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Aluminum and zirconium oxynitride abrasive grains

a zirconium oxynitride and abrasive grain technology, applied in the field of abrasive grains, can solve the problem of limited efficiency of quenching

Inactive Publication Date: 2005-12-29
PEM ABRASIFS REFRACTAIRES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012] The subject of the invention is corundum—zirconia abrasive grains containing more than 50% of a eutectic alumina—zirconia mixture, characterised in that they contain more than 0.3% of nitrogen, preferably from 0.3% to 3% of nitrogen, and more preferably from 0.3 to 1% of nitrogen, and in that less than 25% of the zirconia crystals are in m

Problems solved by technology

The patents mentioned above always indicate that the product is prepared by casting the molten product followed by vigorous quenching, a process that tends to stabilise the metastable cubic form; however, experience shows that the efficiency of this quenching is fairly limited, which is the reason for the interest in patent U.S. Pat. No. 4,457,767 that divulges that yttrium oxide stabilises the cubic phase of ZrO2.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0027] 2500 kg of powder Bayer alumina with a size grading of less than 100 μm was mixed with 1000 kg of powder aluminum with a size grading of less than 1.2 mm. This mixture was placed in a sealed furnace, vacuum degassed and then heated under a nitrogen pressure of 1 atm.

[0028] Nitriding began at about 700° C., and the nitrogen pressure was maintained to facilitate the increase in the temperature of the load. The exothermal reaction resulted in a temperature of about 1750° C. at the end of the operation.

[0029] After cooling, and at the end of the operation, the mass of porous, homogenous and mechanically unsound aluminum oxynitride recovered was 4010 kg.

[0030] The operation was repeated three times and finally a batch of 16 100 kg of product was obtained and was ground to a size grading of less than 10 mm, and then sampled and analysed; the result of the analysis gave an equivalent AlN content equal to 35.6%.

example 2

[0031] 400 kg of a mixture composed of 30 kg of the product obtained in example No. 1, 100 kg of baddeleyite with 95% of ZrO2 and 270 kg of Bayer alumina, was prepared.

[0032] This load was melted in a 100 kW melting arc furnace; the molten mass was cast on an ingot mould composed of 12 vertical cast iron plates (0.8 m×0.8 m×0.05 m) separated by 0.025 m. The cast mass was 390 kg; the product analysis was:

Equivalent AlN content:2.3%Zr content expressed in ZrO2:23.6%Al content expressed in Al2O3:73.7%

[0033] An examination of the product structure demonstrated the existence of two majority phases:

[0034]α alumina and cubic zirconia, and two minority phases: zirconium nitride and monoclinical zirconia. The chemical analysis also gave a free AlN content of 0.07% in the product.

[0035] The hardness and tenacity measurements are shown in Table 1, which also shows the results for similar product:

TABLE 1KnoopVickershardnesshardnessTenacityProduct in19.9 GPa18.9GPa2.8 MPa · m1 / 2example 2C...

example 3

[0037] A batch of F80 abrasive grains (according to the FEPA standard) was prepared starting from the product prepared in Example 2 and tested in grinding according to the following procedure:

[0038] A single layer of grains is fixed on the side part of a 160 mm diameter metallic drum using an acrylic thermosetting resin. The grinding test consists of attacking an 18-8 stainless steel bar with section 12 mm×12 mm pushed perpendicular with a force of 85 Newtons, in contact with the side face of the drum driven at 6000 rpm. The duration of the operation is three times one minute.

[0039] The mass of the stainless steel bar is tested after one minute, two minutes and three minutes to evaluate the weight loss. The steel mass removed expressed in grams per minute are shown in Table 2, which also shows the results of this test obtained with other products using F80 grains.

TABLE 2Mass removed minute byminuteProductSupplier123CorundumThe applicant11.07.56.8zirconia with25% ZrO2CorundumComp...

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Abstract

Corundum-zirconia abrasive grains containing more than 50 wt % of an alumina-zirconia eutectic mixture. The grains contain 0.3 to 3% nitrogen, and more than 75% of the zirconia crystals are cubic in shape. The abrasive grains are of particular use for making grinding wheels, abrasive fabrics and papers, polishing compounds and sprayed abrasives.

Description

BACKGROUND OF THE INVENTION [0001] The invention relates to the domain of abrasive grains, and particularly agglomerated grains intended for grinding wheels, grains applied to fabric and paper type supports, and grains used for spraying or contained in a polishing paste. [0002] Description of Related Art [0003] Alumina-zirconia based electromolten abrasives have been known for more than forty years and in particular have been described in several patents by the Norton company. Patent U.S. Pat. No. 3,181,939, filed in 1962, describes alumina-zirconia type electromolten abrasives with ZrO2 content between 10 and 60%, and a microstructure comprising an alumina-zirconia eutectic and zirconia and α alumina crystals. Patent U.S. Pat. No. 3,891,408 filed in 1971 relates to alumina-zirconia type electromolten abrasives with ZrO2 content of between 35 and 50%. Patent U.S. Pat. No. 3,993,119 published in 1976 describes a molten abrasive oxides casting machine capable of vigorously quenching t...

Claims

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Application Information

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IPC IPC(8): C04B35/119C04B35/581C04B35/653C09K3/14
CPCC04B35/119C09K3/1427C04B35/653C04B2235/3217C04B2235/3244C04B2235/3865C04B2235/3869C04B2235/3886C04B2235/402C04B2235/46C04B2235/668C04B2235/76C04B2235/762C04B2235/80C04B2235/96C09K3/1418C04B35/581
Inventor BOURLIER, FLORENTPEILLON, FLORENCE
Owner PEM ABRASIFS REFRACTAIRES
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