Research On Self-propagating Sintering Process Of MAX Phase Binder For Diamond Tool Products

In recent years,the ternary MAX phase material has become a hot spot in the field of materials science due to its unique physical and chemical properties.It not only has good thermal conductivity and processing properties of metals,but also has the high melting point,high thermal s Tableility and good oxidation resistance of ceramics.As a matrixed binder for diamond tool products,it is expected to solve the matching dilemma between the strength and wear resistance for the traditional metal or ceramic bond materials.At the same time,the traditional hot-pressing and pressureless sintering process to prepare MAX-phase materials has several problems,such as limited sample size,long sintering cycle,and high energy consumption.It is necessary to explore a green and energy-saving sintering method compatible with MAX-phase diamond tool binders.In this paper,two typical MAX phase binders,Ti₃AlC₂and Ti₃SiC₂,are adopted as the research objects.The MAX phase/diamond composite binder is prepared by high-temperature self-propagating sintering method.The influence of the raw material formula（including the ratio of three-component,diamond abrasive grain size and content,etc.）and self-propagating sintering process parameters（self-propagating reaction induction temperature,sintering time,etc.）was discussed.According to the analysis of microstructure and performance of MAX phase samples after sintering,the optimized process conditions for preparing MAX phase by high-temperature self-propagating sintering was obtained.Modern analysis methods such as XRD and SEM were used to study the phase composition,fracture morphology,and microstructure parameters of the self-propagating sintered samples,such as the holding state of the diamond abrasive by the bond,and the self-propagating sintering mechanism was analyzed.（1）The self-propagating reaction induction temperature of Ti₃AlC₂ is 950℃,while Ti₃SiC₂ can induce self-propagating reaction at 820℃.Using the relative density and hardness of the sample as evaluation indicators,through orthogonal experimental design,it is found that the best sintering conditions for self-propagating sintering Ti₃AlC₂ are n _Ti:n_Al:n_C=3:1.2:2,sintering temperature at 1300℃,sintering time for5min.The samples sintered under different conditions were characterized by XRD and SEM microstructure,which demonstrated the rationality of the optimal process conditions from the microscopic level.Adding 0.2%Si to Ti₃AlC₂ raw material as a sintering aid can benefit the increase of the purity of the MAX phase corresponding to the reaction.（2）The particle size and content of diamond affect the bonding state of the abrasive in the self-propagating reaction sample.When the diamond particle size is140/170 mesh and the mass concentration is 10%,the Ti₃AlC₂ phase purity in the self-propagating sintered sample is the highest,and the bonding effect between the binder and the diamond particles is the best;while the Ti₃SiC₂ sample is the best diamond particle size for the self-propagating sintering It is 140/170 mesh,and the mass concentration is 5%.（3）Appropriately increasing the Si content in the Ti₃SiC₂ formula is beneficial to increase the MAX phase purity of the sample.The best molar ratio is n _Ti:n_Si:n _C=3:1.3:2.And adding 0.2%Sn sintering aid to the Ti₃SiC₂ raw material is helpful to the improvement of the purity of the MAX phase sample,and the promotion effect of adding the same concentration of Al as a sintering aid is not obvious.