The work is mainly to study the thermal stability including the phase stability, microstructure and tribo-mechanical properties of the AlB_2-type WB_2 and W–B–N(5.6 at.% N) films annealed in vacuum at various temper...The work is mainly to study the thermal stability including the phase stability, microstructure and tribo-mechanical properties of the AlB_2-type WB_2 and W–B–N(5.6 at.% N) films annealed in vacuum at various temperatures, which are deposited on Si and GY8 substrates by magnetron sputtering. For the WB_2 and W–B–N films deposited on Si wafers, as the annealing temperature increases from 700 to 1000 °C, a-WB(700 °C) and Mo_2B_5-type WB_2(1000 °C) are successively observed in the AlB_2-type WB_2 films, which show many cracks at the temperature ≥ 800 °C resulting in the performance failure; by contrast, only slight α-WB is observed at 1000 °C in the W–B–N films due to the stabilization eff ect of a-BN phase, and the hardness increases to 34.1 GPa fi rst due to the improved crystallinity and then decreases to 31.5 GPa ascribed to the formation of α-WB. For the WB_2 and the W–B–N films deposited on WC–Co substrates, both the WB_2 and W–B–N films react with the YG8(WC–Co) substrates leading to the formation of CoWB, CoW_2B_2 and CoW_3B_3 with the annealing temperature increasing to 900 °C; a large number of linear cracks occur on the surface of these two films annealed at ≥ 800 °C leading to the fi lm failure; after vacuum annealing at 700 °C, the friction performance of the W–B–N films is higher than that of the deposited W–B–N films, while the wear resistance of the WB_2 films shows a slight decrease compared with that of the deposited WB_2 films.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51701157 and 51505378)the Natural Science Foundation of Shaanxi Province of China (No. 2017JQ5031)
文摘The work is mainly to study the thermal stability including the phase stability, microstructure and tribo-mechanical properties of the AlB_2-type WB_2 and W–B–N(5.6 at.% N) films annealed in vacuum at various temperatures, which are deposited on Si and GY8 substrates by magnetron sputtering. For the WB_2 and W–B–N films deposited on Si wafers, as the annealing temperature increases from 700 to 1000 °C, a-WB(700 °C) and Mo_2B_5-type WB_2(1000 °C) are successively observed in the AlB_2-type WB_2 films, which show many cracks at the temperature ≥ 800 °C resulting in the performance failure; by contrast, only slight α-WB is observed at 1000 °C in the W–B–N films due to the stabilization eff ect of a-BN phase, and the hardness increases to 34.1 GPa fi rst due to the improved crystallinity and then decreases to 31.5 GPa ascribed to the formation of α-WB. For the WB_2 and the W–B–N films deposited on WC–Co substrates, both the WB_2 and W–B–N films react with the YG8(WC–Co) substrates leading to the formation of CoWB, CoW_2B_2 and CoW_3B_3 with the annealing temperature increasing to 900 °C; a large number of linear cracks occur on the surface of these two films annealed at ≥ 800 °C leading to the fi lm failure; after vacuum annealing at 700 °C, the friction performance of the W–B–N films is higher than that of the deposited W–B–N films, while the wear resistance of the WB_2 films shows a slight decrease compared with that of the deposited WB_2 films.
