La_(0.2)Ba_(0.8)(Co_(0.2)Fe_(0.8))_(1-x)Zr_xO_(3-δ)透氧膜材料的微结构与氧分离性能研究

Preparation and Oxygen Separation Property inLa_(0.2)Ba_(0.8)(Co_(0.2)Fe_(0.8))_(1-x)Zr_xO_(3-δ) System

采用固相法制备了La0.2Ba0.8(Co0.2Fe0.8)1-xZrxO3-δ(x=0、0.05、0.1、0.15)片状陶瓷膜,用稳态法测试了不同成分制备样品的透氧性能,并利用XRD和SEM手段分析研究了样品的相结构和晶粒形貌及它们对材料性能的影响.研究表明:固相法较难合成x=0的纯钙钛矿相,可用改进的Pechini法合成,另B位Zr的替代有利于去除材料中非钙钛矿杂相;x=0.1的样品中有少量BaZrO3析出,并导致晶粒细化(1-2μm),而这种微结构状态稳定且不受高温长时间退火和氧分压梯度的影响.晶粒细化样品的力学性能和氧渗透性能均有较大提高,x=0.1的样品较x=0样品的氧渗透性能提高了一个数量级,在1010℃,样品厚1.2mm时体系的透氧率达到4.6×10-7mol·cm-2·s-1.

The ceramic oxygen permeation membranes of La0.2Ba0.8(Co0.2 Fe0.8)1-xZrxO3-δ with x=0, 0.05, 0.1 and 0.15 were fabricated by a solid state reaction method. The phase structure, microstructure, including morphology, size of crystal grain and second phase in the sample, were investigated by XRD and SEM, respectively. The influence to the properties of oxygen separation and mechanics of samples, caused by microstructure, were also studied. The research results show that the synthesis of single perovskite-structured phase of x=0 by the solid reaction method is difficult, but it can be realized by means of wet synthesis method or by adding some suitable amounts of ZrO2 into the parent phase. A small amount of BaZrO3 as second phase appeared in the sample with x=0.1 makes the sample possess small crystal grains, with high stability during long time oxygen permeation at high temperature, and larger mechanical strength compared to other composition samples. For the membrane with x=0.1, the oxygen permeation flux can reach to 4.6×10-7mol &middot cm-2 &middot s-1 at 1010°C with thickness of 1.2 mm under one side exposed to air and the other side feeding with He flow.