WO2011029286A1

WO2011029286A1 - Composite sintering agent and method for preparing nano crystalline ceramics at low temperature using the same

Info

Publication number: WO2011029286A1
Application number: PCT/CN2010/001526
Authority: WO
Inventors: 韩敏芳; 刘泽; 雷泽; 于立安; 彭苏萍
Original assignee: 中国矿业大学(北京)
Priority date: 2009-09-10
Filing date: 2010-09-29
Publication date: 2011-03-17
Also published as: JP5464723B2; JP2013505884A; CN101654366A; CN101654366B

Abstract

A composite sintering agent and a method for preparing nano crystalline ceramic at low temperature using the same are provided. The composite sintering agent comprises a sintering aid and a grain growth inhibitor. The sintering aid comprises oxides of one or more metals selected from Li, Na, Ga, In, Mn, Fe, Co, Ni, Cu, Zn and Bi. The grain growth inhibitor comprises oxides of one or more metals selected from Mg, Ca, Al, Zr and Y. The nano crystalline ceramic can be obtained by adding the composite sintering agent into ceramic material and the sintering temperature is not higher than 900℃.

Description

Composite combustion aid and method for preparing nanocrystalline ceramics at low temperature

The present application claims priority to the Chinese Patent Application No. 200910092906. X, filed on Sep. 10, 2009, which is incorporated herein by reference. for reference. Technical field

The invention relates to a low temperature preparation technology of nano ceramics, in particular to a composite combustion aid and a method thereof for preparing nanocrystalline ceramics at low temperature. Background technique

Compared with other materials such as metal materials and polymer materials, ceramic materials have the advantages of high temperature resistance, corrosion resistance, high strength, and high hardness. However, ceramic materials are typical brittle materials, which are determined by their structure. Ceramic materials are mainly composed of crystal phase, glass phase and pore phase. Compared with the example of pores, the development of dense ceramics can effectively improve the material properties. On the other hand, the grain size in conventional ceramic materials is generally from several micrometers to several tens of micrometers, and such grain size and structure are also disadvantageous for the development of high performance ceramics. Nanocrystalline ceramic materials not only have the advantages of traditional ceramic materials, but also can effectively improve the toughness of ceramic materials and obtain good mechanical properties.

With traditional ceramic materials and high-temperature sintering technology, it is easy to cause grain growth and it is difficult to obtain nano-sized ceramic materials.

In the prior art, non-sintering methods have been used to prepare nanocrystalline ceramics, such as spray pyrolysis technology, laser pulse deposition, vacuum sputtering, etc., and nanocrystalline ceramics are directly obtained without high temperature sintering. The above method is generally referred to as the "precursor method".

Nanocrystalline ceramics can be obtained by the precursor method, but the density of the ceramic material is difficult to meet the requirements; in addition, if the above materials are subjected to a high temperature stage, the crystal grains will further grow and the nanocrystal grains cannot be maintained. Summary of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a composite sintering aid which can be sintered at a low temperature to obtain a dense nanocrystalline ceramic material and a method for preparing the nanocrystalline ceramic at a low temperature.

The object of the invention is achieved by the following technical solutions:

The composite sintering aid of the present invention comprises a sintering aid and a grain growth inhibitor, and the sintering aid comprises the following oxides of one or more metals: Li, Na, Ga, In, Mn, Fe, Co, Ni, Cu, Zn, Bi;

The grain growth inhibitor comprises an oxide of one or more of the following metals: Mg, Ca, Al, Zr, Y. The method for preparing nanocrystalline ceramics at low temperature by using the above composite sintering aid according to the present invention, by using ceramic raw materials The above composite sintering agent is added to obtain a nanocrystalline ceramic, and the sintering temperature is less than or equal to 900 °C.

It can be seen from the technical solution provided by the above invention that the composite sintering aid and the method for preparing the nanocrystalline ceramic at low temperature according to the present invention, the composite sintering aid includes sintering aid and grain growth inhibitor, sintering The auxiliary agent comprises an oxide of one or more of the following metals: Li, Na, Ga, In, Mn, Fe, Co, Ni, Cu, Zn, Bi; the grain growth inhibitor comprises one or more of the following metals Oxide: Mg, Ca, Al, Zr, Y. The nanocrystalline ceramic is obtained by sintering the above composite sintering aid to the ceramic raw material, and the sintering temperature is less than or equal to 90 CTC. The dense nanocrystalline ceramic material can be obtained by sintering at a low temperature. detailed description

A preferred embodiment of the composite sintering aid of the present invention and a method for preparing the nanocrystalline ceramic at a low temperature is that the composite sintering aid includes a sintering aid and a grain growth inhibitor, and is improved by adding a sintering aid. The low-temperature sintering activity of the ceramic suppresses excessive growth of crystal grains by adding a grain growth inhibitor, and obtains a dense nanocrystalline ceramic at a low temperature. Specifically, a dense nanocrystalline ceramic is obtained by sintering a composite sintering aid at a temperature not higher than 90 CTC.

The type of the sintering aid in the composite sintering aid includes at least one of the following or an oxide of several metals: Li, Na, Ga, In, Mn, Fe, Co, Ni, Cu, Zn, Bi;

The type of grain growth inhibitor in the composite sintering aid includes at least one of the following oxides selected from several metals: Mg, Ca, Α1, Ζι^ΠΥ.

In the sintering process, the amount of the sintering aid added in the composite sintering aid is measured by the molar number of the ceramic raw material.

01 - 10%。 The amount of the molar amount of the ceramics is 0. 01 - 10%.

The nanocrystalline ceramic belongs to an oxide ceramic and may include at least one of the following materials: cerium oxide, doped cerium oxide, zirconium oxide, doped zirconia, alumina, doped alumina. Wherein, the element doped with cerium oxide may be any one or more of the following elements: cerium, lanthanum, cerium, calcium, lanthanum, cerium, calcium, etc.; the element doped with zirconia may be any of the following elements Species or several: 钇, 钪, 铈, calcium, magnesium, etc.

The raw material powder for preparing the nanocrystalline ceramic may have a grain size of 1 to 50 nm.

The specific method for preparing the nanocrystalline ceramic at a low temperature comprises adding a composite sintering aid and low-temperature sintering to realize nano-grain ceramic densification, and specifically includes the following implementation steps:

Mixing the raw material powder with the metal salt or metal oxide of the composite sintering agent, adding ethanol, acetone or isopropanol for grinding or ball milling, then drying at 50-100 ° C in air, then at 400-800 ° C Calcination for 1 to 4 hours causes the metal salt to decompose into metal oxides. Choose any of a variety of traditional ceramic block or film forming processes including dry press forming, isostatic pressing, extrusion, roll forming, tape casting, injection molding or mud coating. A ceramic block or film green body is prepared.

The obtained ceramic block or film green body is raised to a temperature of 1.0 to 10 ° C / min to 700 ~ 90 (TC, and kept at this temperature for 1 to 24 hours, and then at a temperature of 1- 30 ° C / min cooling rate Drop to room temperature.

The nanocrystalline ceramic prepared by the above steps has a relative density of not less than 95% and a grain size of not more than 100 nm; an optimized relative density of 98% or more and a grain size of 50 nm or less.

In the present invention, a dense nanocrystalline ceramic material can be obtained by sintering at a low temperature by adding a sintering aid, and the material may be a bulk material or a thin film material. The invention is mainly directed to binary oxide ceramics, but this method is by no means limited to binary oxides and can easily be extended to ternary, quaternary or even more oxide ceramics.

Specific embodiment:

The substantive features and significant advancements of the present invention are further illustrated by the following detailed description of the invention, and it should be emphasized that the present invention is by no means limited to these embodiments.

Example 1

The 20 mol% SmOl.5 doped Ce02 powder having an average grain size of 10 dishes was mixed with cobalt nitrate (1 mol% of the raw material powder) and magnesium nitrate (0.0 mol% of the raw material powder) and then added to the ethanol. The ball was ground and then dried in an air atmosphere at 50 ° C, and the obtained dry powder was calcined at 500 Torr for 2 hours. The above powder was pressed into a sheet by a dry pressing method, and raised to 860 ° C at a heating rate of 3 ° C /min, kept for 4 hours, and then lowered to room temperature at a rate of 5 ° C / mi n , and the obtained porcelain body was relatively The density is greater than 98% and the grain size is about 70 nm.

Example 2:

10 mol% of GdOl. 5 doped Ce02 powder having an average grain size of 15 nm was mixed with lithium nitrate (5 mol% of raw material powder) and aluminum nitrate (0.0 mol% of raw material powder) and added to ethanol. The ball was ground and then dried in an air atmosphere at 70 ° C, and the obtained dry powder was calcined at 60 CTC for 2 hours. The above powder was pressed into a tablet by dry pressing, raised to 800 ° C at a heating rate of Γ C /min, kept for 5 hours, and then lowered to room temperature at a rate of 5 ° C / min, and the relative density of the obtained ceramic body was greater than 98%, the grain size is about 50nm.

Example 3:

8 mol% Y203 stabilized Zr02 (8YSZ) powder with an average grain size of 12 nm was mixed with copper nitrate (5 mol% of raw material powder) and lanthanum nitrate (l mol% of raw material powder), and then added to acetone ball mill, and then Drying in an air atmosphere at 60 ° C, the obtained dry powder was calcined at 50 (TC for 2 hours. The above powder was compressed into tablets by dry pressing, and raised to 830 ° C at a heating rate of 2 ° C /min, and kept warm. After 10 hours, the temperature was lowered to room temperature at a rate of 5 ° C/min, and the resulting ceramic had a relative density of more than 95% and a grain size of about 50 nm.

The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that may be easily conceived within the scope of the present invention are intended to be included within the scope of the present invention.

Claims

Claim

A composite sintering aid characterized by comprising a sintering aid and a grain growth inhibitor, the sintering aid comprising an oxide of one or more of the following metals: Li, Na, Ga, In, Mn , Fe, Co, Ni, Cu, Zn, Bi _;

The grain growth inhibitor comprises an oxide of one or more of the following metals: Mg, Ca, Al, Zr, Y.

2. A method for preparing a nanocrystalline ceramic at a low temperature by using the composite sintering aid according to claim 1, wherein the nanocrystalline ceramic is obtained by adding the composite sintering aid according to claim 1 to a ceramic raw material, and sintering is performed. The temperature is less than or equal to 900 °C.

0- 01 01- The number of moles of the ceramic raw material is 0. 01- 20%;

01-10%。 The amount of the molar amount of the ceramics is 0. 01-10%.

The method for preparing a nanocrystalline ceramic at a low temperature according to claim 3, wherein the nanocrystalline ceramic comprises at least one of the following materials: cerium oxide, doped cerium oxide, zirconium oxide, doped zirconia, oxidized Aluminum, doped alumina;

The doping element doped with cerium oxide includes one or more of the following elements: barium, strontium, barium, calcium, strontium, barium, calcium;

The doping element of the doped zirconia includes one or more of the following elements: lanthanum, cerium, lanthanum, calcium, magnesium.

The method for preparing a nanocrystalline ceramic at a low temperature according to claim 2, 3 or 4, characterized by comprising the steps of:

First, the ceramic raw material is made into a raw material powder having a grain size of l-50 nm;

Then, the raw material powder and the metal salt or metal oxide of the composite sintering agent are mixed, and added to ethanol, acetone or isopropanol for grinding or ball milling;

Thereafter, drying in a 50-10 CTC air atmosphere, followed by calcination at less than or equal to 90 (TC for 1-4 hours to decompose the metal salt into a metal oxide;

The sintered material is prepared into a ceramic block or a film green body, and the green body is raised to a temperature of 700 to 900 ° C at a temperature increase rate of 1- lOTVmin, and is kept at the temperature for 1 to 24 hours, and then The temperature drop rate at 1- 30 ° C / min is reduced to room temperature.

The method of producing a nanocrystalline ceramic at a low temperature according to claim 5, wherein the mixture of the raw material powder has a calcination temperature of 400 to 80 CTC.

7. The method of preparing a nanocrystalline ceramic at a low temperature according to claim 5, wherein the prepared nanocrystal is The crystalline ceramic has a relative density of not less than 95% and a grain size of not more than 100 nm.

The method for preparing a nanocrystalline ceramic at a low temperature according to claim 7, wherein the nanocrystalline ceramic has an optimized relative density of 98% or more and a crystal grain size of 50 nm or less.