The effect of unbalanced coefficient of magnetron （UCM） on the structure and tribological properties of CrNx hard coatings was studied.The CrNx coatings were deposited on both Si wafer and hardened tool steel substr...The effect of unbalanced coefficient of magnetron （UCM） on the structure and tribological properties of CrNx hard coatings was studied.The CrNx coatings were deposited on both Si wafer and hardened tool steel substrates using a closed-field unbalanced magnetron sputtering ion plating technique in a gas mixture of Ar＋N2 under different unbalanced magnetron conditions.The coatings were characterized by means of XRD,XPS,SEM,microhardness tester and pin-on-disc tribometer to study respectively their structure,chemical bonding state,microstructure,hardness and tribological properties.The experimental results show that the UCM has a profound effect on the structure,hardness and tribological properties of the CrNx coatings.With increasing the values of UCM,the dominant phases in the deposited coatings evolved from Cr＋Cr2N to Cr2N＋CrN,the microstructure became denser and the hardness increased;in addition,reduced coefficient of friction and improved wear resistance of CrNx coatings were also observed under a larger UCM.展开更多
The load-bearing performance(LBP)of pumpable supports(PPS)is crucial for the stability of longwall pre-driven recovery room(PRR)surrounding rock.However,the unbalanced bearing coefficient(UBC)of the PPS(undertaking un...The load-bearing performance(LBP)of pumpable supports(PPS)is crucial for the stability of longwall pre-driven recovery room(PRR)surrounding rock.However,the unbalanced bearing coefficient(UBC)of the PPS(undertaking unequal load along the mining direction)has not been investigated.A mechanical model of the PRR was established,considering the main roof cantilever beam structure,to derive an assessment formula for the load,the failure criteria,and the UBC of the PPS.Subsequently,the generation mechanisms,and influencing factors of the UBC were revealed.Global sensitivity analysis shows that the main roof hanging length(l_(2))and the spacing between the PPS(r)significantly impact the UBC.A novel design of the PPS and the coupling control technology were proposed and applied to reduce the UBC of the PPS in the adjacent longwall PRR.Monitor results showed no failure of the PPS at the test site,with the UBC(ζ)reduced to 1.1 consistent with the design value(1.15)basically,fully utilizing the collaborative LBP of the PPS.Finally,the maximum roof-to-floor convergence of the PRR was 234 mm,effectively controlling the stability of the surrounding rock of the PRR and ensuring the mining equipment recovery.展开更多
基金Funded by the National High-technology Research and Development Programm of China(No.2005AA33H010)
文摘The effect of unbalanced coefficient of magnetron （UCM） on the structure and tribological properties of CrNx hard coatings was studied.The CrNx coatings were deposited on both Si wafer and hardened tool steel substrates using a closed-field unbalanced magnetron sputtering ion plating technique in a gas mixture of Ar＋N2 under different unbalanced magnetron conditions.The coatings were characterized by means of XRD,XPS,SEM,microhardness tester and pin-on-disc tribometer to study respectively their structure,chemical bonding state,microstructure,hardness and tribological properties.The experimental results show that the UCM has a profound effect on the structure,hardness and tribological properties of the CrNx coatings.With increasing the values of UCM,the dominant phases in the deposited coatings evolved from Cr＋Cr2N to Cr2N＋CrN,the microstructure became denser and the hardness increased;in addition,reduced coefficient of friction and improved wear resistance of CrNx coatings were also observed under a larger UCM.
基金financial support provided by the Xinjiang Uygur Autonomous Region Key R&D Project Task Special-Department and Department Linkage Project(No.2022B01051)Major Project of Regional Joint Foundation of China(No.U21A20107)+1 种基金Hunan Provincial Natural Science Foundation of China(No.2024JJ4021)the Xinjiang Uygur Autonomous Region Tianchi Introduction Plan(No.2024XGYTCYC03)。
文摘The load-bearing performance(LBP)of pumpable supports(PPS)is crucial for the stability of longwall pre-driven recovery room(PRR)surrounding rock.However,the unbalanced bearing coefficient(UBC)of the PPS(undertaking unequal load along the mining direction)has not been investigated.A mechanical model of the PRR was established,considering the main roof cantilever beam structure,to derive an assessment formula for the load,the failure criteria,and the UBC of the PPS.Subsequently,the generation mechanisms,and influencing factors of the UBC were revealed.Global sensitivity analysis shows that the main roof hanging length(l_(2))and the spacing between the PPS(r)significantly impact the UBC.A novel design of the PPS and the coupling control technology were proposed and applied to reduce the UBC of the PPS in the adjacent longwall PRR.Monitor results showed no failure of the PPS at the test site,with the UBC(ζ)reduced to 1.1 consistent with the design value(1.15)basically,fully utilizing the collaborative LBP of the PPS.Finally,the maximum roof-to-floor convergence of the PRR was 234 mm,effectively controlling the stability of the surrounding rock of the PRR and ensuring the mining equipment recovery.
