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

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.