Zinc oxide voltage-sensitive ceramic composite powder

Abstract

The invention relates to zinc oxide voltage-sensitive ceramic composite powder, which takes an active powder material as a specified additive on the basis of a zinc oxide voltage-sensitive ceramic formula. According to the zinc oxide voltage-sensitive ceramic powder prepared by the preparation method disclosed by the invention, an organic polymer does not need to be added as an adhesive, the strength of a pressed and molded zinc oxide voltage-sensitive ceramic green body is greater than 0.80 MPa, the density is greater than 3.20 g / cm < 3 >, and the zinc oxide voltage-sensitive ceramic with excellent comprehensive performance can be provided.

Description

Technical Field

[0001] The present invention belongs to the technical field of varistor ceramics, and more specifically, the present invention relates to zinc oxide varistor ceramic composite powder. Background Art

[0002] The preparation of zinc oxide varistor ceramic composite powder is the primary process before zinc oxide varistor ceramic molding, which is crucial to whether zinc oxide varistor ceramics with uniform structure and excellent performance can be obtained. In order to obtain materials that meet the requirements of granulation and compression molding, surfactants such as polymer organic binders, dispersants and defoamers must be added to the slurry. Zinc oxide varistor ceramic mixed slurry has typical colloidal solution characteristics and belongs to a multiphase inhomogeneous system. The use of organic additives makes the physical and chemical reactions of the sizing system complex and disordered. Since the organic additives themselves have ions with different acidic and alkaline properties, they can easily react with inorganic additives (such as Al(NO3)3·9H2O, MgO, B2O3, H3BO3). Under the thickening effect of organic binders, the colloids and flocs are more destructive to relatively uniform dispersion. In addition, impurity elements in organic additives such as Na + The above factors will also have an adverse effect on the electrical properties of zinc oxide surface resistors.

[0003] In particular, the amount of organic binder used is large (0.5 wt.% ~ 2 wt.%), which occupies a large volume in the zinc oxide varistor green body, takes a long time to remove binder, and has a large porosity after removal, which makes the zinc oxide varistor have a large porosity and a small body density, which is very unfavorable to its electrical properties such as pressure ratio and flow capacity. Therefore, how to reduce the amount of organic additives used in zinc oxide varistor ceramic composite powder is the key to shortening the removal time and improving electrical performance. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention proposes a zinc oxide varistor ceramic composite powder, which can be pressed and formed by means of physical adsorption force and intermolecular interaction between powders, avoiding the introduction of organic binders and providing excellent electrical properties.

[0005] The specific scheme of the present invention is as follows: In the basic formula of zinc oxide varistor ceramics, part of zinc oxide or other doping additives are replaced with active zinc oxide or active dopant materials with high surface area. The above active materials are used as additives in a prescribed form, and their adsorption and intermolecular forces can be used to form strong interaction forces during pressing and molding, replacing organic binders to give green strength.

[0006] The active material with high surface energy can be a liquid sol, high specific surface area particles, or powder material modified with oxygen-containing functional groups. The weight ratio of the active material is 0.4% to 10%.

[0007] Compared with the prior art, the present invention has the following beneficial technical effects: According to the present invention, the content of organic matter in the zinc oxide varistor ceramic green body is reduced, the debinding time can be shortened, the porosity is reduced, and the comprehensive performance of the zinc oxide varistor ceramic is improved. DETAILED DESCRIPTION

[0008] The technical solutions involved in the present invention are further described below in conjunction with specific embodiments.

[0009] Example 1 The raw materials of this embodiment are prepared according to the following molar percentages, and the specific formula is as follows: Bi2O3: 3.12%; Sb2O3: 3.33%; Co2O3: 1.95%; Mn3O4: 0.55%; Cr2O3: 0.42%; NiO: 0.38%; SiO2: 0.71%; MgO: 0.06%; Al(NO3)3·9H2O: 0.03%; boron glass powder: 0.15%; ZnO: 88.70%, porous nano ZnO: 0.60%.

[0010] Furthermore, the specific surface area of ​​the nano ZnO is 200 m 2 / g.

[0011] The above formula was ground and added with appropriate dispersants and defoamers, and the conventional production processes of zinc oxide varistor ceramics such as granulation, water addition, dry pressing, sintering, heat treatment, aluminum spraying, glazing, and testing were carried out to prepare zinc oxide varistor ceramics. The prepared zinc oxide varistor ceramics had a diameter of 42 mm and a height of 20 mm.

[0012] Example 2 The raw materials of this embodiment are prepared according to the following molar percentages, and the specific formula is as follows: Bi2O3: 3.12%; Sb2O3: 3.33%; Co2O3: 1.95%; Mn3O4: 0.55%; Cr2O3: 0.42%; NiO: 0.38%; SiO2 sol: 0.71%; MgO: 0.06%; Al(NO3)3·9H2O: 0.03%; silver glass powder: 0.15%; ZnO: 89.30%.

[0013] Furthermore, the particle size of the SiO2 sol is 15 nm.

[0014] The above formula was ground and added with appropriate dispersants and defoamers, and the conventional production processes of zinc oxide varistor ceramics such as granulation, water addition, dry pressing, sintering, heat treatment, aluminum spraying, glazing, and testing were carried out to prepare zinc oxide varistor ceramics. The prepared zinc oxide varistor ceramics had a diameter of 42 mm and a height of 20 mm.

[0015] Comparative Example 1 The raw materials of comparative example 1 are prepared according to the following molar percentages, and the specific formula is as follows: Bi2O3: 3.12%; Sb2O3: 3.33%; Co2O3: 1.95%; Mn3O4: 0.55%; Cr2O3: 0.42%; NiO: 0.38%; SiO2: 0.71%; MgO: 0.06%; Al(NO3)3·9H2O: 0.03%; silver glass powder: 0.15%; ZnO: 89.30%. The zinc oxide varistor ceramics are produced according to the conventional production process of zinc oxide varistor ceramics. The prepared zinc oxide varistor ceramics have a diameter of 42 mm and a height of 20 mm.

[0016] The physical properties and electrical properties of the zinc oxide-based varistor ceramics of Example 1, Example 2 and Comparative Example 1 obtained from testing are shown in Table 1 and Table 2, respectively.

[0017] In summary, the zinc oxide varistor ceramic composite powder proposed in the present invention still has a high green strength without adding organic binder, the organic matter content is reduced by more than 50%, the debinding time is reduced by at least 34%, and the flow capacity and pressure ratio of the zinc oxide varistor ceramic are improved, which fully verifies the beneficial technical effects described in the present invention.

Claims

1. A zinc oxide varistor ceramic composite powder, characterized in that: One or more active powders are used as prescribed additives, with a weight ratio of 0.4% to 10%.

2. The zinc oxide varistor ceramic composite powder according to claim 1, characterized in that: The active powder includes liquid sol, high specific surface area powder or powder material modified with oxygen-containing functional groups.

3. The zinc oxide varistor ceramic composite powder according to claim 2, characterized in that: The specific surface area of ​​the high specific surface area powder is 40 m 2 / g ~ 300 m 2 / g.

4. The zinc oxide varistor ceramic composite powder according to claim 3, characterized in that: The specific surface area of ​​the high specific surface area powder is 50 m 2 / g ~ 200 m 2 / g.

5. The powder material modified with oxygen-containing functional groups according to claim 2, characterized in that: The content of the oxygen-containing functional group is 0.5 mmol / g to 3 mmol / g; the oxygen-containing functional group is hydroxyl and carboxyl.

6. The zinc oxide varistor ceramic composite powder according to any one of claims 1 to 5, characterized in that: The active powder and the formula material of zinc oxide varistor ceramic are ground evenly to obtain a composite powder, and the D50 particle size of the composite powder is less than 2 μm.

7. The zinc oxide varistor ceramic composite powder according to claim 6, characterized in that: The D50 particle size of the composite powder is less than 1 μm.

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