固相烧结SiC陶瓷的非线性电学行为研究

doi:10.15541/jim20160171

摘要/Abstract

摘要：

固相烧结SiC(SSiC)陶瓷大多数用于结构陶瓷材料, 用于电子和电阻元器件的研究很少。实验以添加不同C含量的致密SSiC陶瓷材料为研究对象, 研究了添加不同C含量SSiC陶瓷的伏安特性、电阻率与电流密度的变化关系及电阻率与温度的变化关系。研究结果表明: SSiC陶瓷表现出明显的非线性电学特性, 其电阻率随着电流的增大而降低; 对于添加3wt% C含量的SSiC陶瓷, 当电场强度超过15.8 V/mm时, 晶界势垒被击穿; 对于添加6wt% C含量的SSiC陶瓷, 当电场强度超过70.7 V/mm时, 晶界势垒被击穿, 它们的电阻率将为晶粒所控制, 电阻率较小; 同时在电场强度1 V/mm条件下, SSiC陶瓷电阻率随着温度的升高而降低, 表现出很好热敏特性, 从常温的10⁶ Ω·cm变化为400℃的5 Ω·cm左右。

关键词: SiC, 固相烧结, 非线性电阻, 热敏电阻

Abstract:

The solid state sintered SiC (SSiC) ceramics are mainly used for structural materials, but they are rarely used for electronic devices and resistance components. In this work, the electrical properties of the SSiC ceramics with different carbon additives were investigated, including V-I characteristic, the relationship between current and resistance, as well as the relationship between temperature and resistance. These results show that the SSiC ceramics present obvious nonlinear electrical behavior and their resistance decreases with the current increase. When the electrical field intensity is over 15.8 V/mm for the SSiC ceramics with 3wt% carbon additives, as well as 70.7 V/mm for the SSiC ceramics with 6wt% carbon additives, the boundary barrier is breakdown and the resistance becomes very low, due to the resistance being only controlled by the grain size. The resistance of the SSiC ceramics decreases with the temperature increase at the electrical field intensity of 1 V/mm, indicating thermo-sensitive characteristic of SSiC ceramics of which the resistance is changed from 10⁶ Ω·cm at 25℃ to 5 Ω·cm at 400℃.

Key words: SiC, solid state sintered, nonlinear resistance, thermistor

中图分类号:

TQ174

陈健, 殷杰, 朱云洲, 杨勇, 陈忠明, 张景贤, 刘学建, 黄政仁. 固相烧结SiC陶瓷的非线性电学行为研究[J]. 无机材料学报, 2017, 32(1): 45-50.

CHEN Jian, YIN Jie, ZHU Yun-Zhou, YANG Yong, CHEN Zhong-Ming, ZHANG Jing-Xian, LIU Xue-Jian, HUANG Zheng-Ren. Nonlinear Electrical Behavior of Solid State Sintered SiC Ceramics[J]. Journal of Inorganic Materials, 2017, 32(1): 45-50.

图/表 8

表1 不同C含量SSiC陶瓷室温下的性能

Table 1 Properties of SiC with different C contents at room temperature

C additives	Density/ (g·cm^-3)	Relative density/%	Flexural strength/MPa
3wt%	3.08±0.03	97%	303.7±17.3
4wt%	3.09±0.02	98%	378.3±10.1
5wt%	3.09±0.01	98%	405.4±19.2
6wt%	3.11±0.01	99%	486.2±20.4

图1 不同C含量SSiC陶瓷的微观结构

Fig. 1 Microstructure of SSiC with different C contents(a) 3wt%; (b) 4wt%; (c) 5wt%; (d) 6wt%

图2 6wt%C-SSiC陶瓷SEM照片(a)和元素扫描图(b-Si/C/B, c-Si, d-C, e-B)

Fig. 2 SEM images (a) and element distribution (b-Si/C/B, c-Si, d-C, e-B) of 6wt%C-SSiC ceramics

图3 不同含量C的SSiC陶瓷的Nyquist 图谱(a)和理想的Nyquist图谱(b)及其等效电路图(c)

Fig. 3 Nyquist plots of SSiC ceramics with different C contents (a), theory Nyquist plots (b) and equivalent circuits (c).

表2 不同C含量SSiC陶瓷晶粒电阻率

Table 2 Grain resistance of SSiC ceramics with different carbon contents

C	3wt%	4wt%	5wt%	6wt%
R_G/(Ω·cm)	150	148	146	48

图4 不同C含量SSiC陶瓷伏安特性曲线(a)及电阻率随电流密度变化曲线(b)

Fig. 4 V-I curves of SSiC ceramics with different C contents (a) and relationship between current density and resistance (b)

表3 不同C含量SSiC陶瓷非线性系数和压敏电压

Table 3 Non-linear coefficient and varistor voltage of SSiC ceramics

C	3wt%	4wt%	5wt%	6wt%
α	1.80	1.60	1.44	1.16
U_1mA/(V·mm^-1)	2.2	3.7	4.2	10.6

图5 不同C含量SSiC陶瓷的热敏特性(a, b-取对数)

Fig. 5 Thermosensitivity of SSiC ceramics with different C contents (a, b- logarithmic)

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