圆锥压头递增载荷对材料的划痕行为

Scratch Behavior of Materials under Progressive Load by Conical Indenter

用Rockwell C金刚石压头对16种材料(2种玻璃、2种聚合物、4种陶瓷、4种金属和4种金属玻璃)进行微米划痕测试。结果表明,这些材料都存在与弹性恢复相关的最大划痕保持率(残余深度与压入深度之比),可作为表观摩擦系数变化曲线的分段过渡点。划痕的表观摩擦系数由黏着摩擦系数和犁沟摩擦系数组成,使用三维力学接触模型可较为准确地表征除金属玻璃外的摩擦系数。材料的初始摩擦系数与泊松比有一定的关系。聚合物(PC和PMMA)因堆积和下沉效应出现独有的双划痕沟槽现象。16种材料的划痕硬度与压痕硬度的比值为0.33~2.5,划痕硬度与体积模量呈线性关系。使用线弹性断裂力学(LEFM)模型和微观能量尺寸效应(MESEL)模型计算了材料的断裂韧性。结果表明,LEFM模型、Akono’s MESEL和Hubler’s MESEL模型都能较为准确地表征断裂韧性较低材料(玻璃、陶瓷和高分子)的断裂韧性,而对断裂韧性较大的金属材料其表征结果偏差较大。用Liu’s MESEL模型可表征断裂韧性较大材料(金属材料和部分金属玻璃)的断裂韧性。材料的断裂韧性,与泊松比呈分段线性相关。

The scratch characteristics in micron scale on 16 kinds of materials(2 kinds of glasses,2 kinds of polymers, 4 kinds of ceramics, 4 kinds of metals and 4 kinds of metallic glasses) were assessed by means of Rockwell C diamond indentation with progressive load. The results show that these materials all have the maximum scratch retention rate(the ratio of residual indentation depth to indentation depth) related to elastic recovery, which can be used as the transition point of the apparent friction coefficient curve. The apparent friction coefficient of scratches is composed of adhesive friction coefficient and furrow friction coefficient. The three-dimensional mechanical contact model can be used to accurately characterize the friction coefficient except for metallic glass. The initial friction coefficient of the material is related to the Poisson’s ratio. Polymeric materials(PC and PMMA) have special double scratch grooves due to stacking and sinking effects. The ratio of the hardness of scratched materials to the indentation hardness for 16 kinds of materials is 0.33~2.5, and there is a linear relationship between the scratch hardness and the volume modulus. The linear elastic fracture mechanics(LEFM) model and microscopic energy size effect(MESEL) model were used to calculate the fracture toughness of the material. The results show that: LEFM model, Akono’s MESEL model and Hubler’s MESEL model can accurately characterize the fracture toughness of materials with low fracture toughness(glasses, ceramics and polymers), while the deviation of calculation results for metal materials with high fracture toughness is large. Liu’s MESEL model can be used to characterize the fracture toughness of materials with large fracture toughness(metallic materials and some metallic glasses). The fracture toughness of the material has a piecewise linear correlation with Poisson’s ratio.