Deformation and Cracking Mechanism in CrN/TiN Multilayer Coatings
Deformation and Cracking Mechanism in CrN/TiN Multilayer Coatings
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DOI：
10.3390/coatings9060363
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发表时间：
2019-06-01
期刊：
影响因子：
3.4
通讯作者：
Mayrhofer, Paul Heinz
中科院分区：
文献类型：
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作者：
Azizpour, Ahmad;Hahn, Rainer;Mayrhofer, Paul Heinz
采用非平衡反应磁控溅射PVD工艺在Custom 450钢基体上制备了CrN/TiN多层涂层，研究了涂层组织性能对涂层变形和损伤机制的影响。所有的涂层制造的总厚度为1.5 μ m，但不同的双层周期（λ）。通过XRD分析和纳米压痕实验研究了涂层的结构和力学性能。在涂层表面进行了100、300和450 mN三种载荷的压痕试验，然后用SEM和TEM分析了断裂压痕的横截面。通过测量压痕载荷下裂纹的长度，分析载荷-位移曲线，计算了多层涂层的表观断裂能。我们观察到，双层周期为4.5-15 nm的多层系统具有超晶格结构，这也导致较高的杨氏模量和硬度值以及较高的断裂能。横截面SEM和TEM观察结果的比较表明，具有较小的双层周期的涂层倾向于通过剪切滑动机制变形，由于存在的长期增长的柱，而短分散的晶粒生长在具有较大的双层周期的涂层通过局部晶界滑动和晶粒旋转导致变形。
In this study, the effects of the microstructural properties on the deformation and damage mechanism of CrN/TiN multilayer coatings deposited on Custom 450 steel using the unbalanced reactive magnetron sputtering PVD process were studied. All coatings were fabricated with an overall thickness of 1.5 mu m, but different bilayer periods (Lambda). Structural and mechanical properties of coatings were investigated by XRD analysis and nanoindentation experiment, respectively. Indentation tests at three loads of 100, 300, and 450 mN were performed on the coatings' surface and then, cross-sections of fractured imprints were analyzed with SEM and TEM. Measuring the length of the cracks induced by indentation loads and analyzing the load-displacement curves, apparent fracture energy values of multilayer coatings were calculated. We observed that multilayer systems with bilayer periods of 4.5-15 nm possess superlattice structure, which also results in higher values for Young's modulus and hardness as well as higher fracture energy. Comparison of cross-sectional SEM and TEM observations showed that coatings with smaller bilayer periods tend to deform by shear sliding mechanism due to the existence of the long-grown columns, while short dispersed grains-growing in the coatings with a larger bilayer period-led to deformation via local grain boundary sliding and grain rotation.