氧化鈣之添加對Li_2O-Al_2O_3-SiO_2-TiO_2玻璃陶瓷結晶及性質之影響

The Effect of CaO Addivtives on Crystallization and Properties of Li_2O-Al_2O_3-SiO_2-TiO_2 Glass-Ceramic

王木琴(M. C. Wang) ； 洪敏雄(M. H. Hon)

《鑛冶：中國鑛冶工程學會會刊》 37卷2期 (1993/06) Pp. 101-113

摘要

本研究係利用熱膨脹儀、示差熱分析（DTA）、X-光繞射分析（XRD）、高溫X-光繞射分析（HTXRD）、掃描式電子顯微鏡（SEM）、掃描穿透式電子顯微鏡（STEM）及電子繞射（ED），研究Li_2O-CaO-AI_2O_3-SiO_2-TiO_2（LCAST）系玻璃陶瓷結晶相變化。由XRD知本研究所用三種不同成份之A、B、C試樣，其結晶相皆為正方晶系之β-鋰輝石（β-spodumene），晶格常數分別為a_0＝7.516Å 7.515Å 7.538 Å；C_0=9.155Å 9.172Å、9.180Å。除β-鋰輝石之外，在A與B試樣中尚有少量之桐石（titanite，CaO．TiO_2．SiO_2），而於C試樣中除上述兩種結晶相外，尚有矽灰石（wollastonite）。A、B、C三試樣結晶相變化所需之活化能分別為59.6 kcal／mol、36.3 kcal／mol及45.2kcal／mol；而由25℃至700℃之熱膨脹係數則分別為3.50×10^(-6)／℃、3.81×10^(-6)／℃及3.92×10^(-6)／℃。

並列摘要

The effect of additives of CaO on the crystallization and properties of Li_2O-AI_2O_3-SiO_2-TiO_2 glass-ceramic systern has been investigated using DTA, XRD, STEM, SEM, ED and dilatometer. The major phase in the three specimens A, B and C was crystallized in the tetragonal system with lattice parameters of a_0= 7.516Å 7.515Å and 7.538Å; c_0=9.155Å, 9.172Å and 9.180Å, respectively. On the basis of the close resemblance, this system was considered to correspond toβ-spodumene, Li_2O．Al_2O．4SiO_2. A minor phase of titanite, CaO．TiO_2．SiO_2 was also found in all specimens. Beside, the wollastonite phase was present in C specimen. The activation energies for nucleation and growth in the glass crystallization process are 69.6, 36.3 and 45.2 kcal/mol; and the thermal expansion coefficients from 25°C to 700°C are 3.50×10^(-6), 3.81×10^(-6) and 3.92×10^(-6)/°C for the specimens, respectively.