片式PTC热敏电阻瓷片再氧化工艺的研究

Reoxidation process of thermistor ceramics of laminated PTC

以乙酸钡(Ba(CH3COO)2)、钛酸四丁酯(Ti(OC4H9)4)和硝酸钇(Y(NO3)3.6H2O)为原料,采用溶胶-凝胶法制备掺1.6%(质量分数)施主钇(Y)的钛酸钡nm粉体.用此粉体制备叠层片式正温度系数热敏电阻(PTCR)用瓷片,其中用氮化硼(BN)和钛酸钡作为玻璃相原料.利用流延方法成型,流延生胚在体积分数为97%的N2和体积分数为3%的H2的还原气氛下烧结成瓷.通过采用不同的再氧化温度和时间去氧化烧成的瓷片,研究再氧化工艺对正温度系数(PTC)瓷片电性能的影响.结果显示:室温电阻率随再氧化温度的升高先增加后减小,而PTC效应逐渐增加;室温电阻率随再氧化时间的增加会出现一个最小值,再氧化时间对PTC效应影响不大;样品的耐压值随着再氧化温度或时间的增加而增大.

1.6% Y donor doped barium titanate nanocrystalline powder was prepared by sol-gel technique with barium acetate （Ba（CH3COO）2）, tetrabutyl titanate （Ti（OC, H9 ）4 ） and nitric acid yttrium （Y（NO3）3 · 6H2O） as raw materials. The ceramics for laminated PTCR （positive temperature coefficient resistance） was prepared by the powder. Boron nitride （BN） and barium titanate were used as the glass phase. Tape-casting method was used to form the green sheets. The green sheets were sintered at a reducing atmosphere of 97% N2-3G H2. The effects of reoxidation on the electrical properties of the PTC （positive temperature coefficient） ceramics were studied by using different reoxidation temperature and time to reoxidize the samples. The results show that the room temperature resistivity first increases and then decreases when the temperature of the reoxidation increases, and the PTC effect gradually increase; room temperature resistivity appears a minimum with the increase of reoxidation time, while the PTC effect is not influenced greatly by the reoxidation time; the withstand voltage increases with the increase of reoxidation temperature and/or time.