过渡金属氮化物光谱涂层发射率影响机理探究

Solar selective coatings are one of the key materials of parabolic trough collector. An ideal solar selective coating should absorb as much of the incident sunlight as possible. Simultaneously, the loss of the heat to the surroundings via connection or conduction, i.e. emittance, should be very low, with a thermal stability up to the operating temperature of the receivers. There are several absorption mechanism had been studied, including energy level transition, destructive interference, Effective medium theory, et al. Nevertheless, the emissivity mechanism has been barely researched..The project focuses on fundamental scientific problems of emissivity influence mechanism for transition metal nitride solar selective coatings. The microstructure of coatings, surface and interface, thickness and optical parameters on the influence of emissivity will be discussed. Based on the research, theories of the influence of surface and interface and internal particles on the infrared radiation will be established. The accumulation theory and experimental parameters will be benefit for the development of high quality solar selective coatings.

太阳光谱选择性吸收涂层（简称为光谱涂层）是槽式聚光集热系统中高温真空集热管的关键材料，其具有高吸收率与低发射率，以及良好的高温稳定性等特点。针对吸收率的机理已有较多研究，包括能级跃迁、相消干涉吸收、等效介质理论等。但目前尚缺乏针对发射率影响机理的研究。.本项目旨对过渡金属氮化物太阳能光谱选择性吸收涂层发射率影响机制所涉及到的基础科学问题开展相关探索，拟在对涂层的微观结构、表面与界面、厚度及光学参数等对发射率的影响规律相关研究，并在此基础上探明涂层的表面与界面以及内部粒子对红外辐射的作用的相关理论问题，希望能为开发出高品质太阳能光谱选择性吸收涂层积累理论和实验参数。

太阳光谱选择性吸收涂层是槽式聚光集热系统中高温真空集热管的关键材料，针对吸收率的机理已有较多研究，目前尚缺乏针对发射率影响机理的研究。. 本课题围绕光谱涂层的红外发射率变化机理进行系统的理论研究和实验探索。研究了厚度、基底粗糙度和基底温度对Ag膜反射光谱的影响，研究结果表明随着Ag膜厚度的增加，晶粒逐渐生长团聚，其红外波段的反射光谱先升高后降低。当Ag膜厚度为120nm时，红外发射率最低，仅为0.6%。 研究了Ag/Ti1-xAlxN/Ti1-yAlyN/AlN涂层各组成层的厚度或成分对涂层反射光谱及吸收率的影响。研究结果表明Ti1-xAlxN吸收层成分对反射光谱有重要影响：随着HMVF层中Ti含量的升高，近红外反射光谱先升高后降低；随着LMVF层中Ti含量的增加，近红外反射光谱先降低后升高。. 本课题确定降低光谱涂层的红外发射率的有效方法，对提高涂层的光学性能及槽式光热电站的光热转换效率等相关科学难题具有十分重要的意义。项目的研究成果为开发出高品质太阳能光谱选择性吸收涂层积累理论和实验参数。