Direct Observation of the Mechanics of Friction at a Single Asperity on Mineral Surfaces

9706580科尔斯泰特提出了一项研究，这将有助于我们理解岩石的摩擦行为，特别是发生在滑动岩石表面之间的凹凸处的变形过程。对同一或不同矿物表面单一粗糙度滑动时的变形机制和流变学的实验研究将阐明这一过程。通过检测单个粗糙面处的摩擦响应，PI可以直接根据观察到的微结构损伤来解释测量的力学性能。实验将在一系列矿物上进行，包括橄榄石、方解石和岩盐表面，这些矿物在室温下表现出一系列的脆性和可塑性。静态压痕和动态划痕实验将使用最近开发的两种独特的微/纳米机械测试设备进行。将确定脆性断裂和塑性流动过程之间的应变分配以及这种分配与滑移率、渗透率和湿度的关系。还将测量滑动-保持-滑动试验和速度阶跃试验中限制其演变的摩擦系数。微观结构将使用光学、扫描电子、传输电子和原子力显微镜技术进行表征。***

9706580 Kohlstedt The PI proposes a study that will contribute to our understanding of the frictional behavior of rocks, particularly the deformation processes occurring at asperities between sliding rock surfaces. Insight into this process will be elucidated from an experimental investigation of the deformation mechanisms and rheology at a single asperity sliding on the surface of the same or a different mineral. By examining the frictional response at a single asperity, the PI can directly interpret the measured mechanical properties in terms of the observed microstructural damage. Experiments will be performed on a suite of minerals including olivine, calcite and halite surfaces which exhibit a range of brittleness versus plasticity at room temperature. Both static indentation and dynamic scratch experiments will be carried out using two unique micro/nanomechanical testing apparatuses that have been recently developed. The partitioning of strain between brittle fracture and plastic flow processes and the dependence of this partitioning on slip rate, penetration rate and humidity will be determined. The coefficient of friction in slide-hold-slide tests and velocity-step tests to constrain its evolution will also be measured. Microstructures will be characterized using optical, scanning electron, transmission electron, and atomic force microscopy techniques. ***