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
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
  • C23C22/08—Orthophosphates
  • C23C22/18—Orthophosphates containing manganese cations

Definitions

• This invention relatesto a process of rustprooting iron articles and to the articles rustproofcd in this manner.
• the invention relates to producing on the surface of iron articles a coating of phosphates which are insoluble in Water, and to the articles coated in this manner.
• the ratio of the metal to phosphorus is a trifle greater than that which would result from the coating being one-half monohydrogen phosphate and one-half nor- With manganese forming about one-half of the metal in the coating, the proportion of metal in the coatingto phosphorus in the coating was found to mdicate a proportion of approximately 6/? normal phosphate and 1/7 monohydrogen phosphate. In the monohydrogenphosphate these atoms of metal and phosphorus are in 1926. semi No. 108,162.
• Normal phosphate is much less soluble than monohydrogen phosphate, and corrosion tests corroborate the analyses described above. That is, coatings comparatively high in manganese and apparently high in normal phosphate are found to be much more resistant to rusting than coatings. consisting largely of monohydrogen phosphate.
• proofing solution twenty to twenty-five pounds being the preferred amount.
• an iron article, or an article havlng asurface containing iron is immersed in such a solution, the formation of a, rust-proofing coating begins at once. There is no preliminary pickling of the work to bring the solution into balance, such as necessarily results where free acid is added to the bath and where iron must be dissolved from the work to bring the solution into balance, and the articles do not lose appreciably in weight or measurably in size. Nevertheless, in the process of forming the coating, a certain amount of the iron is dissolved in the bath.
• insoluble phosphates Some of this .is fixed as insoluble phosphates in coating, some of it forms insoluble phosphates which are deposited as art of it remains as ferrous dihydrogen p osphate dissolved in the bath. It will be readily understood that more of the phosphate radicals are in combination with a given amount of manganese in the dihydrogen phosphate than there are in the insoluble coating and, therefore, the phosphate introduced into the bath introduces sufficient phosphate radicals to form the phosphates of iron mentioned above.
• the bath If the bath is used continuously for rustproofing purposes for a considerable time, it constantly becomes less rich in manganese and richer in iron, reference being had to these materials dissolved in the bath in the form of dihydrogen phosphate.
• the bath is replenished by an additional amount of manganese phosphate, the proportion of manganese to 1ron is increased, but is not brought back to the proportion which it had originally.
• the proportion of iron in the bath continues'to increase until it reaches a certain percentage in proportion to the maximum acidity.
• the iron in the bath seems to remain approximately constant, whereas the manganese and acid are increased when constant iron content is replenished with manganese phosphate, it maybe easily brought up to a point where the manganese 4 will be more than half as much as the iron in the bath, but as this bath is used for" rust-proofing purposes the manganesemay be almost completely exhausted from the bath before the deposition of a coatingwill cease.
• the'coating last formed is principally ferrous monohydrogen phosphate.
• manganese in the bath may be kept above one-third as much as the iron, with a result of producing more normal phosphate than monohydrogen phosphate in the coating.
• the strength of the rust-proofing solution may be varied considerably and still rustproofeffectively.
• the amount of iron in the bath seems to be approximately relative to the maximum acidity of the bath, it is preferable to replenish the bath to bring it each time to approximately the same strength. In this way the proportion of'manganese to iron is increased to the highest practicable amount at. each replenishment.
• the bath should be kept as nearly as is practicable to the highest available proportion of manganese.
• the coating produced with a less percentage of manganese is entirely suflicient for the desired purposes, and in such cases less care is required in maintaining the bath with a uniformly high manganese content.
• Iron or steel or articles com osed or having asurface of iron or steel urnished with a coating or deposit of hosphates of iron and of manganese, there eing at least one-half as much manganese as iron in the coating.
• Iron or steel or articles com osed or having a surface of iron or steel rnished with a coating or deposit of phosphates of iron and of manganese, there being in the coating more than six atoms of the metal to five atoms of phosphorus.
• a method of rust-proofin articles of iron or having a surface of iron or steel which consists in forming a dilute solution of phosphoric acid and dihydrogen phosphates of iron and manganese, there being at least one-third as much manganese as iron in the solution and there being sufficient dihydrogen phosphates in the solution in proportion to the free acid to rustroof articles without reducing the weight thereof, placing iron or steel articles in the solution and maintaining the solution hot until ⁇ the articles are rust-proofed.
• the method of rust-proofing articlesof iron or having a surface of iron or steel which consists in forming a dilute solution of phosphoric acid and dihydrogen phosphates of iron and manganese, there being at least one-third as much manganese as iron in the solution and there being sufiicient dihydrogen phosphates in the solution in proportion to the free acid to rust-proof articles without reducing the weight thereof, placing iron or'steel articles in the solution and maintaining the solution hot until the articles are rust-proofed, introducing other articles into the bath and repeating the process and adding tothe solution from time to time materials which maintain the amount of manganese in the solution above one-third the iron in the solution.
• a solution for rust-proofing purposes containing dihydrogen phosphates of manganse and iron and free acid, the phosphates being in sufiicient amounts so as to rustproof an immersed iron article without significant loss of-weight and the manganese in the dissolved phosphates being more than one-third as much as the iron in the dissolved phosphates.

Landscapes

• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Treatment Of Metals (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)

Priority Applications (6)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22320651

Family Applications (1)

Country Status (6)

Cited By (1)

• 0
  • BE BE341226D patent/BE341226A/xx unknown
  • NL NL25645D patent/NL25645C/xx active
• 1926
  • 1926-05-10 US US108162A patent/US1639694A/en not_active Expired - Lifetime
• 1927
  • 1927-04-07 FR FR632342D patent/FR632342A/fr not_active Expired
  • 1927-04-14 DE DEP55036D patent/DE508785C/de not_active Expired
  • 1927-04-25 GB GB11035/27A patent/GB270679A/en not_active Expired

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