Zeng Guosong, Sun Wei, Song Renbo, Tansu Nelson, Krick Brandon A
Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA, 18015, USA.
Center for Photonics and Nanoelectronics, Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, PA, 18015, USA.
Sci Rep. 2017 Oct 26;7(1):14126. doi: 10.1038/s41598-017-14234-x.
We explore how crystallographic order and orientation affect the tribological (friction and wear) performance of gallium nitride (GaN), through experiments and theory. Friction and wear were measured in every direction on the c-plane of GaN through rotary wear experiment. This revealed a strong crystallographic orientation dependence of the sliding properties of GaN; a 60° periodicity of wear rate and friction coefficient was observed. The origin of this periodicity is rooted in the symmetry presented in wurtzite hexagonal lattice structure of III-nitrides. The lowest wear rate was found as 0.6 × 10 mm/Nm with <1[Formula: see text]00>, while the wear rate associated with <1[Formula: see text]10> had the highest wear rate of 1.4 × 10 mm/Nm. On the contrary, higher friction coefficient can be observed along <1[Formula: see text]00> while lower friction coefficient always appeared along <1[Formula: see text]10>. We developed a simple molecular statics approach to understand energy barriers associated with sliding and material removal; this calculated change of free energy associated with sliding revealed that there were smaller energy barriers sliding along <1[Formula: see text]10> as compared to the <1[Formula: see text]00> direction.
我们通过实验和理论研究了晶体学有序性和取向如何影响氮化镓（GaN）的摩擦学（摩擦和磨损）性能。通过旋转磨损实验，在GaN的c平面的各个方向上测量了摩擦和磨损。这揭示了GaN滑动性能对晶体学取向的强烈依赖性；观察到磨损率和摩擦系数具有60°的周期性。这种周期性的起源源于III族氮化物纤锌矿六边形晶格结构中呈现的对称性。发现最低磨损率为0.6×10⁻³mm/Nm，对应于<100>方向，而与<110>相关的磨损率最高，为1.4×10⁻³mm/Nm。相反，沿<100>方向可观察到较高的摩擦系数，而沿<110>方向总是出现较低的摩擦系数。我们开发了一种简单的分子静力学方法来理解与滑动和材料去除相关的能垒；这种计算出的与滑动相关的自由能变化表明，与<100>方向相比，沿<110>方向滑动的能垒较小。
