| In the solar thermal power generation system,the solar selective absorption film is mainly deposited on the key component of the concentrator collector surface to realize photothermal conversion,and thus it not only has a high light-thermal conversion efficiency,but also in the medium and high temperature(T?400 ?)service conditions should also have structural performance and stability.In order to further improve the conversion efficiency and effectively reduce the cost of solar thermal power generation,it is urgent to develop high-temperature photothermal thin film materials that can directly serve in the atmospheric environment with high anti-oxidation capabilities.For this reason,this issue is aimed at the tandem structure of TiAl(O)N thin films developed in the previous stage:(1)The effect of the scale of the Mo-TiAlN/Mo-TiAI(O)N double absorber layer on the selective absorption of the thin film remains to be still determined and optimized;(2)The influenc.ing rule of the radio frequency process parameters on the anti-reflection characteristics of alumina anti-reflection layer remains to be still determined and optimized;(3)The structure of TiAl(O)N photothermal thin film in series structure is complex,process control difficulty and preparation The problem of high cost and so on,based on selective absorption theory,the simulation and optimization design of double-absorber layer functional layer of TiAl(O)N photothermal film with tandem structure was performed.Based on this,the corresponding structure was prepared and verified by DC reactive magnetron sputtering.The double-absorber functional layer film of the scale has been studied experimentally to study the effect of the absorption layer dimension on the photothermal absorption performance and compositional structure characteristics of the film,clarifying the absorption layer dimension to the tandem structure Cu with a trace amount of the Mo doped TiAlN/TiAlON double absorption layer.The absorption properties of the Mo/TiAlN/Mo-TiAl(O)N thin film are affected by the law;the influence of the RF sputtering process parameters on the structural properties of the Al2O3 anti-reflection layer is experimentally studied,and the radio frequency sputtering Al2O3 anti-reflection is formed.Based on theoretical simulation,the AMA interference stack Cu/Al2O3/Mo/Al2O3 and Cu/Al2O3/MoOx/Al2O3 photothermal thin films with different absorption layer configuration dimensions but simpler structure are designed and fabricated.The AMA interference stack Cu/Al2O3/Mo/Al2O3 and Cu/Al2O3/MoOx/Al2O3 with different absorption layer configuration but simpler structure were designed and prepared.The thermal film,through its experimental study of its structure,absorption characteristics and thermal oxidation stability,has initially clarified its photothermal absorption performance,thermal oxidation stability level and major performance bottlenecks,and developed high oxidation resistance for the use of AMA thin film material system.The research base and technical support have been formed for the development of low-cost preparation technology for high-temperature photothermal film materials with high anti-oxidation capabilities using AMA thin film material systems.The Research indicates:(1)The selective absorption properties of the Mo-TiAlN/Mo-TiAl(O)N double-absorbing films are highly sensitive to the dimensional change of the sub-absorption layer,and its optimal size range is 40±20 nm;the scale of the main absorption layer the change has little effects on the absorption characteristics of the double-absorbing films,and there is a critical dimension of 120 nm,above this critical value and the film performance remains basically unchanged,otherwise,it will make the absorption limit left;with the double absorption layer scale changes,the elemental composition and the phase structure of the films are stable;the as-deposited thin films all exhibit obvious selective absorption characteristics,and the average absorption rate reaches more than 75%in the wavelength range of 300-500 nm,the thermal emissivity is maintained at about 0.1.(2)The effects of RF process parameters on the composition of Al2O3 films is slight.The RF power is 100/150/200 W,and the substrate temperature is 200/300/400 ?,the Al2O3 films prepared by RF sputtering method are all amorphous and the average transmittance of the film is above 95%.Due to the effects of RF process parameters on the degree of crystallinity and surface morphology of the film,the Al2O3 films prepared at 200 W and 400 ? have the best anti-reflection effect and the average transmittance reaches a maximum of 98.01%.(3)The AMA-type Cu/Al2O3/MoOx/Al2O3 and Cu/Al2O3/Mo/Al2O3 films with multi-layer structures matching the designed scale can be successfully fabricated by the DC and RF alternating deposition techniques,the as-deposited surface morphology is dense and uniform and the main phases are the nanocrystalline Cu and amorphous Al2O3.When the semitransmissive intermediate layer is a pure metal Mo,the overall absorption rate of the film is only 0.70@500 nm,and the normal emissivity ? = 0.05@RT,while the semi-permeable layer is a cermet MoOx prepared under the oxygen condition and the overall absorption performance of the film is more ideal.At this time,the absorption rate can reach a=0.90@500 nm,and the normal emissivity is ?=0.02@RT.After being annealed at different temperatures(400,500 ?)for 8 h in the air,the structural integrity of the above two films was destroyed,which was mainly due to the preferential oxidation and destruction of the Cu metal in the infrared reflective layer.This shows that the main performance bottleneck of the AMA interference stack thermal-optical absorption film in the medium-high temperature oxidation environment is that its overall scale is thin and there is no oxide-non-oxide composition gradient structure characteristics,therefore,each functional layer needs to have strong oxidation resistance and it is necessary to further optimize the material selection and composition structure of the metal infrared reflective layer and the semi-permeable intermediate layer. |
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