In-situ detection and heating of high pressure metallic phase of silicon during scratching.

摘要

Scratching tests, using a diamond stylus, are performed to generate high pressures at the tool-work piece interface to investigate the pressure induced phase transformation phenomenon in silicon. Electrical resistance and optical transmittance of the transformed high pressure metallic phase of silicon are assessed during the scratching tests. These in-situ measurements provide direct evidence for the transient existence of the high pressure phase transformation in silicon from the covalent to a metallic crystalline structure during a material deforming process achieved by scratching.; Electrical resistance and infrared (IR) laser heating elements are integrated into a scratching apparatus. Experiments are conducted, with each system individually, to preferentially heat and soften the high pressure metallic phase of silicon in-situ. The objective of these experiments is to verify and evaluate the effectiveness of selective thermal softening the high pressure metallic phase of silicon.; Post process analyses techniques used to evaluate the experimental results from the heat assisted scratching tests include the following: Atomic Force Microscope (AFM), Scanning Electronic Microscope (SEM) and Micro Raman. Real time IR thermal images of the heated interface, between the diamond tool and high pressure silicon, show an apparent temperature rise in the contact region, which could indicate effective absorption of the IR laser energy by the high pressure metallic phase of silicon.; Numerical, analytical and experimental evaluation of the IR heating system is provided to characterize the efficiency of the IR heating system. This work also provides guidance for the future tool design of a micro laser assisted machining (mu-LAM) systems.