On the corrosion of Zr48Cu36Al8Ag8 and (Zr48Cu36Al8Ag8)Si0.25 BMGs containing various amounts of crystals in 0.1 M NaCl solution

翁崎(Ongki Budi Anggriawan)

指導教授 ： 林景崎

國立中央大學/工學院/機械工程學系/碩士(2014年)

摘要

本論文以電化學技術來研究結晶程度不同(0%, 25%, 50% 和100%)的Zr48Cu36Al8Ag8和(Zr48Cu36Al8Ag8)Si0.25金屬玻璃在0.1M 氯化鈉水溶液中的腐蝕行為。金屬玻璃Zr48Cu36Al8Ag8 與 (Zr48Cu36Al8Ag8)Si0.25中的結晶化程度，分別以471℃和480℃持溫的時間長短來控制。電化學腐蝕研究方法包括開路電位(OCP)、直流電極化阻抗(PR)、塔弗曲線(TP)、循環陽極動態極化(CAPD)、電化學組抗頻譜(EIS)等測量，以估計試片之腐蝕速率。
由電化學研究結果歸納出: Zr48Cu36Al8Ag8及(Zr48Cu36Al8Ag8)Si0.25的腐蝕速率隨著所含結晶百分比由0%增高至25%而明顯下降，然而隨著結晶百分比由25%增至50, 70甚至100%時，腐蝕速率則隨之增大。與Zr48Cu36Al8Ag8相比，添加0.25%Si的(Zr48Cu36Al8Ag8)Si0.25耐蝕性較佳，尤其以含25%結晶百分比的 (Zr48Cu36Al8Ag8)Si0.25試片抗蝕性最佳(其腐蝕電位最高；腐蝕速率最低)，之所以具有如此優異的抗蝕性歸因於熱處理時試片內部應變能的釋放。反之，當試片內結晶百分比由25 %增至50 %以上時，結晶程度提升，晶界數量增加，晶界處成為主要腐蝕區域，進而加速了腐蝕速率。試片的密度測定，顯示(Zr48Cu36Al8Ag8)Si0.25之密度高於Zr48Cu36Al8Ag8，推測填加Si原子於Zr48Cu36Al8Ag8金屬玻璃時，將會填入玻璃結構的空隙位置，增高此金屬玻璃原子之堆積密度，因而在相同結晶百分比下，(Zr48Cu36Al8Ag8)Si0.25的結構比Zr48Cu36Al8Ag8緊密，較具抗蝕性。

關鍵字

金屬玻璃 ； Zr-Cu-Al-Ag ； Zr-Cu-Al-Ag-Si ； 腐蝕 ； NaCl

並列摘要

The corrosion behavior of Zr48Cu36Al8Ag8 and (Zr48Cu36Al8Ag8)Si0.25 BMGs containing various amounts (0, 11, 25, 50, 70 and 100 %) of crystalline forms in NaCl 0.1 M solution was investigated by electrochemical techniques in this work. The percentage of the crystals in BMGs were adjusted by annealing at 471 oC for Zr48Cu36Al8Ag8 and at 480 oC for (Zr48Cu36Al8Ag8)Si0.25 for changing durations. The open circuit potential (OCP), direct-current polarization resistance (PR), Tafel plot (TP), cyclic anodic potentiodynamic polarization (CAPD), and electrochemical impedance spectroscopy (EIS) where investigated to estimate the corrosion rate of all the specimens.
Resulting from electrochemical studies on both Zr48Cu36Al8Ag8 and (Zr48Cu36Al8Ag8)Si0.25, we concluded that the corrosion rate decreased with increasing the percentage of crystal form from 0 to 25%, and it increased with increasing the crystal percentages in the range from 50% to 100%. The corrosion rate was lower for (Zr48Cu36Al8Ag8)Si0.25 than for Zr48Cu36Al8Ag8. The specimen containing 25% crystal in the (Zr48Cu36Al8Ag8)Si0.25 system revealed the highest Ecorr with the lowest corrosion rate (the lowest corrosion current density) than that in the Zr48Cu36Al8Ag8. Greater corrosion resistance for the annealed specimens containing 25% crystal may be ascribed to relaxation of the strain energy and decreased free volume that resulted from annealing in the preparation of BMGs. On the contrary, an increase of corrosion rate with increasing the crystal content from 50 to 70 and 100 % may be contributed to an increase of grain boundary area resultant from higher percentage of crystals. Determination of the gravimetrical density revealed that it was greater for (Zr48Cu36Al8Ag8)Si0.25 than Zr48Cu36Al8Ag8. This fact implied that the addition of silicon inclined to fill up the interstitial sites in Zr48Cu36Al8Ag8, hence resulted in an increase of atomic packing density in the BMGs. As a result, the more compact (Zr48Cu36Al8Ag8)Si0.25 structure displayed better corrosion resistance than Zr48Cu36Al8Ag8 at the same percentages of crystals.

並列關鍵字

Metallic glasses ； Zr-Cu-Al-Ag ； Zr-Cu-Al-Ag-Si ； corrosion ； NaCl

參考文獻

[55] C. L. Qin, W. Zhang, H. Kimura, K. Asami, and A. Inoue, “Corrosion behavior and surface characteristics of Ni-based and Cu-based metallic glasses”, Meeting 214th, Electrochemical Society, pp. 1609, (2008).

[3] A. Inoue, A. Makino, T. Mizushima, “Ferromagnetic bulk glassy alloys”, Journal of Magnetism and Magnetic Materials, vol. 215-216, pp. 246-252, (2000).

[5] W. Basu and S. Ranganathan, “Bulk metallic glasses: A new class of engineering materials”, Sadhana, vol. 28, pp. 783–798, (2003).

[6] T. R. Anantharaman, “Metallic glasses: Production, properties and applications”, Trans. Tech. Publications, (1984).

[7] V. Schroeder, C. J. Gilbert and R. O. Ritchie, “Comparison of the corrosion behavior of a bulk amorphous metal, Zr41.2Ti13.8Cu12.5Ni10Be22.5, with its crystallized form”, Materials Science and Mineral Engineering, vol. 38, pp. 1481–1485, (1998).