Design And Synthesis Of ZrAlN/ZrB₂ And W/ZrB₂ Nanoscale Multilayered Coatings By Magnetron Sputtering Techneque

This paper reported the design and synthesis of ZrAlN/ZrB₂ and W/ZrB₂ multilayered coatings with nanoscale bilayer period on Si (100) using ultrahigh vacuum on magnetron sputtering. X-ray diffraction(XRD) and scanning electron microscopy(SEM) were employed to investigate layered and crystal structure of the coatings. The mechanical properties of the multilayered coatings including hardness, elastic modulus and adhesion were measured by profiler (XP-2) and Nano Indenter XP system. Our aim is to obtain insight into the significance of different process parameters on the structure and mechanical properties of the multilayered coatings.Based on data of monolithic coatings, the ZrAlN/ZrB₂ multilayered coatings with nanoscale bilayer periods have been synthesized from ZrAl (DC) and ZrB₂ (RF) target on Si (100). The influence of modulation periods, thickness ratio and N₂/Ar ratio on microstructure and properties of the coatings was discussed. The nanoscale multilayered modulation structure and clear interface was confirmed by SEM and low-angle XRD. The multilayer with modulation period of 40 nm, t_ZrAlN∶t_ZrB2=1∶3, N₂/Ar ratio=1/3 and working pressure of 0.3/0.4 Pa displays the highest hardness of 36.4 GPa, and the elastic modulus, fracture resistance, and residual stress are all improved compared to the monolithic coatings. At the same time, high-angle XRD patterns show a marked polycrystalline structure with the strong mixture of ZrAlN (111), ZrB₂ (001), ZrB₂ (101), and AlN (111), which is one reason of the hardness enhance.Choose W and ZrB₂ as monolithic materials, a series of W/ZrB₂ multilayered coatings have been synthesis by the RF magnetron sputtering at room temperature, and the influence of modulation periods, thickness ratio and working pressure on microstructure and mechanical properties of the coatings was investigated. The low-angle XRD pattern and SEM indicated a well-defined composition modulation and layer structure of the multilayered coating. Besieds all multilayers possess higher hardness and elastic modulus than the monolithic coatings, the residual stress of the multilayers is also improved. At∧= 30 nm, t_W∶t_ZrB2=1∶4 and the working pressure is 0.6 Pa, the multilayers exhibit W (111) and ZrB₂(001) preferred orientations and show abnormal enhancement of hardness and elastic modulus with maximum values of 41.5 GPa and 539.9 GPa respectively.Little academic paper on relationship between microstrure and properties of nanoscale ZrAlN/ZrB₂ and W/ZrB₂ multilayered coatings have been reported in recent literatures. In addition to synthesis the high hardness, high elastic modulus, well adhesion and low residual stress and obtain the optimal technologic parameter, the analysis on the hardness enhance of the different structure system of ZrAlN/ZrB₂ and W/ZrB₂ multilayer is discussed. Therefore, these studies have great potential as protective coatings, enhancing the hardness of the multilayer system, improving the performance of material surface, exploiting the new superhardness materials and expanding the application of industry on nanoscale multilayered coatings.