EP0115702A2 — Shaped refractory metal boride articles and metho…

Claim 1

Independent Claim 96 words

A shaped refractory article of group IV b, V b, or VI b metal boride, which article has a microstructure with a weight average grain diameter of from 0.5 to 5 microns and substantially no grains larger than 10 microns diameter, from 10% to 45% by volume being made up of interconnected pores the majority having a diameter not substantially greater than 5 microns, porosity and grain size being substantially uniform throughout the microstructure, the article containing not more than about 0.2% by weight of oxygen and not more than about 0.5% by weight of carbon.

Claim 2

Dependent Claim 96 words

A shaped refractory article of group IV b, V b, or VI b metal boride, which article has a microstructure with a weight average grain diameter of from 0.5 to 5 microns and substantially no grains larger than 10 microns diameter, from 10% to 45% by volume being made up of interconnected pores the majority having a diameter not substantially greater than 5 microns, porosity and grain size being substantially uniform throughout the microstructure, the article containing not more than about 0.2% by weight of oxygen and not more than about 0.5% by weight of carbon.

Claim 3

Dependent Claim 16 words

A shaped refractory article as claimed in claim 1, wherein the metal boride is titanium diboride.

Claim 4

Dependent Claim 20 words

A shaped refractory article as claimed in claim 2, having a density of from 2.5 to 4.0 mg/mm 3 .

Claim 5

Dependent Claim 108 words

A shaped refractory composite of an inert particulate material in a matrix of a group IV b, V b, or VI b metal boride, which matrix has a microstructure with a weight average grain diameter of from 0.5 to 5 microns and substantially no grains larger than 10 microns diameter, from 10 to 45% by volume being made up of interconnected pores of which the majority have a diameter not substantially greater than 5 microns, porosity and a grain size being substantially uniform throughout the microstructure, the matrix containing not more than about 0.2% by weight of oxygen and not more than about 0.5% by weight of carbon.

Claim 6

Dependent Claim 108 words

A shaped refractory composite of an inert particulate material in a matrix of a group IV b, V b, or VI b metal boride, which matrix has a microstructure with a weight average grain diameter of from 0.5 to 5 microns and substantially no grains larger than 10 microns diameter, from 10 to 45% by volume being made up of interconnected pores of which the majority have a diameter not substantially greater than 5 microns, porosity and a grain size being substantially uniform throughout the microstructure, the matrix containing not more than about 0.2% by weight of oxygen and not more than about 0.5% by weight of carbon.

Claim 7

Dependent Claim 35 words

A shaped refractory composite as claimed in claim 4, wherein the inert particulate material is TiB 2 , A1 2 0 3' AION or AlN, and the metal boride of the matrix is titanium diboride.

Claim 8

Independent Claim 115 words

A method of making a shaped refractory article of a group IV b, V b, or VI b metal boride, or a refractory shaped composite of an inert particulate material in a matrix of the metal boride, which method comprises forming a uniformly mixed body of reactants containing the said metal as an oxide sub-oxide, borate or carbide, boron as an element, oxide or carbide, and if necessary carbon in the stoichiometric proportions desired to form the desired metal boride, boron suboxides and carbon monoxide, forming the reaction mixture optionally together with an inert particulate material into a shaped compact, and heating the shaped compact in an inert atmosphere to form a reaction sintered product.

Claim 9

Independent Claim 115 words

A method of making a shaped refractory article of a group IV b, V b, or VI b metal boride, or a refractory shaped composite of an inert particulate material in a matrix of the metal boride, which method comprises forming a uniformly mixed body of reactants containing the said metal as an oxide sub-oxide, borate or carbide, boron as an element, oxide or carbide, and if necessary carbon in the stoichiometric proportions desired to form the desired metal boride, boron suboxides and carbon monoxide, forming the reaction mixture optionally together with an inert particulate material into a shaped compact, and heating the shaped compact in an inert atmosphere to form a reaction sintered product.

Claim 10

Dependent Claim 31 words

A method as claimed in claim 6, wherein the uniformly mixed body of reactants is formed by precipitating one reactant on to a dispersion of another reactant and drying the mixture.

Claim 11

Dependent Claim 28 words

A method as claimed in claim 6, wherein the uniformly mixed body of reactants is formed by co-precipitating two or more of the reactants and drying the mixture.

Claim 12

Independent Claim 19 words

A method as claimed in'any one of claims 6 to 8, wherein the metal boride is TiB 2 .

Claim 13

Dependent Claim 60 words

A method as claimed in claim 9, wherein the reaction mixture is formed by providing one or more of the reactants as a dispersion in an aqueous solution of a titanium halide and precipitating the titanium values on to the one or more dispersed reactants and drying the mixture and heating to convert the titanium values to Ti0 2 .

Claim 14

Dependent Claim 14 words

A method as claimed in claim 10, wherein the titanium halide is titanium tetrachloride.

Claim 15

Independent Claim 77 words

A method as claimed in any one of claims 9 to 11, wherein the uniformly mixed body of reactants is formed by pre-heating a comminuted mixture of 2 molar parts of Ti0 2 , substantially one molar part of B 4 C and substantially 3 atomic parts of C in vacuum or inert atmosphere to a temperature at which CO is evolved but below that at which-TiB 2 is formed, and then cooling and grinding the mixture.

Claim 16

Independent Claim 67 words

A method as claimed in any one of claims 9 to 11, wherein the uniformly mixed body of reactants is formed by pre-heating a comminuted mixture of Ti0 2 and C to produce an intermediate product consisting essentially of one or more titanium sub-oxides, and grinding and mixing the intermediate product with B 4 C and C in the proportions required to produce TiB 2 and C0.

Claim 17

Dependent Claim 20 words

A method as claimed in claim 12, wherein the comminuted mixture is pre-heated at a temperature not greater than 650°C.

Claim 18

Independent Claim 44 words

A method as claimed in any one of claims 9 to 14, wherein the uniformly mixed body of reactants is heated at a temperature of at least 1300°C for a time to effect essentially complete formation of the TiB 2 and evolution of C0.

Claim 19

Independent Claim 99 words

A method as claimed in any one of claims 6 to 15, wherein the metal boride matrix has a microstructure with a weight average grain diameter of from 0.5 to 5 microns and substantially no grains larger than 10 microns diameter, from 10 to 45% by volume being made up of interconnected pores of which the majority have a diameter not substantially greater than 5 microns, porosity and a grain size being substantially uniform throughout the microstructure, the matrix containing not more than about 0.2% by weight of oxygen and not more than about 0.5 by weight of carbon.

Shaped refractory metal boride articles and method of making them

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