硬脂酸表面改性对PLZT压电陶瓷粉末注射成型性能的影响

doi:10.15541/jim20180323

摘要/Abstract

摘要：

以硬脂酸为粉末改性剂, 聚乙二醇/聚乙烯醇缩丁醛/聚甲醛(PEG/PVB/POM)为粘结剂体系制备锆钛酸铅镧(PLZT)粉末注射成形喂料, 并通过先水脱脂后烧结的工艺制备了PLZT压电陶瓷。研究了硬脂酸用量对粉末特性、喂料黏度、水脱脂率以及坯体强度的影响, 并对烧结后陶瓷的微观形貌与电性能进行对比与分析。结果表明：硬脂酸通过湿法改性成功包覆于PLZT粉体表面, 硬脂酸改性打破了粉末间的团聚, 且当硬脂酸包覆量为2wt%时, 喂料具有较低的剪切黏度及较高的坯体弯曲强度。但过量改性反而使得喂料黏度上升, 坯体弯曲强度下降。改性后的粉体在坯体内分散均匀, 烧结后的陶瓷晶粒生长完善, 具有更大的烧结致密度。与未改性的PLZT陶瓷相比, 在2 kV/mm极化电压下, 2wt%硬脂酸改性的PLZT的压电常数d₃₃由638 pC/N提高为682 pC/N。

关键词: 硬脂酸, 粉末改性, PLZT, 注射成型, 压电性能

Abstract:

A powder injection molding feedstock of lead zirconate titanate (PLZT) was successfully prepared using stearic acid as powder modifier and polyethylene glycol/polyvinyl butyral/polyoxymethylene (PEG/PVB/POM) as binder system. Then, PLZT piezoelectric ceramics were prepared by degreasing and post-sintering processes. The effects of stearic acid (SA) dosage on powder properties, feedstock viscosity, water degreasing rate and green body strength were studied. The microstructure and electrical properties of the sintered ceramics were compared and analyzed. The results showed that stearic acid was successfully coated onto the PLZT powder by wet modification. The modification of stearic acid broke the agglomeration between the powders, and when the amount of stearic acid was 2wt%, the feedstock had a lower shear viscosity and a higher green body bending strength. However, excessive modification caused the feed viscosity to increase and the bending strength of the green body to decrease. The modified powder was uniformly dispersed in the body, and the sintered ceramic had higher density with well grown grains. As compared to the unmodified sample, the piezoelectric constant d₃₃ of the PLZT modified with 2wt% SA increased from 638 pC/N to 682 pC/N.

Key words: stearic acid, powder modification, PLZT, injection molding, piezoelectric performance

中图分类号:

TF124

吴盾, 秦帅, 刘春林, 方必军, 曹峥, 成骏峰. 硬脂酸表面改性对PLZT压电陶瓷粉末注射成型性能的影响[J]. 无机材料学报, 2019, 34(5): 535-540.

Dun WU, Shuai QIN, Chun-Lin LIU, Bi-Jun FANG, Zheng CAO, Jun-Feng CHENG. Surface Modification by Stearic Acid on Property of PLZT Piezoelectric Ceramics Prepared via Powder Injection Molding[J]. Journal of Inorganic Materials, 2019, 34(5): 535-540.

图/表 13

图1 硬脂酸与粉末改性前后的红外谱图

Fig. 1 Infrared spectra of stearic acid and powder before and after modification

图2 PLZT粉末改性前(a)和后(b)的SEM照片

Fig. 2 SEM images of PLZT powder before (a) and after (b) modification

图3 不同硬脂酸用量喂料的流变性能

Fig. 3 Rheological properties of feedstock with different contents of stearic acid

图4 生坯及水脱脂坯的弯曲强度

Fig. 4 Bending strength of green body and brown body

图5 水脱脂过程示意图

Fig. 5 Schematic diagram of the process of water degreasing

图6 脱脂率随脱脂时间的变化曲线

Fig. 6 Curves of degreasing rate with degreasing time

图7 水脱脂前后坯体表面SEM照片

Fig. 7 Surface SEM images of the green body and brown body

图8 改性和未改性PLZT的XRD图谱

Fig. 8 XRD patterns of modified and unmodified PLZT piezoelectric ceramics

图9 不同温度烧结PLZT的表面SEM照片

Fig. 9 Surface SEM images of PLZT sintered at different temperatures

表1 不同温度烧结陶瓷的孔隙率和密度

Table 1 Porosities and densities of ceramics sintered at different temperatures

Sample	1200 ℃		1240 ℃		1280 ℃
Sample	Porosity/%	Density/(g·cm^-3)	Porosity/%	Density/(g·cm^-3)	Porosity/%	Density/(g·cm^-3)
Unmodified	2.45	6.42	0.12	7.54	0.07	7.63
Modified	0.91	7.23	0.04	7.62	0.02	7.68

图10 PLZT压电陶瓷在100 kHz下介电常数(a)和介电损耗(b)与温度的关系曲线

Fig. 10 Temperature dependence of dielectric constant (a) and dielectric loss (b) for PLZT piezoelectric ceramics at 100 kHz

图11 PLZT压电陶瓷在13 kV/cm、10 Hz下的电滞回线

Fig. 11 Hysteresis loops of PLZT piezoelectric ceramics at 13 kV/cm and 10 Hz

图12 PLZT压电陶瓷的压电常数与极化电压的关系

Fig. 12 Relationship between piezoelectric constant and polarization voltage of PLZT piezoelectric ceramics

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