in Example 1 heated to 200 C.
• the treatment was carried out in argon atmosphere as in Example 1. After lapse of one minute, the specimen was withdrawn and washed with 500- cc. of hexane. Then, the specimen was contacted with 500 cc. of hexane containing 0.01% by weight of water at 20 C. for one minute and thereafter taken out into the air.
• the thus obtained steel sheet plated with aluminum had a luster of silver white color and good surface properties.
• the average thickness of the aluminum film was 2.1 determined by the amount increased.
• Said steel sheet was also subjected to the same acid resistance test as in Example 1 and no bubbles were generated even after lapse of 10 minutes.
• EXAMPLE 3 A steel sheet of 50 mm. x 50 mm. x 0.6 mm. was dipped in a 0.5 weight percent aqueous hydrofluoric acid solution at room temperature for 15 seconds, then was Washed with water and subsequently with alcohol and then dried. Thus treated sheet was used as a specimen.
• steel sheet plated with aluminum had an excellent luster of silver white color and good surface properties.
• the steel sheet was surrounded by solid parafiin in a width of 10 mm. around the sheet and dipped in 500 cc. of 25 weight percent aqueous nitric acid solution at 20 C. to carry out an acid resistance test. As the result, even after lapse of 40 1nin utes, no bubbles were generated and no change in the aluminum film surface was observed. The average thickness of the film was 1.9 determined by increase in the weight.
• EXAMPLE 4 The same specimen as in Example 3, which was washed in the same manner as in Example 3 was used in this example. This specimen was pre-heated to 500 C. and dipped in an alkyl aluminum solution having the same compositions as that of Example 3, which was heated to 200 C.
• the treatment was carried out in argon atmosphere as in Example 3. After lapse of one minute, the specimen was withdrawn from the alkyl aluminum solution and washed with 500 cc. of hexane. Then, said specimen was contacted with argon atmosphere containing chlorine gas of 1 mm. Hg for one minute and thereafter, taken out into the air.
• the thus obtained steel sheet plated with aluminum had a luster of silver white color and good surface properties.
• the average thickness of the aluminum film was 2.1 1 determined by increase in the weight. This steel sheet was subjected to the same acid resistance test as in Example 3 and no bubbles were generated even after lapse of 10 minutes.
• the improvement which comprises contacting the substrate covered with aluminum produced by the thermal decomposition of said alkyl aluminum compound and before exposure to air but after the thermal decornposition process, with a surface treating agent selected from the group consisting of a solution containing 10,000 p.p.m. of an active hydrogen-containing compound, a gas atmosphere containing the active hydrogen-containing compound of 001- mm. Hg, a solution containing 1010,000 p.p.m. of oxygen, a gas atmosphere containing oxygen of 001-100 mm. Hg, a solution containing 10- 2,000 p.p.m. of a halogen and a gas atmosphere containing a halogen of 001-20 mm. Hg, at a temperature from 0 to 300 C.
• alkyl aluminum compound is selected from dialkyl aluminum hydride, trialkyl aluminum having alkyl groups containing 220 carbon atoms and mixtures thereof.
• the active hydrogen-containing compound is selected from the group consisting of Water, ammonia, primary and secondary amine compounds, sulfides, monoand poly-hydric alcohols, carboxylic acids, and inorganic acids.
• a method according to claim 4, wherein the primary and secondary amine compounds are selected from the group consisting of dimethyl amine, and monobutyl amine.
• sulfide is selected from the group consisting of hydrogen sulfide, ethyl thioalcohol, dodecy thioalcohol.
• a method according to claim 4, wherein the monoand poly-hydric alcohols are methanol ethanol, isopropylalcohol, butanol, ethylene glycol, propylene glycol and glycerine.
• carboxylic acid is selected from the group consisting of acetic acid, naphthenic acid, stearic acid, adipic acid, maleic acid and phthalic acid.
• inorganic acid is selected from the group consisting of hydrogen chloride, hydrogen fluoride, hydrogen bromide and nitric acid.
• halogen is selected from chlorine, fluorine and bromine.
• the surface treating agent is an active hydrogen-containing compound dissolved in an aromatic hydrocarbon, aliphatic hydrocarbon or a mixture thereof.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Chemically Coating (AREA)
• Chemical Treatment Of Metals (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

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Cited By (4)

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• 0
  • BE BE758112D patent/BE758112A/xx unknown
• 1970
  • 1970-10-26 US US84188A patent/US3674541A/en not_active Expired - Lifetime
  • 1970-10-28 GB GB1294985D patent/GB1294985A/en not_active Expired
  • 1970-10-28 SE SE7014568A patent/SE374140B/xx unknown
  • 1970-10-28 FR FR7038913A patent/FR2066673A5/fr not_active Expired
  • 1970-10-28 CA CA096,787A patent/CA944633A/en not_active Expired
  • 1970-10-29 DE DE2053242A patent/DE2053242C3/de not_active Expired
  • 1970-10-29 NL NL707015887A patent/NL143624B/xx unknown

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