摘要
Li2O-Al2O3-SiO2(LAS)微晶玻璃具有许多优良性能,广泛应用于许多领域,目前主要采用压制法生产。浮法工艺是生产平板玻璃的最佳方法,因此考虑将浮法成形工艺引入到LAS微晶玻璃的生产中,所以本文主要研究了LAS玻璃抛光和摊平过程的规律,探讨LAS系平板玻璃浮抛机理,为生产浮法LAS微晶玻璃提供理论支持。
本文主要通过高温粘度、表面张力及密度的测试,分析了LAS玻璃高温粘度、表面张力、密度与温度的变化规律及三者间的关系,测定了不同组分LAS玻璃厚度随温度、时间因素的变化关系。利用超景深显微镜测试LAS玻璃的抛光效果,从理论上研究LAS玻璃平整化的过程。采用DTA、XRD、SEM等测试手段研究了不同热历史过程对浮法LAS玻璃的析晶的影响,并就析晶对粘度、密度以及表面抛光效果的影响进行探讨。
结果表明：含晶核剂LAS玻璃的平衡厚度在7.24-7.26mm左右；未含晶核剂LAS玻璃的平衡厚度大约在7.12-7.22mm。LAS玻璃的平衡厚度均随着温度的升高略有降低。
含晶核剂LAS玻璃厚度到达平衡的时间为8-10min左右,而未含晶核剂LAS玻璃厚度到达平衡的时间约为4min。玻璃的抛光过程体现了表面张力与粘度比值的微观效应,平整化过程则是体现了表面张力与粘度比值的宏观效应。未含晶核剂LAS玻璃的高温表面张力、密度随着温度的升高呈线性降低,其在1250℃便可达到良好的抛光效果,而含晶核剂LAS玻璃在1340℃后开始有着较好的抛光效果。
未含晶核剂LAS玻璃的理论平整化时间随着温度升高而缩短,在1308.1℃(粘度为103.7dPa·s)时,平整化时间约为31s；在1236.4℃(粘度为104.2dPa`s)时大约需要101s。要想实现浮法成形,其表面张力与粘度的比值应控制在96-108(10-5Ncm-1/dPa·s)的范围内,考虑从粘度和表面张力两方面的因素来调整LAS玻璃的组成。
随着温度的升高,不同组分LAS玻璃析出的晶相均出现了晶型转变,β-石英固溶体向β-锂辉石固溶体过渡。不仅温度会对LAS玻璃内部晶相的类型、微观结构有影响,等温热处理的时间也是重要影响的因素。
LAS玻璃在低温到高温的过程中出现了析晶,而在高温到低温的热处理后仍为玻璃态没有晶体析出。LAS玻璃析晶导致玻璃抛光温度增加,并使玻璃抛光效果降低。
(LAS) glass-ceramics have many excellent properties, widely used in many fields, which are produced by holding technique currently. Float process is the best way to produce flat glass, therefore introducing float process to the production of LAS glass-ceramic was considered. The regularity of polishing and flatting process of LAS glass was studied. The float polishing mechanism of LAS system plate glass was investigated, providing theoretical support for the production of float LAS glass-ceramics.
In this paper, by testing high temperature viscosity, surface tension and density, the variation of high-temperature viscosity, surface tension, density and temperature of LAS glass was investigated. The variation relation of thickness of the different components of LAS glass with temperature and time was measured. The depth of field microscopy was used to analyze polishing effect. The flatting process of LAS glass was analyzed theoretically. The effect of different thermal history on the crystallization of LAS float glass was studied by DTA, XRD and SEM. Besides, effect of crystallization on the viscosity, density, surface tension and surface polishing effect was also investigated.
The results showed that the equilibrium thickness of LAS glass containing nucleating agents was about 7.24-7.26mm. The equilibrium thickness of LAS glass excluding nucleating agents was about 7.12-7.22mm. The equilibrium thickness of LAS glass thickness decreased slightly with temperature increasing.
The thickness of LAS glass containing nucleating agents reaching equilibrium needed 8-10min, about 4min for LAS glass excluding nucleating agents. Glass polishing process reflected the micro effect of surface tension/viscosity ratio, and the flatting process was the embodiment of the macro effect of surface tension/viscosity ratio.The surface tension and density of LAS glass excluding nucleating agents increased linearly as the temperature decreased, which achieved a good polishing effect at 1250℃, while LAS glass containing nucleating agents needed above 1340℃.
The theoretical flatting time of LAS glass excluding nucleating agents shortened with increasing temperature, which was about 31s at 1308.1℃(103.7dPa·s), approximately 101s at 1236.4℃(104.2dPa·s). In order to realize the float forming of LAS glass, the surface tension/viscosity ratio should be controlled within the range of 96 to 108(10-5Ncm-1dPa·s), considering the viscosity and surface tension to adjust the composition of LAS glass.
As the temperature increased, the crystalline phase of different components of LAS glass appeared crystalline transformation, transition fromβ-quartz solid solution toβ-spodumene solid solution. Not only temperature influenced crystal phase of the LAS glass, the time of isothermal heat treatment was also an important factor.
From low temperature to high temperature, LAS glass occurred crystallization, while still being glassy state during high temperature to low temperature heat treatment process. The crystallization of LAS glass increased polishing temperature of glass required, and reduced the polishing effect.
引文
[1]Scheidler H, Rodek E. Li2O-Al2O3-SiO2 Glass-Ceramics [J]. J Am Ceram Soc Bull,1989, 68(11):1926-1930.
[2]Beall G H, Pinckney L R. Nanophase glass-ceramics [J]. J Am Ceram Soc,1999,82 (1):5-16.
[3]H. Bach. Low Thermal Expansion Glass-Ceramics [M]. Springer, Berlin,1995.
[4]陈正树.浮法玻璃.武汉工业大学出版社,1997：105-108.
[5]程金树等编著.微晶玻璃[M].北京：化学工业出版社,2004：350-351.
[6]George H. Beall, Duke D A. Transparent glass-ceramics [J]. Mater. Sci.1969,4:340-52.
[7]H.Bach. Low Thermal Expansion Glass-Ceramics [M]. Springer,1995.
[8]McMillan P W. Glass-ceramics [M],2nd Edition, Academic press, London, New York, San Francisco,1982:12-39.
[9]程金树等编著.微晶玻璃[M].北京：化学工业出版社,2004：17-20.
[10]Kangguo Cheng. Determining crystallization kinetic parameters of Li2O-Al2O3-SiO2 glass from derivative differential thermal. Materials Science and Engineering,1999,60:194-199.
[11]Jean Rocherulle, Patricia Benard-Rocherulle. The devitrification of a LAS glass matrix studied by X-ray powder diffraction. Solid State Sciences,2002,4:999-1004.
[12]Xingzhong Guo. Crystallization and microstructure of Li2O-Al2O3-SiO2 glass containing complex nucleating agent. Thermochimica Acta,2006,444:201-205.
[13]A.M. Hu. Phase transformations of Li2O-Al2O3-SiO2 glasses with CeO2 addition. Ceramics International,2005,31:11-14.
[14]陈正树.浮法玻璃.武汉：武汉工业大学出版社,1997：4-5.
[15]莫瑞华等.浮法玻璃表面泡的来源与消除.建筑玻璃与工业玻璃,2006,(4)：9-10.
[16]马立云,王道德.保护气体组成对浮法玻璃性能的影响.玻璃,2002,(2)：18-19.
[17]J.A. Johnson, J. Greengrass.Characterization of tin at the surface of float glassJournal of Non-Crystalline Solids,1998,242:183-188.
[18]M.K. Tiwari, M.H. Modi.Non-destructive surface characterization of float glass:X-ray reflectivity and grazing incidence X-ray fluorescence analysis.Journal of Non-Crystalline Solids,2005,351:2341-2347.
[19]高鸿锦.液晶显示材料产业现状及发展趋势.产业透视,2004,(6)：48-55.
[20]应浩,嵇训烨,王峰.谈微型浮法玻璃生产线.玻璃,2004,172(1)：22-24.
[21]李西平,刘志海.微型浮法玻璃现状及发展趋势.中国建材,2008,2：62-64.
[22]薛建鹏,肖晶,尹洪基等.单片浮法防火玻璃的研制.中国建材,2003(6)：47-49.
[23]Glen B. Cook, Reid F. Cooper. Redox dynamics in the high-temperature float processing of glasses. Ⅰ. Reaction between undoped and iron-doped borosilicate glass melts and a gold-tin alloy. Journal of Non-Crystalline Solids,1999,249:210-227.
[24]Glen B. Cook, Reid F. Cooper. Redox dynamics in the high-temperature float processing of glasses. Ⅱ. Reaction between undoped and iron-doped aluminoborosilicate glassmelts and a gold-germanium alloy. Journal of Non-Crystalline Solids,2001,283:34-46.
[25]Claire Pettersen, Reid F. Cooper. Float-reaction between liquid bronze and magnesium aluminosilicate and ZnO-doped magnesium aluminosilicate glass-ceramic-forming glassmelts. Journal of Non-Crystalline Solids,2008,354(27):3194-3206.
[26]T. Kloss, G. Lautenschlager & K. Schneider. Advances in the process of floating borosilicate glasses and some recent applications for specialty borosilicate float glasses. Glass Tech, 2000,41 (6):177-181.
[27]陆平.耐热冲击硼硅酸盐玻璃浮法成形工艺原理的研究[D].武汉：武汉理工大学,2008.
[28]万军鹏.浮法生产硼硅酸盐防火玻璃的研究[D].武汉：武汉理工大学,2005.
[29]Friedrich Sibebers. Lithium-aluminosilicate flat float glass. USA. US2005/0250639A1. Nov.10,2005.
[30]张战营等编著.浮法玻璃生产技术与设备.北京：化学工业出版社,2005：86-93.
[31]Wolfram HOland, George Beall. Glass-Ceramic Technology [M]. Westerville:The American Ceramic Society,2002.
[32]范建峰,袁章福,柯家骏.高温熔体表面张力测量方法的进展.化学通报,2004,11：802-807.
[33]袁章福,范建峰.一种在线测量高温熔体表面张力、接触角和密度的装置.中国.发明专利.CN1591016A.2005-03-09.
[34]杨南如主编.无机非金属材料测试方法.武汉：武汉理工大学出版社,2004：19-25.
[35]杨南如主编.无机非金属材料测试方法.武汉：武汉理工大学出版社,2004：145-150.
[36]西北轻工业学院主编.玻璃工艺学.中国轻工业出版社,1982：66-67.
[37]陈正树.浮法玻璃.武汉：武汉工业大学出版社,1997：65-66.
[38]赵彦钊,殷海荣.玻璃工艺学.北京：化学工业出版社,2006：75-78.
[39]刘清.硼硅酸盐玻璃浮抛机理的研究[D].武汉：武汉理工大学,2007.
[40]陈正树.浮法玻璃.武汉：武汉工业大学出版社,1997：69-71.
[41]西北轻工业学院主编.玻璃工艺学.中国轻工业出版社,1982：79-81.
[42]赵彦钊,殷海荣.玻璃工艺学.北京：化学工业出版社,2006：86-88.
[43]黄钧.浮法玻璃的原理和生产.洛阳玻璃厂,1987：24-27.
[44]程金树等编著.微晶玻璃[M].北京：化学工业出版社,2004：109-112.
[45]赵彦钊,殷海荣.玻璃工艺学.北京：化学工业出版社,2006：61-63.
[46]Maier V. and Muller G. Mechanism of Nucleation in lithium aluminosilicate glass ceramics. J.Am.Cerm.Soc.1989, 10C:176-178.
[47]程金树等编著.微晶玻璃[M].北京：化学工业出版社,2004：144-148.
[48]G. Partridge.Glass Tech.1982,23:24-26.
