Papers by Author: Hua Guo

Abstract: Single crystal SiC has been considered as a leading wide band gap semiconductor for its excellent properties even in severe environments. While the outstanding chemical and mechanical inertness also makes it a difficult to process material. In this work, a flexible machining method was proposed to polish 6H-SiC wafers with semi-consolidated diamond tools prepared by sol-gel technology. To confirm the machining mechanism of this newly developed method, free abrasive polishing slurry and fixed abrasive lapping film were also used for comparative experiments. The results indicated that high quality wafer surface with roughness of Ra 0.962 nm was achieved by using semi-consolidated polishing film with diamond grit size of 1 μm. And compared to the other two machining methods, the abrasive in this flexible tool would take a retraction when polishing, leading to a smoother and scratch-free surface of the work piece.

Abstract: The wear behavior of monolayer brazed diamond beads was investigated during wire sawing of granite. Diamonds were bounded onto the beads by brazing in vacuum. Brazed beads were abrasive sawed on a wire sawing machine and the wear of the brazed diamond beads were traced and observed by using a digital microscope. The results reveal that the wear of root fractured, characterized by breaking off grit at its bonding level, was the fatal failure of the cutting ability of grit as well as the main wear behavior of brazed grits on brazed bead.

Abstract: Magnetic field assisted machining is an earlier technology of Energy field assisted machining, magnetic effect has a beneficial effect on the process of controlling local high temperature and the residual stress. This technology has a great prospect in the field of materials processing. In this article, magnetic field assisted manufacturing technology are reviewed in the magnetic effect in the machining process. To verify the magnetocaloric effect, the temperature drop curves of pure iron in two conditions of constant magnetic field and without magnetic field are selected.

Abstract: Fixed-abrasive wires, such as electroplated diamond wires and resinoid diamond wires, employed for slicing ingots have the problems of high tool wear. A novel brazed diamond wire has been developed to overcome these problems. This paper investigates the effect of process parameters, including brazing temperature, brazing time and brazing filler composition, on the brazed diamond wire manufacturing with CuSnTi brazing filler. The 3D micro-video system was used to observe the brazed diamond wire surface. Tensile, bending and torsional test were carried out to evaluate the mechanical properties of brazed diamond wire. A brazed diamond wire with 3km length was fabricated with the optimization process parameters, which was successfully used to slice glass.

Abstract: Diamond is a promising material especially applied in advanced machining tools, wear-resistant coatings, and the EPD technique should provide a simple method to develop hard coatings for precision machining tools or wear-resistant parts. Therefore, it is useful to research electrophoretic deposition characteristics of diamond powder itself, including the impact of adding ions on direction of EPD especially. In this paper, the effects of suspension concentration and applied voltage, deposition time, and added Ca2+ or Al3+ ions on electrophoretic characteristics of ultra-fine diamond powder were discussed, and electrophoretic deposition (EPD) parameters were optimized by a trial-and-error approach. The results show that smooth, uniform and dense coatings of diamond were obtained under suspension concentration of 1%-1.5% and applied voltage of 30-70 V. The thickness of diamond coating can be controlled by adjusting deposition time under constant voltage and suspension concentration. If deposition direction changed, the appropriate concentration of added Ca2 + and Al3 +, respectively, is in the range of 0.005% to 0.01% and 0.05% to 0.10%.

Abstract: Based on the analysis of problems of diamond cut-off wheels used in slot grinding of ceramics at present, a brazed diamond cut-off wheel was produced and analyzed. Two typical advanced ceramics, alumina and silicon nitride, were used as the workpiece materials. In the experiments of slot grinding of ceramics, grinding ratio, wear process of the wheel and grinding quality of the work were studied. Experimental results showed that the brazed diamond cut-off wheel obtained good grinding ratio and abrasive resistance. The surface roughness of ground silicon nitride was better than that of alumina.