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
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
  • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
  • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
  • C23C28/321—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer with at least one metal alloy layer
• • 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
• • 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
  • C23C2/003—Apparatus
  • C23C2/0034—Details related to elements immersed in bath
  • C23C2/00342—Moving elements, e.g. pumps or mixers
  • C23C2/00344—Means for moving substrates, e.g. immersed rollers or immersed bearings
• • 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
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
  • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
  • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
• • 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
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
  • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
  • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
  • C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
• • 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
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
  • C23C4/10—Oxides, borides, carbides, nitrides or silicides; Mixtures thereof
• • 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
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
  • C23C4/123—Spraying molten metal

Definitions

• the present invention relates to a pot roll for continuous hot-dip galvanizing used in a galvanizing bath of continuous hot-dip galvanizing process line.
• the pot roll having such spray coating has given performances for the present, concerning a corrosion resistance to a zinc and wear resistance to a steel belt by controlling reaction with-the zinc and its higher hardness, as compared with the case when a stainless steel was directly used. But, problems were found that the Co component in the cermet was diffused into the zinc, and the coating was embrittled with the increase in WC ratio of the coating, and then flaking troubles of the WC-Co cermet were induced. And so, the performances thereof was not always sufficient.
• a hot-dip Pot roll on the surface of which the coating, proposed by the inventors of Japanese Applied Patent Publication No.52-17,490, is formed has recently been used.
• This coating composed of a silicon nitride or substituent thereof which replaced silicon with aluminum and nitrogen with oxygen respectively, is free from reaction with zinc and has a increased hardness and excellent wear resistance.
• Thermal spray coating method is utilized in order to form a ceramic coating, but pores exist inside the coating which formed by spraying, some of which pass therethrough. Because such through pores never fail to exist in the coating of ceramic or cermet group, this problem is unavoidable as far as the formation of coating is dependent upon the thermal spray coating method. Also, when a ceramic coating is sprayed on a roll surface, thermal expansion difference between the ceramic and roll substrate of stainless group causes the coating to create thermal stresses and cracks inside the coating. A cermet can be sprayed as the lower layer in order to moderate the thermal stress as much as possible, but pores also exist in the cermet coating. Moreover, in case of the lower layer, sealing by chemical adhesion method or the like cannot generally be employed, in order to ensure adhesiveness to the upper layer, and so the fact was that cracks or zinc penetrations passing through pores could not be prevented.
• the molten zinc which penetrated and passed inside the through pore portion of both the upper ceramic and lower cermet coating then reaches the roll surface of stainless group, and, at that contact portion, react chiefly with Fe component among the chemical compositions of stainless group to produce a alloy of Zn-Fe, or a ternary intermetallic compound of Ze-Fe-Al when Al is added into the galvanizing bath. Because the ternary intermetallic compound is accompanied with any volume expansion, both the lower and upper layer are partly flaked in the form of pushing upward. The inventors learned by their experiences that, when such troubles had occurred, a number of circular flaking of 3-5 mm diameter are created at the portion where the roll and steel belt contacted together and external stresses were applied.
• a shielding layer is located between the sprayed cermet and roll substrate in order to prevent the zinc, passed inside through pores which occurred unavoidably during ceramic or cermet spraying, from reaching the roll substrate of stainless group and further the shielding layer has a characteristic such as effect self-sealing even if the zinc should pass therethrough.
• the present invention is aiming to provide means to solve these problems.
• the present invention intends to elongate the life of Pot roll used for continuous hot-dip galvanizing.
• the present invention provides a pot roll. for continuous hot-dip galvanizing in a galvanizing bath, characterized by comprising a pot roll surface where three spray coating layers composed of an alloy of high Co ratio (Co-based alloy) or cermet of high ratio of said alloy (cermet-based alloy) as the first layer, a cermet containing an oxide or carbide or boride as the second layer and a ceramic of oxide group as the third layer are formed in order of coating.
• Co-based alloy Co-based alloy
• cermet-based alloy cermet of high ratio of said alloy
• a spray coating composed of a alloy containing cobalt, or a alloy or cermet of high ratio of the alloy is located as the first layer of the coatings, is that the amount of pores in the coating layer is extremely reduced, because this kind of spray coatings have a melting point of about 1,500°C, which are lower in comparison with other cermets or ceramics, and so this portion melt by the heat of the spray frame.
• intermetallic compounds formed inside pores may effect selflocking as a sealing material even if the through pores exist.
• cermet containing a oxide, carbide or boride is located as the second layer is that there are less deformations against external stresses during contacting with a steel belt and the strain of a ceramic coating layer as the third layer is minimized, because this kind of cermets have thermal expansion coefficients intermediate stainless steels and ceramics and the coating is higher in its hardness and mechanical strength.
• test piece as a comparative example, associated with Japanese Non-examined Patent Publication No.1-225,761 mentioned above, which formed a spray coating of ZrO2 group as the upper layer after spraying directly a cermet as the lower layer, 3 - 4 circular flaking of about 3 mm in diameter were created on the surface layer.
• Thermal expansion coefficient of coating of each layer according to the example at normal temperature is shown in Table 2.
• Table 2 Thermal expansion coefficient of coating of each layer according to the example at normal temperature Name of layer portion Thermal expansion coefficient Roll substrate of stainless group 17.5 x 10 ⁇ 6 Alloy contianing Ni-Co-Cr (the first layer) 15.5 x 10 ⁇ 6 Mo cermet (the second layer) 8.0 x 10 ⁇ 6 Ceramic composed chiefly of partly stabilized ZrO2 (the third layer) 5.6 x 10 ⁇ 6
• the improvement in operation rate of process line become possible, because of a largely elongated life of the pot roll for a galvanizing bath, a reduced maintenance cost by reduced frequency of roll exchanges and a reduced shutdown of the line accompanied with the reduced frequency of roll exchanges.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Metallurgy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Coating With Molten Metal (AREA)
• Coating By Spraying Or Casting (AREA)
• Other Surface Treatments For Metallic Materials (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=17313709

Family Applications (1)

Country Status (4)

Cited By (1)

Citations (3)

Family Cites Families (8)

• 1994
  • 1994-10-24 JP JP25796794A patent/JP3312709B2/ja not_active Expired - Fee Related
• 1995
  • 1995-10-23 KR KR1019950036565A patent/KR100272298B1/ko not_active Expired - Fee Related
  • 1995-10-23 EP EP95116671A patent/EP0712939A3/de not_active Withdrawn
  • 1995-11-08 TW TW084111828A patent/TW293850B/zh active

Patent Citations (3)

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