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標題: | 共摻氧化鎳與氧化鈮對釔穩定氧化鋯/氧化鋁複合材料之相組成及機械性質研究 Effect of Co-doping NiO and Nb2O5 on Phase Stability and Mechanical Properties of Yttria-Stabilized Zirconia (YSZ)/Alumina Composite |
作者: | Pei-Chia Chen 陳珮嘉 |
指導教授: | 段維新(Wei-Hsing Tuan) |
關鍵字: | 釔穩定氧化鋯,氧化鋁強化氧化鋯,共摻系統,相分析,相變態韌化,機械性質,熱傳導,電化學阻抗, Yttria-stabilized zirconia,alumina-toughened zirconia,co-doping,phase analysis,transformation toughening,mechanical properties,thermal conductivity,impedance spectroscopy, |
出版年 : | 2015 |
學位: | 碩士 |
摘要: | 添加重量百分比二十氧化鋁於三莫耳釔穩定氧化鋯展現傑出的機械性質。此外,根據電性的補償效應,摻雜異價元素可以改變氧空缺的濃度,進一步地影響氧化鋯在室溫下的相穩定性。目前已有許多針對三莫耳釔穩定氧化鋯的研究,但在三莫耳釔穩定氧化鋯內摻雜超過一種異價元素的研究仍較少。在本研究中,將少量的氧化鎳以及氧化鈮同時添加至氧化鋁強化釔氧化鋯內,這些摻雜元素改變了氧空缺的濃度,進而影響了相組成,這些因摻雜而產生的缺陷也會彼此互相產生影響。在此共摻系統中,我們使用無壓燒結以攝氏一千六百度將試片燒結到完全緻密,除了相分析和機械性質量測之外,同時藉由量測試片的導熱性和導電性估算試片內部缺陷濃度。實驗結果證明四方晶氧化鋯隨著添加的摻雜物增加而變為較不穩定,此現象增加了相變態韌化,因而提高了破斷韌性,當添加百分之一莫耳的氧化鎳及零點五莫耳的氧化鈮時,韌性值增加了一倍之多。透過電化學阻抗法也發現了試片的晶粒內電阻以及晶界電阻隨著摻雜量增加而增加,由於試片內部的氧空缺濃度可能隨著摻雜量增加,因此,此電性改變可歸因於試片內部缺陷締合的形成。 The 20% alumina added 3mol% yttria-stabilized zirconia exhibits outstanding mechanical properties. The doping of aliovalent ions into zirconia alters its concentration of oxygen vacancy owing to the compensation effect. The addition also changes the phase stability of zirconia at room temperature. Although many studies had been conducted on 3YSZ, few of them focus on the effect of co-doping. In the present study, both NiO and Nb2O5 were incorporated into alumina-strengthened yttria-stabilized zirconia. These dopants alter the concentration of oxygen vacancies. The phase evolution during sintering is consequently affected. The defects may also interact with each other. The YSZ/Al2O3/NiO/Nb2O5 composites were prepared using the pressureless sintering at 1600°C to achieve full densification. Apart from phase analysis and mechanical properties, thermal conductivity and electrical impedance were measured to evaluate the effects of these dopants. The results demonstrated that the tetragonal phase is less stable with the higher dopant content. The fracture toughness is therefore increased owing to the transformation toughening. The fracture toughness of the co-doped system is almost two times than that of un-doped alumina-strengthened yttria-stabilized zirconia after the addition of 1 mol% NiO and 0.5 mol% Nb2O5. The impedance analysis demonstrates that the co-doping of NiO and Nb2O5 increases the gain boundary resistance and the grain resistance. The concentration of oxygen vacancy is likely increased with the increase of dopant content. Therefore, the change of the resistance may be resulted from the formation of defect associations. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/51711 |
全文授權: | 有償授權 |
顯示於系所單位: | 材料科學與工程學系 |
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