Research On Brazed Diamond Grinding Head Made By High-frequency Induction Heating

In recent years,nickel-based brazing filler has been widely used in the brazing of diamond tools.Due to high liquidus temperature of the brazing filler,thermal damage can be formed in diamond grits.Some researchers has been exploring such methods as shortening brazing time,metallization of diamond surface and reducing melting temperature of brazing filler by adding some minor elements.These effects are quite limited because of ways used in a single way.Therefore,thermal damage of brazed diamond has been fundamentally solved in this paper by combined mean included induction brazing,plasma activated treatment of diamond surface and changing brazing filler to further improve service life of brazing diamond tools.The topic takes induction brazing diamond grinding heads for example,and the main creative contents have been done as follows:1)Activated treatment of diamond surface has been conducted by DC plasma chemical vapor deposition method.The results showed that diamond-like carbon film is very homogenous under the condition of H2/CH4 flow ratio of 80/5(SCCM).2)Nickel-based brazing filler has been used to braze uncoated and coated diamond by combination of shortening the brazing time and activated treatment of diamond surface.The results demonstrated that lath carbides grow on the surface of brazed uncoated diamond grit,while carbides with uniform porosity on the surface of brazed coated ones are perpendicular to abrasive surface and easy to be filled with brazing filler.3)Copper-based brazing filler has been employed to braze uncoated and coated diamond by combination of shortening the brazing time,activated treatment of diamond surface and reducing liquidus temperature of brazing filler.The results revealed that small and flat carbides form on the uncoated diamond surface,while brazed coated ones are vertical to the grit surface;phase analysis showed that more carbides of coated surface grow than that of uncoated one.4)In this paper,grinding tests has been conducted with diamond grinding heads brazed using nickel-and copper-based brazing filler.The results proved that service life of coated diamond grinding heads can be 20%longer than that of uncoated ones;due to the different hardness and wear resistance of nickel-and copper-based brazing filler,the main failure modes of grits are whole grain fracture and pullout respectively.Combined method of multi means used in this topic to reduce the thermal damage of brazed diamond changes the single idea which improves the performance of brazed diamond tools.Especially,induction brazing coated diamond with copper-based brazing filler not only enlarges its application scope in diamond tools,but also has an important inspiration to optimize and consummate brazing process at a higher level in the future.