US4670407A — Refractories with a high content of alumina and t…

Claim 1

Independent Claim 65 words

Refractory material for use at high temperatures consisting essentially of more than 95% by weight of aluminum oxide particles having a particle size ranging from 0.1 to 5 mm with at least one half by weight of the particles being larger than 0.2 mm and less than 1% by weight of silicon oxide bound by a binder consisting essentially of aluminum nitride and aluminum oxycarbide.

Claim 2

Dependent Claim 65 words

Refractory material for use at high temperatures consisting essentially of more than 95% by weight of aluminum oxide particles having a particle size ranging from 0.1 to 5 mm with at least one half by weight of the particles being larger than 0.2 mm and less than 1% by weight of silicon oxide bound by a binder consisting essentially of aluminum nitride and aluminum oxycarbide.

Claim 3

Dependent Claim 52 words

The refractory material for use at high temperatures in accordance with claim 1, wherein said material has a melting point above 1,850° C., is stable at said temperature in a reducing atmosphere, has an open porosity of less than 15%, and a modulus of rupture greater than 200 bars at 1,500° C.

Claim 4

Independent Claim 77 words

A method for producing a refractory material comprising: ( 1) preparing a mixture consisting essentially of: (a) 50% to 80% by total weight of particles selected from the group consisting of electrofused corundum, sintered corundum and mixtures of electrofused and sintered corundum having a particle size ranging from 0.1 to 5 mm with at least one half by weight of the particles being larger than 0.2 mm, (b) 20% to 50% of a binder consisting essentially of:

Claim 5

Independent Claim 77 words

A method for producing a refractory material comprising: ( 1) preparing a mixture consisting essentially of: (a) 50% to 80% by total weight of particles selected from the group consisting of electrofused corundum, sintered corundum and mixtures of electrofused and sintered corundum having a particle size ranging from 0.1 to 5 mm with at least one half by weight of the particles being larger than 0.2 mm, (b) 20% to 50% of a binder consisting essentially of:

Claim 6

Dependent Claim 171 words

3 (i) 5% to 20% by total weight of ultrafine alumina having a particle size less than 100 micrometers, (ii) 5% to 20% by total weight of aluminum powder having a particles size less than 200 micrometers, (iii) 0.5% to 5% by total weight of carbon selected from the group consisting of an organic resin binder residue, lampblack, a mixture of an organic resin binder residue and lampblack, microcrystalline graphite carbon originating from a member selected from the group consisting of an in situ organic binder residue, a milling liquid in situ residue, and a mixture of an in situ organic binder residue and a milling liquid in situ residue, (iv) 0.5% to 4% by total weight of a nitriding and carbiding catalyst selected from the group consisting of iron oxide, titanium oxide, lime and magnesia (2) milling said mixture with a milling organic resin and then shaping by pressing at a minimum pressure of 600 bars; and (3) firing at a minimum temperature of 1,250° C. in a reducing atmosphere.

Claim 7

Dependent Claim 171 words

3 (i) 5% to 20% by total weight of ultrafine alumina having a particle size less than 100 micrometers, (ii) 5% to 20% by total weight of aluminum powder having a particles size less than 200 micrometers, (iii) 0.5% to 5% by total weight of carbon selected from the group consisting of an organic resin binder residue, lampblack, a mixture of an organic resin binder residue and lampblack, microcrystalline graphite carbon originating from a member selected from the group consisting of an in situ organic binder residue, a milling liquid in situ residue, and a mixture of an in situ organic binder residue and a milling liquid in situ residue, (iv) 0.5% to 4% by total weight of a nitriding and carbiding catalyst selected from the group consisting of iron oxide, titanium oxide, lime and magnesia (2) milling said mixture with a milling organic resin and then shaping by pressing at a minimum pressure of 600 bars; and (3) firing at a minimum temperature of 1,250° C. in a reducing atmosphere.

Claim 8

Dependent Claim 33 words

The method in accordance with claim 3, wherein the milling organic resin is a liquid organic resin which decomposes to provide the totality of the carbon required for the formation of aluminum carbide.

Claim 9

Dependent Claim 27 words

The method in accordance with claim 4, wherein the milling organic resin liquid contains a member selected from the group consisting of phenolic resin and furfuryl resin.

Claim 10

Dependent Claim 18 words

The method in accordance with claim 3 wherein said minimum pressure is a pressure of approximately 1,000 bars.

Claim 11

Dependent Claim 15 words

The method in accordance with claim 3 wherein said minimum temperature is approximately 1,500° C.

Claim 12

Dependent Claim 17 words

The method in accordance with claim 3 wherein said firing is performed in the presence of nitrogen.

Claim 13

Dependent Claim 18 words

The method in accordance with claim 3 wherein said firing is performed in an atmosphere of pure nitrogen.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1990-06-01	1990-12-01	1991-06-02	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1994-06-01	1994-12-01	1995-06-02	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1998-06-01	1998-12-01	1999-06-02	$7700.00	Window Closed / Lapsed

Refractories with a high content of alumina and the process for their production

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