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
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/653—Processes involving a melting step
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B21/00—Nitrogen; Compounds thereof
  • C01B21/082—Compounds containing nitrogen and non-metals and optionally metals
  • C01B21/0821—Oxynitrides of metals, boron or silicon
• • 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
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
  • C04B35/107—Refractories by fusion casting
• • 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
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
  • C04B35/111—Fine ceramics
  • C04B35/1115—Minute sintered entities, e.g. sintered abrasive grains or shaped particles such as platelets
• • 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
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
  • C04B35/111—Fine ceramics
  • C04B35/117—Composites
• • 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
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
  • C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
  • C04B35/581—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on aluminium nitride
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
  • C09K3/1409—Abrasive particles per se
  • C09K3/1418—Abrasive particles per se obtained by division of a mass agglomerated by sintering
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
  • C09K3/1409—Abrasive particles per se
  • C09K3/1427—Abrasive particles per se obtained by division of a mass agglomerated by melting, at least partially, e.g. with a binder
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/80—Compositional purity

Definitions

• the invention relates to the domain of abrasive grains, particularly agglomerated grains designed for use on grinding wheels, grains applied to cloth and paper type supports, and grains used for projection or in polishing paste.
• alumina based products occupy an important place and have been done for many years, since the use of emery was already known in the Greek world.
• the most commonly used product nowadays is electrically melted corundum, which is white corundum composed of almost pure alumina, or brown and less pure corundum obtained by melting-reduction of bauxite.
• Patent GB 786815 (National Lead) filed in 1954 describes hard abrasive grains in which fine crystals of titanium carbide are dispersed in a corundum matrix.
• patent EP 0273569 (3M) describes abrasive particles composed of alumina, ⁇ aluminium oxynitride (AlON) and possibly a nitride of a metal in group IVb in the periodic classification table, prepared by sol-gel method and reactive sintering.
• AlON aluminium oxynitride
• the high cost of these products has caused a search for abrasive grains capable of giving a better quality-price ratio.
• Patent EP 0494129 filed by the applicant describes a direct process using nitrogen for the nitridation of metals with a low melting point, and particularly aluminium.
• Patent EP 0509940 filed by the applicant describes a wide range of abrasive or refractory products based on oxynitrides obtained by melting in an electric furnace, including AlON type aluminium oxynitride-based products.
• Patent FR 2720391 filed by the applicant describes abrasives based on AlON oxynitride, obtained by melting in an electric furnace, for which the hardness has been improved by dispersing fine crystals of titanium carbide in the basic material.
• the purpose of the invention is to provide abrasive grains based on aluminium oxynitride, that will be used as grains applied to cloth and paper type supports, or agglomerated grains in metal and metallic alloy grinding wheels, or in projection or in a polishing paste, and capable of high performances.
• the purpose of the invention is abrasive grains based on aluminium oxynitride, with an equivalent content of AlN as measured on an Al 2 O 3— AlN pseudo-binary diagram equal to between 2.5% and 7.5%, and preferably between 3 and 6% by weight, and a structure composed mainly of ⁇ ′ AlON and ⁇ AlON.
• These grains usually have a metal aluminium content of less than 0.3% by weight and preferably 0.1%, and a free aluminium nitride content AlN of less than 0.3% and preferably less than 0.1%.
• Another purpose of the invention is a process for preparation of such abrasive grains including the preparation of a charge of alumina, aluminium nitride AlN and/or oxynitride Al X O Y N Z , and possibly titanium oxide and/or chromium oxide, this charge being melted and cooled at less than 1° C. per minute.
• Another purpose is a process for preparation of such abrasive grains including the preparation of a mix of alumina, aluminium nitride AlN and/or oxynitride Al X O Y N Z and possibly titanium oxide and/or chromium oxide powders, reactive sintering of this mix at a temperature of between 1950 and 2000° C., and cooling of the sintered grains at less than 1° C. per minute.
• the applicant has attempted to develop abrasive grains based on aluminium oxynitride of the ⁇ AlON type, with an equivalent content of AlN between 11 and 12.5%, prepared by direct nitridation and melting according to patents EP 0 494 129 and EP 0 509 940, and obtained by fast cooling from the molten material.
• the abrasive properties of this material are admittedly better than the properties of ⁇ alumina, but are not as good as the properties of abrasive grains prepared using the sol-gel method.
• This material was then produced using a Higgins type furnace instead of the melting furnace; in this technique, the furnace is filled gradually and the contents are not poured from it. The furnace is abandoned when it is full and is allowed to cool naturally. Note that the cooling rate of the material thus produced depends directly of the size of the furnace.
• the product obtained is mechanically stable in contact with water.
• washing of the grain product with water can eliminate traces of residual AlN without corrupting the mechanical quality of the grains; thus, the real content of AlN in grains can be lowered to less than 0.01%.
• the advantage of washing with water in this way is essentially to provide grains that will not release any smell when it comes into contact with moisture later on.
• materials according to the invention used in these processes may be prepared with Al contents of less than 0.3%, or less than 0.1%. If care is taken to perform washing with water to destroy AlN traces with acid water with a pH of between 5 and 7, for example with sulphuric acid, the content of residual aluminium can be lowered at the same time to less than 0.01%.
• a tougher material could be obtained by adding titanium and/or chromium oxide with a global content of between 0.2 and 3.5%, and preferably between 2.5 and 3.5% by weight of the total content.
• brown corundum containing titanium oxide some or all of the alumina in the contents of the Higgins furnace can be replaced by brown corundum containing titanium oxide.
• the result obtained for a content of brown corundum containing 3% of TiO 2 and aluminium oxynitride prepared by the process according to patent EP 0494129 is materials with toughness more than 2 MPa ⁇ square root ⁇ m.
• Products according to the invention can also be made by sintering under an inert atmosphere of nitrogen or argon, starting from basic materials at temperatures of between 1950° C. and 2000° C.
• the abrasive properties of the abrasive grains thus obtained are similar to the properties of the product obtained by passing through the liquid phase, provided that this material is restored to ambient temperature at comparable cooling rates.
• the equivalent AlN content was measured on 5 mg samples weighed to within 0.1 mg, by combustion in a LECO CT 436 gas analyzer, and analysis by thermal conductivity for nitrogen, and infrared absorption spectrometer for oxygen.
• the result given for each sample is the average of five measurements.
• the content of free AlN is measured by acid attack in a sulphuric medium and analyses of the NH 4 +ions obtained.
• Nitridation started at about 700° C., and the nitrogen pressure was maintained to facilitate the temperature increase of the content.
• the exothermal reaction made it possible to reach about 1750° C. at the end of the operation.
• the mass recovered after cooling at the end of the operation was 4010 kg, and it is porous, homogenous, and not very strong mechanically.
• This mix was melted in a 1.8 MW Higgins furnace.
• the furnace was shutdown at the end of the operation, and allowed to cool naturally. After five days, the mass obtained was sufficiently cool so that it could be broken.
• the product obtained was ground and packaged in grains.
• the product was ground, washed with water, dried and then packaged and sorted into different size gradings, including F30 grains and F80 grains according to the FEPA standard.
• Table 1 contains the results: TABLE 1 Knoop Vickers hardness hardness Toughness Product of 18.1 GPa 17.7 GPa 1.65 MPa ⁇ m 1/2 example 2 White 20.3 GPa 20 GPa 2.0 MPa ⁇ m 1/2 corundum Al oxynitride 18.0 GPa 17.3 GPa 1.6 MPa ⁇ m 1/2 according to prior art Sol-gel type 21.5 GPa 21.2 GPa 3.7 MPa ⁇ m 1/2 abrasive
• Table 2 contains the results obtained in terms of the three frequently used parameters: material removal, G ratio (material removal/grinding wheel wear) and absorbed power: TABLE 2 Product of Sol - gel alumina example 2 Grade Grade Grade Grade Grade Grade I K M I K M Material 15.6 8.9 5.3 19.0 15.0 13.0 removal (g/min) G ratio 50.6 38.3 27.7 48.7 42.8 43.3 Absorbed 955 1068 1113 912 1350 1560 power (W) Energy / removal of 1.02 2.0 3.5 0.8 1.5 2.0 material (kwh/kg)
• Table 3 contains the results expressed in terms of the three frequently used parameters: material removal, G ratio (material removal/grinding wheel wear) and absorbed power: TABLE 3 Energy/ Material Material Absorbed removal removal removal G ratio power (W) (kwh/kg) Product of 13.0 43.3 1560 2.0 example 2 Al oxynitride 5.4 20.6 1231 3.8 according to prior art Sol-gel type 5.3 27.7 1113 3.5 abrasive White corundum 4.9 15.0 1558 5.3
• a mix was prepared composed of 20% of the product obtained in Example No. 1 and 80% of Bayer alumina. This mix was ground to a size grading of less than 2 ⁇ m.
• a paste was prepared by mixing with the addition of 1% of carboxymethylcellulose, and was then pressed to 500 bars and extruded into 1 mm diameter cylindrical rods.
• This unbaked material was then treated at 1950° C. and then cooled to ambient temperature at a rate of 1° C. per minute.
• Table 4 contains the results of these tests: TABLE 4 Knoop Vickers hardness hardness Toughness Product of 17.9 GPa 17.5 GPa 1.6 MPa ⁇ square root ⁇ m example 3 Sol-gel type 21.5 GPa 21.2 GPa 3.7 MPa ⁇ square root ⁇ m abrasive Energy/ Material Material Absorbed removal removal (g) G ratio power (W) (kwh/kg) Product of 7.9 43 1232 2.6 example 3 Sol-gel type 5.3 27.7 1113 3.5 abrasive
• Example 2 was repeated, replacing the Bayer alumina in the content of the Higgins furnace by brown corundum with a TiO 2 content of 3.6%.
• the expression “expressed in TiO 2 ” means that the determined content of elementary titanium has been multiplied by 80/48, by making the simpler and partially incorrect assumption that all titanium is present in the form of oxide.
• the product obtained was then ground, washed with water, dried, then packaged and sorted into different size gradings, including F30 grains and F80 grains according to the FEPA standard.
• Table 5 contains the results: TABLE 5 Knoop Vickers hardness hardness Toughness Product of 18.1 GPa 17.7 GPa 1.65 MPa ⁇ m 1/2 example 2 White corundum 20.3 GPa 20 GPa 2.0 MPa ⁇ m 1/2 Al oxynitride 18.0 GPa 17.3 GPa 1.6 MPa ⁇ m 1/2 according to prior art Sol-gel type 21.5 GPa 21.2 GPa 3.7 MPa ⁇ m 1/2 abrasive Product of 18.9 GPa 18.0 GPa 2.4 MPa ⁇ m 1/2 example 4
• Table 6 contains the results obtained in the grinding test: TABLE 6 Grade I Grade K Grade M Material removal 16.6 12.0 8.0 (g/min.) G ratio 47.4 41.4 32.0 Absorbed power (W) 896 1224 1200 Energy/removal of 0.9 1.7 2.5 material (kWg/kg)
• This mix was ground to a size grading of less than 2 ⁇ m.
• a paste was prepared by mixing with the addition of 1% of carboxymethylcellulose, and then pressed at 500 bars and extruded in 1 mm diameter cylindrical rods.
• This unbaked material was then treated at 1980° C. and then cooled to an ambient temperature at a rate of 1° C. per minute.
• This material was then ground, washed, dried, then sorted; the mechanical properties of the material were measured on the F30 grains thus obtained.
• Table 7 contains the results of these tests: TABLE 7 Knoop Vickers hardness hardness Toughness Product of 19.0 GPa 18.6 GPa 2.2 MPa ⁇ m 1/2 example 5 Sol-gel type 21.5 GPa 21.2 GPa 3.7 MPa ⁇ m 1/2 abrasive
• the furnace was shutdown and allowed to cool naturally. After five days, the mass obtained was sufficiently cooled so that it could be broken.
• the product was then ground, washed with water, dried and then packaged and sorted into different size gradings including F30 grains and F80 grains according to the FEPA standard.
• Table 8 contains the results: TABLE 8 Knoop Vickers hardness hardness Toughness Product of 18.1 GPa 17.7 GPa 1.65 MPa ⁇ m 1/2 example 2 White corundum 20.3 GPa 20 GPa 2.0 MPa ⁇ m 1/2 Al oxynitride 18.0 GPa 17.3 GPa 1.6 MPa ⁇ m 1/2 according to prior art Product of 18.5 GPa 18.0 GPa 2.0 MPa ⁇ m 1/2 example 4 Product of 18.9 GPa 18.4 GPa 2.4 MPa ⁇ m 1/2 example 6

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• Ceramic Engineering (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Structural Engineering (AREA)
• Inorganic Chemistry (AREA)
• Composite Materials (AREA)
• Polishing Bodies And Polishing Tools (AREA)
• Compositions Of Oxide Ceramics (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)

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• 2002
  • 2002-02-28 FR FR0202554A patent/FR2836472B1/fr not_active Expired - Lifetime
• 2003
  • 2003-02-24 EP EP03722668.5A patent/EP1480924B1/fr not_active Expired - Lifetime
  • 2003-02-24 WO PCT/FR2003/000594 patent/WO2003072523A1/fr not_active Ceased
  • 2003-02-24 AU AU2003229836A patent/AU2003229836A1/en not_active Abandoned
  • 2003-02-24 HU HUE03722668A patent/HUE038649T2/hu unknown
  • 2003-02-24 CA CA2477162A patent/CA2477162C/fr not_active Expired - Fee Related
  • 2003-02-24 SI SI200332571T patent/SI1480924T1/en unknown
  • 2003-02-24 BR BR0308068-4A patent/BR0308068A/pt not_active Application Discontinuation
  • 2003-02-24 US US10/504,154 patent/US20050160678A1/en not_active Abandoned
  • 2003-02-25 TW TW092103926A patent/TWI295316B/zh not_active IP Right Cessation

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