RU2455261C2 - Mixture for ceramic material based on zirconium and aluminium oxides and zirconium nitride - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to ceramic material science, particularly to production of ceramic material based on heat-resistant non-oxygen and oxide compounds, characterised by high strength and crack-resistance, and can be used to make a cutting tool, in oil and gas industry (valve devices and sealing rings of pumps), in making nozzle extensions for air-sand blowers and chemical solution sprayers. The ceramic material is obtained from a mixture which contains components in the following ratio, wt %: Al₂O₃ 10-40, ZrN 20-65, ZrO₂ - the balance, at sintering temperature 1700-1800°C and nitrogen pressure during sintering of 0.10-0.12 MPa without a complex operation for isostatic moulding using high pressure.

EFFECT: obtaining ceramic material with high crack-resistance (coefficient of intensity of critical stress 7-14 MPa·m^1/2 s) and bending strength 650-750 MPa.

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Description

The invention relates to ceramic materials science, in particular to the production of ceramic materials based on refractory oxygen-free and oxide compounds for high-temperature applications, characterized by high strength, hardness and crack resistance, and can also be used for the manufacture of cutting tools in the oil and gas industry (valve devices and o-rings of pumps), in the manufacture of nozzle nozzles for sandblasting machines and chemical spray guns moat.

A number of solutions are known for the technology and compositions of ceramic materials based on aluminum oxide or zirconium oxide.

US patent No. 4316964 (publ. 23.02.82) proposes a ceramic material based on Al ₂ O ₃ , ZrO ₂ and the addition of up to 2 wt.% Such oxides as Y ₂ O ₃ , CeO ₂ , La ₂ O ₃ , Er ₂ About ₃ . The specified material has brittleness and insufficiently high strength.

In Russian patent No. 2336245, IPC С04В 35/488, С04В 35/58, (published on October 20, 2008, Bull. No. 29), the patent holder OJSC COMPOSIT proposes ceramic material containing ZrB ₂ and ZrO ₂ , characterized in that that it additionally contains ZrN, Y ₂ About ₃ and (or) TiN. The disadvantage of the material is low mechanical bending strength (400-480 MPa) and crack resistance (5.8-6.1 MPa · m ^1/2 ), which limits the scope of the material.

The closest in technical essence to the claimed invention is a ceramic material proposed in US patent No. 5916833, IPC С04В 35/56, С04В 35/58, СВВ 35/101, publ. 06/29/1999, patent holder - NGK SPARK PLUG Co Ltd (Japan). In this patent, a ceramic material is proposed, including zirconium and aluminum oxides in a volume ratio of 80:20 (zirconium oxide contains an addition of 3 mol.% Yttrium oxide to stabilize the cubic phase ZrO ₂ ), an additional 25-60 vol.% Is added to the charge ZrN. The production method includes co-mixing in a drum mill in an alcohol environment, spray drying, granulation and molding by casting or extrusion, removal of plasticizer at a temperature of 450-530 ° C, sintering at a temperature of 1480-1550 ° C in argon at a pressure of 2-5 atm .

The disadvantages of this method include insufficiently high crack resistance (5.2 MPa · m ^1/2 ), which limits the scope of the material.

The objective of the proposed technical solution is to increase the crack resistance of the ceramic material.

The solution to this problem is provided by the fact that the proposed mixture for a ceramic material containing ZrO ₂ and ZrN, characterized in that it additionally contains Al ₂ About ₃ in the following ratio of components, wt.%:

Al ₂ O ₃ 10-40 Zrn 20-65 ZrO ₂ rest.

The preparation of the proposed ceramic material includes mixing and grinding of the starting components, pressing, drying and sintering of the ceramic material at 1700-1800 ° C in a nitrogen atmosphere at a pressure of 0.10-0.12 MPa with holding at a final temperature for 1 hour.

The proposed ceramic material has a high crack resistance (intensity coefficient of critical stress 7-14 MPa · m ^1/2 ). In addition, these properties are achieved at a significantly lower nitrogen pressure during sintering (0.10-0.12 MPa), while forming blanks, a complex casting (or extrusion) operation is not required.

With the introduction of ZrN in excess of 20 wt.%, Partial or complete stabilization of the cubic phase of ZrO ₂ occurs, which increases the strength and heat resistance of the material.

The introduction of alumina together with zirconium nitride creates a barrier to diffusion processes, which significantly slows down the recrystallization process during sintering and allows one to obtain materials with a small grain size (1-3) μm, which leads to an increase in strength and crack resistance.

During the interaction of zirconium oxide and nitride, solid solutions of variable composition (zirconium oxynitrides ZrN _1-X O _X ) are formed at the grain boundary, which leads to a decrease in the sintering temperature and to obtain a densely sintered material with a porosity of 1-2% or less.

The level of mechanical and physical properties will make it possible to use the materials of this system as structural, corrosion-resistant, and resistive materials that are stable in contact with molten metals, as coatings and cutters for non-ferrous metals.

The proposed solution has a novelty, inventive step and is industrially applicable. The compositions of the ceramic material and properties are shown in the table.

Examples of the proposed method.

Example 1

By co-grinding in a vibration mill to a fineness of 1-2 μm in ethanol with the addition of polyethylene glycol as a plasticizer, a powder mixture is made consisting of 20 wt.% Alumina, 40 wt.% Zirconia and 40 wt.% Zirconium nitride.

Samples are pressed from the resulting mixture at a pressure of 100-110 MPa. Sintering is carried out at a temperature of 1750 ° C in a nitrogen atmosphere at a pressure of 0.10-0.42 MPa with exposure at a final temperature for one hour.

(Properties in the table)

Example 2

The powder mixture consists of 5 wt.% Alumina, 30 wt.% Zirconia and 65 wt.% Zirconium nitride. The sintering temperature in nitrogen is 1700 ° C.

Example 3

The powder mixture consists of 20 wt.% Alumina, 60 wt.% Zirconia and 20 wt.% Zirconium nitride. Sintering temperature in nitrogen medium 1800 ° С.

Example 4

The powder mixture consists of 40 wt.% Alumina, 20 wt.% Zirconia and 40 wt.% Zirconium nitride. Sintering temperature in a nitrogen atmosphere of 1750 ° C.

These examples are shown in the table. The table also shows examples (4, 5) outside the claimed field and an example of the prototype method.

The inventive method allows to obtain high-strength ceramic material for the manufacture of wear-resistant products, with a density of up to 99% of theoretical, grain size of 1-3 microns and, as a consequence, high strength and crack resistance.

Table MIXTURE FOR CERAMIC MATERIAL BASED ON ZIRCONIUM AND ALUMINUM AND ZIRCONIUM NITRIDES Example No. The content of components, wt.% Sintering temperature, ° С Crack resistance, MPa · m ^1/2 Al ₂ O ₃ ZrO ₂ Zrn one twenty 40 40 1750 fourteen 2 10 25 65 1700 13 3 twenty 60 twenty 1800 10 four 40 twenty 40 1750 8.1 5* 8 12 80 1820 5.8 6 * 45 40 fifteen 1650 5.5 7 * 17 65 eighteen 1700 5.2 Prototype 1500 5.1 * - Examples outside the claimed field

Claims (1)

The mixture for a ceramic material with high crack resistance, containing ZrO ₂ and ZrN, characterized in that it additionally contains Al ₂ O ₃ in the following ratio of components, wt.%:
Al ₂ O ₃ 10-40 Zrn 20-65 ZrO ₂ rest