A series of simulations of chemical mechanical polishing (CMP) were conducted to investigate the contact force between abrasive particles and specimens by using the finite element method (FEM). In this paper, a micro-contact model, which only involves the mechanical interactions, was set up to simulate the polishing process by changing the processing parameters, including the downward pressure, abrasive size, and polishing speed. Simulation results show that the contact force becomes larger when the downward pressure increases. In addition, when the downward pressure and abrasive size increase, the fluctuation of the contact force becomes large, whereas it declines with decreases in the polishing speed. In addition, corresponding CMP experiments were done to investigate the material removal rate (MRR) and polished average roughness (Ra) under different simulation conditions. Through the establishment of the contact force properties in the simulation and the MRR and Ra in the CMP experiment, qualitative research has been done on the relationship between the contact force in the simulation and experimental results. Experimental results indicate that the MRR and surface roughness are influenced by the contact force. A high MRR can be obtained by a large contact force and dramatic fluctuations can lead to poor surface-finish quality. The investigation contributes to obtaining higher polishing efficiency and lower surface roughness through optimization of the polishing parameters.

In this article, the specimen of Q235 (low carbon steel, C 0.22%, Mn: 0.3%-0.8%, Si 0.3%, P 0.045%, S 0.05%) has been tested in in situ tensile tests. Especially, different types of scratches are prefabricated with 1, 2, and 3 mm in depth. In addition, three scratch angles (u = 0°, 45°, and 90°) are adopted to explore the changes of tensile strength. The cross profile of the scratch groove is measured with in situ observation method (Olympus DSX500), which is taken as an important indicator to verify the experiments. According to the results of experiments, scratch depth and angle can influence the tensile strength of material. When the depth and scratch angle increase, there is a decrement in the value of tensile strength. This indicates that the surface damage really has effect on the tensile strength of specimen.

For exploring the mechanical properties and behaviors of new materials, a novel in situ nanoscratch device compatible with commercial microscope has been developed. The developed device with specific dimensions of 178 mm 3 165 mm 3 78 mm includes the coarse positioning module, the precise feed module, the measurement module, and the control module. Integrating the servo motor, worm and gears, ball screw, flexure hinge, and piezoelectric actuator, the device can realize macroscopical coarse positioning motion and precise feed motion. A novel arrangement of load sensor and indenter with no middle chain is used to reduce the measurement error. Closed-loop control system is established to guarantee the accuracy of load and displacement control. Mechanical properties of the developed device have been proved by calibrating the load sensor, finite element analysis of flexure hinge, and verifying the output performance. The in situ nanoscratch test has been conducted on the single crystal copper. The captured images and finite element analysis prove the feasibility and accuracy of the developed device.