Nano-structured CrN/AlN multilayer coatings synthesized by pulsed closed field unbalanced magnetron sputtering
Nano-structured CrN/AlN multilayer coatings synthesized by pulsed closed field unbalanced magnetron sputtering
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DOI：
10.1016/j.surfcoat.2009.04.013
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发表时间：
2009-12
影响因子：
5.4
通讯作者：
Jianliang Lin;J. J. Moore-J.;B. Mishra;M. Pinkas;W. Sproul
中科院分区：
文献类型：
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作者：
Jianliang Lin;J. J. Moore-J.;B. Mishra;M. Pinkas;W. Sproul
采用脉冲闭合场非平衡磁控溅射系统制备了双层周期为2.5 ~ 22.5 nm的CrN/AlN超晶格涂层。涂层的Al/(Cr+Al)比值在61.5% ~ 66.5%之间。当AlN层厚度大于3.3 nm时，AlN层呈现纤锌矿型结构。CrN和AlN层之间的结构差异导致涂层硬度低（23-25 GPa），附着力差，耐磨性低。当AlN层厚度足够小（≤3.3 nm）时，CrN层外延稳定AlN层为nacl型结构。NaCl型CrN/AlN涂层在Λ 3.0 ~ 4 nm处具有40 GPa以上的超高硬度。在Λ=3 nm处硬度最高，达到45 GPa。Λ为3.0 ~ 4.7 nm的涂层具有较好的附着力、韧性和良好的耐磨性，其中摩擦系数为0.32，磨损率在10−7×mm3N−1m−1范围内表现优异。为了避免在CrN/AlN超晶格涂层中形成纤锌矿型AlN结构，应仔细控制AlN层厚度（如本研究≤3.3 nm）。
CrN/AlN superlattice coatings with bilayer period of 2.5 to 22.5 nm were prepared using a pulsed closed field unbalanced magnetron sputtering system. The Al/(Cr+Al) ratios of the coatings were in a range of 61.5%–66.5%. It was found that the AlN layers exhibit Wurtzite type structure when the AlN layer thickness is larger than 3.3 nm. The structure difference between CrN and AlN layers led to low hardness (23–25 GPa), poor adhesion, and low wear resistance of the coatings. The CrN layers epitaxially stabilize the AlN layers to NaCl-type structure as the thickness of the AlN layer is small enough (≤3.3 nm). The NaCl type CrN/AlN coatings exhibit super hardness above 40 GPa at Λ of 3.0–4 nm. The highest hardness of 45 GPa was achieved at Λ=3 nm. The coatings with Λ of 3.0–4.7 nm also showed improved adhesion, toughness, and excellent wear resistance, in which a low coefficient of friction of 0.32 and excellent wear rates in the low 10−7×mm3N−1m−1range were achieved. To avoid the formation of Wurtzite type AlN structure in CrN/AlN superlattice coatings, the AlN layer thickness should be carefully controlled (e.g. ≤3.3 nm in the present study).