Preparation of broadband antireflective coating by sol-gel method

A sol-gel method for the preparation of silica coating that varied in refractive index is developed. Silicon dioxide sol is obtained by hydrolysis and co-condensation reactions occurred in acid-catalyzed system. Surface morphology, refractive index, and transmission spectrum of the samples are studied. The results of transmission spectra of single-sided coatings show that the average transmittance of the samples increases about 4% compared with the uncoated one in the spectra range from 400 to 1 200 nm in the case of vertical incidence. For the double-sided coating the maximum transmittance is 99% at the wavelength of 840 nm.     

Study of aluminum coating prepared by PVD used as anti-corrosion in liquid lead-bismuth

Liquid metals-such as lead （Pb） or lead-bismuth （PbBi） are used as reactor core coolants for accelerator driven systems （ADS） proposed for high-level radioactive waste transmutation. Compatibility of steels with liquid PbBi is a key problem because steels are attacked by dissolution of the components in PbBi, so it has to form a stable coating on steel surface. There are many methods to prepare anti-corrosion coatings on steel, such as hot dipping, pack cementation, plasma spaying, and physical vapor deposition （PVD）. Compared with other methods, the PVD method is easy to control the thickness of the coating and the obtained coatings are dense which is crucial to the anti-corrosion ability of the coatings. In this letter, PVD aluminum coatings are developed on the surface of T91 steel and different heat-treatment atmosphere is used to adjust the microstructure, aluminum content, and the phase of the coatings. It is found that the coatings have good adherence ability with steel. The aluminum content and the phase of the coating can be adjusted by the heat-treatment atmosphere. Corrosion tests are performed in oxygen-saturated liquid PbBi at 550 ℃ for 1 000 h, the phase and composition of the coating do not change drastically. All the results indicate that the PVD is a useful method to prepare coatings on the surface of steel used in liquid PbBi.     

248 nm高反膜抗激光损伤性能

用电子束蒸发法在熔融石英基底上沉积了适用于248nm的HfO2/SiO2高反膜,为提高其抗激光损伤能力,设计并制备了两种保护层,一种是在常规高反膜系的基础上镀制二分之一波长厚度的SiO2保护层,另一种是用Al2O3/MgF2做保护层。测试了3种高反膜样品的激光损伤情况,通过损伤形貌的变化分析了两种保护层使抗激光损伤能力提高的原因以及存在的问题。