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
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
  • C23G1/04—Cleaning or pickling metallic material with solutions or molten salts with acid solutions using inhibitors
  • C23G1/06—Cleaning or pickling metallic material with solutions or molten salts with acid solutions using inhibitors organic inhibitors
  • C23G1/061—Cleaning or pickling metallic material with solutions or molten salts with acid solutions using inhibitors organic inhibitors nitrogen-containing compounds

Definitions

• One object of the present invention is to provide a pickling solution, the use of which decreases the metal loss and also the quantity of acid used during the pickling operation. Another object is to provide a solution that will not deleteriously alfect the metal, i. e. the metal upon removal from the bath Will not have turned gray or become pitted by immersion or other treatment in the pickling bath. A further object of the invention is to prevent the embrittlement of the metal which ordinarily results from the pickling operation. Embrittlement, which seriously afiects the quality of the metal, is caused by the absorption by the metal of a portion of the hydrogen evolved by the action of the acid on the metal.
• aromatic nitriles have the property of efliciently inhibiting or minimizing the solvent action of acids, particularly inorganic acids such as sulfuric or of acid sulfates on iron, steel and other metals, and do not deleteriously affect the metals undergoing treatment.
• aromatic nitriles may in clude all compounds having the general form ula RON, in which R represents an aromatic radical.
• Benzo nitrile and its homologues such as toluo or xylonitrile, or alpha naphthonitrile, beta naphthonitrile, or any mixtures of these two isomeric nitriles or other aromatic nitriles may be used.
• a naphthonitrile and more par ticularly alpha naphthonitrile is added to the pickling bath or the pickling bath formed to contain this compound.
• Pure alpha naphthonitrile melts at 37.5 C. and boils at 299 C.
• aromatic nitriles can be formed by melting the alkali salts of the aromatic sulfonic acid with the corresponding alkali cyanide, and naphthonitriles can therefore be synthesized by fusing the sodium salts of naphthalene sulfonic acid with sodium cyanide to form the naphthonitrile and sodium sulfite as indicated below:
• the pickling bath is preferably made by mixing .0270 by volume of the aromatic mtrile, preferably alpha naphthonitrile, with 5% sulfuric acid (by weight).
• the presence of the nitrile in the pickling bath results in an economy in the acid consumption; substantially prevents the dissolution of the iron, steel or other metal undergoing treatment, and embrittlement is reduced to a minimum.
• Test pieces of soft steel measuring x x 3" were immersed for 30 minutes in 5% sulfuric acid containing naphthonitrile and in 5% sulfuric acid containing no inhibitor, both tests being conducted at 160 F. The test ieces were then removed from the pickling aths, washed, dried and weighed. The metal I losses in grams are tabulated below:
• Naphthonitrfle 5% acid It will be noted that in every case the use of the naphthonitrile inhibitor caused a substantial saving of metal and consequently also efi'ected an economy in the acid consumption. In other words, the acid which functions to dissolve the metal when no inhibitor is used will be beneficially utilized when an inhibitor is used to dissolve rust or scale. Metal loss increases with increasing temperature of P101:-
• the metal loss is apprecia 1y greater than that quoted above if the specified proportion of .2 cc. of the nitrile per liter of 5% sulfuric acid is used. In this case it is desirable to double the proportion of inhibitor, thereby reducing the metal loss to a satisfactory degree.
• a pickling bath for metals comprising an inorganic acid and an aromatic nitrile.
• a pickling bath for metals com rising approximately 5% sulfuric acid an naththonitrile.
• a pickling bath for iron or steel comprising approximately 5% sulfuric acid and alpha naphthonitrile.
• a pickling bath for iron or steel comprising approximately 5% sulfuric acid and approximately .02% by volume of alpha naththonitrile.
• a substantially non-iron dissolving solution comprising sulfuric acid and naph- I

Landscapes

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

Priority Applications (4)

Applications Claiming Priority (1)

Publications (1)

Family

ID=23228688

Family Applications (1)

Country Status (4)

Cited By (2)

Families Citing this family (2)

• 1928
  • 1928-10-31 US US316350A patent/US1759840A/en not_active Expired - Lifetime
• 1929
  • 1929-10-11 GB GB30932/29A patent/GB334418A/en not_active Expired
  • 1929-10-15 DE DEB146217D patent/DE522922C/de not_active Expired
  • 1929-10-17 FR FR683470D patent/FR683470A/fr not_active Expired

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