Study On The Diffusion Reaction Sintering Between The Non-stoichiometric TiN And Refractory Carbides Under High Pressure

The main content of this study is, With the nonstoichiometric titanium nitride (TiN0.3)as the main body, by adding one or more of the transition metal carbides, under hightemperature and high pressure sintering to improve the comprehensive mechanicalproperties and microstructure. Make it as c-BN tools binder, keeping high hardness andfracture toughness in the process of work, to extend the service life, to enhance theefficiency of the work.The experimental process mainly three stages: TiN0.3with VC, Mo2C and TaC mixedsintering respectively; the diffusion dynamics research of TiN0.3respectively with VC,Mo2C and TaC; TXY-811series is put forward and comprehensive analysis of binder.Due to the high concentration of N vacancy in TiN0.3and the vacancy distribution oforder/disorder will have strong influence on compound properties, Such as disorderly stateof vacancy in high energy, can reduce the sintering temperature; The vacancy isadvantageous to the atomic diffusion migration, can make the organization structure moreuniform. In the first part of the study, We recognize that adding VC can significantlyincrease the hardness of the sintered body, and have the complete ability solid solutionwith TiN0.3. Mo2C and TaC prove the performance of the hardness is limited, solid solutionis also less than VC. For the influence of microstructure, the effect of three kinds ofmaterial is consistent, can restrain the growth of the grain, to achieve the effect of finegrains. In the second phase diffusion dynamics research, the classical diffusion couplingmethod is used. Combining the theory of Boltzmann-Matano, detailed comparison of thethree atoms (V, Mo, Ta) in TiN0.3diffusion ability, V atom diffusion, Ta atoms take secondplace, most easily Mo atom diffusion ability the weakest. Three kinds of atoms (V, Mo, Ta)diffusion activation energy respectively is145.99±1.36kJ/mol,367.08±1.11kJ/mol and305.31±0.2kJ/mol.In the last part, the TXY-811series binder performance and structure are analyzedand compared. TVM-811at1400℃sintering can obtain high hardness (19.28GPa) andfracture toughness (6.5MPa·m1/2), TMT-811and TVT-811binder of hardness is stable, but poor fracture toughness. To TVM-811modified TA-V10M10, hardness value stable near25GPa and fracture toughness increase to9.8MPa·m1/2, but not stable. Further fine-tuningin the ingredients, TA-V5M15binder hardness can still keep in more than23GPa, fracturetoughness can stabilize near9MPa·m1/2.