Classifications

• • 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
  • C09K3/1436—Composite particles, e.g. coated particles
  • C09K3/1445—Composite particles, e.g. coated particles the coating consisting exclusively of 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
  • 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
• • 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
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/628—Coating the powders or the macroscopic reinforcing agents
  • C04B35/62802—Powder coating materials
  • C04B35/62805—Oxide ceramics
  • C04B35/62818—Refractory metal oxides
  • C04B35/62821—Titanium oxide
• • 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
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/628—Coating the powders or the macroscopic reinforcing agents
  • C04B35/62802—Powder coating materials
  • C04B35/62828—Non-oxide ceramics
  • C04B35/62839—Carbon
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/40—Compounds of aluminium
  • C09C1/407—Aluminium oxides or hydroxides
• • 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
  • C09K3/1436—Composite particles, e.g. coated particles
• • 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
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
  • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
  • C23C18/1229—Composition of the substrate
  • C23C18/1245—Inorganic substrates other than metallic
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
  • C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
  • C01P2004/84—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases one phase coated with the other
• • 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

Definitions

• the present invention relates to an abrasive grain on the basis of electrofused aluminum oxide with a surface coating comprising titanium oxide and/or carbon.
• Abrasive grains are used in loose or bonded form, in
• abrasive grains are used in the form of abrasive belts, abrasive papers , abrasive wheels or other bonded abrasives, wherein the efficiency of the machining of the surface does not only depend on the characteristics of the abrasive grain itself, but to a considerable extent also on the type and stability of the integration of the abrasive grains in the respective abrasives .
• the bounding surface between the abrasive grain and the binder phase is of particular importance thereby. Said bounding surface determines the force which is required to break an abrasive grain out of a bond. The harder and more stable an abrasive grain, the larger are the demands on the bond and on the adhesive forces at the bounding surfaces, because the easier it will be to break an abrasive grain out of the bond due to grinding .
• U.S. 2 , 527, 044 A describes a fused aluminum oxide abrasive grain provided with a coating of fine-particulate metal oxide particles, for example iron oxide, so as to improve the embedding in resin-bonded abrasives .
• the metal oxide particles adhere to the surface of the abrasive grain by means of a glass-like binder.
• U.S. 2 , 541 , 658 describes the coating of abrasive grains with a phosphate binder and iron oxide pigments .
• EP 0 014 236 Al describes the treatment of a titanium oxide- containing abrasive grain on the basis of aluminum oxide , wherein a layer of a ceramic mass is fused onto the abrasive grain. Thereby, at the same time an oxidation of the titanium oxide , which is contained in the abrasive grain, takes place associated with a transformation of the structure of the abrasive grain.
• fi e grain particles are applied to the abrasive grain surface together with abrasion-active substances by means of a glass frit .
• Abrasive grains comprising a coating of an aqueous binding agent and a com lex fine-particulate oxide compound with the general composition A x B y O z are described in DE 102 57 554 B4.
• EP 0 346 832 discloses a coated silicon carbide abrasive grain coated with a highly dispersive hydrophilic metal oxide
• the highly dispersive hydrophilic metal oxide is thereby preferably mixed in the dry state with the abrasive grains and does subsequently adhere to the surface thereof . Even though the binder was abandoned in this case, however, due to the fact that the particles adhere to the surface only due to physical adhesion, it can also be observed herein that the stability of the bond in the
• abrasives decreases during the grinding operation and the abrasive grain breaks out of the bond.
• EP 0 652 918 describes an abrasive grain comprising a metal oxide coating, wherein precursors of alpha-aluminum oxide abrasive grains are coated with a coating composition
• Green bodies which are obtained via a sol-gel method from a boehmite dispersion after drying and calcination and which are treated by means of a solution comprising a metal alkoxide, are used as base particles .
• the green bodies treated in this manner are subjected to a temperature
• the coated base particles are
• a disadvantage of this method is that it is very complicated and furthermore limited to abrasive grains which are obtained via sol-gel methods . There is thus still the need for a coating having advantages as compared to the state of the art, in particular for abrasive grains produced via a melting process. It is thus the object of the present invention to provide a coated abrasive grain on basis of electrofused aluminum oxide comprising an enlarged surface, which grain can be integrated well and permanently in the abrasives even in response to a strong mechanical and thermal stress and which thus does not have the described disadvantages of the state of the art.
• the object is solved by means of an abrasive grain on the basis of electrofused aluminum oxide with a surface coating comprising titanium oxide and/or carbon, wherein compounds of titanium oxide and/or carbon particles formed at the abrasive grain surface by means of a temperature treatment are tightly con ected to the abrasive grain surface.
• a direct tight bond without an additional binding agent is thereby formed by reactive sintering between the abrasive grain surface and the titanium oxide and/or carbon compounds comprising an average particle size of between 10 nm and 10 ⁇ .
• a particularly well-suited base material for the coating is a pyrogenic titanium oxide which is offered by Evonik under the name Aeroxide Ti0 2 P25 and the average primary particle size of which is 21 nm. Further tests then showed that also
• the average size of the primary particles is preferably between 10 nm and 1 ⁇ , more preferably between 10 nm and 100 nm.
• the grain toughness of the abrasive grains was determined via the micro grain decomposition by grinding in a ball mill , wherein 10 g of corundum (of corresponding grit size) are ground in a ball mill filled with 12 steel balls (diameter 15 mm, weight 330-332 g) at 188 revolutions per minute for a predetermined period of time .
• the ground abrasive grain is subsequently screened in a screening machine (Haver Bocker E L 200) for 5 minutes via a. corresponding fine screen, which is 2 classes finer than the bottom screen, which is defined for the corresponding grit size, and the fine fraction is weighed out .
• the MKZ value follows from:
• mixtures of titanium oxide with carbon were then also used, so as to possibly further improve the physical characteristics of the individual grains by simultaneously forming reduced titanium oxide compounds .
• coated abrasive grains which, on the one hand, encompass excelling stability values and which, on the other hand, reveal good grinding efficiencies , are not only obtained when partially, but also when completely replacing ti anium oxide with carbon .
• This characteristic temperature exceeds in all cases 800°C, mostly 1000°C and 1250°C, respectively, so that the titanium oxide and/or carbon particles are sintered at a temperature of more than 800 °C, preferably more than 1000 °C, and more preferably more than 1250°C.
• the percentage by weight of the surface coating is
• the layer thickness of the surface coating is preferably less than 10 ⁇ .
• the ratio of Ti0 2 to carbon should be advantageously in the range from 10 : 1 to 1:10 prior to the sintering when using mixtures of titanium o ide and carbon .
• electrofused aluminum oxide are characterized i Table 1 below via the micro grain decomposi ion.
• Figure 1 thereby shows the surface of an abrasive grain coated with 2 % by weight of Ti0 2 in 2.000-fold magnification, on which relatively coarse, mostly elongated Ti0 2 crystals or aluminum titanate crystals can be seen, wherein some particles reach a longitudinal expansion of more than 10 pm.
• the average particle size lies in the range of between 0.01 urn and 10 ]i , preferably in the range of between 1 urn and 10 um.
• Pyrogenic Ti0 2 with an average particle size of between 10 and 50 nm was used as base material , so that also a strong irregular crystal growth had to have taken place during the temperature
• Figure 2 shows the surface of an abrasive grain coated with 1 % by weight of carbon also in 2.000-fold magnification.
• the carbon comprising particles show an amorphous structure, wherein some clusters having a diameter of more than 10 ⁇ are also present in this case .
• the sinter- fused particles are carbides, oxy-carbides or other mixed crystals in the system Al, C, O, and N.
• the average particle size herein also lies within a range of between 0.01 and 10 ⁇ .
• the amorphous rounded shape of the carbon comprising particles suggests that the integration of the correspondingly treated abrasive grains into the binding agent matrix will not be as tight as that of the abrasive grains with the Ti0 2

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• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
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• 2015
  • 2015-03-17 DE DE102015103934.6A patent/DE102015103934A1/de not_active Ceased
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  • 2015-04-10 EP EP15715280.2A patent/EP3131998B1/en active Active
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