Preparation of calcium-aluminate glass by air suspension technology and its properties
Calcium-aluminate glass,with Al2O3 and CaO as its main components,is an infrared optical glass.However,it has a strong crystallization tendency,resulting in poor glass formtion ability which has to some extent affected its applications in the field of optics,such as infrared imaging guidance systems and infrared lasers.By adding trace amounts of network-forming agent SiO2,the glass-forming ability can be improved.A large amount of(1-x)CaAlO3-x SiO2 glass microspheres were rapidly prepared using the air suspension technology due to its simplicity,high operability,low experimental environment requirements,and ease of observation.Glass composed of CaAlO3-SiO2 with different SiO2 molar fractions were prepared using 4N7 grade SiO2,and their thermal stability,phase structure,microstructure,mechanical properties,and optical characteristics were tested.The experimental results showed that when the SiO2 molar fraction is 10%,i.e.,CAS-2(90%CaAlO3-10%SiO2),the thermal stability parameter ΔT(ΔT=Tc-Tg,Tc is crystallization temperature of glass,Tg is glass transition temperature)is the largest(ΔT=435 K),indicating the strongest glass-forming ability and the best thermal stability.The heat-treated CAS-2 sample remained in the glass phase,demonstrating that the heat treatment did not alter its phase structure.CAS-2 exhibited an average Vickers hardness value of 639,indicating relatively good mechanical properties.Optical tests for refractive index,transmission,and infrared transparency also confirmed the excellent optical characteristics of this sample.
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