考虑压痕尺寸效应的岩石矿物摩擦特性研究

Study on friction characteristics of rock minerals considering indentation size effect

岩石矿物组分间的力学特性差异是影响宏观摩擦行为的关键因素。基于靶向试验法测试砂岩矿物在8种法向荷载下的压痕力学特性,并研究其在基本稳定法向荷载下的划痕摩擦特性。结果表明:随着法向荷载的增加,硬相矿物的变形参数(硬度和弹性模量)呈现负压痕尺寸效应,软相矿物的变形参数呈现无明显压痕尺寸效应,综合确定4种矿物的基本稳定法向荷载为8 mN;在稳定法向荷载下,随着划痕长度的增加,硬相矿物中石英和钠长石的摩擦力先快速增加后保持稳定,而方解石与软相矿物中绿泥石的摩擦力均先快速后缓慢增加,统计计算得到4种矿物对应的平均弹性恢复率分别为13.29%,15.81%,35.91%和42.28%。进一步结合微观机制分析发现,矿物的位错蠕变和位错演化分别是影响压痕尺寸效应和划痕黏滑行为的关键因素。上述研究结果为岩石宏微观力学行为的关联性研究提供参考意义。

The difference between the mechanical properties of rock mineral components is a key factor affecting the macroscopic friction behavior.Based on the target test method,the indentation mechanical properties of sandstone minerals are tested under eight normal loads,and the scratch friction properties of these minerals are studied under basically stable normal load.The results show that as the normal load increases,the deformation parameters(hardness and elastic modulus)of hard-phase minerals exhibit a negative indentation size effect,while the indentation size effect of deformation parameters of soft-phase minerals is not obvious,and the comprehensive basic stable normal load for the four minerals is determined as 8 mN.Under the stable normal load,as the scratch length increases,the friction force of quartz and albite in the hard-phase minerals increase rapidly and then remain stable,while the friction force of calcite and chlorite in the soft-phase minerals both increase rapidly and then slowly.Statistical calculations show that the average elastic recovery rates for the four minerals are 13.29%,15.81%,35.91%and 42.28%respectively.Further combined with the analysis of microscopic mechanism,it is found that dislocation creep and dislocation evolution of minerals are the key factors affecting the indentation size effect and scratch stick-slip behavior respectively.The above research results provide reference significance for the study of correlation between macro and micro mechanical behaviors of rocks.