| In this paper, the novel alumina matrix ceramic cutting tool materials were designed and fabricated. The effects of material components, sintering temperature and sintering time on the phase composition, microstructure and mechanical properties of the alumina matrix ceramic cutting tool materials were analyzed. The cutting performance of the novel alumina matrix ceramic cutting tools was studied.The design scheme for the novel alumina matrix ceramic cutting tool materials was proposed. Micron Al2O3was chosen as the matrix and micron TiC, micron TiN, nanometer TiN were chosen as the additives. MgO was added as the sintering aids, Ni and Mo were added as the metal binders. Four kinds of Al2O3matrix ceramic cutting tools materials were fabricated, which were Al2O3-TiNn ceramic cutting tool materials (AN), Al2O3-TiNn-TiNμ ceramic cutting tool materials (ANU), Al2O3-TiC-TiNμ ceramic cutting tool materials (ACU), and Al2O3-TiC-TiNμ-TiNn ceramic cutting tool materials (ACUN).The phase composition and its effects on the mechanical properties were investigated. The results showed that the metal binders dissolved the elements of the ceramic phases and replaced the atoms of the ceramic phases during the sintering process. The final phases such as C0.7N3.3Ti and cubic-Mg0.4Ni0.6O could improve the flexural strength. The final phases such as trigonal-Ti8C5, cubic-Al3Mg2and cubic-NiAl2O4could improve the hardness. The final phases such as obornite-TiN, tetragonal-Mo2N, cubic-Al0.96Ni1.9494and cubic-Alo.9Ni3.22could improve the fracture toughness. The phases such as spinel-MgAl2O4, cubic-MoC, cubic-NiTi and orthorhombic-MoNi could improve the flexural strength and hardness at the same time, the phase cubic-AlNi3could increase the flexural strength and hardness, but it would decrease the fracture toughness. The phase tetragonal-AlNi3would decrease the mechanical properties. The microstructure of the ceramic tool materials and its effects on the mechanical properties were studied. The results showed that the mechanical properties were better when the microstructure was dense, the metal phases wetted the hard phase well and the adhesive strength among particles was strong. The core-rim structures which were formed by the wetting effect of metal phases on the hard phases could improve the mechanical properties, where the fracture toughness could be improved significantly. The flexural strength could be improved when the particles in the microstructure were uniform, the adhesive strength among particles was strong and the additives had pinning effect on the crack. The Vickers hardness could be improved when the hard phase particles were big while the binding phase particles were small. The fracture toughness could be improved when the metal phases wetted the hard phase well, the particles were big and the crack propagation path was tortuous.The effects of TiN content, sintering temperature and sintering time on the mechanical properties were investigated. The results showed that when the sintering pressure was32MPa, the optimized sintering process for the ACU material system was1650℃and30min, in which AC2U ceramic cutting tool material owned the flexural strength of853.1MPa, Vickers hardness of20.23GPa and fracture toughness of6.75MPa·m1/2. The optimized sintering process for the ACUN material system was1600℃and50min, in which AC2U4N ceramic cutting tool material owned the flexural strength of861.1MPa, Vickers hardness of20.83GPa and fracture toughness of6.97MPa·m1/2. The optimized sintering process for the AN material system was1700℃and45min, in which Al2O3-10vol%TiNn ceramic cutting tool material owned the flexural strength of896.8MPa, Vickers hardness of21.08GPa and fracture toughness of7.90MPa·m1/2. The optimized sintering process for the ANU material system was1650℃and30min, in which ANU25ceramic cutting tool material owned the flexural strength of444.2MPa, Vickers hardness of21.57GPa and fracture toughness of8.81MPa·m1/2.Three kinds of novel Al2O3-TiC-TiN ceramic cutting tools were developed successfully after repeatability tests, which were AC2U micro-composite ceramic cutting tool (Al2O3-20vol%TiC-10vol%TiNμ), AC2UN2nano-composite ceramic cutting tool (Al2O3-20vol%TiC-3vol%TiNμ-7vol%TiNn) and AC2UN4nano-composite ceramic cutting tool (Al2O3-20vol%TiC-2vol%TiNμ-8vol%TiNn). The flexural strength, Vickers hardness and fracture toughness of AC2U were876.5MPa,20.96GPa and 6.75MPa·m1/2, respectively. The flexural strength, Vickers hardness and fracture toughness of AC2UN2were887.2MPa,20.21GPa and5.94MPa·m1/2, respectively. The flexural strength, Vickers hardness and fracture toughness of AC2UN4were904.2MPa,19.54GPa and5.85MPa·m1/2, respectively. The mechanical properties of the novel ceramic cutting tools were good and steady.The cutting performance of the novel alumina matrix ceramic cutting tools was investigated in continuous turning the quenched alloy steel40Cr and quenched carbon tool steel T10A. The results showed that when turning quenched40Cr continuously with the cutting depth ap=0.1mm, AC2U had better wear resistance at a low cutting speed and small feed, but tool breakage was liable to happen at the end of turning process. AC2UN4had better wear resistance at a high cutting speed and big feed. When turning quenched carbon tool steel T10A continuously with the cutting depth ap=0.1mm and the feed f=0.1mm/r, the novel ceramic cutting tools AC2U and AC2UN2both showed better wear resistance than LT55.
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