Silicon carbide (SiC) ceramic matrix composites (CMC) are a new kind of advanced materials which are widely used in aerospace, aviation, and automobile industries due to their attractive characteristics of high temperature resistance, wear resistance, chemical resistance and low thermal expansion coefficient. In recent years, SiC fiber reinforced SiC ceramic matrix composite (SiCf/SiC CMC) has been an increasingly promising material in aerospace industrial. Compared with nickel-based alloys, the density of SiCf/SiC CMC is merely about one third of that of nickel-based alloys while the working temperature could be as high as 1250℃, which is about 150~200℃ higher than that of nickel-based alloys. In addition, under high working temperature, SiCf/SiC CMC could still keep a high specific strength, which makes it a promising material in aeroengine for turbine blades, turbine guide vanes and combustor.However, due to the high brittleness, hardness, and anisotropy of reinforced fibers and matrix materials, SiCf/SiC CMC is typically difficult-to-cut and the severe tool wear often occurs during machining process. It has been reported by scholars that in conventional machining SiCf/SiC CMC is hard to be cut even using polycrystalline diamond (PCD) tools. Then, taking advantages of the high processing efficiency, low cutting force and tool wear, improving tool life, the ultrasonic vibration assisted machining technology has been widely used in precision machining of the hard and brittle materials especially for optical glass, carbon ceramic composite, ceramic and ceramic matrix composite. However, even with ultrasonic vibration assisted machining technique, the terrible cutting tool wear and short tool life is still an urgent problem needed to be solved for machining SiCf/SiC CMC. Up to now, with great efforts of global researchers, the electroplated diamond tool and brazed diamond tool are suggested in ultrasonic vibration assisted machining SiCf/SiC CMC. Still, the tool wear and tool life are not quite satisfactory and further attempts should be made.In this paper, the tool performance in ultrasonic vibration assisted milling-grinding SiCf/SiC CMC is investigated and analyzed. The tool wear and tool life of polycrystalline diamond compact (PDC) tool, which is self-designed, is comparatively studied with electroplated diamond tool (100 mesh) and brazed diamond tool (50 mesh and 200 mesh) under the same machining conditions. The material removal volume is selected for representing the tool life and the tool wear morphology is investigated using scanning electron microscope (SEM). From experimental results, it is found that the tool wear of electroplated diamond tool and 200 mesh brazed diamond tool is extremely terrible indicating that they are not suitable for milling-grinding SiCf/SiC CMC. An unexcepted performance of PDC is achieved with a 9720 mm3 material removal volume and that of the rest tools is 192, 810, and 2362.5 mm3 respectively. The tool life of PDC is 4.11 times as longer as that of 50 mesh brazed diamond tool. It is recommended that PDC could be applied for high precision machining of ultrasonic vibration assisted milling-grinding SiCf/SiC CMC and 50 mesh brazed diamond tool could be used for rough machining or semi finish machining of SiCf/SiC CMC.

Investigation on Tool Performance in Ultrasonic Vibration Assisted Cutting SiCf/SiC_x000B_Ceramic Matrix Composites

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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