0-3型钛酸锶钡与聚四氟乙烯复合材料的冷烧结制备与介电性能研究

0-3型钛酸锶钡(BST)与聚四氟乙烯(PTFE)复合材料是一种新型的陶瓷/高聚物功能复合材料,可以兼具BST材料与PTFE材料的优点,可表现出较高的介电常数和介电可调性。但是受聚合物相介电常数低的限制,常规方法(流延法)制备的以聚合物为基体,以陶瓷为填充相的复合材料的介电常数基本在100以下。为了进一步提高BST/PTFE复合材料的介电性能,本研究采用一种新型烧结工艺——冷烧结工艺实现BST陶瓷与PTFE高聚物的共烧。在试验中以BST为基体,引入体积比例为5%的PTFE,并引入固相八水合氢氧化钡(Ba(OH)₂·8H₂O)作为过渡液相以辅助烧结过程进行,制备0-3型BST/PTFE复合材料,并探究了不同冷烧结条件下复合材料的介电性能。结果表明,复合材料样品在冷烧结温度为275 ℃,压力为200 MPa,时间为2.5 h的条件下,介电常数可达到500以上(25 ℃,1 kHz)。相对于常规制备工艺,冷烧结工艺制备出的复合材料的介电常数有很大改进,这对陶瓷/高聚物功能复合材料的低温制备与研究有一定参考意义。

Cold Sintering Preparation and Dielectric Properties of 0-3 Type Barium Strontium Titanate/Polytetrafluoroethylene Composites

0-3 type barium strontium titanate (BST)/polytetrafluoroethylene (PTFE) composites are new types of ceramic/polymer functional composites. They combine advantages of BST ceramic and PTFE polymer, and show high dielectric constant and dielectric adjustability. However, due to the low dielectric constant of polymer phase, the dielectric constant of composites with polymer as matrix and ceramic as filling phase prepared by conventional methods such as flow casting method is basically below 100. In order to further improve the dielectric properties of BST/PTFE composites, a new sintering process (cold sintering process) was used to realize the co-sintering of BST ceramic and PTFE polymer. In the experiment, 0-3 type BST/PTFE composites were prepared by introducing PTFE with a volume ratio of 5% into BST matrix, and solid barium hydroxide octahydrate (Ba(OH)₂·8H₂O) as transient liquid phase to assist the sintering process. The dielectric properties of the composites under different cold sintering conditions were investigated. The results show that the dielectric constant of the composite samples reach more than 500 (25 ℃, 1 kHz) under the conditions of cold sintering temperature of 275 ℃, pressure of 200 MPa and time of 2.5 h. Compared with the conventional preparation process, the dielectric constant of the composites prepared by cold sintering process has been greatly improved, which has a certain reference significance for the low-temperature preparation and research of ceramic/polymer functional composites.