CN102643087B - A kind of preparation method of SnO2-Zn2SnO4 composite varistor ceramics - Google Patents

Abstract

A SnO ₂ -Zn ₂ SnO ₄ composite varistor ceramic, made by mixing and pressing SnO ₂ powder and Zn ₂ SnO ₄ powder, and sintering, and each mole of composite varistor ceramic material consists of Xmol of SnO ₂ powder And (1-X) mol Zn ₂ SnO ₄ powder composition, wherein the value of X is 0.82-0.88. Compared with traditional ZnO, SrTiO ₃ , TiO ₂ and other materials, the SnO ₂ -Zn ₂ SnO ₄ composite ceramic prepared by SnO ₂ and Zn ₂ SnO ₄ in the present invention is easy to obtain or prepare the required materials, and it does not need to be doped. It has pressure-sensitive properties, simple process and can be used for large-scale industrial production.

Description

A kind of preparation method of SnO2-Zn2SnO4 composite varistor ceramics

technical field

The invention relates to a ceramic material in the field of inorganic non-metal, in particular to a SnO ₂ -Zn ₂ SnO ₄ composite pressure-sensitive ceramic and a preparation method thereof.

Background technique

Varistor ceramic is an important high-tech functional material. Its own resistance can change with the change of applied voltage. The varistor element made of this material shows a high resistance state within a certain voltage range. When the applied voltage After exceeding the limited range, the resistance of the piezoresistor itself decreases rapidly, and the current passing through it increases sharply in an exponential manner. This non-linear relationship between current and voltage is typical of varistors. At present, varistors have been widely used in various overvoltage protection and voltage stabilization circuits. the

Among the numerous varistor ceramics, ZnO-based varistor ceramics are the most widely used materials at present. In order to be suitable for the application in the low-voltage field, several material systems such as ZnO, SrTiO ₃ , TiO ₂ , and WO ₃ are mainly studied at present. Among them, several materials such as ZnO, SrTiO ₃ , and TiO ₂ need to be doped with complex elements to have pressure-sensitive properties. Due to the coexistence of triclinic and monoclinic phases, WO ₃ ceramics have poor electrical stability. That is, the current changes rapidly with time under a certain voltage. Therefore, in order to obtain a stable WO ₃ varistor, it must also be doped with complex elements.

Contents of the invention

In order to solve the problem that the varistor ceramics in the prior art need complex doping to have stable varistor properties, the present invention provides a SnO ₂ -Zn ₂ SnO ₄ composite varistor ceramic and its preparation method. The pressure-sensitive ceramics have good pressure-sensitive properties.

The technical solution adopted by the present invention to solve the above technical problems is: a SnO ₂ -Zn ₂ SnO ₄ composite pressure-sensitive ceramic, which is made by mixing and pressing SnO ₂ powder and Zn ₂ SnO ₄ powder, and sintering. The composite pressure-sensitive ceramic material is composed of Xmol SnO ₂ powder and (1-X)mol Zn ₂ SnO ₄ powder, and the value of X is 0.82-0.88;

The preparation method of the SnO ₂ -Zn ₂ SnO ₄ composite varistor ceramics is as follows:

1) Preparation of Zn ₂ SnO ₄ powder

Mix the analytically pure chemical reagents SnO ₂ and ZnO in a molar ratio of 1:2, and put them into a nylon ball mill tank, then add alcohol and ball mill for 12 hours at a speed of 120 rpm to obtain a slurry;

After the ball milled slurry is dried at 21°C~150°C, it is sent into a powder tablet press, and pressed into a disc with a diameter of 30 mm under the condition of 80 MPa, and then sent into a muffle furnace. Calcined at 1000°C for 2 hours, then naturally cooled to 20°C, and crushed to obtain Zn ₂ SnO ₄ powder for later use;

2) Weigh the analytically pure chemical reagent SnO ₂ and the Zn ₂ SnO ₄ powder prepared in step 1 for dry mixing, then put them into a nylon ball mill jar, and ball mill them with alcohol at a speed of 120 rpm for 12 hours, Obtain slurry, standby;

Wherein, the molar ratio of SnO ₂ and Zn ₂ SnO ₄ is X: (1-X), and the value of X is 0.82-0.88;

Dry the ball-milled slurry at 21°C~150°C and weigh its weight, then add 5-7% of its weight and 10% polyvinyl alcohol solution to it, and use the powder under the pressure of 160MPa Press the tablet machine into discs with a diameter of 15 mm and a thickness of 1.5 mm for use;

3) Debinding the wafer prepared in step 2 at 650°C for 1 hour, then sintering at 1300°C for 2 hours, and then naturally cooling to 21°C to obtain the product.

In the present invention, the alcohol added during ball milling has a concentration of 99%, and the addition is 0.5cm of the material to be milled;

The grinding balls used in ball milling are all zirconia balls, the mass ratio of zirconia balls to materials is 4:1, the diameters of the zirconia balls put in are: 8.5mm, 4.5mm, 2.6mm, and three The mass ratio of the balls is 4:3:4.

Beneficial effects: Compared with traditional ZnO, SrTiO ₃ , TiO ₂ and other materials, the SnO ₂ -Zn ₂ SnO ₄ composite ceramic prepared by SnO ₂ and Zn ₂ SnO ₄ in the present invention is easy to obtain or prepare the required materials without the need for Doping has pressure-sensitive properties, the process is simple, and can be used for large-scale industrial production.

Description of drawings

Fig. 1 is the non-linear relationship between the current and voltage of the SnO ₂ -Zn ₂ SnO ₄ composite ceramics prepared by various embodiments of the present invention;

In the figure, C1 is the sample made in Example 1, C2 is the sample made in Example 2, C3 is the sample made in Example 3, and C4 is the sample made in Example 4.

Detailed ways

The present invention will be further elaborated below in conjunction with specific embodiments. the

Example 1

A SnO ₂ -Zn ₂ SnO ₄ composite varistor ceramic, the preparation method of which is:

1) Preparation of Zn ₂ SnO ₄ powder

Mix the analytically pure chemical reagents SnO ₂ and ZnO in a molar ratio of 1:2, and put them into a nylon ball mill jar, then add alcohol and ball mill for 12 hours at a speed of 120 rpm to obtain a slurry;

After the ball milled slurry is dried at 21°C~150°C, it is sent into a powder tablet press, and pressed into a disc with a diameter of 30 mm under the condition of 80 MPa, and then sent into a muffle furnace. Calcined at 1000°C for 2 hours, then naturally cooled to 20°C, and crushed to obtain Zn ₂ SnO ₄ powder for later use;

2) Weigh and analyze 0.82mol of pure chemical reagent SnO ₂ and 0.18mol of Zn ₂ SnO ₄ powder prepared in step 1 for dry mixing, then put them into a nylon ball mill tank, and put alcohol under the condition of 120 rpm Ball milled for 12 hours to obtain the slurry for subsequent use;

Dry the milled slurry at 21°C~150°C and weigh it, then add 6% of its weight and 10% polyvinyl alcohol solution to it, and press it into tablets under a pressure of 160MPa Machine pressed into discs with a diameter of 15 mm and a thickness of 1.5 mm, and set aside;

3) Debinding the wafer prepared in step 2 at 650°C for 1 hour, then sintering at 1300°C for 2 hours, and then naturally cooling to 21°C to obtain the product.

Example 2

A SnO ₂ -Zn ₂ SnO ₄ composite varistor ceramic, the preparation method of which is:

1) The preparation of Zn ₂ SnO ₄ powder is the same as in Example 1;

2) Weigh 0.84 mol of the analytically pure chemical reagent SnO ₂ and 0.16 mol of the Zn ₂ SnO ₄ powder prepared in step 1 for dry mixing, then put them into a nylon ball mill tank, and put alcohol under the condition of 120 rpm Ball milled for 12 hours to obtain the slurry for subsequent use;

Dry the milled slurry at 21°C~150°C and weigh it, then add 8% of its weight and 10% polyvinyl alcohol solution to it, and press it into tablets under a pressure of 160MPa Machine pressed into discs with a diameter of 15 mm and a thickness of 1.5 mm, and set aside;

3) Debinding the wafer prepared in step 2 at 650°C for 1 hour, then sintering at 1300°C for 2 hours, and then naturally cooling to 21°C to obtain the product.

Example 3

A SnO ₂ -Zn ₂ SnO ₄ composite varistor ceramic, the preparation method of which is:

1) The preparation of Zn ₂ SnO ₄ powder is the same as in Example 1;

2) Weigh 0.86 mol of the analytically pure chemical reagent SnO ₂ and 0.14 mol of the Zn ₂ SnO ₄ powder prepared in step 1 for dry mixing, then put them into a nylon ball mill tank, and grind the alcohol at a speed of 120 rpm Ball milled for 12 hours to obtain the slurry for subsequent use;

Dry the ball-milled slurry at 21°C~150°C and weigh it, then add 4% of its weight and 10% polyvinyl alcohol solution to it, and press it into tablets under a pressure of 160MPa Machine pressed into discs with a diameter of 15 mm and a thickness of 1.5 mm, and set aside;

3) Debinding the wafer prepared in step 2 at 650°C for 1 hour, then sintering at 1300°C for 2 hours, and then naturally cooling to 21°C to obtain the product.

Example 4

A SnO ₂ -Zn ₂ SnO ₄ composite varistor ceramic, the preparation method of which is:

1) The preparation of Zn ₂ SnO ₄ powder is the same as in Example 1;

2) Weigh 0.88 mol of the analytically pure chemical reagent SnO ₂ and 0.12 mol of the Zn ₂ SnO ₄ powder prepared in step 1 for dry mixing, then put them into a nylon ball mill tank, and grind alcohol at a speed of 120 rpm Ball milled for 12 hours to obtain the slurry for subsequent use;

Dry the ball-milled slurry at 21°C~150°C and weigh it, then add 5% of its weight and 10% polyvinyl alcohol solution to it, and press it into tablets under a pressure of 160MPa Machine pressed into discs with a diameter of 15 mm and a thickness of 1.5 mm, and set aside;

3) Debinding the wafer prepared in step 2 at 650°C for 1 hour, then sintering at 1300°C for 2 hours, and then naturally cooling to 21°C to obtain the product.

In each of the above-mentioned embodiments, the concentration of alcohol added during ball milling is 99%, and the amount added is 0.5 cm of the material to be ball milled; the grinding balls used during ball milling are all zirconia balls, and the mass of zirconia balls and material The ratio is 4:1, the diameters of the zirconia balls put in are: 8.5mm, 4.5mm, 2.6mm respectively, and the mass ratio of the three kinds of zirconia balls is 4:3:4. the

Samples made from the products prepared in the above embodiments were taken respectively for testing, and the nonlinear relationship between the current and voltage was measured as shown in the accompanying drawings. the

Claims (3)

1. A preparation method of SnO ₂ -Zn ₂ SnO ₄ composite varistor ceramics, characterized in that: by SnO ₂ powder and Zn ₂ SnO ₄ powder are mixed and pressed, and sintered, and the composite varistor per mole The ceramic material is composed of Xmol SnO ₂ powder and (1-X) mol Zn ₂ SnO ₄ powder, and the value of X is 0.82-0.88; The specific operation steps are as follows: 1) Preparation of Zn ₂ SnO ₄ powder Mix the analytically pure chemical reagents SnO ₂ and ZnO in a molar ratio of 1:2, and put them into a nylon ball mill jar, then add alcohol and ball mill for 12 hours at a speed of 120 rpm to obtain a slurry; After the ball milled slurry is dried at 21°C~150°C, it is sent into a powder tablet press, and pressed into a disc with a diameter of 30 mm under the condition of 80 MPa, and then sent into a muffle furnace. Calcined at 1000°C for 2 hours, then naturally cooled to 20°C, and crushed to obtain Zn ₂ SnO ₄ powder for later use; 2) Weigh the analytically pure chemical reagent SnO ₂ and the Zn ₂ SnO ₄ powder prepared in step 1 for dry mixing, then put them into a nylon ball mill jar, add alcohol, and ball mill at a speed of 120 rpm for 12 Hour, obtain slurry, standby; Wherein, the molar ratio of SnO ₂ and Zn ₂ SnO ₄ is X: (1-X), and the value of X is 0.82-0.88; Weigh the ball-milled slurry after drying at 21°C~150°C, then add 4-8% of its weight and 10% polyvinyl alcohol solution to it, and use it under the pressure of 160MPa The powder tablet press is compressed into discs with a diameter of 15 mm and a thickness of 1.5 mm for standby; 3) Debinding the wafer prepared in step 2 at 650°C for 1 hour, then sintering at 1300°C for 2 hours, and then naturally cooling to 21°C to obtain the product. 2. A method for preparing SnO ₂ -Zn ₂ SnO ₄ composite pressure-sensitive ceramics according to claim 1, characterized in that: the alcohol added during the ball milling has a concentration of 99%, and the added amount is no more than The material to be ball milled is 0.5cm. 3. A method for preparing SnO ₂ -Zn ₂ SnO ₄ composite pressure-sensitive ceramics according to claim 1, characterized in that: the grinding balls used in the ball milling are all zirconia balls, and the zirconia balls and materials The mass ratio of the three zirconia balls is 4:1, the diameters of the zirconia balls put in are: 8.5mm, 4.5mm, and 2.6mm, and the mass ratio of the three kinds of zirconia balls is 4:3:4.

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