Magnesium oxide based dielectric ceramics with ultrahigh dielectric breakdown strength and its preparation method

Patent metadata

Field	Value
Publication number	US-11299427-B2
Application number	US-202016822950-A
Country	US
Kind code	B2
Filing date	Mar 18, 2020
Priority date	Mar 26, 2019
Publication date	Apr 12, 2022
Grant date	Apr 12, 2022

Abstract

The present application relates to a magnesium oxide based dielectric ceramics with ultrahigh dielectric breakdown strength and a preparation method thereof. The composition of the magnesium oxide based dielectric ceramic material comprises: (1−x)MgO—xAl2O3, wherein 0<x≤0.12 and x is a mole percentage. The material has a specific composite structure with magnesium aluminate spinel acting as a second phase surrounding a principal crystalline phase, MgO.

First claim

The invention claimed is:

1. A magnesium oxide based dielectric ceramic material, having a composition of (1−x)MgO—xAl 2 O 3 , wherein 0.08≤x≤0.1 and x is a mole percentage, and having a composite structure with magnesium aluminate spinel acting as a second phase surrounding a principal crystalline phase, MgO;
wherein the magnesium oxide based dielectric ceramic material has a dielectric breakdown strength of 111.5 to 126.4 kV/mm and a surface flashover strength of 74.3 to 78.7 kV/cm; and
wherein the magnesium oxide based dielectric ceramic material is prepared by a method including:
weighing and mixing magnesia and alumina according to the composition of the magnesium oxide based dielectric ceramic material to obtain mixed powders, wherein the magnesia is light-burnt magnesia obtained by calcining magnesium source at a temperature of 800 to 1,000° C. for a period of 2 to 6 hours;
preparing a green body from the mixed powders; and
sintering the green body at a temperature of 1,500 to 1,550° C. for a period of 1 to 3 hours to obtain the magnesium oxide based dielectric ceramic material having the composition of (1−x)MgO—xAl 2 O 3 .

2. The magnesium oxide based dielectric ceramic material according to claim 1 , wherein the average grain size of the principal crystalline phase is 1 to 5 μm.

Assignees

• Shanghai Inst Ceramics Cas

Inventors

• Dong Xianlin
• Zhang Chi
• Chen Ying

Classifications

• H01B3/12

  ceramics · CPC title

• C04B2235/3222

  Aluminates other than alumino-silicates, e.g. spinel (MgAl2O4) · CPC title

• C04B2235/784

  Monomodal · CPC title

• C04B35/053 Primary

  Fine ceramics · CPC title

• C04B2235/602

  Making the green bodies or pre-forms by moulding · CPC title