论文总字数：21502字

摘 要

氧化铝陶瓷作为支撑和密封的绝缘材料而被广泛应用于真空设备中。然而,氧化铝陶瓷的真空耐电压通常低于同等尺寸真空间隙的耐电压，更远低于其介电击穿强度。氧化铝绝缘子在一个较低的电压时发生沿面闪络，这个闪络方位通常位于表面的脆弱区域，故常对仪器造成巨大的伤害，造成不可估量的损失；严重影响了绝缘材料的应用前景。随着真空设备小型化的发展, 提高氧化铝陶瓷的真空表面耐压性能已经越来越重要,具有很重要的意义。

此文重点在于绝缘材料在真空环境下的沿面闪络机理，通过对前人资料的查询；找到了沿面闪络机理的主要影响因素，并将其一一呈现于本文。总结得知，复合掺杂改性的方法是用来改善绝缘陶瓷的真空耐压性能最好的办法之一。因此，制定了干压、等静压再无压烧结氧化铝陶瓷的工艺方案，以及注凝成型工艺方案。通过各种测试手段，同类添加剂不同含量、不同添加剂相同含量等等方法来研究其对氧化铝绝缘陶瓷的材料物相、微观结构形貌、烧结性能、介电常数和真空耐压性能的影响，以及注凝成型样品浆料的粘度、注凝成型样品弯曲强度、物相、显微结构的影响。

以掺有0.5wt%Cr₂O₃的95%氧化铝陶瓷瓷料为基料，选择CuO、Ta₂O₅作为添加剂，添加量为0～1.5wt%。粉料经过球磨、干燥、造粒、成型等工艺后，在1550℃的条件下烧结，并机械加工到相应测试尺寸。

实验中的氧化钽掺杂样品以及铬铜复合掺杂样品，均随着添加剂含量的增加，气孔率呈现下降趋势，密度略有增大。与此同时，伴随添加剂含量的增加，所得样品晶体气孔较少，晶粒发育良好，颗粒尺寸均匀，表面情况较好。并且，所得实验结果显示；随着添加剂含量的增加，两种样品的弯曲强度越来越大。铬铜复合掺杂样品的介电常数随添加剂含量的增加而减小，真空耐压性能得到显著提高。铬掺杂氧化铝陶瓷注凝成型注样品浆料的粘度随固含量的增加而增大；注凝成型的本体（0wt% Cr₂O₃）成型样品的弯曲强度为8.21±1.13MPa，随固含量的增大样品晶体气孔减少，晶粒发育良好，性能得到明显改善。

关键词： Al₂O₃陶瓷 真空沿面闪络 复合掺杂

Abstract

Alumina ceramics have been widely used in vacuum devices, usually as insulators, under props and airproof parts. However, it has been experimentally shown that the voltage hold-off capability of alumina in vacuum is usually less than that of a similar-sizedvacuum gap and also is far below its bulk breakdown strength. The valnerable area lies in the Surface of alumina insulator along which the breakdown (surface flashover) of the insulatorin vacuum usually takes place at a relatively low voltage. So. cause great harm to the instrument, causing incalculable damage; seriously affected the prospects of insulating material， Withthe development of vacuum devices to miniaturization, findingways to improve the surface insulating performance of alumina ceramic in vacuum has become of more and more important,It has incredible mearning.

This article focuses on the insulating material in a vacuum environment creeping flashover mechanism by the previous query information; find the main factors flashover mechanism, and presented one by one in this article. That summary, the composite doping method is one of the best ways to improve the performance of the vacuum pressure of insulating ceramic. Therefore, the development of dry pressing, isostatic pressing no sintered alumina ceramic technology program And gel-casting process scheme. Through a variety of testing methods, similar additives different content, different additive methods to study the same content, and so the material was alumina ceramic insulating phase, microstructure morphology, sintering properties Effect of vacuum pressure coefficient, dielectric constant and performance. And the viscosity of the slurry sample Gelcasting, Gelcasting Samples Bending strength, phase, microstructure of.

Ta₂O₅ ranging from 0 to 1.5wt% were separately considered to be mixed with 95wt% alumina powders doped with 0.5wt% Cr₂O₃. After the processes of milling 、drying、granulation and molding, power was sintered at 1550℃, and machined to the testing size.

Experiment tantalum oxide doped with chromium and copper composite sample doped samples, with the increase of additive content, porosity show a downward trend, density increases slightly. Meanwhile, with the increase in additive content of less porosity resulting sample crystal grains are well developed, uniform particle size, surface condition is better. Furthermore, experimental results obtained show; additive content increases, the bending strength of the two samples is increasing. Chromium copper composite sample doped dielectric constant with increasing additive content decreases, the vacuum pressure performance has been significantly improved. Viscosity chromium doped alumina ceramic gel-casting slurry injection sample with increasing solids content increases; the bending strength Gelcasting body (0wt% Cr₂O₃) molded sample was 8.21 ± 1.13MPa, with increasing solids large pores reduce sample crystal grains are well developed, the performance improved significantly.

Key words: alumina ceramic; vacuum surface flashover; co-doping

目 录

摘 要 I

Abstract II

第1章 绪 论 1

1.1 研究氧化铝陶瓷材料真空闪络的意义 1

1.2 真空中绝缘材料的沿面闪络现象机理及影响因素 1

1.3 氧化铝陶瓷 1

1.3.1 氧化铝陶瓷的晶体结构 1

1.3.2 氧化铝陶瓷性能与应用 2

1.4 改善氧化铝陶瓷真空耐压性能的研究现状 2

1.5 本课题研究的目的和内容 3

第2章 实验及表征 4

2.1 实验原料 4

2.1.1 干压-等静压实验原料 4

2.2.2 注凝成型实验原料 4

2.2 制备工艺与设备 4

2.2.1 氧化铝陶瓷材料的制备 4

2.2.2 实验设备 6

2.3 材料测试与表征 6

2.3.1 烧结性能 6

2.3.2 物相和显微结构 7

2.3.3 力学性能测试 7

2.3.4 介电性能测试 7

2.3.5 体积电阻率 8

2.3.6 真空耐电压测试 8

第三章 氧化钽掺杂对氧化铝陶瓷性能的影响 10

3.1 氧化钽掺杂样品的烧结性能 10

3.2 氧化钽掺杂样品的XRD与显微结构分析 10

3.3 氧化钽掺杂样品的基本性能 12

3.4 本章小结 13

第四章 铬铜复合掺杂对氧化铝陶瓷性能的影响 14

4.1 铬铜复合掺杂样品的烧结性能 14

4.2 铬铜复合掺杂样品的XRD与显微结构分析 14

4.3 铬铜复合掺杂样品的基本性能 16

4.4 铬铜复合掺杂样品的真空耐压性能 16

4.5 本章小结 17

第五章 铬掺杂氧化铝陶瓷注凝成型工艺研究 18

5.1 铬掺杂氧化铝陶瓷注凝成型样品的粘度比较 18

5.2 铬掺杂氧化铝陶瓷注凝成型样品的弯曲强度 18

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