Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/18—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by using pressure rollers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression

Definitions

• ABSTRACT A process is provided for rolling metal strip particularly iron or iron alloy strip, directly from powdered metal using a technique in which a self-supporting metal powder/binder strip is formed on a support surface from a slurry containing the metal and binder composition, the support surface being precoated with a release agent.
• Typical release agents are mono-basic fatty acids, such as steric and oleic acids.
• This invention relates to a process for the production of metal strip from powdered metal which is particularly, but not exclusively, applicable to the production of steel strip.
• the powdered metal is initially deposited onto the support surface as a coating in the form of a slurry comprising a suspension of metal powder in a binder composition, one example of a suitable binder composition being an aqueous methyl cellulose solution.
• the resulting metal powder binder strip is removed from the substrate and then subjected to rolling to effect compaction of the powdered metal and the compacted strip is then sintered.
• the slurry formed from the binder and the powdered metal is sufficiently viscous, little difficulty is normally experienced in cleanly stripping the dried film from a smooth substrate, such as a stainless steel band. It is, however, desirable in order to increase the line speed of the process to reduce the viscosity of the slurry to the minimum consistent with maintaining good metal powder/binder strip formation and adequate suspension of the powdered metal.
• the hygroscopic substance is a water-soluble polyhydroxy compound, such as glycerol, low moleculor weight polyalkylene glycols, e.g., trimethylene glycol, polyhydric alcohols, e.g., sorbitol, mannitol, and sugars, e.g., invert sugar.
• Inorganic hydroscopic materials may also be employed, such as calcium chloride.
• the hydroscopic substance is preferably present in an amount up to 1.0 percent by weight of the suspension employed. It has been noted that if a substantially larger portion of the hydroscopic substance is employed, too much water tends to be retained in the cellulose derivative during the slurry drying which leads to difficulties in the subsequent processing steps.
• the present application is concerned with a solution to the problem of undesirable adhesion to the substrate of dried films formed from powdered metal/binder compositions. We have now discovered, that this difficulty can be overcome by coating the substrate with a thin film of a release agent prior to the deposition of the slurry of powdered metal and binder composition.
• Suitable release agents are fatty acids, e.g., mono-basic acids such as oleic and stearic acids fluorinated hydrocarbons, particularly fluorinated hydrocarbon polymers,
• the release agent is desirably coated in a thin film onto the support surface and in the case of mono-basic fatty acid, this may be achieved directly (i.e. alone without the agency of a solvent or dispersant) or in the form of a solution or dispersion with subsequent removal of the continuous phase of the solution or dispersion.
• Convenient solvents for fatty acids are, for example, trichloroethylene or ethanol.
• the solution or dispersion (when used) may be applied to the support surface by any convenient method, such as roller coating, spraying or using a rotating lambswool coated roller impregnated with the solution.
• the continuous phase may be evaporated or allowed to evaporate before the suspension of powdered metal and binder composition is applied to the support surface.
• a 1 percent solution of a mono-basic fatty acid such as oleic or stearic acid
• a mono-basic fatty acid such as oleic or stearic acid
• trichloroethylene or ethanol a very thin film of oleic acid or stearic acid can be applied to the surface and this ensures that the deposited, dried metal powder/binder strip film can be readily removed from the substrate.
• the fatty acid is applied continuously to the support surface.
• the slurry is coated continuously onto an endless belt or drum, as described in our co-pending application Ser. No. 683,983 the fatty acid is conveniently applied continuously to the belt or drum at a point upstream of the slurry coating station.
• a process for the production of a strip from powdered metal which comprises:
• slurry comprising a suspension of powdered metal in an aqueous solution of a film-forming cellulose derivative, said slurry having a viscosity of less than 50,000 centipoises;
• the support surface is a drum or an endless metal belt onto which the slurry is continuously coated and from which the dried coating is continuously removed.
• release agent is a fluorinated hydrocarbon or a silicone.
• release agent is a fatty acid and is deposited on the support surface from a solution or dispersion.
• the slurry includes a hygroscopic substance selected from the group consisting of, low molecular weight polyalkylene glycols, polyhydric alcohols, sugars, and calcium chloride.
• a process for the production of a strip from powdered metal which comprises:

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Composite Materials (AREA)
• Materials Engineering (AREA)
• Powder Metallurgy (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Laminated Bodies (AREA)

Applications Claiming Priority (1)

Publications (1)

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Family Applications (1)

Country Status (9)

Cited By (11)

Families Citing this family (3)

Citations (6)

• 1968
  • 1968-07-10 GB GB3295768A patent/GB1257033A/en not_active Expired
• 1969
  • 1969-07-01 US US838325A patent/US3658517A/en not_active Expired - Lifetime
  • 1969-07-04 AT AT642669A patent/AT295173B/de active
  • 1969-07-08 LU LU59065D patent/LU59065A1/xx unknown
  • 1969-07-08 BE BE735806D patent/BE735806A/xx not_active IP Right Cessation
  • 1969-07-08 FR FR6923117A patent/FR2012647A1/fr not_active Withdrawn
  • 1969-07-09 ES ES369321A patent/ES369321A1/es not_active Expired
  • 1969-07-09 NL NL6910545A patent/NL6910545A/xx active Search and Examination
  • 1969-07-09 SE SE09726/69A patent/SE356452B/xx unknown

Patent Citations (6)

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