The Interfacial Reaction between Silver Electrode and Glass Ceramics
Date Issued
2005
Date
2005
Author(s)
Wang, Yu-Ju
DOI
zh-TW
Abstract
本研究針對銀電極與La-Si-B-O-mullite系(LSBM)及Mg-Si-B-Al系(MSBA)玻璃陶瓷在不同的燒結條件下共燒，研究分析所產生的反應層形態及其控制機構。其介面生成相藉由X光繞射分析儀( XRD )予以分析，其微結構使用掃描式及穿透式電子顯微鏡( SEM and TEM )來觀察。
為探討在空氣中燒結時在LSB玻璃中銀擴散的現象，將D-LSBM/Ag燒結至760oC-840oC，介面處產生一明顯的反應層，其反應活化能為246 kJ/mole，此反應層在燒結後出現了銀的奈米結晶，大小約幾10~200nm左右。銀在燒結升溫過程中先氧化，並藉由玻璃相擴散，並在降溫時析出在玻璃相中。由於銀擴散進入玻璃相的關係，使得玻璃轉移溫度( Tg )、結晶起始溫度( To )及結晶尖峰溫度( Tp )等溫度下降，導致燒結後的胚體緻密度下降，反應層中之結晶量明顯的增加。此反應層生長之控制機構主要為銀離子在硼矽玻璃中的擴散。但若在氬氣中燒結，在玻璃陶瓷層鄰近LSBM/Ag介面處偵測不到銀的訊號，更無明顯的反應層生成。
另一方面，將銀與MSBA玻璃陶瓷複材共燒，觀察其介面的微結構，銀同樣地擴散進入玻璃相中。介面之反應層分成三個區域，各區域之玻璃基底皆含銀成份，結晶相中則無銀的訊號。由於反應層1中Mg-Al-Si結晶相之生成，減少銀擴散進入玻璃之路徑，使得擴散梯度趨於平緩，又由於鎂往電極方向聚集，且鋁在反應層2中稍有增加，造成反應層1及2中之銀含量低於反應層3，故最終銀濃度之分布並非呈現一般擴散現象。
In this research, the reaction layers produced from silver electrode cofired with La-Si-B-O-mullite (LSBM) or Mg-Si-B-Al (MSBA) glass ceramic composites in different sintering conditions were analyzed, and the controlled mechanism was investigated. The grown phases were characterized by X-ray diffractometry (XRD), and the microstructures were studied by scanning and transmission electronic microscopy (SEM and TEM).
In order to study the phenomenon of Ag diffusion into the LSB glass in air, the D-LSBM/Ag laminated samples was sintered at 760oC-840oC and characterized. The activation energy was 246 kJ/mole and the Ag nano-crystals in the sizes between 10~200nm were found appearing in the reaction zone after sintering. Ag, at first, was oxidized in the sintering process, and diffused into the glass. Then Ag nano-particles grow by over-saturation in the glass when cooling. The glass transition temperature (Tg), onset crystallization temperature (To), and the crystallization peak temperature (Tp) decreased because of the Ag diffusion into the glass. The diffusion also degraded the densification, but increased the amount of crystalline phase in the reaction zone. Ag+-ion diffusion in Si-B-O glass was the main controlled mechanism of the formation of reaction zone. However, if the LSBM/Ag sintered in Ar atmosphere, the Ag signal could not be detected on the glass ceramic layer nearby LSBM/Ag interface, and no obvious reaction zone was produced.
On the other hand, when the Ag cofired with MSBA glass ceramic composite, the microstructure of the interface revealed that Ag had diffused into the glass. The reaction of the interface consisted of three zones. Each zone appeared a glass matrix consisting of Ag. But, there was no Ag signal in the crystal phase. The path of the Ag diffusion was gradually blocked by the production of Mg-Al-Si crystalline phase in the zone 1. Because of the Mg content diffused toward electrode, and the slight increase of Al content in zone 2, the Ag concentration in zone 1 and 2 was lower than that in zone 3. The final distribution of Ag concentration didn’t reflect a general diffusion phenomenon.
Subjects
介面反應
銀
玻璃陶瓷
擴散
interfacial reaction
silver
glass ceramics
diffusion
Type
thesis