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
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/30—Fluxes or coverings on molten baths
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12785—Group IIB metal-base component
  • Y10T428/12792—Zn-base component
  • Y10T428/12799—Next to Fe-base component [e.g., galvanized]

Definitions

• ABSTRACT Low-fuming galvanizing fluxes are provided which exhibit superior fluxing activity and which contain zinc chloride or zinc bromide and a zinc phosphate or zinc phosphite as the active agents.
• Galvanizing fluxes of this invention may also contain a small amount of a foaming agent and the chloride or bromide of sodium, potassium, lithium, magnesium and/or calcium.
• a top flux and possibly even a preflux is employed in the galvanizing of metal articles.
• Such fluxes traditionally contained ammonium chloride or some ammonium halide at a high concentration (greater than 9 percent) to aid in the effective cleaning and wetting of the surface of the article to be galvanized.
• such expedients promoted the fluidity of the flux and effectively stirred the flux mixture via sublimation or the evolution of decomposition products.
• the use of fluxes containing such agents allows a continuous, adherent film of zinc, substantially free of pinholes and other imperfections to be deposited on the surface of the substrate tobe galvanized.
• the galvanizing fluxes of this invention may also contain a small amount of a foaming agent and/or the chloride or bromide salt of sodium, potassium, lithium, magnesium and/or calcium.
• Small amounts of ammonium halide, preferably ammonium chloride or ammonium bromide, most preferably ammonium chloride may also be used in the fluxes of this invention without the detriment heretofore attendant upon its use.
• the unique fluxes of this invention retain their effectiveness notwithstanding quite broad variation in their composition.
• the fluxes of this invention must contain either a zinc phosphate or zinc phosphite and zinc chloride or zinc bromide as an adjuvant, preferably zinc chloride. While the amounts of these essential agents in the flux composition may be varied widely, preferably from about to about parts by weight of the zinc chloride or bromide and about 3 to about 15 parts by weight of the zinc phosphate or zinc phosphite are employed.
• the zinc phosphate is a zinc orthophosphate, a zinc triphosphate, a zinc metaphosphate, a zinc pyrophosphate or a zinc ammonium phosphate compound.
• suitable phosphates include ZN2P207 Any suitable zinc phosphite may also be employed.
• the galvanizing flux will contain preferably from 80 to 100 parts by weight of the desired admixture.
• the amounts of the chloride or bromide salts of sodium, potassium, lithium, magnesium and/or calcium which are employed must be such that an admixture of the zinc chloride or zinc bromide with one or more of the salts will be completely molten at the operatingtemperature of the bath.
• compositions contain from 20 to 60 parts by weight of the chloride or bromide salt of sodium, potassium, lithium, magnesium and/or calcium and 40 to 80 parts by weight of the zinc chloride and/or zinc bromide and are completely molten at temperatures of from about420 to 425C, most preferably 421C.
• foaming agent or surfactant or stabilizer
• concentrations of from to about 0.5 part by weight of the foaming agent are used.
• Any suitable foaming agent which acts to stadiamino naphthalene, 1,3, 6-hexane triamine, propylene triamine, 1,2,3-benzene triamine, 2,6-diamino pyridine and the like and mixtures thereof.
• an ammonium halide such as ammonium chloride and/or ammonium bromide and the like, preferably ammonium chloride is used but only at concentrations of from 0 up to a maximum of about 5 parts by weight.
• the decomposition rate of the ammonium halide at such low concentrations is very slow and only a negligible amount of decomposition takes place at any given time.
• the effectiveness of the ammonium halide at such low concentrations is primarily limited to the initiation of' the activity of the flux at the start-up of v fluxing operations after which the zinc phosphate or zinc phosphite compound takes overas the active ingredient.
• any of the various embodiments of this invention may be combined in any given ates efficiently and effectively without the noxious fumes of commercial ammonium chloride containing fluxes and without the less than excellent results which attend the use of prior art fluxes containing no ammonium chloride or else only low concentrations of the ammonium compound.
• the fluxes of this invention are advantageously em ployed whether the bath metal is zinc, as in conventional galvanizing, a zinc alloy or even an alloy such as Su-Pb which is used in terne coatingl
• articles of any desired shape can be coated with the bath metal using the fluxes'of this invention as discussed, for example, in Hat-Dip Galvanizing Practice, William H. S'powers, Jr., The Penton Publishing Company, Cleveland, Ohio, 1938, pp. 32-70.
• the instant fluxes are most advantageous for the coating of ferrous and tin articles.
• the first method utilizes a Brookfield viscometer, model LVT, modified to measure viscosities of fluxes at elevated temperatures by the insertion of an adaptor between the spindles and the meter to provide thermal insulation.
• the adaptor which is tubular in shape, constructed of heat resistant cloth reinforced phenolic resin, measures 1% L X /2 OD X 54; lDand weighs 4.2
• Viscosity Summary Table of Examples Example ZnCl NaCl KCl NH ZnPO n;1(PO,) ,'2H O Zn;1(PO NH,CI PET" Viscosity l 100 5 I cps 2 99 5 l 0.3 5 sec 3 79 5 1 0.2 20 sec 4 I00 5 5 0.3 2 sec 5 I00 5 5 5 sec- 6 I00 l5 5 0 l 20sec 7 99 3 25'5 cps '8 100 3 3 0.2 S sec 9 )9 31 23 7 25 cps It) 100' I 3i 23 7 5 0.l 2 sec 1 l 90 20 7 3 0.1 5 sec cps units indicate measurement by Method l; sec (seconds) units indicate measurement by Method 2 flux composition as desired, or all of the embodiments grams.
• the adaptor is pushed over the serrated tip of may be employed simultaneously as desired. No matter how the flux compositions of this invention are varied; it has been found that the resulting composition operthe spindle and fastened thereto by a set screw.
• the other end of the adaptor is similarly attached to the meter shaft so that metal to metal contact between the spindle and shaft is prevented
• a thin asbestos sheet is also placed between the spindle-guard bracket and the meter to provide further thermal insulation to the meter.
• the spindle In measuring flux viscosity, the spindle is submerged V in molten flux maintained at a temperature of 355C.
• the viscometer is cleaned and checked against a standard solution of 95 percent glyeerine and 5 percent water at a temperature of 30C. after each measurement of flux viscosity.
• the second method is a semi-qualitative one in which a 3 inch wide steel spatula is inserted into a layer of molten flux floating on the surface of a zinc bath maintained at a temperature of 455C. When the tip of the spatula reaches the surface of the molten zinc, the
• spatula is swept quickly through the molten flux layer
• a galvanizing kettle of about X 10 X l0 inch size containing molten zinc at 455C. is used to evaluate the fluxes of Examples A, B and 1-1 l-.'The Prime Western grade zinc is used in the evaluation.
• Approximately 300 grams of the flux are placed in the kettle which is equipped with a darn dividing the molten zinc surface into two halves.
• the flux is placed on the surface of one of the halves in one spot from which it melts away to cover that half of the molten zinc surface. All of the flux melts in about 4 minutes.
• the flux is heated for about 10 minutes longer before galvanizing is begun. I Soft steel coupons are used toevaluate the effectiveness of the flux.
• Coupons of 3% X 2% X /4 inch in size are first degreased by heating in a solution prepared by dissolving 39 grams of sodium hydroxide, 104 grams of sodium metasilicate and 2.5 grams of a sodium hydrocarbon sulfonate wetting agent in a sufficient amount of water to make 1 gallon solution. After being heated at 88C. for minutes in this solution, the coupons are rinsed and pickled in a 10 percent sulfuric acid solution at 70C. for 20 minutes. After being rinsed with water the coupons are allowed to dry.
• the coupons When the coupons are completely dry, they are lowered slowly into the molten zinc through the flux which has been heated for l0 minutes on the surface of the molten zinc at 455C. The coupons are held in thezinc for 90 seconds before being withdrawn through the molten zinc surface which does not contain a layer of flux and they are then cooled with water.
• composition A is a regular commercial flux heretofore generally employed in the prior art.
• Composition B is a low fuming flux currently available commercially.
• EXAMPLE 1 The molten flux of this example formed a thin, substantially foam free layer on the surface of the molten zinc and fumed only slightly more than low-fuming flux B initially, however, the fuming subsided to level of flux B after about 5 minutes of heating.
• the coatings obtained using this flux covered the entire surface of the coupon and were smooth, lustrous, uniform and defectfree'.
• coupons galvanized under identical conditions except that no top flux was used remained about 90 percent uncoated.
• EXAMPLE 4 EXAMPLE 5
• the galvanized coating obtained using-the flux of this example is unifonn, smooth, lustrous and free from defects and covers the entire surface of the coupon.
• EXAMPLE 6 The molten flux formed a layer of foam about two inches thick on the molten zinc and fumed only slightly more than flux B in the initial 3 minutes of heating but subsided to about the same level as flux B. The coating obtained when this flux was used covered the-entire surface of the coupon and was smooth, uniform, lustrous and defect-free.
• EXAMPLE 8 The fluxof this example. fumes no more than flux B throughout the heating and forms a foam layer about one and one half inches thick on the surface of the zinc. A smooth, lustrous, defect-free coating uniform across the entire surface of the coupon is obtained when the flux of this example is employed.
• EXAMPLE 9 The flux of this example fumes about the same as flux B throughout the heating and, when molten forms a thin, substantiallyfoam free layer on the zinc surface. Smooth, uniform, lustrous and defect-free coating discernible is obtained across the entire surface of the coupon when this flux is used.
• EXAMPLE 11 This flux fumes about the same as flux B on heating and forms a foam layer about one and one half inches thick. A smooth, lustrous, uniform and defect-free galvanized coating is obtained across the entire surface of the coupon is obtained when the flux of the Example is employed.
• the flux of claim 2 which contains a zinc orthophosphate, a zinc triphosphate, a zinc metaphosphate, a zinc pyrophosphate or a zinc ammonium phosphate.
• foaming agent is a polyalcohol, a polyamine, sawdust. flour, the chaff of bran or mixtures thereof.
• the flux of claim 6 in which the mixture contains from about 20 to about 60 parts by weight of the chloride or bromide salt in admixture with from about 40 to about parts by weight of the zinc chloride or zinc bromide and is molten at a temperature of 421C.
• the flux of claim 1 which contains 80 to parts by weight of zinc chloride, 3 to 15 parts byweight of a zinc phosphate, 0 to 0.5 part by weight of a foaming agent and 0 to 5 parts by weight of ammonium chloride.
• the flux of claim 9 in which the zinc phosphate 11.
• the improvement which comprises passing the article through a flux composition of 80 to 100 parts by weight of zinc chloride or zinc bromide; 3 to 15 parts by weight of a zinc phosphate or zinc phosphite; 0 to 0.5 part by weight of a foaming agent and 0 to 5 parts by weight of ammonium chloride or ammonium bromide.
• a bath for galvanizing articles which comprises molten zinc having a molten layer ofa flux composition on the surface thereof, the improvement which co-mprises, as the molten layer of flux, a composition of 80 to 100 parts by weight of zinc chloride or zinc bromide; 3 to 15 parts by weight of a zinc phosphate or Zinc phosphite; 0 to 0.5 part by weight'of a foaming agent and O to 5 parts by weight of ammonium chloride or ammonium bromide.
• the flux of claim 1 which contains 80 to 100 parts by weight of zinc chloride, 3 to l5 parts by weight ofa zinc phosphite, O to 0.5 part by weight ofa foaming agent and O to 5 parts by weight of ammonium chloride.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
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• Organic Chemistry (AREA)
• Coating With Molten Metal (AREA)

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Citations (12)

• 1973
  • 1973-04-13 US US00350797A patent/US3816188A/en not_active Expired - Lifetime
  • 1973-12-12 NL NL7317024A patent/NL7317024A/xx unknown
  • 1973-12-14 DE DE2362137A patent/DE2362137A1/de active Pending
  • 1973-12-14 IT IT3010/73A patent/IT1000855B/it active
  • 1973-12-14 AU AU63622/73A patent/AU6362273A/en not_active Expired
  • 1973-12-17 FR FR7345122A patent/FR2210674B3/fr not_active Expired
  • 1973-12-17 AR AR251554A patent/AR200588A1/es active
  • 1973-12-18 JP JP48140454A patent/JPS4990230A/ja active Pending

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