| Micro-laminated composite ceramic tool material is a kind of biomimetic structure material, which simulates the microstructure of shells, and can improve the fracture toughness of the ceramic materials effectively. It has become one of the toughening mechanisms of ceramic materials. The aim of this study is to fabricate a new kind of micro-laminated composite ceramic tool material and apply it in cutting nickel-base superalloy efficiently.According to the selection principles of micro-laminated composite ceramic tool materials, Al2O3-TiN-(W,Ti)C (ANWT) was selected as the matrix material. Al2O3-TiC (A15T) was selected as the micro-laminated material. The number of layer was selected as5,7and9respectively. The thickness of micro-laminated layer was selected as200μm,150μm and100μm respectively.The sintering temperature and sintering time of Al2O4-TiC micro-laminated composite ceramic tool materials were optimized. It was shown that the best sintering temperature and sintering time was1650℃and30min respectively. When the sintering temperature was too high or too low, the grains were not uniform and the interface bonding was loose in micro-laminated composite ceramic cutting tool materials. The mechanical properties of the Al2O3-TiC micro-laminated composite ceramic tool materials increased firstly and then decreased with an increase in the sintering time. When the sintering time was50min, the grains of the matrix layer and micro-laminated layer grew rapidly, which could reduce the mechanical properties.The finite element analysis software (ABAQUS) was used to analyze the residual stress of micro-laminated composite ceramic tool materials. Due to the mismatch of thermal expansion coefficients between different layers, the radial tensile stress would be generated in the matrix layer, and the radial compressive stress would be generated in micro-laminated layer which could improve the mechanical properties of micro-laminated composite ceramic tool materials.The effect of the number of layer and the thickness of micro-laminated layer on the mechanical properties, residual stress and microstructure were studied. With an increase in the number of layer and a decrease in the thickness of micro-laminated layer, the interface bonding of materials was stronger and the grains were more uniform, so the mechanical properties of materials increased. The radial compressive stress in the micro-laminated layer decreased and the radial tensile stress in the matrix layer increased with an increase in the number of layer. The radial compressive stress in the micro-laminated layer increased with a decrease in the thickness of micro-laminated layer, which could improve the mechanical properties of materials effectively.Three types of Al2O3-TiC micro-laminated composite ceramic tools such as A9-200, A5-100and A7-100with good mechanical properties were developed. As for A9-200, the number of layer was9and the thickness of micro-laminated layer was200μm. Its positive equivalent flexural strength and lateral equivalent flexural strength were1155MPa and975MPa respectively, the Vickers hardness of the micro-laminated layer and matrix layer were17.54GPa and18.21GPa respectively, and the fracture toughness of the micro-laminated layer and matrix layer were8.14MPa·m1/2and7.82MPa·m1/2respectively. As for A5-100, the number of layer was5and the thickness of micro-laminated layer was100μm. Its positive equivalent flexural strength and lateral equivalent flexural strength were1166MPa and878MPa respectively, the Vickers hardness of the micro-laminated layer and matrix layer were17.3GPa and17.76GPa respectively, and the fracture toughness of the micro-laminated layer and matrix layer were7.74MPa·m1/2and7.21MPa·m1/2respectively. As for A7-100, the number of layer was7and the thickness of micro-laminated layer was100μm. Its positive equivalent flexural strength and lateral equivalent flexural strength were1132MPa and934MPa respectively, the Vickers hardness of the micro-laminated layer and matrix layer were17.59GPa and17.85GPa respectively, and the fracture toughness of the micro-laminated layer and matrix layer were7.94MPa-m1/2and7.71MPa-m1/2respectively.The cutting performance of Al2O3-TiC micro-laminated composite ceramic tools such as A9-200, A5-100and A7-100was studied when cutting the nickel-base superalloy by comparison with that of the commercial ceramic tool SG4. The cutting parameters of AbO3TiC micro-laminated composite ceramic tool A9-200were optimized. The optimal cutting parameters were a cutting speed of40m/min, a depth of cut of0.5mm and a feed of0.125r/min. In the condition of optimal cutting parameters, the cutting performance of A9-200was best. The cutting performance of SG4was worst and the cutting distance was less than30m. The main tool wear mechanisms of A9-200, A5-100and A7-100were adhesive wear, diffusion wear and boundary wear. |
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