添加微量氧化鐵對氧化釔安定氧化鋯之燒結行為與電性之影響

Abstract

本研究以微量的氧化鐵作為添加劑，添加進入三莫耳氧化釔穩定氧化鋯(3YSZ)基材中，並探討其相穩定性、電性、硬度、韌性與顏色等性質的影響。藉由添加鐵離子，材料的燒結活性也隨之上升，包括生胚開始收縮的溫度與達最大收縮速率的溫度，都隨著鐵的添加而下降。而由熱分析儀與X光光電子能譜儀的結果得知，鐵在燒結時會產生價數變化，而此現象會對氧化鋯的燒結活性也會有所影響。在燒結過程時，氧化鐵會固溶進入3YSZ內，而鐵離子會與鋯離子會產生取代型缺陷，材料中的氧空缺濃度會因此而改變，結晶相也同時受到影響。包括單斜晶(Monoclinic)的量與晶粒大小都隨著鐵的添加而增加。結果顯示，材料中單斜晶的產生會對材料機械性質產生負面影響。而加入鐵所產生的鐵缺陷會同時影響了晶粒與晶界的導電行為。除此之外，藉由對試片進行不同溫度的熱處理，能更進一步釐清添加鐵缺陷對於氧化鋯的影響。而藉由控制鐵的添加量與燒結環境，材料的微結構特性與顏色都能被調整。

Effect of a small amount of iron oxide addition on the sintering of 3 mol% yttria-stabilized zirconia (3YSZ) has been investigated in the present study. The phase stability, electrical conductivity, hardness, toughness and color of Fe-doped 3YSZ are evaluated. The iron oxide is dissolved into 3YSZ after sintering. Since the presence of iron ions, the concentration of oxygen vacancy is altered. The addition of iron enhances the sintering activity of 3YSZ in terms of the starting temperature for shrinkage and the temperature at maximum densification rate. Through the analysis of thermal and X-ray photoelectron spectrum, the valence transformation of Fe would also affect the sintering activity. However, the phase evolution during sintering is consequently altered. The amount of monoclinic phase and grain size are increased along with the increasing of iron addition. The results from electrical conductivity demonstrate that both the grain and grain boundary conductivities are affected by the iron addition. The formation of m-phase imposes detrimental effect on mechanical property. By treating with the various heat treatments, the influence of iron on the defect in zirconia can be clarified. In addition, the microstructural characteristics and color can be manipulated by controlling the iron addition and sintering condition.