Study On Ceramic/Metal Composite Bonds For Cubic Boron Nitride Grinding Tool

Copper, Aluminum, Nickel and their alloys (Copper alloy, Aluminum alloy, and Nickel alloy) were introduced to Na₂O-B₂O₃ -Al₂O₃ -SiO₂ basic vitrified bond respectively, and ceramic/metal composite bonds were prepared by the method of mechanical ball milling. Their effects on the main properties of the vitrified bond and grinding tools including refractoriness, fluidity, thermal expansion coefficient, bending strength, impact strength and microstructure were investigated using refractory cone method, plane flow method, thermal expansion linear coefficient determinator, three-point bending strength tester, impact strength machine, Archimedes method, scanning electron microscope (SEM) and X-ray diffractometer. Moreover, the influences of different sintering temperature and different atmosphere on properties of ceramic/metal composite bond grinding tools were discussed comparatively.The experimental results showed that copper and copper alloy increased the thermal expansion coefficient of the vitrified bond, while the introduction of aluminum made the thermal expansion coefficient decrease. The refractoriness and fluidity of the basic vitrified bond were influenced by copper and copper alloy at different degrees. The copper showed slight influence on the refractoriness and fluidity. Introducing a little copper alloy could make the bond's refractoriness increase obviously and its fluidity decrease greatly. There was a similar influence on the bond's refractoriness and fluidity by aluminum and its alloy. The refractoriness increased and fluidity decreased with the increase of aluminum or its alloy additive. The change of bond's refractoriness was nearly same after adding the nickel and its alloy, while the bond's fluidity showed tiny difference. With 4wt% copper, 2wt% aluminum and 6wt% aluminum alloy, the strength and microstructure of grinding tool sintered at properly chosen temperatures were improved greatly.The more amount of copper alloy, the better strength of grinding tool. Moreover, with the addition of 6wt% nickel and 4wt% its alloy, the strength and microstructure of grinding tool were also improved. The sintering atmosphere had limited effect on the property of grinding tool. The strength and microstructure of grinding tool sintered at N2 were worse than that of grinding tool sintered at atmosphere.