Coating processes – With post-treatment of coating or coating material – Heating or drying
Reexamination Certificate
2000-07-03
2001-09-04
Beck, Shrive P. (Department: 1762)
Coating processes
With post-treatment of coating or coating material
Heating or drying
C427S453000, C427S376300, C427S397800, C427S419200, C427S419300, C427S427000
Reexamination Certificate
active
06284320
ABSTRACT:
TECHNOLOGICAL FIELD
The present invention relates to a manufacturing method for material for use in molten metal baths, such as rollers or the like, which are installed in molten metal baths in continuous molten metal plating lines for thin steel plates employed in the manufacture of automobiles, household electronic appliances, office equipment, construction materials, and the like, and relates to a manufacturing method for materials for use in molten metal baths having flame coatings which have superior corrosion resistance with respect to molten zinc plating baths, molten aluminum plating baths, and molten zinc-aluminum plating baths. The materials for use in molten metal baths manufactured by means of the present invention include not merely the rollers or various members which are immersed in the plating bath, but also members for metal plating accessory facilities onto which molten metal is splattered.
BACKGROUND ART
Conventionally, as rollers which were employed in continuous molten zinc plating baths, continuous molten aluminum plating baths, or continuous molten zinc-aluminum plating baths, as well as members of molten plating accessory facilities onto which these molten metals are splattered, rollers made of heat-resistant steel, the surface of which is coated with various types of cermet system materials or oxide system ceramic materials, and which is then subjected to sealing treatment using a chromic acid system solution, a metal alkoxide alcohol solution, a colloidal silica solution, or the like, are employed, and have had some success.
However, when members are employed in which various types of cermet materials or oxide system ceramic materials are flame-coated onto the surface of a roller in a molten metal plating bath, and then conventional sealing treatment is carried out, when such members are employed in molten metal baths for a long period of time, there is intrusion of molten metal into the flame coating as a result of a decline in the corrosion resistance with respect to molten metal of sealing treatment itself, or there is intrusion of molten metal into the holes present in the flame coating, and thereby, erosion or alloying of the material parts of the members for use in molten metal baths occurs, and this is a cause of peeling of the flame coating.
Furthermore, when rollers for use in molten metal plating baths are employed which have sealing treatment executed by conventional flame-sprayed surface coatings, as a result of contact with the passing plate material (steel plate), the flame coating on the surface of the roller in the bath, which was subjected to sealing treatment, is likely to be abraded, so that the sealing effect decreases, and thereby, intrusion of the molten metal into the flame coating occurs, and this is also a cause of the peeling of the flame coating as described above.
It has been proposed, in Japanese Patent Application No HEI 9-122904, that as a means for solving this problem, an oxide ceramic flame coating in which a variety of oxides are combined be formed after flame coating a cermet material, comprising metal borides within a range of 5-60 weight percent, one or more of Co, Cr, Mo, or W in an amount within a range of 5-30 weight percent, the remainder comprising metal carbides and unavoidable impurities, onto the surface of a steel member, and conducting sealing treatment using an inorganic sealing agent on this composite coating. An example of the inorganic system sealing agent described here is a colloidal silica solution. With respect to this colloidal silica solution, in general, this is a solution comprising only a colloid of ultrafine granules of silicic acid having a grain diameter within a range of 1-100 nanometers. By means of this, there is a sealing effect; however, it is not sufficient, and concrete measures for improving the properties thereof have been desired.
The present invention solves the problems described above in the conventional technology; it has as an object thereof to provide a manufacturing method for members for use in molten metal baths, which have flame coatings having superior resistance to corrosion and resistance to peeling with respect to molten metal.
DISCLOSURE OF THE INVENTION
As a result of diligent study by the present inventors in order to attain the object described above, it was learned that a flame coating for sealing by using a solution which contains inorganic binder at a weight ratio within a range of 0.3-3.0 with respect to a weight of 1.0 of inorganic colloid in an inorganic colloid compound solution containing 5-50 weight percent of an inorganic colloid having a grain diameter within a range of 5-50 nanometers, has superior corrosion resistance and resistance to peeling with respect to molten metal, and thus the present invention has been made.
In the present invention, which is based on the discovery described above, a fundamental principle is a manufacturing method for members used in molten metal baths having a coating which has superior molten metal corrosion resistance, wherein, with respect to a cermet flame coating formed on the outermost surface of a substrate, or with respect to the coating formed by oxide system ceramics formed on the outermost surface of a substrate (including a coating formed by an oxide system ceramic formed on a cermet flame coating formed on the surface of a substrate), when the coating forms the uppermost coating layer of the product, a solution in which an inorganic binder is mixed at a weight ratio within a range of 0.3-3.0 with respect to a weight of 1.0 of an inorganic colloid present in an inorganic colloid compound solution, in an inorganic colloid compound solution containing 5-50 weight percent of an inorganic colloid having a grain diameter within a range of 5-50 nanometers, is applied or sprayed as a sealing solution and is allowed to permeate, and is then baked to carry out sealing treatment.
Furthermore, it is also a fundamental principle in the present invention that the inorganic colloid compound solution contains one or more of SiO
2
, Al
2
O
3
, TiO
2
, and ZrO
2
, having a grain diameter within a range of 5-50 nanometers, and that the cermet flame coating formed on the surface of the substrate contains metal borides within a range of 5-60 weight percent, and contains one or more of Co, Cr, Mo, and W in an amount within a range of 5-30 weight percent, the remainder comprising metal carbides and unavoidable impurities.
Furthermore, in the present invention, it is a fundamental principle that phosphate systems or silicate systems be used as the inorganic binder, and that the uppermost layer of the roller barrel employs a cermet flame coating or a ceramic flame coating comprising oxides.
Additionally, the present invention includes, in the fundamental principles thereof, application to those in which a) the oxide system ceramic flame coating formed on the outermost surface of the substrate comprises an oxide containing 5% or more of a compound oxide comprising one or more of Al, Ti, V, Cr, Fe, Co, Rh, In, and rare earths (Sc, Y, and lanthanides) which are trivalent metal elements, and b) one or more rare earths (Sc, Y, and lanthanides) differing from a).
The structure and function of the present invention will now be explained.
In the cermet flame coating or oxide system ceramic flame coating which is produced on the surface of rollers or members immersed in the molten metal plating bath or molten plating accessory equipment onto which molten metal is splattered, the molten metal intrudes into the holes remaining within the coating, and this is a cause of peeling of the flame coating.
In the cermet flame coating or oxide system ceramic flame coating, it is necessary to fill the holes remaining within the flame coating layer with a sealing treatment component, and furthermore, it is necessary to provide corrosion resistance with respect to molten metal, so that, in the present invention, an inorganic colloid compound solution having an inorganic colloid as the main component thereof is selected as the sealing agent.
Japanese Pate
Hiroshige Munetoshi
Tarumi Kiyohiro
Barr Michael
Beck Shrive P.
Kanesaka & Takeuchi
Nippon Steel Hardfacing Co. Ltd.
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