Preparation And Properties Of Ti Doped DLC And AlN Multi-layered Solar Spectrally Selective Coatings

Plasma enhanced chemical vapor deposition and reaction magnetron sputtering methodswere employed in this work to study two different multi-layered solar spectrally selectivecoatings: Ti/Ti-DLC/DLC and Al/Ti-AlN/AlN component films. The relationship betweenfilms’ nano structure and optical properties were investigated. The results are as follows:(1) Plasma enhanced chemical vapor deposition (PECVD) method was employed todeposit hydrogenated amorphous carbon (a-C:H) films. The relation between applied negativebias and films’ structure (bonding ratio of sp3and sp2) and properties (refraction index andoptical reflectivity) were investigated. The results showed that the as deposited films own arich amount of sp2bonding. The sp2-C amount gets raised as the increase of negative bias,which was63.4%,63.5%,63.8%and68.2%at-300V,-500V,-700V and-900V, respectively.Meanwhile, the films’ refraction index was also increased linearly, which was2.2,2.6,3and3.3at-300V,-500V,-700V and-900V, respectively.(2) The TiC nano particles are embedded into a-C:H matrix to form the new threelayered amorphous carbon-nanocrystalline Ti/Ti-DLC/DLC solar selective coatings throughnano component technology. Moreover, the solar selective coatings’ optical properties(absorption α and emmitance ε) were investigated. Coatings with layer structure ofTi/Ti-DLC/DLC, which was called the “blue coatings”, exhibit solar selectively property.And the TiC nano particles were proved to be doped exists in the a-C:H to form the dispersionstrengthening component films, which has a rough surface at nano scale to improve films’absorption. The as-deposited Ti/Ti-DLC/DLC films owns an absorption of0.89and anemittance of0.12.(3) Magnetron sputtering was employed to fabricate Al/Ti-AlN/AlN component coatings,which was consist of infrared reflection layer Al, Ti-AlN absorption layer and an AlNanti-reflection layer. And the component coatings owned an absorption of0.94and anemittance of0.07. In the sputtering process, the AlN stop growing at axial direction to formdense crystal bars at high power supply, while at low power supply, the crystal bars are morelikely to grow at axial direction, thus to from a nano-sized rough surface to improve the films’absoption.