Integrity Assessment of High-Performance Thin-Film Coated Materials by Meso-mechanics

高性能涂层材料在应用前应充分评估其耐久性。本工作旨在建立评估此类材料耐久性的程序。采用射频磁控溅射法在硼硅酸盐玻璃表面涂覆陶瓷膜，并对涂层玻璃材料的力学性能进行了研究。首先，研究了单陶瓷膜、氧化铝（Al_2O_3）、碳化硅（SiC）和氮化泰坦（TiN）涂层材料的力学性能。结果表明，在玻璃表面涂覆陶瓷材料可提高玻璃的强度性能。在强度性能方面，TiN镀膜玻璃优于Al_2O_3镀膜玻璃和SiC镀膜玻璃，但TiN镀膜材料的表面性能在实际应用中还有待改进。提出了一种将相对硬度和粗糙度与溅射时间相结合来估计涂层材料强度的新方法。用所提出的方法可以很好地估计实验中的强度。研究了Al_2O_3-SiC两层涂层的可能性。对涂层表面粗糙度和孔隙率的测量表明，在本工作所采用的溅射条件下，形成了相对光滑致密的涂层。由于较软的玻璃基板避免了效果，因此发现较厚的薄膜较硬。较高的射频输出功率导致较硬的薄膜。溅射时间的延长和涂层的孔隙率降低了涂层的抗弯强度。通过与单陶瓷镀膜玻璃材料和玻璃基板的对比，阐明了两层镀膜可提高镀膜玻璃材料的强度和硬度。

he durability of coated materials with higher performances should be adequately evaluated prior to their applications. This work aims at the establishment of procedure to estimate the durability of such materials. In the present work, the borosilicate glass was coated with ceramic films by the radio-frequency (RF) magnetron sputtering method, and mechanical properties of coated glass materials were investigated. At first, mechanical properties of materials coated with single ceramic film, alumina (Al_2O_3), silicon carbide (SiC) or titan nitride (TiN) were investigated. It was found that the strength properties are improved by coating ceramic materials on glass. As for the strength properties, TiN coated glass is superior to Al_2O_3 and SiC coated ones, though it was suggested that the surface properties of TiN coated material should be improved in its application. A new procedure to estimate the strength of coated materials was proposed by incorporating relative hardness and roughness with sputtering time. The strength in experiments was well estimated by using the proposed procedure. The possibility of a two-layer coating using Al_2O_3-SiC was also examined as a processing for the improvement. The measurements of surface roughness and porosity of coating film revealed that relatively smooth and dense coating films were formed under the sputtering condition adopted in this work. Thicker film was found to be harder because of the avoidance of effect due to softer glass substrate. Higher RF output power resulted in harder film. The bending strength was reduced by longer time of sputtering as well as porosity of coating film. By comparison with glass materials coated with single ceramics and the glass substrate, it was clarified that the strength and hardness of coated glass materials were improved by two-layer coating.