CN109081691B

CN109081691B - Tubular ceramic preparation method

Info

Publication number: CN109081691B
Application number: CN201811068122.9A
Authority: CN
Inventors: 赵鹏; 李卓; 景明海; 苏兴华
Original assignee: Changan University
Current assignee: Changan University
Priority date: 2018-09-13
Filing date: 2018-09-13
Publication date: 2021-01-08
Anticipated expiration: 2038-09-13
Also published as: CN109081691A

Abstract

The invention discloses a preparation method of tubular ceramic. The disclosed method comprises: pre-burning ceramic powder, adding an adhesive, and forming to obtain a columnar body; sintering the columnar body under the conditions of proper temperature, proper current of the radial section of the columnar body and proper sintering time duration, so that a texture loose column body is generated in the columnar body locally along the axial direction, and a texture compact tube body is formed outside the texture loose column body; removing the loose cylinder to obtain the tubular ceramic. According to the invention, the ceramic sample is subjected to overburning by controlling the electric sintering condition, and a hollow structure is formed directly in the ceramic densification engineering; the obtained tubular electronic ceramic has small and uniform crystal grains and excellent dielectric property.

Description

Tubular ceramic preparation method

Technical Field

The invention belongs to the technical field of electronic ceramic material preparation, and particularly relates to a tubular ceramic preparation method.

Background

The auxiliary sintering technology of the power plant is a novel ceramic sintering method appearing in recent years. The earliest article presented by Hill in 1952, which describes a method of making bulk cermet materials by passing an electric current directly through a rapidly elevated temperature cermet body under pressure assist. Flash firing, now known as a new sintering concept, was reported in Cologna et al in 2010, where sintering of zirconia [ 3% (mole fraction) Y2O 3-ZrO 2, 3YSZ ] ceramic bodies gave good results, but insulator current sintering was relatively difficult.

The tubular electronic ceramic belongs to a hollow structure, a special die is needed for pressure forming, and holes are formed in a sintered compact ceramic body, so that laser processing is needed, and time and labor are wasted.

Disclosure of Invention

Aiming at the defects and shortcomings in the prior art, the invention provides a tubular ceramic preparation method.

The preparation method of the tubular ceramic provided by the invention comprises the following steps: pre-burning ceramic powder, adding an adhesive, and forming to obtain a columnar body; sintering the columnar body under the conditions of proper temperature, proper current of the radial section of the columnar body and proper sintering time duration, so that a texture loose column body is generated in the columnar body locally along the axial direction, and a texture compact tube body is formed outside the texture loose column body; removing the loose cylinder to obtain the tubular ceramic.

Further, the columnar body is a cylinder.

Optionally, the current is an alternating current or a direct current.

Further, the invention also provides a preparation method of the tubular barium strontium titanate ceramic. The preparation method of the provided tubular barium strontium titanate ceramic comprises the following steps:

pre-burning barium strontium titanate ceramic powder, adding an adhesive, and forming to obtain a columnar body; sintering the columnar body for 0.5-10 minutes at the temperature of 700 ℃ and the radial section current of the columnar body of 10-50 milliamperes/square millimeter, and locally generating a texture loose column in the columnar body along the axial direction and forming a texture compact tube body outside the texture loose column; removing the loose-texture column to obtain the tubular barium strontium titanate ceramic.

Preferably, the mole number of strontium atoms in the barium strontium titanate ceramic accounts for 15% -85% of the total mole number of barium strontium atoms; the adhesive is PVA, the adhesive accounts for 0.8-1.2% of the barium strontium titanate powder by mass, and the pre-sintering temperature is 900-.

The invention has the advantages that:

(1) according to the invention, the ceramic sample is subjected to overburning by controlling the electric sintering condition, and a hollow structure is formed directly in the ceramic densification engineering.

(2) The tubular electronic ceramic has small and uniform crystal grains and excellent dielectric property.

Drawings

FIG. 1 is a graph showing the dielectric properties of the tubular ceramic material obtained in example 1.

Detailed Description

The process of the invention is suitable for the preparation of tubular ceramic materials, and the barium strontium titanate ceramic is selected as an example to further explain the invention. For other kinds of ceramics, the ceramic tube can be obtained by selecting proper temperature, current and sintering time according to the idea of the invention, and the tubular ceramic material can be obtained by selectively optimizing the formula of the ceramic material and the pre-sintering link.

Example 1:

presintering barium strontium titanate ceramic powder with a barium strontium molar ratio of 7:3 at 1000 ℃ for 2 hours, adding 1% of PVA (polyvinyl alcohol) adhesive, and molding under 200MPa to form a cylinder with the diameter of 6 mm and the length of 3 mm; applying voltage on the cylinder, controlling the total current within the range of 300 milliamperes, and sintering at the furnace temperature of 970 ℃ for 300 seconds to obtain a cylindrical body as shown in figure 2; as shown in fig. 2, the obtained sintered columnar body has an excessively large crystal grain powder due to overburning and a loose columnar body (the black line marks the area) without mechanical strength, and as can be seen from the figure, the color of the loose columnar body is lighter than that of the peripheral dense material and is close to white, and the tubular ceramic is obtained by removing the loose columnar body by mechanical or laser means. The dielectric properties of the tubular electronic ceramics measured by a dielectric spectrum sweep test at a temperature of-30 ℃ to 140 ℃ are shown in Table 1. The dielectric property curve is shown in FIG. 1.

TABLE 1

Maximum dielectric constant	Loss tangent	Curie Point C
			11766	0.08425	6.0

Example 2:

pre-sintering barium strontium titanate ceramic powder with a barium-strontium ratio of 8:2 at 1100 ℃ for 1 hour, adding 1% of PVA (polyvinyl alcohol) adhesive, and molding into a cylinder with the diameter of 6 millimeters and the length of 3 millimeters under the pressure of 300 MPa; applying direct current voltage, controlling the current within the range of 1000 milliamperes, and sintering for 400 seconds at the furnace temperature of 700 ℃; removing the loose columnar bodies in the middle part by adopting a mechanical or laser method to obtain the tubular ceramic. The dielectric properties of the tubular electronic ceramics measured at-30 ℃ to 140 ℃ are shown in Table 2.

TABLE 2

Maximum dielectric constant	Loss tangent	Curie Point C
			10621	0.00353	9.0

Example 3:

pre-sintering barium strontium titanate ceramic powder with a barium-strontium ratio of 1:1 at 900 ℃ for 2 hours, adding 1.2% of PVA (polyvinyl alcohol) adhesive, and molding into a cylinder with the diameter of 6 millimeters and the length of 3 millimeters under the pressure of 300 MPa; applying direct current voltage by adopting a silver electrode, controlling the current within 600 milliamperes, and sintering for 400 seconds at the furnace temperature of 850 ℃; removing the loose columnar bodies in the middle part by adopting a mechanical or laser method to obtain the tubular ceramic. The dielectric properties of the tubular electronic ceramics measured at-30 ℃ to 140 ℃ are shown in Table 3.

TABLE 3

Maximum dielectric constant	Loss tangent	Curie point
			8162	0.05502	3.8

Claims

1. A method of preparing a tubular ceramic, the method comprising:

pre-burning ceramic powder, adding an adhesive, and forming to obtain a columnar body;

sintering the columnar body under the conditions of proper temperature, proper current of the radial section of the columnar body and proper sintering time duration, so that a texture loose column body is generated in the columnar body locally along the axial direction, and a texture compact tube body is formed outside the texture loose column body;

removing the loose cylinder to obtain the tubular ceramic.

2. The method of preparing a tubular ceramic of claim 1 wherein the cylindrical body is a cylinder.

3. The method of preparing a tubular ceramic of claim 1 wherein the electrical current is an alternating current or a direct current.

4. A preparation method of tubular barium strontium titanate ceramic is characterized by comprising the following steps:

pre-burning barium strontium titanate ceramic powder, adding an adhesive, and forming to obtain a columnar body;

sintering the columnar body for 0.5-10 minutes at the temperature of 700 ℃ and the radial section current of the columnar body of 10-50 milliamperes/square millimeter, and locally generating a texture loose column in the columnar body along the axial direction and forming a texture compact tube body outside the texture loose column;

removing the loose-texture column to obtain the tubular barium strontium titanate ceramic.

5. The method for preparing a tubular barium strontium titanate ceramic according to claim 4, wherein the method comprises: the mole number of strontium atoms in the barium strontium titanate ceramic accounts for 15-85% of the total mole number of barium strontium atoms; the adhesive is PVA, the adhesive accounts for 0.8-1.2% of the barium strontium titanate powder by mass, and the pre-sintering temperature is 900-.