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
  • 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

Definitions

• compositions have been employed in the art for the purpose of inhibiting corrosion of metal surfaces in water-carrying systems.
• the most common inhibitors include polyphosphates, phosphonates and zinc.
• the instant invention is directed to a corrosion inhibiting admixture, comprising: (A) 10-90%, by weight, of a water-soluble orthophosphate compound, and (B) 10 to 90%, by weight, of a polyether.
• the instant invention is also directed to a method of inhibiting corrosion of steel in an aqueous system, comprising the step of treating the system with at least 0.1 ppm of an admixture comprising: (A) 10 to 90%, by weight, of a water-soluble orthophosphate compound and (B) 10 to 90%, by weight, of a polyether.
• the water-soluble orthophosphate compounds which are operable for the present purposes generally include phosphoric acid, sodium orthophosphates, the potassium orthophosphates, the lithium orthophosphates and ammonium orthophosphates.
• the following specific compounds may be mentioned as exemplary: H 3 PO 4 phosphoric acid, LiH 2 P0 4 lithium diacid phosphate, Na 3 PO 4 trisodium orthophosphate, Na 2 HPO 4 disodium orthophosphate, NaH 2 PO 4 monosodium orthophosphate, NaH 5 (PO 4 ) 2 hemisodium orthophosphate, K 3 PO 4 tripotassium orthophosphate, K 2 HP0 4 dipotassium orthophosphate, KH 2 PO 4 monopotassium orthophosphate, (NH 4 ) 3 PO 4 triammonium orthophosphate, (NH 4 ) 2 HP0 4 diammonium ortho phosphate, and (NH 4 )H 2 PO 4 monoammonium orthophosphate.
• the admixture should contain 10 to 90%, preferably 40 to 60%, by weight, of a water-soluble orthophosphate compound and 10 to 90%, preferably 40 to 60%, by weight, of a polyether.
• Any polyether may be used. Examples include polyalkylene oxide compounds, polyalkylene glycol, polyalkylene glycol acrylate, polyalkylene glycol methacrylate, and mono- and di-polyalkylene glycol maleate, fumate and itacomate. Also mixtures of polyethers formed from polyethylene oxide with other polyalkylene oxides, such as propylene or butylene oxide may be used.
• the polyether chain may be capped, with an alkyl, aralkyl, sulfonate or phosphonate group, or uncapped.
• the polyether preferably should have a weight average molecular weight of 1,000 to 50,000 as determined by light scattering.
• the polyether may also be copolymerized with acrylic acid or methacrylic acid.
• Zinc may also optionally be added to the admixture.
• the ratio of zinc to the above-described admixture should be 10:1 to 10:1.
• the admixtures are used in a minimum dosage of 0.1 ppm in inhibiting corrosion, preferably in a dosage of 1 to 500 ppm, and most preferably 1 to 200 ppm.
• the corrosion rate (mils per year) was determined for the corrosion inhibitors listed in Table 1 by the following method:
• the electrochemical cell used in these experiments consists of the coupon holder (working electrode); reference electrode (S.C.E.), counterelectrode (graphite rods) and aerator.
• Test coupons were presanded to 120 grit and rinsed with acetone before insertion into coupon holders. After the addition of inhibitor to test solutions, pH was adjusted to that of the particular medium under observation. There was no pretreatment of coupons at elevated dosages of inhibitor in any of these tests. Following twenty-four hours aeration at 50°C, the cell was analyzed electrochemically via potentio- dynamic control. Corrosion data are obtained from composite information from two types of tests: polarization resistance and Tafel plot.
• Corrosion current is then converted to a corrosion rate by the formula:

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

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• 1985
  • 1985-09-24 EP EP85401856A patent/EP0177406A3/de not_active Withdrawn

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