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
  • C23C22/68—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 solutions with pH between 6 and 8
• • 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
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
  • C23F11/18—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using inorganic inhibitors
  • C23F11/185—Refractory metal-containing compounds

Definitions

• the present invention relates to a process for treating surfaces of certain metals to improve the corrosion resistance thereof by forming a rust-proof film on the metal surface by immersing the metals, especially steel and steel pipes, in certain molybdate solutions.
• rust-proofing processes have been practiced by immersing the metals in a chromate solution to prevent red rust from forming on cold-rolled steel plates during storage. While most prior rust prevention has been effected by chomate treating, metals so treated do not have satisfactory adherence with paints when painted thereafter.
• a process for rust-proofing steel comprising immersing the steel in an alkaline earth metal molybdate solution.
• the rust-proof film according to this treatment has comparatively good adhesive property with paints.
• the treatment is very easily conducted only by immersing a steel in a molybdate solution having a definite concentration at a definite temperature for an arbitrary time after the steel is subjected to degreasing and acid pickling if necessary.
• the concentration of magnesium molybdate solution and calcium molybdate solution is preferably within the range from 0.025 molar to 0.1 molar and proper temperature is within the range from the normal (room) temperature to 80 C.
• the film obtained in accordance with the present invention comprises y-Fe o Fe O Mo O (0H) M00
• the present invention may be applied to plain carbon steels, low alloy steels and high alloy steels, etc.
• Alkali molybdate solution is not proper for a molybdate solution because the corrosion resistance of a steel treated with alkali molybdate solution is not excellent.
• EXAMPLE 1 Cold-drawn steel plate is treated with a molybdate soludate solution by immersing it into a solution consisting of $5 molar of magnesium molybdate, calcium molybdate or sodium molybdate at 60 C. for such a time; as shown in 3,703,418 Patented Nov. 21, 1972 ice Table l which shows the results of immersion test and wetting test for such reagents.
• Wetting test was carried out by leaving samples of the plate in a tank maintained at a temperature of 50 C. and a humidity of 98% for 24 hours.
• Non-treated l 3 4. 04 C 1 Plate used in Example 2. 2 Hours. 8 Average for 3 sheets.
• EXAMPLE 2 Adherence with paint test is conducted on a non-treated steel plate, chromate treated steel plate which is commonly marketed, and the present invention steel plate.
• non-treated steel plate has bad corrosion resistance but is excellent in its adherence with paints. Therefore, such a steel is used as a sample in the test in order to show excellent adherence with paints.
• Steels subjected to surface treatment generally shows excellent corrosion resistance and bad adherence with paints. Therefore, chromate treated steel plate is used in the test in order to show bad adherence with paints.
• a non-treated :1 ste'elplate'and a steel plate treated alkali earth molybdate solution show substantially the same adherence, the latter is regarded as having good adherence.
• Sample steel plates are painted with baking type acr'ylate resin paint and baking type melamine resin paint with an ordinary method and baked. Then, steel plates thus obtained are tested by cross cut test, drawing test and impact test. In cross cut test, a hundred square incisions having an area of 1 mm. which is deep enough to reach the base plate, are made on the painted surface of the plates to be tested with a diamond needle. Adherence with paints is evaluated by the number of squares left not peeled oif.
• a diamond needle in contact with the painted surface of the plates to be tested is loaded at the end thereof with a weight of 700 g. placed on a scale, and the needle is rotated in such a way as to describe a circle having a definite diameter on the surface of the plates to be tested which is moved. In such a way, a continuous arc is described on the surface of the plates. Adherence with paints is evaluated based upon the observation of scratches made on the surface of the plates.
• Impact test is conducted with an impact tester with 12.5 mm. in diameter of an impact area, load of 300 g. and a height of 500 mm. Elasticity and adherence of paints are evaluated based upon the results of the impact test.
• the present method comprises immersing metals, especially steel plates and steel pipes into alkali earth metal molybdate solution, whereupon a rust-proof film such as a molybdenum compound is produced on the surface of the metals.
• a rust-proof film such as a molybdenum compound is produced on the surface of the metals.
• the corrosion resistance is increased, and rust-proofing is improved.
• a greater immersion of cold-rolled steel plate into the molybdate solution shows clearly a rust-proof effect.
• the plates or pipes thus treated have excellent adherence with paints, so that this treatment can also be applied as an undercoating for painted metal surfaces.
• the present invention is applicable on an industrial scale.
• steel plate treated with an alkali earth metal molybdate solution has excellent corrosion resistance as shown in Ex-

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

Applications Claiming Priority (1)

Publications (1)

Family

ID=13562347

Family Applications (1)

Country Status (4)

Cited By (3)

Families Citing this family (2)

Family Cites Families (1)

• 1966
  • 1966-11-16 JP JP41074959A patent/JPS512419B1/ja active Pending
• 1967
  • 1967-11-14 GB GB51815/67A patent/GB1180951A/en not_active Expired
  • 1967-11-16 FR FR1554777D patent/FR1554777A/fr not_active Expired
• 1970
  • 1970-12-31 US US103339A patent/US3703418A/en not_active Expired - Lifetime

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