Mandal Ashis K, Mandal B, Illath Kavya, Ajithkumar T G, Halder A, Sinha P K, Sen Ranjan
CSIR-Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Road, Kolkata, - 700032, India.
Central NMR Facility and Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr.Homi Bhabha Road, Pune, - 411008, India.
Sci Rep. 2018 Apr 18;8(1):6195. doi: 10.1038/s41598-018-24287-1.
Iron impurity in raw material remains a major challenge in producing colourless glass. In this investigation, we report microwave (MW) heating capable of altering Fe-redox ratio (Fe/∑Fe) enabling preparation of colourless phosphate glass. The effect of Sn concentration in retention of Fe[II] in glass melted in MW was compared with conventional glasses. Colourimetric study developing Fe-ferrozine colour complex reveals Fe-redox ratio ≥0.49 required to obtain colourless phosphate glass. In microwave heating, addition of 1 wt.% Sn metal powder can impart the desired effect whereas addition of 1.9 wt.% Sn metal powder is required in conventional heating. The correlation equation of Fe-redox ratio with concentration of Sn metal is found to be different in microwave and conventional heating. Thus, exploiting this different redox changes in MW heating optical properties can be tailored. Preservation of higher Fe[II] in MW melted glass is also confirmed by XPS and TGA. P MAS NMR spectra suggest that transition from cross linked ultra phosphate to linear polymer metaphosphate network in incorporation of Sn is found different in glass prepared adopting microwave irradiation. A1 MAS NMR spectra suggest higher relative content of Al in glass obtained from MW heating. Energy consumption analysis revels 3.4 kWh in MW heating while 14 kWh in conventional glass melting using resistance heating. Further, glass melting in MW can be completed within 2 h unlike ~5 h needed in conventional. MW heating plays a significant role in improving properties to make colourless phosphate glass in addition to significant energy and time saving.
原材料中的铁杂质仍然是生产无色玻璃的一个主要挑战。在本研究中，我们报告了微波（MW）加热能够改变铁的氧化还原比（Fe/∑Fe），从而能够制备无色磷酸盐玻璃。将微波加热熔化的玻璃中锡浓度对保留Fe[II]的影响与传统玻璃进行了比较。通过显色研究形成铁 - 菲罗嗪显色络合物表明，要获得无色磷酸盐玻璃，铁的氧化还原比≥0.49。在微波加热中，添加1 wt.%的锡金属粉末可产生所需效果，而在传统加热中则需要添加1.9 wt.%的锡金属粉末。发现微波加热和传统加热中铁氧化还原比与锡金属浓度的相关方程不同。因此，利用微波加热中这种不同的氧化还原变化可以调整光学性能。XPS和TGA也证实了微波熔化的玻璃中保留了更高的Fe[II]。P MAS NMR光谱表明，在采用微波辐射制备的玻璃中，锡掺入时从交联超磷酸盐到线性聚合物偏磷酸盐网络的转变有所不同。A1 MAS NMR光谱表明，微波加热获得的玻璃中铝的相对含量更高。能耗分析显示，微波加热能耗为3.4 kWh，而传统电阻加热玻璃熔化能耗为14 kWh。此外，微波加热玻璃熔化可在2小时内完成，而传统方法需要约5小时。除了显著节省能源和时间外，微波加热在改善性能以制造无色磷酸盐玻璃方面也发挥着重要作用。
