88 / 2021-06-30 22:25:25

Design, preparation, and properties of the Zr-B-N/ZrO2 multilayers by hybrid magnetron sputtering technology

Zr-B-N/ZrO2 multilayer, reverse design, reducing atmosphere, hybrid magnetron sputtering technology, wear resistance

In order to resolve the problem of tool wear and short service life for the carbide tools when cutting super alloys at high speed, this work proposed a method of "reverse design of coating composition" and developed the high purity and high quality Zr-B-N coating. The reactive deposition was achieved under reducing atmosphere, which could remove residual O₂ in the coating chamber, and lowered requirements of coating equipment. Then the ZrO₂ layer was implanted periodically to be used as thermal barrier and chemical barrier. A series of Zr-B-N/ZrO₂ multilayers were prepared by high power impulse magnetron sputtering and pulsed DC magnetron sputtering hybrid techniques. Through regulating the heterogeneous interfaces of the multilayers, the mechanical and tribological properties of Zr-B-N/ZrO₂ multilayers were improved, and the service life and machining efficiency of coated carbide tools were also increased. The microstructure and mechanical properties of Zr-B-N/ZrO₂ multilayers were characterized and tested by XRD, SEM, nano-indenter, and tribometer, etc. The research revealed that the Zr-B-N/ZrO₂ multilayers mainly consisted of ZrO₂ and ZrN phases, and contained a small amount of amorphous. When the modulation period was 80 nm and the modulation ratio was 7:1, the resulted multilayer possessed the highest hardness of about 30.2 GPa, which is 29.8% and 24.7% higher than that of the Zr-B-N film (23.2 GPa) and ZrO₂ film (24.2 GPa), respectively. The lattice constant mismatch of ZrO₂ (a_ZrO2=5.3) and ZrN (a_ZrN=4.57) resulted in the eutectic distortion at the interlayer interface. The alternating stress field increased the resistance to dislocation, which strengthened the Zr-B-N/ZrO₂ multilayer. In this case, the values of H/E and H³/E*² reached 0.096 and 0.228 GPa, respectively. When the modulation period was 80 nm and the modulation ratio was 5:1, the resulted multilayer possessed the best adhesion. When the modulation period was 80 nm and the modulation ratio was 7:1, the Zr-B-N/ZrO₂ multilayer film had excellent wear resistance, the wear rate was 5.0×10^-7 mm³/N·mm.