Boron suboxide composite material

a composite material and boron suboxide technology, applied in the field of boron suboxide composite materials, can solve the problems of reducing the usefulness of the material in the industry, reducing the overall reducing the yield of boron suboxide, so as to improve the hardness of the composite material, increase the wear resistance, and improve the effect of chemical stability

Inactive Publication Date: 2010-12-02
ANDREWS ANTHONY +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The invention is a composite material made of boron suboxide and a secondary phase containing a mixture of metal oxides. This composite material has high hardness and fracture toughness, which are important properties for many applications. The secondary phase can be present in a bonded, coherent form and can be amorphous or partially crystalline. The composite material can also contain a boride, which can further enhance its properties. The fracture toughness of the composite material is measured using the DCM method and the hardness is measured using the Vickers method. The invention also provides a method for producing the composite material by milling boron suboxide in the presence of a milling medium and a method for measuring the hardness and fracture toughness of the composite material."

Problems solved by technology

With each of these known procedures however, there are drawbacks which retard the usefulness of the material in industry.
For example, the reduction of B2O3 with magnesium produces a solid solution of magnesium and magnesium boride contaminants in the suboxide, while the reduction of magnesium oxide with boron produces only a relatively small yield of boron suboxide and is very inefficient.
The aluminium phases present in the composite are soft and although they may improve the fracture toughness of the resulting composite, they do not contribute to the overall hardness of the composite.
Moreover, in addition to a crystalline aluminium borate, a boron oxide rich, chemically unstable amorphous phase and microporosity was formed, further resulting in reduced hardness [10, 11].

Method used

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  • Boron suboxide composite material
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Examples

Experimental program
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Effect test

example 1

[0037]B6O starting powder was milled using an attritor mill with steel balls for 50 hours. The iron contaminants were removed by washing in HCl. The powder was subsequently washed in methanol to remove any B2O3 present. The average particle size after milling was 500 nm.

[0038]The milled powder was admixed with 2% by weight of Al2O3 and 2.65% by weight of Y2O3 in methanol and milled for two hours using a planetary mill. The milled mixture was dried using a rotary evaporator and then placed in a boron nitride cell (inside a graphite die) and sintered using a hot press at a temperature of 1800° C. and a pressure of 50 MPa, under an argon atmosphere for about 20 minutes. A fully densified composite material comprising boron suboxide particles was produced within which a secondary phase was uniformly dispersed. No crystalline phase in the secondary phase was identified by XRD. The grain boundary was an amorphous grain boundary phase containing Y2O3, Al2O3 and remaining B2O3.

[0039]A cross...

example 2

[0041]A boron suboxide composite material was produced using the same components and conditions set out in Example 1, save that the amount of Y2O3 and Al2O3 components was reduced by half, with the ratio between the two being kept the same. The composite material produced was fully densified and was also found to contain Y2O3, Al2O3 and remaining B2O3. It had a hardness of 30.4 GPa and a fracture toughness of 6.0 MPa.m0.5.

example 3

[0042]A boron suboxide composite material was produced using the same components and conditions set out in Example 1, save that the components for the secondary phase included an additional 1.0 weight % SiO2. The composite material produced was fully densified and was found to contain an amorphous grain boundary phase containing Y2O3, Al2O3 and remaining B2O3. It had a hardness of 33.5 GPa and a fracture toughness of 5.0 MPa.m0.5.

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Abstract

The invention provides a boron suboxide composite material comprising boron suboxide and a secondary phase, wherein the secondary phase contains a mixture of at least two metal oxides, neither of which is a boron-containing oxide. At least one of the oxides may be selected from oxides of elements of Groups IA, IIA, IIIA, and IVA of the periodic table. Also, at least one of the oxides may be a rare earth metal oxide selected from the oxides of scandium, yttrium, and elements of the ianthanide series. The secondary phase of the composite material may also contain a boride, and particularly a boride selected from the borides of transition metals of the fourth to eighth groups of the periodic table.

Description

BACKGROUND OF THE INVENTION[0001]The invention relates to a boron suboxide composite material.[0002]The development of synthetic ultrahard materials which have hardness values approaching or even exceeding that of diamond has been of great interest to material scientists. With a Vickers hardness of between 70 to 100 GPa, diamond is the hardest material known, followed by cubic boron nitride (HV˜60 GPa) and boron suboxide herein referred to as B6O. Hardness values of 53 GPa and 45 GPa have been determined at 0.49N and 0.98N load respectively for B6O single crystals, which are similar to those of cubic boron nitride [9].[0003]It is known that B5O may also be non-stoichiometric i.e. exist as B6O1-x (where x is in the range 0 to 0.3). Such non-stoichiometric forms are included in the term B6O. The strong covalent bonds and short interatomic bond length of these materials contribute to the exceptional physical and chemical properties such as great hardness, low mass density, high thermal...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): C09K3/00
CPCC04B35/01C04B35/6264C04B35/64C04B35/645C04B2235/3206C04B2235/3208C04B2235/3213C04B2235/3215C04B2235/3217C04B2235/3224C04B2235/3225C04B2235/3227C04B2235/3244C04B2235/3258C04B2235/3409C04B2235/3418C04B2235/3804C04B2235/3813C04B2235/386C04B2235/404C04B2235/652C04B2235/656C04B2235/666C04B2235/77C04B2235/79C04B2235/80C04B2235/85C04B2235/96Y10T428/2982
InventorANDREWS, ANTHONYSIGALAS, IAKOVOSHERRMANN, MATHIAS
OwnerANDREWS ANTHONY