Lifu Xu

Drilling of SiCp/Al Metal Matrix Composites with Polycrystalline Diamond (PCD) Tools

High-volume-fraction SiCp/Al composites have attracted considerable interest for their excellent thermo-physical properties. However, popularization of high volume fraction SiCp/Al composites is still hampered by their poor machinability. In this study, the influences of the cutting speed and feed rate on the drilling performance of SiCp/Al composites with 56% SiC particles were investigated experimentally. The drilling characteristics were evaluated in terms of drilling forces, tool wear, and the surface quality of drilled-hole. It was found that the feed rate is one of the main cutting parameters that affect the drilling performance, while the cutting speed has no significant effect on the thrust force.

The Effect of Rare Earth on the Clearance of Carbon during High Speed Polishing of Diamond Films

A new setup for polishing of diamond films on a high speed rotating stainless plate has been developed, and a rare earth metal plate was used to clear the carbon atoms diffused into the polishing plate. The surface morphology and clearance mechanism were studied by using scanning electron microscopy and X-ray photo-electron spectroscopy before and after polishing, respectively. The results showed that the chemical reaction between the rare earth metal and carbon diffused into the polishing plate took place and the rare earth metal could clear the carbon element effectively during the super-high speed polishing.

Study of the mechanism of ductile-regime grinding of SiCp/Al composites using finite element simulation

Abstract Based on indentation experiments under different loads, the mechanism of ductile-regime grinding of SiCp/Al composites has been investigated. The factors that influence the ductile-regime removal of SiC particles, such as tip radius of abrasive grains, intrusion depth, and volume fraction of SiC particles, have been analyzed by three-dimensional finite element simulation. The calculation results indicate that a sharp abrasive grain without tip radius cannot produce a plastic deformation region under the indenter and brittle fracture of the SiC particle takes place rather than ductile model of failure. The critical grinding depth of ductile-regime removal decreases with increasing tip radius of abrasive grains, but increases with decreasing SiC particle volume fraction.

The coupled FEM analysis of super-high angular speed polishing of diamond films

Abstract Super-high angular speed polishing of diamond films is a new polishing method. During the polishing process, the rotational velocity of the cast iron polishing plate is higher than that of conventional polishing methods, and friction between the polishing plate and the diamond film during rotary motion generates heat that creates a diffusion condition for carbon atoms. The temperature and strain energy density distributions of the polished surface directly affect the polishing quality of diamond films. In this paper, a three-dimensional thermo-mechanical coupled finite element analysis was employed to analyze the temperature and strain energy due to the friction between the polishing plate and the thick diamond film while the polishing plate rotates at super-high angular speed. The results indicate that when the diamond film and polishing plate rotate in the same direction, the differences of temperature and strain energy evidently decrease, and the temperature and strain energy in the diamond film become more uniform. The removal rate by super-high speed polishing has been quantitatively described by the diffusion mechanism, and it agrees well with the experiment data. This work will provide theoretical guidance to the design and operation of the super-high speed polishing of diamond films.