| Ti(C,N) ceramic matrix composite material has high hardness and wear resistance, as well as good resistance to oxidation and chemical stability. As cutting tool material and high-temperature structural material, Ti(C,N) ceramic matrix composite material is very promising. But its machining performance is poor, and it is difficult to manufacture complex components. When connected with metal materials, large thermal stress exists in the joint and the joint strength is low. Auxiliary pulse current diffusion bonding generates interface higher temperature through resistance thermal effect, so that tight bonding of ceramic to steel or other metal materials form under low temperature of base material, sharply reducing the thermal stress joints and significantly improvding joint strength.In this paper, Cu-Ti amorphous filler/Cu/Ag-Cu composite layer was used to connect Ti(C,N)-Al2O3 with 40 Cr by auxiliary pulse current diffusion bonding. Results showed that the typical organizational structure of joints is: Ti(C,N)-Al2O3/Cu-based solid solution +Cu4Ti+Cu3Ti2/Cu-based solid solution+ Cu4Ti3/Cu-based solid solution/Cu/Fe-based solid solution/40 Cr steel. Holding time have an impact on the interface structure and the mechanical performance of the joint interface, and the duty cycle have great impact on the structure and the mechanical performance of the joints. The four-point bending strength of joint at condition of 850℃/10min/12(on):2(off) is largest, that is 236 MPa.Interfacial behavior and properties of Ti(C,N)-Al2O3/Cu53Zr47/Cu/Cu53Zr47/Ti(C,N)-Al2O3 joint was experimentally researched. Results showed that the activity element Zr has good wetting reaction performance to Ti(C,N)-Al2O3 ceramic matrix composites, thermodynamic calculation showed that Zr diffuses into Ti(C,N)-Al2O3 ceramic matrix composites and substitution reaction between Zr and Al2O3 there. Then the activity of Al atoms are stimulated, enhance the diffusion capacity of the Al element, and generate the ZrO2 phase; The four-point bending strength of 930℃/6min joint is the highest, that is 432.8 MPa. Too high welding temperature will cause more microstructure stratification, brittle compound layer thickening and four-point bending strength reducing; The reason of fracture failure is mainly due to the larger welding residual stress and the brittle compound layer in joint, microstructure maked up by a-Zr phase and CuZr2 intermetallic compounds is the weakness in the weld.Using Ag-Cu-Ti/Cu/Ag-Cu and Ag-Cu-Zr/Cu/Ag-Cu composite layers, joints of Ti(C,N)-Al2O3/40 Cr were connected by auxiliary pulse current diffusion bonding. The results showed that: Zr elements showed similar diffusion and reaction behavior to adopting Cu53Zr47 amorphous filler. Relationship between Welding temperature, holding time and joint four-point bending strength obeys the rule of parabola. The four-point bending strength of welding joints using Ag-Cu-Zr are generally higher than that of joints using Ag-Cu-Ti. The largest four-point bending strength was achieved at 750℃/5min using Ag-Cu-Zr, that is 275.1MPa.Zr/Cu/Ti diffusion couples were connected by auxiliary pulse current diffusion bonding under the condition of 850℃/10 min, interfacial compact bonding and thick diffusion layer were acquired; Under the same welding process parameters, Cu/Zr side diffusion transition layer is thicker than that of Cu/Ti side, which showes that the diffusion capacity of Zr in Cu was stronger than that of Ti. Heat preservation time produces great impaction on interface behavior of Zr/Cu/Ti diffusion couple: when heat preservation time is short, the element diffusion is inadequate and interface reaction degree is low, so the metallurgical combination of interface is not dense enough, the diffusion layer is narrow too; when extending heat preservation time, elements have enough time to diffuse adequately and participate in the interface reaction, which lead to the thickness of diffusion layer increases. |
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