Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D1/00—Casings; Linings; Walls; Roofs
  • F27D1/16—Making or repairing linings increasing the durability of linings or breaking away linings
  • F27D1/1636—Repairing linings by projecting or spraying refractory materials on the lining
  • F27D1/1642—Repairing linings by projecting or spraying refractory materials on the lining using a gunning apparatus
  • F27D1/1647—Repairing linings by projecting or spraying refractory materials on the lining using a gunning apparatus the projected materials being partly melted, e.g. by exothermic reactions of metals (Al, Si) with oxygen
  • F27D1/1652—Flame guniting; Use of a fuel
• • 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
  • C23C24/00—Coating starting from inorganic powder
• • 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
  • C23C4/04—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
  • C23C4/11—Oxides
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
  • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
  • C25C3/16—Electric current supply devices, e.g. bus bars
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D1/00—Casings; Linings; Walls; Roofs
  • F27D1/0003—Linings or walls
  • F27D1/0006—Linings or walls formed from bricks or layers with a particular composition or specific characteristics
• • 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
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/25—Process efficiency

Definitions

• the invention relates to the flame spray coating of materials and involves coating the materials with magnesla.
• One object of the invention is successfully to flame spray and to coat materials with magnesia. Another object is to protect materials from molten metal such as molten zinc, molten aluminum and molten lead. Another object is to line melting pots for protection from molten metal. Another object is to provide coatings for cathode bars which are used in aluminum reduction cells. As an example, in relatively new types of cells cathode bars made out of zirconium boride and out of titanium boride have been found to be promising. These bars extend through furnace walls and to avoid loss of electric energy it is desirable to insulate the bars from the walls. Magnesia is not only resistant to attack by molten aluminum, but it is also an electrical insulator. Currently these cathode bars made out of zirconium boride and alternatively made out of titanium boride are being coated with magnesia by means of my process throughout that area of the bar which desirably should be insulated from the wall.
• Another object of the invention is to produce oxide coatings on metals which have a thermal coelficient of expansion not too far different from that of the metal involved.
• Magnesia has a thermal coeflicient 01f expansion close to that of many metals.
• I provide powder of magnesia, MgO, containing from 1% to 10% of silica, SiO with not more than 5% impurities.
• I mean by the above that the particles of powder are made of magnesia with the amount of silica specified, etc.
• the powder should be flowable, meaning that it shall readily flow from the hopper through the channel and orifices of the flame spray gun. In addition to this it should have a particle size finer than 90 mesh.
• magnesia that was used undoubtedly had other material besides magnesia and silica but only to the extent of very small percentages properly classified as traces.
• Example II Using mesh particle size magnesia powder containing :1.2% of silica, I produced with a flame spray powder gun a coating on steel. I 'found this coating to be usable but somewhat soft. This is where I get the low limit of 1% of silica.
• Example III procured magnesia powder of 180 mesh particle size containing as closely as I can estimate 3 /270 of silica, impurities merely traces. Using this powder in a flame spray powder .gun, -I produced good, adherent and hard coatings on plates of steel. This is the best example (best mode). However I should state that the material coated depends upon the use and so there is no best mode for that.
• the coating according to my invention is .a coating of magnesia with from 1% to 10% of silica, and having not more than 5% of material selected from the group consisting of metal oxide and metal and mixtures and not more than .5% of other matter and preferably not more than 11% of other matter.
• Metal oxides and metals are compatible with my coatings and therefore that is the reason for the specification of a possible amount thereof up to 5% Other materials are not so compatible and that is the reason for limiting them to smaller amounts.
• the coating should be all magnesia and silica but it is impossible to avoid traces of impurities.
• Rods made out of magnesia bonded with clay bond were also tried by me in a flame spray gun of the type disclosed in the Mor-f patent.
• the rods were made out of 96% magnesia and the rest clay and in another case out of 92% magnesia .the rest clay.
• the rods were fired to cone 16 in the usual manner. No adherent coatings were produced with the rods containing 96% of magnesia. Only inferior coatings were produced with the rods containing 92% magnesia. The use of more clay bond would produce coatings of inferior quality for the most important uses mentioned herein. In these experiments using magnesia with clay bond, the spray rate was extremely slow and the rods spat causing non-uniform coatings.
• zirconium oxide with the normal content .of hafnium oxide is referred to as zirconium oxide and zirconium boride with its normal content of 2% or 3% hafnium boride is referred to as zirconium boride.
• zirconium oxide boride with its normal content of 2% or 3% hafnium boride is referred to as zirconium boride.
• Titanium, zirconium and hafnium are all of them in group IV of the periodic table and they are the only transition metals in this group. Therefore it will be seen that they are extremely closely related to each other.
• Any solid material can be coated with magnesia in accordance with my invention. Even flexible materials can be coated although the desirability of doing this is not apparent. Metals which melt at a low temperature can be protected by cooling, and materials like wood which burn can be protected by an atmosphere of non-oxidizing gas.
• the invention is useful for coating borides, other ceramics, and metals so far as now known and other uses will be developed in due course.
• Coatings according to my invention should be at least one mil thick but it doesnt matter how much thicker they are provided specifications of size, weight and cost are met and so the upper limit is indefinite. In this specification all percentages are by weight. In the best mode of the invention the amount of silica is from 2% to 4% It will thus be seen that there has been provided by this invention a method of flame spray coating with magnesia and the coatings so produced in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiments above set forth, it is to be understood that all matter hereinbefore set forth is to be interpreted as illustrative and not in a limiting sense.
• a cathode bar for insertion through the wall of an aluminum reduction cell made of boride selected from the group consisting of titanium boride and zirconium boride and mixtures thereof, said bar having a laminate adherent coating of magnesia over an area intermediate the ends of the bar and being at least one mil thick, said magnesia having from 1% to 10% silicia, not more than 5% of other material selected from the group consisting of metal oxide and metal and mixtures thereof and not more than .5% of other matter, all by weight.

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

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

Family

ID=25326314

Family Applications (1)

Country Status (4)

Cited By (2)

Citations (5)

• 0
  • NL NL258356D patent/NL258356A/xx unknown
• 1959
  • 1959-12-07 US US857586A patent/US3088906A/en not_active Expired - Lifetime
• 1960
  • 1960-11-30 GB GB41131/60A patent/GB935768A/en not_active Expired
  • 1960-12-05 CH CH1357960A patent/CH416258A/de unknown

Patent Citations (5)

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