Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
  • C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling

Definitions

• Castings of such alloys are almost invariably contaminated with the ingredients of the moulding composition particularly .core compositions, which become attached to or embedded in the surface of the casting. This contamination is difficult to remove and consequently it has been common practice to clean the casting by sand blasting or shot blasting.
• this procedure is effective in cleaning the casting from the moulding composition contaminants, the resultant casting is found to have considerably less resistance to corrosive action than castings which are cleaned by strong chemical agents or by machining, both of which are in many cases undesirable for various reasons.
• the casting is subjected with its moulding contaminants thereon to anodic treatment whilst immersed in an aqueous solution of ammonium fluoride (NH4F or NH4F.HF) in quantity at least two percent ammonium fluoride by weight of the water, and continuing the treatment until current flow is substantially stopped automatically.
• aqueous solution of ammonium fluoride NH4F or NH4F.HF
• the solution may contain ammonium fluoride from 2 percent up to the quantity representing the limit of solubility together with ammonia in quantity corresponding to 5-15 of aqueous ammonia solution of .880 specific gravity.
• the casting to be treated is made the anode in an electrical circuit supplied with D. C. or A. C. current.
• the time of treatment depends on various factors such as current density and the degree of contamination of the casting, and may take from half a minute or less for fairly clean castings and up to thirty minutes or more for badly contaminated castings. The time of treatment will however usually be at least fifteen minutes.
• the electrolyte was prepared by adding to a bath of water 10% by weight of ammonium bi-fluoride and 10% of an aqueous solution of ammonia of .880 specific gravity.
• the castings were suspended in this electrolyte by means of magnesium clamps which were made the anode in an electrical circuit which included a source of D. C. current supply of volts.
• the voltage fell to 5 and the current density was about 5 amps. per square foot of casting.
• the cur-rent density fell to a few microamps and the voltage rose to 80.
• the current was then switched 01f and the castings removed and rinsed in running water and were found to be completely free from burnt-on and embedded mould and core compositions.
• a method of cleaning castings of magnesium base alloys having mould contaminants in the surface thereof which comprises removing said mould contaminants thereon by subjecting the said casting to anodic treatment whilst immersed in an aqueous solution consisting of ammonium fluoride, said ammonium fluoride being selected from the group of fluorides consisting of NH4F and NH4F.HF, said aqueous solution containing in quantity at least two percent ammonium fluoride by weight of the water.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10312293

Family Applications (1)

Country Status (6)

Cited By (7)

Citations (5)

• 0
  • NL NLAANVRAGE7607736,A patent/NL170633B/xx unknown
  • BE BE512440D patent/BE512440A/xx unknown
  • NL NL94743D patent/NL94743C/xx active
• 1951
  • 1951-07-04 GB GB15857/51A patent/GB721445A/en not_active Expired
• 1952
  • 1952-06-20 FR FR1058578D patent/FR1058578A/fr not_active Expired
  • 1952-06-30 CH CH307338D patent/CH307338A/fr unknown
• 1954
  • 1954-05-06 US US428120A patent/US2766199A/en not_active Expired - Lifetime

Patent Citations (5)

Also Published As

Similar Documents