ISSN   1004-0595

CN  62-1224/O4

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试样倾斜和正压力对球形压头微米划痕测试紫铜的影响

Effect of Sample Tilt and Normal Load on Micro-Scratch Test of Copper with a Spherical Indenter

  • 摘要: 采用球形压头对紫铜进行微米划痕试验,研究了不同恒定正压力下试样倾斜对划痕测试紫铜的影响. 结果表明:试验测得的名义摩擦系数与试样倾斜角度线性相关,且斜率不受正压力的影响. 建立了球形压头与试样倾斜状态的位置关系模型,发现试样倾斜对名义摩擦系数中的黏着组分无影响,而犁耕组分随倾斜角度线性变化. 试样倾斜时的摩擦系数可通过球-面接触力学模型进行校正,获得试样无倾斜时的摩擦系数. 摩擦系数与正压力之间呈非线性关系,其中犁耕组分线性增大,黏着组分非线性增大并趋于稳定. 通过划痕形貌测量的残余划痕宽度几乎不受试样倾斜的影响,但与正压力的0.5次方存在线性关系. 分析了划痕硬度随正压力的变化,发现由残余划痕宽度计算得到的划痕硬度几乎为恒定值,不受正压力影响,而由接触投影面积计算得到的划痕硬度随正压力增大而增大,随后趋于稳定.

     

    Abstract: Micro-scratch experiments were performed on copper with a spherical indenter, and the effect of sample tilt on the scratch response of copper under different constant normal loads was studied. The results showed that the experimentally measured nominal friction coefficient was linearly related to the sample tilt angle, with their slope being unaffected by the normal load. The geometrical model considering the positional relationship between the spherical indenter and the tilted sample was established. It was found that the inclination of the sample had no effect on the adhesive component of the nominal friction coefficient, and the ploughing component of friction coefficient linearly changed with the tilt angle. The friction coefficients can be corrected by a sphere-to-flat contact mechanical model for tilted samples, so as to obtain the true friction coefficients corresponding to the condition without tilting. There was a non-linear relationship between the friction coefficient and the normal load with the ploughing component increasing linearly with the normal load, while the adhesive component increased non-linearly and then gradually stabilized. The residual scratch width measured by the scratch topography was hardly affected by the tilt of the sample, and had a linear relationship with the square root of the normal load. The change of scratch hardness with normal load was analyzed, and the scratch hardness calculated from the residual scratch width was found to be a constant value, while the scratch hardness calculated from the projected contact area increased with normal load, and then gradually stabilized.

     

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