铬–陶瓷复合结合剂的机械合金化制备工艺及性能研究

Study on property of chromium-ceramic composite bond and its preparing methods by mechanical alloying

以金属铬粉和陶瓷结合剂粉体为初始原料,按照不同比例配混,采用机械合金化(MA)工艺对其进行处理。工艺参数为:球料比R=20∶1,转速n=350 r/min,球磨时间t=12 h;添加适量的无水乙醇为过程控制剂。将获得的复合粉体在660～740℃进行无压烧结,用SiC埋烧。采用三点弯曲法测试烧结后试样的抗弯强度,利用X射线衍射仪(XRD)测试试样的物相构成,用扫描电子显微镜(SEM)观察试样断口的微观形貌,采用阿基米德原理测试试样的密度和显气孔率。实验结果表明:利用MA处理工艺,可以获得金属相与陶瓷相均匀分布的复合结合剂;当金属铬粉的质量分数为30%,烧结工艺为700℃/30 min时,所得试样的抗弯强度达到最大值,为187 MPa。金属铬粉通过其颗粒表层的CrO与陶瓷形成良好的界面结合,从而提高复合结合剂的抗弯强度。

Chromium powder and ceramic powder are used as initial material to prepare Cr-ceramic binder at different ratios by using mechanical alloying(MA).The mixture are treated with the following parameters:mass ratio of ball and powder 20∶1,rotation speed 350 r/min,balling time 12 h and some anhydrous ethanol as process control agent.Then the obtained composite powders are buried in SiC and sintered at 660 to 740℃.Mechanical tests are implemented to measure the flexural strength(by using three point bending method)and density and apparent porosity(by using Archimedes principle)of the specimens,and SEM and XRD are used to analyze the microstructure at fracture section and phase composition of the specimen.Results show that MA process could help to obtain uniformly distributed metal phase and ceramic phase in the composite bond.When the mass fraction of Cr powder is 30%and the mixture is sintered at 700℃for 30 min,the flexural strength of the specimen reaches its maximum,which is 187 MPa.The chromium powders are well bonded to the ceramic powder through CrO on the surface of Cr particle,thus improving the overall flexural strength.