Study on microstructure and mechanical properties of laser cladding CBN grinding blocks assisted by various ultrasonic vibration powers

Grinding tools produced via laser cladding often exhibited issues such as cracking, compositional segregation, and irregular abrasive particle aggregation. In view of this, ultrasonic vibration-assisted laser cladding technology was employed in this study to fabricate cubic boron nitride (CBN) grinding blocks. The motion behavior and distribution of the CBN grits in the melting pool under ultrasonic vibration were analyzed by 3D measuring laser microscope and SEM. The microstructure of the interfaces between the substrate, the bonding material, and the grits at different ultrasonic power levels was characterized by EDS. Additionally, the effect of ultrasonic vibration on the microhardness and wear resistance of CBN grinding blocks was investigated using a hardness tester and a reciprocating friction and wear tester. The results show that ultrasonic vibration accelerated the floating of the CBN grits within the melting pool, inhibited the irregular aggregation of the grits, and promoted the homogenization of the coating composition, thus enhancing the overall microhardness and wear-resistant properties of CBN grinding blocks. At 30 % ultrasonic power, the number of grits on the block surface increased by 18.4 %. The microhardness of the substrate/bonding layer interface, the bonding layer, and the grinding layer surface increased by 34.1 %, 6.4 %, and 6.9 %, respectively. Besides, the coefficient of friction of the block decreased by 15.1 %, and the roughness of the ground surface of the workpiece decreased by 51.9 %. • Applying ultrasound during the fabrication of grinding tools using laser cladding. • Ultrasonic vibration accelerates the floating upwards of grits in the melting pool. • Ultrasound suppresses the irregular accumulation of grits on the tool surface. • Excessive ultrasonic power weakens the effect of improving the tool performance.