Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
  • C25F3/00—Electrolytic etching or polishing
  • C25F3/16—Polishing
  • C25F3/18—Polishing of light metals
  • C25F3/20—Polishing of light metals of aluminium

Definitions

• the invention relates to a polishing process for parts made of aluminum or aluminum alloys.
• Aluminum parts such as aluminum pressed or rolled profiles, are used, among other things, in the building hardware and lighting industry or in particular in motor vehicle construction with, for example, window frame systems or also as decorative frames, finishers and the like. Like. Used. It is also known to use parts made of aluminum or aluminum alloys that have a colored anodized surface. Here, the parts are generally subjected to a gloss treatment as a preliminary step before coloring (both in their own color and in color). A well-known glossy treatment of parts made of aluminum or aluminum alloy is the so-called “Brytal” process (cf. Wernick, Pinner "The surface treatment of aluminum 1969, page 84). However, it has been shown that chemically polished aluminum parts after the The Brytal process disadvantageously forms a glossy structure or orange peel, and this disadvantage also arises when using acidic glossy electrolytes.
• the present invention is based on the object of demonstrating a glossing process for parts made of aluminum or aluminum alloys, with which an optimal surface reflection or gloss effect of the parts can be generated.
• a method which, according to the invention, is characterized in that the parts in an alkaline electrolyte of the composition operated by means of direct current: Na3PO4 (trisodium phosphate) 120 g / l NA2CO3 (disodium carbonate) 330 g / l AlPO4 (aluminum phosphate) 10 g / l Extracts from beech wood 5 ml / l be treated at an operating temperature of around 70 - 80 o C.
• the particular advantage of this process consists in the generation of an optimal surface reflection or gloss effect of aluminum parts (profile strips or the like) for the production of colored and natural-colored, anodically produced anodized layers. This results in another significant advantage, a considerable reduction in reworking due to glossy defects.
• the parts preferably are subjected in the electrolyte of a 2-stage treatment, the parts vorgeglänzt in the first stage, at an operating temperature of about 80 o C and nachgeglänzt in the second stage, at an operating temperature of about 70 ° C.
• the electrolyte is therefore operated in two stages, pre-glossing and post-glossing, the two stages containing a similar composition and differing only in the operating temperature.
• the parts are exposed in the first treatment stage with a current density of approximately 3 A / dm2 and in the second treatment stage with a current density of approximately 1.5-2 A / dm2. Due to the higher operating temperature of the first stage, a higher material removal is achieved with a current density of 3 A / dm2.
• the parts are exposed for a total of about 18 minutes. It has proven to be particularly advantageous that the voltage applied is interrupted for about 2 to 10 seconds about one minute before the exposure time expires. It is hereby achieved that the gloss film formed during the shining is largely removed without etching the surface.
• a particularly advantageous development of the invention consists in that the electrolyte is filtered (continuously or discontinuously), that the filter cake formed is rinsed, and that the chemicals recovered in this form are returned to the electrolyte.
• This measure makes the method according to the invention particularly environmentally friendly, as is also a considerable reduction in costs with regard to landfill charges and direct discharges.
• the electrolyte can be filtered in particular by means of a chamber filter press.
• the parts are treated in a cathodically connected container made of structural steel, the parts being used as anodes. It can also be provided that a container equipped with heating and cooling devices is used. Finally, it is advantageous if a container is used which has an overflow leading to a filter station and an inlet coming from the filter station.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Treatment Of Metals (AREA)
• ing And Chemical Polishing (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6381453

Family Applications (1)

Country Status (4)

Families Citing this family (4)

Citations (4)

Family Cites Families (2)

• 1989
  • 1989-05-26 DE DE3917184A patent/DE3917184A1/de active Granted
• 1990
  • 1990-03-23 EP EP19900105559 patent/EP0399170A3/fr not_active Ceased
  • 1990-05-23 US US07/528,058 patent/US4995951A/en not_active Expired - Fee Related
  • 1990-05-28 JP JP2135540A patent/JPH0313595A/ja active Granted

Patent Citations (4)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events