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GB867833A - Improvements in or relating to ceramic articles of sintered alumina - Google Patents

Improvements in or relating to ceramic articles of sintered alumina

Info

Publication number
GB867833A
GB867833A GB15607/56A GB1560756A GB867833A GB 867833 A GB867833 A GB 867833A GB 15607/56 A GB15607/56 A GB 15607/56A GB 1560756 A GB1560756 A GB 1560756A GB 867833 A GB867833 A GB 867833A
Authority
GB
United Kingdom
Prior art keywords
alumina
weight
balls
milling
sintering
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB15607/56A
Inventor
Haldon Burden
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Firth Brown Tools Ltd
Original Assignee
Firth Brown Tools Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Firth Brown Tools Ltd filed Critical Firth Brown Tools Ltd
Priority to GB15607/56A priority Critical patent/GB867833A/en
Publication of GB867833A publication Critical patent/GB867833A/en
Expired legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3217—Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/38—Non-oxide ceramic constituents or additives
    • C04B2235/3817—Carbides
    • C04B2235/3839—Refractory metal carbides
    • C04B2235/3843—Titanium carbides
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/40—Metallic constituents or additives not added as binding phase
    • C04B2235/402—Aluminium
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/40—Metallic constituents or additives not added as binding phase
    • C04B2235/404—Refractory metals
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/54—Particle size related information
    • C04B2235/5418—Particle size related information expressed by the size of the particles or aggregates thereof
    • C04B2235/5436—Particle size related information expressed by the size of the particles or aggregates thereof micrometer sized, i.e. from 1 to 100 micron
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/60—Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
    • C04B2235/604—Pressing at temperatures other than sintering temperatures
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
    • C04B2235/77—Density
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
    • C04B2235/78—Grain sizes and shapes, product microstructures, e.g. acicular grains, equiaxed grains, platelet-structures
    • C04B2235/785—Submicron sized grains, i.e. from 0,1 to 1 micron
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
    • C04B2235/78—Grain sizes and shapes, product microstructures, e.g. acicular grains, equiaxed grains, platelet-structures
    • C04B2235/786—Micrometer sized grains, i.e. from 1 to 100 micron
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance

Landscapes

  • Ceramic Products (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Abstract

Ceramic articles, e.g. cutting tools and wear-resisting surfaces, containing at least 90% by weight of sintered alumina are made by sintering alumina powder with an average grain size not greater than 4 microns while under substantial pressure, e.g. in a mould. Up to about 10% by number of the grains may be between 4 and 10 microns in size. Preferred pressures and temperatures during sintering are 2000-3000 p.s.i. and 1500-1800 DEG C.; these are applied for 5-30 minutes, conveniently in a graphite mould heated by the field of a high frequency generator or by an electric current. Undesirable grain growth during sintering may be inhibited by the addition of up to 10% by weight of titanium or tungsten or either of their carbides or any combination thereof. The carbides may be added as mixed crystals. To prepare the alumina powder for sintering a suitable fineness is obtained by ball-milling commercial calcined alumina for 240 to 360 hours using balls of at least 5 times the weight of alumina powder. If steel balls are used treatment of the alumina with hydrochloric acid is necessary after milling to remove iron. Alternatively, milling may be effected with balls made of tungsten-titanium carbide mixed crystals, small amounts of which are worn off during milling and become admixed with the alumina. Cobalt or nickel may be incorporated in the carbide balls to harden them. Alumina ground with such balls may contain about 3% by weight of the carbide mixed crystals and about 0.3% by weight of cobalt or nickel.ALSO:Ceramic articles, e.g. cutting tools and wear-resisting surfaces, containing at least 90% by weight of sintered alumina are made by sintering alumina powder with an average grain size not greater than 4 microns while under substantial pressure, e.g. in a mould. Up to about 10% by number of the grains may be between 4 and 10 microns in size. Preferred pressures and temperatures during sintering are 2000-3000 p.s.i. and 1500-1800 DEG C.; these are applied for 5-30 minutes, conveniently in a graphite mould heated by the field of a high frequency generator or by an electric current. Undesirable grain growth during sintering may be inhibited by the addition up to 10% by weight of titanium or tungsten or either of their carbides or any combinations thereof. The carbides may be added as mixed crystals. To prepare the alumina powder for sintering, a suitable fineness is obtained by ballmilling commercial coloured alumina for 240 to 360 hours using balls of at least 5 times the weight of alumina powder. If steel balls are used treatment of the alumina with hydrochloric acid is necessary after milling to remove iron. Alternatively, milling may be effected with balls made of tungsten-titanium carbide mixed crystals, small amounts of which are worn off during milling and become admixed with the alumina. Cobalt or nickel may be incorporated in the carbide balls to harden them. Alumina ground with such balls may contain about 3% by weight of the carbide mixed crystals and about 0,3% by weight of cobalt or nickel.
GB15607/56A 1956-05-18 1956-05-18 Improvements in or relating to ceramic articles of sintered alumina Expired GB867833A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB15607/56A GB867833A (en) 1956-05-18 1956-05-18 Improvements in or relating to ceramic articles of sintered alumina

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB15607/56A GB867833A (en) 1956-05-18 1956-05-18 Improvements in or relating to ceramic articles of sintered alumina

Publications (1)

Publication Number Publication Date
GB867833A true GB867833A (en) 1961-05-10

Family

ID=10062182

Family Applications (1)

Application Number Title Priority Date Filing Date
GB15607/56A Expired GB867833A (en) 1956-05-18 1956-05-18 Improvements in or relating to ceramic articles of sintered alumina

Country Status (1)

Country Link
GB (1) GB867833A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3450515A (en) * 1963-03-08 1969-06-17 Norton Co Method of making impregnated sintered bauxite grains and the product thereof
US3711585A (en) * 1968-08-19 1973-01-16 Hitachi Ltd Use of yttria-magnesia mixtures to produce highly transparent sintered alumina bodies
JPS4958104A (en) * 1972-10-06 1974-06-05
JPS4999705A (en) * 1973-01-31 1974-09-20
DE2643131A1 (en) * 1975-09-25 1977-04-07 Tdk Electronics Co Ltd ELECTRICALLY CONDUCTIVE COMPOSITE CERAMICS AND PROCESS FOR THEIR PRODUCTION

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3450515A (en) * 1963-03-08 1969-06-17 Norton Co Method of making impregnated sintered bauxite grains and the product thereof
US3711585A (en) * 1968-08-19 1973-01-16 Hitachi Ltd Use of yttria-magnesia mixtures to produce highly transparent sintered alumina bodies
JPS4958104A (en) * 1972-10-06 1974-06-05
JPS5039445B2 (en) * 1972-10-06 1975-12-17
JPS4999705A (en) * 1973-01-31 1974-09-20
JPS523646B2 (en) * 1973-01-31 1977-01-29
DE2643131A1 (en) * 1975-09-25 1977-04-07 Tdk Electronics Co Ltd ELECTRICALLY CONDUCTIVE COMPOSITE CERAMICS AND PROCESS FOR THEIR PRODUCTION

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