The optical properties of polymethyl methacrylate(PMMA)with varying degrees of artificial scratches have been studied with the aim of reproducing the change of visibility of an aircraft’s PMMA optical windows after b...The optical properties of polymethyl methacrylate(PMMA)with varying degrees of artificial scratches have been studied with the aim of reproducing the change of visibility of an aircraft’s PMMA optical windows after being damaged in their service environment.A novel maintenance method that can perfectly restore the optical property of PMMA has been identified and employed in the repair of the scratches that are formed on the surface of PMMA.This convenient and low-cost method entails polishing PMMA with different types of sandpaper to remove the scratches,and then spin-coating the repair solution in order to restore the optical properties of PMMA.The effect of this repair mechanism and parameters of the repair process were studied.The results indicated that the optical performance of PMMA is closely related to the mesh size of sandpaper,and improper parameter selection destroys the general effect of the repair.When the number of sandpaper mesh is low,the size of the abrasive particle is relatively larger,which can cause deeper friction marks on the surface of PMMA optical windows.Surface treatment using 5000 mesh sandpaper lowers surface roughness(R——a=0.566 nm),and optical transmittance in visible range can be restored to more than 88%.展开更多
A series of VO2 films with different thicknesses(from about 25 nm to 250 nm)were prepared on sapphire substrates by radio frequency magnetron sputtering.The deposition times varied from 15 min to 150 min.The metal to ...A series of VO2 films with different thicknesses(from about 25 nm to 250 nm)were prepared on sapphire substrates by radio frequency magnetron sputtering.The deposition times varied from 15 min to 150 min.The metal to insulator transitions(MIT)of the films were studied.The optical transmittance of the films to infrared light(with a wavelength of 4.0μm)at room temperature(30℃)varied significantly with film thickness,ranging from 86.53%to 41.01%.The modulation property also changes with thickness,decreasing from 22.89%to 14.74%.The phase transition temperature remained approximately 70℃during heating,and approximately 53℃during cooling,despite a tenfold increase in the deposition time,and the resulting thickness of the films.Raman spectroscopy of the films indicated that the intensities of the characteristic peaks corresponding to V2O5 increase with the increasing of film thickness.Temperature-dependent Raman spectroscopy indicated that the peaks corresponding to VO2 undergo reversible changes during heating and cooling of the films,while the peaks corresponding to V2O5 remain unchanged throughout.Careful control of the V2O5 content of the films(by varying the duration of the deposition process)allows control over their transmittance and optical modulation properties without changes in the phase transition temperature.This provides a new method of controlling the optical properties of these materials and shows promise for their potential applications in thermochromic windows.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars(Grant No.51625201)the National Key Research and Development Program of China(Grant No.2016YFE0201600)+2 种基金the National Natural Science Foundation of China(Grant No.51702066)the Open Fund of Key Laboratory of Micro-systems and Micro-structures Manufacturing,Ministry of Education(Grant No.2016KM001)the Major State Basic Search Program(Grant No.2014CB46505)。
文摘The optical properties of polymethyl methacrylate(PMMA)with varying degrees of artificial scratches have been studied with the aim of reproducing the change of visibility of an aircraft’s PMMA optical windows after being damaged in their service environment.A novel maintenance method that can perfectly restore the optical property of PMMA has been identified and employed in the repair of the scratches that are formed on the surface of PMMA.This convenient and low-cost method entails polishing PMMA with different types of sandpaper to remove the scratches,and then spin-coating the repair solution in order to restore the optical properties of PMMA.The effect of this repair mechanism and parameters of the repair process were studied.The results indicated that the optical performance of PMMA is closely related to the mesh size of sandpaper,and improper parameter selection destroys the general effect of the repair.When the number of sandpaper mesh is low,the size of the abrasive particle is relatively larger,which can cause deeper friction marks on the surface of PMMA optical windows.Surface treatment using 5000 mesh sandpaper lowers surface roughness(R——a=0.566 nm),and optical transmittance in visible range can be restored to more than 88%.
基金supported by the National Science Fund for Distinguished Young Scholars(Grant No.51625201)the National Key Research and Development Program of China(Grant No.2016YFE0201600)+1 种基金the National Natural Science Foundation of China(Grant Nos.51702066,51911530123)the Key Project of the National Natural Science Foundation of China(Grant No.U1809210)。
文摘A series of VO2 films with different thicknesses(from about 25 nm to 250 nm)were prepared on sapphire substrates by radio frequency magnetron sputtering.The deposition times varied from 15 min to 150 min.The metal to insulator transitions(MIT)of the films were studied.The optical transmittance of the films to infrared light(with a wavelength of 4.0μm)at room temperature(30℃)varied significantly with film thickness,ranging from 86.53%to 41.01%.The modulation property also changes with thickness,decreasing from 22.89%to 14.74%.The phase transition temperature remained approximately 70℃during heating,and approximately 53℃during cooling,despite a tenfold increase in the deposition time,and the resulting thickness of the films.Raman spectroscopy of the films indicated that the intensities of the characteristic peaks corresponding to V2O5 increase with the increasing of film thickness.Temperature-dependent Raman spectroscopy indicated that the peaks corresponding to VO2 undergo reversible changes during heating and cooling of the films,while the peaks corresponding to V2O5 remain unchanged throughout.Careful control of the V2O5 content of the films(by varying the duration of the deposition process)allows control over their transmittance and optical modulation properties without changes in the phase transition temperature.This provides a new method of controlling the optical properties of these materials and shows promise for their potential applications in thermochromic windows.
