Papers by Author: Ben Wang

Abstract: CMC/Eu complexes were synthesized in different pH values by reacting with Eu³⁺ and CMC, a kind of biodegradable polymer. FT-IR results confirmed that, on CMC chains, carboxyl groups and the oxygen atom of unsubstituted hydroxyl groups and ether bonds were all involved in the reaction with Eu³⁺. TG analysis showed that CMC/Eu complexes were thermally stable in a wide temperature range from 30 to 300°C. The emission intensity decreased when the pH value increased from 7.0 to 12.0. However, at pH=12, because that the extent of reaction of Eu³⁺ and CMC decreased and CMC degraded, the complexes had a weak fluorescence intensity.

Abstract: Aiming at the problem of poor machinability in conventional drilling of aramid/epoxy composites, the formation reason for fuzzing damage was analyzed. In order to obtain better machining quality, a combined machining technology based on sawing and grinding mechanism was proposed and the corresponding drilling tools were developed. Drilling experiments were conducted to explain the machining performance of the drilling tools. The results show that the sawing drilling tool with negative rake angle can effectively restrain fuzzing damage and the sawing-grinding drilling tool decreases the thrust force about 20%~55% with electroplated diamond abrasives. The combined machining technology of sawing and grinding achieves damage-free machining quality in drilling of aramid/epoxy composites.

Abstract: The main source of heat generation during machining of carbon/epoxy composites is the friction among cutting tool, chip and workpiece. The friction coefficient between carbon/epoxy composites and a monocrystalline diamond under different temperatures was investigated. The results show that the friction coefficient between diamond and carbon/epoxy composites changes with the variation of temperature due to the change of properties of epoxy resin. The friction coefficient increases with the increasing temperature. However, when the temperature of workpiece was higher than the glass transition temperature of epoxy resin, the friction coefficient decreased.

Abstract: Carbon fiber reinforced plastics (CFRP) is difficult to machine because of the extremely abrasive nature of the carbon fibers and its low thermal conductivity. CVD diamond films have many excellent properties such as wonderful wear resistance, high thermal conductivity and low friction coefficient, therefore depositing diamond films on the surface of drills is thought to be an effective way to elongate the lifetime of drills and improve the cutting performance. In this study, diamond films are deposited on the WC-Co drill using hot filament chemical vapor deposition (HFCVD) method. The results of characterization by the scanning electron microscope (SEM) and Raman spectrum indicate that the fabricated CVD diamond coated drill is covered with a layer of uniform and high-purity diamond films. The cutting performance of as-fabricated CVD diamond coated drill is evaluated in dry drilling CFRP, comparing with the uncoated WC-Co drill. The results demonstrate that the CVD diamond coated drill exhibits much stronger wear resistance. Its flank wear is about 50μm after drilling 30 holes, about one-third of that of WC-Co drill. Machining quality of the exit and internal wall of drilled holes shows better surface finish obtained by coated drill, which suggests that CVD diamond coated tool has great advantages in drilling CFRP.

Abstract: Strong anisotropy of physical and mechanical properties of Potassium Dihydrogen Phosphate (KDP) crystals significantly affects surface quality during processing the samples. Different processing direction, along [100], [110], and [120] crystallographic orientations, are chosen on (001) crystal plane in order to evaluate the anisotropic characterizations on the processed surface. Scanning electronic microscopy (SEM) is employed to observe the machined surface damage, defects and profiles. At the same time, surface quality is measured by Zygo surface profiler to estimate the processed surface quality. The results show that the machined surfaces along three different orientations under the same processing conditions behave quite differently from each other. Strong anisotropy and complex slip system of KDP crystals lead to several different asymmetric damages on the machined surface. Surface roughness (Ra) values along [100] are the smallest, that along [120] are in average, and that along [110] are largest. Moreover, many illustrations are given to understand the anisotropic nature during processing, including slip system, mechanical properties during processing, and technical parameters, etc.