Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/42—Electroplating: Baths therefor from solutions of light metals
  • C25D3/44—Aluminium

Definitions

• the invention relates to an organometallic electrolyte for the electrodeposition of aluminum and the use of this electrolyte.
• Organometallic electrolytes ie organo-aluminum complex compounds (DE-PS 1 047 450), can be used for the galvanic deposition of aluminum.
• organo-aluminum complex compounds DE-PS 1 047 450
• a large number of compounds have been described which can be used for galvanic aluminizing, for example onium and alkali complex compounds.
• the complex salt NaF described as optimal has been used.
• 2 Al (C 2 H 5 ) 3 used ("Journal for inorganic and general chemistry", Vol. 283, 1956, pp. 414 to 424).
• the object of the invention is to provide an organometallic electrolyte for the electrodeposition of aluminum, which has a high scatterability but also a high conductivity and good solubility and is easily accessible commercially.
• the organoaluminum electrolyte according to formula (1) according to the invention proves to be extremely progressive in terms of electroplating, i.e. it fulfills the demands placed on electrolytes for a technically widely applicable and economical aluminizing process to a far greater extent than was previously possible.
• the electrolyte according to the invention namely has a high scattering capacity and, at the same time, electrical conductivity and solubility required for economical aluminizing, as well as good commercial accessibility. For the first time, it combines the electrotechnical properties relevant to electroplating. Another advantage is also that this electrolyte compared to NaF. 2 Al (C2H5) 3 has a significantly lower sensitivity to oxygen and moisture.
• the electrolyte according to the invention is based on knowledge which has been obtained on the one hand with regard to the relationships between the composition of organo-aluminum complex compounds and the electroplating requirements, such as scatterability, conductivity and solubility (in low-viscosity aromatic hydrocarbons which are liquid at room temperature and have low water absorption). These relationships were previously unknown.
• the metal ion is decisive for the scatterability, whereas the conductivity is influenced both by the metal ion and by the halogen ion and by the length of the alkyl radicals.
• the alkyl residues and the metal ion turn out to be particularly relevant for solubility.
• the electrolyte according to the invention is comparable to cadmium electrolytes in terms of scatterability in the field of electro-technical interest. For the first time there is the possibility to aluminize the same product range as for cadming. This creates the electro-technical prerequisite for replacing cadmium with aluminum as a corrosion protection coating.
• the electrolyte according to the invention is preferably used in the form of a solution.
• Aromatic hydrocarbons which are liquid at room temperature, such as toluene, are advantageously used as solvents, advantageously in the following composition: 1 mol of electrolyte salt per 1 to 10 mol, preferably 1 to 5 mol, of solvent.
• the same method can also be used to produce electrolytes with a different composition.
• the solvent-free electrolytes can also be produced in this way. To do this, however, it is necessary to carry out the reaction above the melting temperature of the respective electrolyte.
• the good scatterability of the electrolyte according to the invention is to be demonstrated on the basis of electroplating tests.
• a galvanizing cell in the form of a rectangular glass vessel (20 cm x 8 cm x 20 cm) was used to carry out the electroplating tests, and an Al anode plate was attached to each end. Since the aluminum electrolytes are sensitive to air and moisture, the electroplating cell was provided with a special cover that has several openings: for a thermometer, for a conductivity cell, for a gas transfer tube (for flooding the cell with nitrogen), for two stirrers (diagonally opposite in the corners of the cell in front of the anodes) and for charging the test specimens to be aluminized. Served as test specimens. Rectangular angle plates made of steel of a certain size. To determine the scatterability, the thickness of the aluminum layer deposited on the angle plates was determined by means of a layer thickness measuring device.
• test specimens were pretreated, as is customary in electroplating, ie pickled and degreased.
• the one on a Ka The test specimen attached to the test rod was first degreased using an organic solvent and pickled by immersion in dilute hydrochloric acid. Subsequently, the specimen was cathodically degreased and provided for improving adhesion with an approximately 1 / um thick nickel layer.
• the toluene-moist test specimen was introduced into the electroplating cell, ie into the electrolyte, and - as a cathode - arranged between the two anodes (cathode area: 2 dm 2 ; distance between anode and cathode: each about 10 cm).
• the electroplating was carried out at an electrolyte temperature of 100 ° C by means of a so-called pulse current (deposition voltage: + 10 V).
• the test specimens were alternately poled cathodically and anodically, the cathodic deposition time in each case 80 ms and the anodic deposition time in each case 20 ms.
• the known electrolyte NaF was examined. 2 Al (C2H5) 3 and, each in a commercially available form, a cadmium electrolyte (cyanidic), a zinc electrolyte (weakly cyanidic) and a nickel electrolyte (weakly acidic), with the last three electrolytes being galvanized using direct current.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electroplating And Plating Baths Therefor (AREA)
• Conductive Materials (AREA)
• Primary Cells (AREA)
• Sealing Battery Cases Or Jackets (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (4)

Family

ID=6153853

Family Applications (1)

Country Status (8)

Cited By (4)

Families Citing this family (18)

Citations (2)

Family Cites Families (2)

• 1982
  • 1982-01-25 DE DE19823202265 patent/DE3202265A1/de not_active Withdrawn
• 1983
  • 1983-01-13 DE DE8383100245T patent/DE3363841D1/de not_active Expired
  • 1983-01-13 EP EP83100245A patent/EP0084816B2/fr not_active Expired - Lifetime
  • 1983-01-13 AT AT83100245T patent/ATE20252T1/de not_active IP Right Cessation
  • 1983-01-18 JP JP58006551A patent/JPS58171591A/ja active Granted
  • 1983-01-24 CA CA000420127A patent/CA1209157A/fr not_active Expired
  • 1983-01-24 DK DK025183A patent/DK154657C/da not_active IP Right Cessation
  • 1983-01-25 US US06/460,817 patent/US4417954A/en not_active Expired - Lifetime
  • 1983-01-25 ES ES519248A patent/ES8403490A1/es not_active Expired

Patent Citations (2)

Also Published As

Similar Documents

Legal Events