Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/04—Anodisation of aluminium or alloys based thereon
  • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
  • C25D11/10—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing organic acids
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/04—Anodisation of aluminium or alloys based thereon
  • C25D11/14—Producing integrally coloured layers

Definitions

• This invention relates to a method of anodising aluminium and its alloys in order to produce hard and coloured coatings using an electrolyte incorporating a first acid selected from dibasic and polybasic organic acids other than oxalic acid with the addition of either glyoxylic or oxalic acid.
• This invention relates to a method of anodising aluminium and its alloys.
• aqueous solutions of other organic dibasic or polybasic acids are used as the electrolyte then in general only thin anodic coatings are produced the thickness of such coatings being roughly proportional to the applied voltage.
• aqueous solutions of certain dibasic or polybasic organic acids instead of forming an anodic coating aqueous solutions of certain dibasic or polybasic organic acids produce pitting of aluminium anodes under an applied potential.
• a method of anodising aluminium and its alloys in which the anodising operation is carried out in an electrolyte comprising a first acid selected from dibasic and polybasic organic acids other than oxalic acid with the addition of a second acid different from said first acid and selected from oxalic acid and glyoxylic acid,
• the first acid is selected from the group consisting of malonic acid, tartaric acid, citric acid, diglycollic acid, malic acid, succinic acid, glutaric acid, itaconic acid, maleic acid, pyromellitic acid, trimellitic acid, citraconic acid, thiomalic acid, thiodiglycollic acid, acetylene dicarboxylic acid, aconitic acid, glyoxylic acid and phthallic acid.
• glyoxylic acid is to be considered as a dibasic acid.
• the first acid may be a solution having a concentration ranging from 1% to saturation and the amount of the second acid incorporated in the electrolyte may vary between 0.1% and 10% by weight of the first acid.
• malonic acid-oxalic acid electrolyte and the malonic acid-glyoxylic acid electrolyte each afford much more abrasion-resistant coatings than other processes used for architectural anodising and hard anodising.
• Thickness Specific 1 Voltage of coatin abrasion Electrolyte range Colour of coating (microns resistance 8% sulphuric acid 19-20 Silver 2-35 2.0 6% tartaric+1.5% oxalic 100-130 Brown-grey 20 7. 5 5% tartaric-W3 oxalic- 110-155 Medium grey- 20 6. 5% citric+1.5% oxalic -104 Greenish-yellow 25 6.9 5% citric+0.3% oxalic -180 Grey-brown. 15 8. 3 5% itaconic+1.5% oxalic" -150 Grey 25 6.9 5% maleic+1.5% oxalic. 92-130 Grey-bronze. 27 8.1 5% malic+1.5% oxalic.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Printing Plates And Materials Therefor (AREA)
• ing And Chemical Polishing (AREA)
• Electroplating And Plating Baths Therefor (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10463565

Family Applications (1)

Country Status (4)

Cited By (3)

Citations (2)

• 1965
  • 1965-12-09 GB GB52347/65A patent/GB1173597A/en not_active Expired
• 1966
  • 1966-12-05 US US598933A patent/US3472744A/en not_active Expired - Lifetime
  • 1966-12-07 DE DE19661496722 patent/DE1496722A1/de active Pending
  • 1966-12-08 FR FR86653A patent/FR1505681A/fr not_active Expired

Patent Citations (2)

Also Published As

Similar Documents