Experimental Study on Surface Quality in Ultrasonic-assisted Grinding of C/C-Zrc-Cu Composites Fabricated with Different Preforms

C/C-ZrC-Cu composite is a new ablation-resistant material with wide application prospects in the aerospace field. The quality of its surface affects the ablative corrosion resistance of the material. Ultrasonic-assisted grinding (UAG) is an effective processing method for hard and brittle materials. Therefore, it is meaningful work to investigate the material removal mechanism of C/C-ZrC-Cu composites in UAG. In this paper, UAG was applied to the processing of C/C-ZrC-Cu composites fabricated with different preforms which include needle-punched preform, pierced preform and felt-based preform. The effects of process parameters on the surface quality of C/C-ZrC-Cu composites fabricated with different preforms were investigated via single-factor tests. The machining tools used for the tests were the electroplated diamond grinding wheels and the ultrasonic vibration direction was parallel to the processed surface. The results indicate that the preforms determine the surface quality of the C/C-ZrC-Cu composites. The surface quality of C/C-ZrC-Cu composites fabricated with felt-based preform is the best because of the lower carbon fiber content. The removal of carbon fibers is mainly by brittle fracture, interface debonding and pull-out, and the removal of hard ZrC particles is mainly by brittle fracture while the Cu-rich area is removed in a plastic manner. In addition, when the ultrasonic amplitude is in the range of 4-9 mu m, the hard ZrC particles are more easily broken thus deteriorating the surface quality.