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
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/18—After-treatment

Definitions

• the present invention relates to a strengthening method for flame sprayed films which are formed by conducting flame spraying of metal, cermet, or ceramics in order to provide resistance to abrasion, corrosion resistance, thermal resistance, and the like, so that structural parts may be provided with a long service life.
• sealing treatment was necessary for flame sprayed films formed on the surface of structural parts, sealing treatment was conducted after the completion of a flame sprayed film having a target thickness.
• penetration of the sealant into the film was approximately 2 - 5 ⁇ m from the surface in the case of films having a high density, and a sealant layer of at most 20 ⁇ m was formed in films having good permeability, so that incomplete sealing was conducted at depths of 5 ⁇ m or greater.
• Sealing treatment was also conducted at reduced pressures in an attempt to increase the permeation of the sealant; however, there was an increase in cost, and there was a limit in permeability in the case of minute flame sprayed films, so that the minuteness of the interior portion of the film was insufficient.
• the present invention solves the problems described above present in the conventional technologies; it has as an object thereof to provide a strengthening method for flame sprayed films which increases the minuteness of minute flame sprayed films in the interior thereof, by means of sealing treatment, and strengthens these films, and exhibits superior resistance to peeling.
• the present invention which is based on this discovery, has as an essential point thereof a strengthening method for flame sprayed films which functions by means of sealing and making minute the interior portion of the film, in which, at a stage of flame sprayed film formation at which the thickness of the film is at the final thickness or less during the formation of the flame sprayed film, sealing treatment is conducted using a sealant with respect to the flame sprayed film which is formed, and after the sealant has been completely dried and solidified, flame sprayed film formation is continued; the present invention also has as an essential point thereof a strengthening method for flame sprayed films in which the inner portion of the film is sealed and made minute, in which the flame sprayed film formation process and the sealing process described above are repeated in an alternating fashion, or in which either or both of heating and brushing are conducted after sealing treatment.
• the resent invention also has as an essential point thereof a strengthening method for flame sprayed films in which the inner portion of the film is sealed and made minute, in which the uppermost portion of the film is finished and sealing treatment is conducted with respect to the flame sprayed layer; furthermore, the use of a sealant which produces, after sealing treatment and within the flame sprayed film, one of Cr 2 O 3 , SiO 2 , Al 2 O 3 , ZrO 2 , CrB 2 , WB, Mo 2 B, SiC, TiC, VC, Cr 7 C 3 , and NbC, or produces the presence of or a mixture of two or more of the above, or the formation of a flame sprayed film having a different flame sprayed film material after the sealing treatment, or the carrying out of sealing treatment within a vessel at high temperatures and pressures, are included in the present invention.
• a sealant which produces, after sealing treatment and within the flame sprayed film, one of Cr 2 O 3 , SiO 2 , Al 2 O 3 , Zr
• sealing treatment is conducted using a sealant which produces oxides, borides, or carbides, or the co-presence or a mixture of two or more of these, within the flame sprayed film after sealing treatment, or using a sealant such as a metal alkoxide alcohol or the like, and this is then sufficiently dried.
• the sealing-treated surface may be heated to 100°C or more, and a sealant solid may be formed.
• a process is again carried out which forms a flame sprayed film of the same material or a different material; prior to flame spraying, the surface is subjected to light brushing, and this is effective in removing excess solids.
• the sealant may be made into a stable compound by means of heat treatment. In this way, it is possible to seal and make the flame sprayed film minute to the deep layers thereof, by means of again conducting flame spraying after sealing treatment.
• the thickness of the portion subjected to sealing treatment may be appropriately set.
• the present invention eliminates the problem present in the conventional flame sprayed film subjected to sealing treatment, that is to say, that the sealing treated layer is too thin, and it is thus possible to effect an enormous increase in the service life of structural parts on which flame sprayed films are formed.
• the concentration and type of the sealants employed in the present invention are determined in accordance with the use to which the flame sprayed film is to be put, and in accordance with the relationship between the sealing treatment time and the thickness of the flame sprayed film.
• Chromic acid system sealants or sealants comprising metal alkoxide alcohol or the like are commonly employed; however, if sealant components are to be employed which exhibit heat and abrasion resistance as well as strong adherence with the flame sprayed film, the sealant composition is not restricted to oxide systems, and boride systems or carbide systems, or a mixture thereof, may be employed.
• Rollers for use in molten zinc plating baths were treated using the method of the present invention. Cermet or ceramic flame spraying was applied to the surface of rollers used in molten zinc plating baths for thin steel plates.
• high speed gas flame spraying was conducted with respect to the untreated roller surface so as to form a boride - WC system cermet having a film thickness of 70 ⁇ m, and then a chromic acid solution (with a Cr 2 O 3 concentration of 30%) or a Si alkoxide alcohol sealant, or both, were applied to the film which was formed, this was sufficiently dried, and then a two pass boride - WC system cermet flame spraying or a Cr 2 O 3 system ceramic flame spraying, or both, were conducted (for a thickness of approximately 20 ⁇ m). Furthermore, to this were applied the chromic acid solution or the Si alkoxide alcohol sealant, or both, and this was baked at a temperature of 400°C.
• a sealing treated layer was obtained which had a thickness more than two times that of the conventional example, in which the thickness of the sealing treated layer reached 40 ⁇ m and only sealing treatment was conducted as the final finishing.
• the useful service life was 50 days when only one of the chromic acid solution and the Si alkoxide alcohol sealant was employed, while the useful service life was 60 days when both were applied.
• the useful service life was 50 days when one or the other of the boride - WC system cermet flame spraying and the Cr 2 O 3 system ceramic flame spraying was employed as the flame spraying of the upper layer.
• the density of the sealing layer is increased, the amount of molten zinc deposited on the surface of the roller decreases, and the corrosion process of the flame sprayed film is greatly decreased, and the quality of the steel plates which pass through is greatly improved.
• the useful service life of a roller used in the molten zinc plating bath is further extended and may be 50 days or more.
• the present invention was applied to the production of a hearth roller.
• MCrAlY system cermet flame sprayed rollers are chiefly employed as hearth rollers in continuous annealing furnaces and as appealing furnace hearth rollers in continuous zinc plating lines. It is commonly known that such rollers which have been subjected to sealing treatment using a chromic acid solution (Cr 2 O 3 concentration of 30%) on the surface thereof after the formation of the flame spraying layer have superior resistance to buildup. However, when the surface thereof is abraded, the resistance to buildup becomes somewhat poorer after approximately two years, depending on the amount of use.
• the flame spraying is halted with the final one pass remaining, sealing treatment is conducted using the chromic acid solution used in the first embodiment, this is lightly baked at 200°C, and then the final flame spraying pass is conducted to a thickness of 15 ⁇ m, whereupon sealing treatment is conducted using the solution described above, and this is then baked in a furnace at 400°C. It was confirmed that as a result of this, the thickness of the sealing layer is increased, the density of the flame sprayed film also increases, and the resistance to buildup does not decline even if the surface thereof is abraded somewhat.
• the present invention was applied to the production of brush up bridle rollers which are employed in acidic solutions.
• the method of the present invention was applied to the production of piston rods for internal combustion engines.
• ceramic flame spraying was first conducted to only half of the total thickness of the flame sprayed film (30 ⁇ m) with respect to the portions of the piston rods subjected to rubbing, and than sealing treatment was conducted using a chromic acid solution (containing 30% Cr 2 O 3 ), and after baking the surface at a temperature of 200°C, the remaining half of the film thickness was flame sprayed, sealing treatment was again conducted, and this was completely baked in a furnace in a temperature of 400°C.
• a chromic acid solution containing 30% Cr 2 O 3
• the method of the present invention was applied to the production of continuous casting molds.
• continuous casting molds are commonly subjected to the flame spraying of a Ni - Cr system self melting alloy after Ni plating base layer treatment.
• the method of the present invention was applied to the production of table rollers for heat stretching plants.
• the table rollers of heat stretching plants require resistance to abrasion, resistance to seizure, and resistance to slippage; conventionally, rollers produced by carrying out self melting alloy flame spraying on a high-Cr cast iron system casting roller were employed.
• the method of the present invention was applied, and in the process of conducting NiCr - WC system self melting alloy or cermet flame spraying onto an untreated roller, the flame spraying was halted before the final two passes (50 ⁇ m), a chromic acid solution (containing 30% Cr 2 O 3 ) was applied and sufficiently dried, and than the final two passes of flame spraying were conducted. Furthermore, the same solution was applied onto this, and heat treatment was finally conducted at a temperature of 400°C.
• the table roller which resulted had abrasion resistance which was more than 20 times greater than that of conventional high-Cr cast iron system casting rollers, and it was confirmed under actual conditions of use that even in the corrosive environment in which cooling water was employed, which could not be employed in the case in which only NiCr - WC system cermet flame spraying was carried out, there was no peeling of the flame sprayed layer.
• the method of the present invention was applied to the production of a corrosive environment liner.
• the method of the present invention was applied to an untreated liner, and during the flame spraying of a NiCr - WC system cermet, the flame spraying was interrupted with the final two passes (20 ⁇ m) remaining.
• a chromic acid solution (containing 30% Cr 2 O 3 ) was applied and sufficiently dried, and then the final two passes of flame spraying were carried out. Furthermore, the same solution was applied on top of this, and heat treatment was finally conducted at a temperature of 400°C.
• the method of the present invention was applied to the production of paper making rollers for a paper making plant.
• the method of the present invention was applied to an untreated roller, so that first, cermet flame spraying was conducted so as to produce only half of the total thickness of the flame sprayed film (100 ⁇ m), sealing treatment was next conducted by applying a chromic acid solution (containing 30% Cr 2 O 3 ) on this, the surface was baked at a temperature of 200°C, and then the remainder of the flame spraying was conducted, sealing treatment was again conducted using the solution described above, and finally baking was conducted in a furnace at a temperature of 400°C.
• cermet flame spraying was conducted so as to produce only half of the total thickness of the flame sprayed film (100 ⁇ m)
• sealing treatment was next conducted by applying a chromic acid solution (containing 30% Cr 2 O 3 ) on this, the surface was baked at a temperature of 200°C, and then the remainder of the flame spraying was conducted, sealing treatment was again conducted using the solution described above, and finally baking was conducted in a furnace at a temperature of 400°C.
• the present invention is as described above, so that the resistance to abrasion, resistance to corrosion, thermal resistance, and the like are improved in comparison with flame sprayed films subjected to conventional sealing treatments, and the useful service life of manufactured parts is increased, so that the present invention is highly useful in industry.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Coating By Spraying Or Casting (AREA)

Applications Claiming Priority (1)

Publications (2)

Family

ID=14153325

Family Applications (1)

Country Status (4)

Cited By (2)

Citations (1)

Family Cites Families (8)

• 1996
  • 1996-05-24 WO PCT/JP1996/001383 patent/WO1997045566A1/fr not_active Application Discontinuation
  • 1996-05-24 AU AU57792/96A patent/AU5779296A/en not_active Abandoned
  • 1996-05-24 EP EP96914423A patent/EP0853135A4/fr not_active Withdrawn
  • 1996-05-24 KR KR1019980700539A patent/KR19990035878A/ko not_active Application Discontinuation

Patent Citations (1)

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events