WC-6MoxC-0.47Cr3C2-0.28VC binderless carbide was prepared by hot pressing （1700 °C, 20 MPa）. The sample was observed and analyzed by scanning electron microscopy, energy dispersive X–ray spectroscopy and X–ra...WC-6MoxC-0.47Cr3C2-0.28VC binderless carbide was prepared by hot pressing （1700 °C, 20 MPa）. The sample was observed and analyzed by scanning electron microscopy, energy dispersive X–ray spectroscopy and X–ray diffraction. The results show that during the hot pressing process, W atoms dissolve substantially into the MoxC crystal lattices; whilst, the reverse dissolution of Mo atoms into the WC crystal lattices takes place. Consequently, the main phase and binder phase structure are formed. The phase compositions of the main phase and binder phase are a WC-based solid solution containing Mo and a Mo2C-based solid solution containing W, respectively. The isotropic dissolution and precipitation of W and Mo atoms do not result in substantial carbide coarsening. The mechanism for the densification was discussed.展开更多
Through systematically theoretical analysis and experimental research,the failure mechanism,of CVD(chemical vapor deposition) coated carbide tools in wear and fracture conditions was studied.On the basis of mechanism ...Through systematically theoretical analysis and experimental research,the failure mechanism,of CVD(chemical vapor deposition) coated carbide tools in wear and fracture conditions was studied.On the basis of mechanism analysis,the specific suitability of the coated tools for cutting conditions was revealed and clarified.展开更多
WC powders were uniformly coated by Ni nanoparticles through a combined chemical co-precipitation and subsequent high temperature hydrogen reduction strategy(abbreviated as CM-WCN),and then were consolidated by vacuum...WC powders were uniformly coated by Ni nanoparticles through a combined chemical co-precipitation and subsequent high temperature hydrogen reduction strategy(abbreviated as CM-WCN),and then were consolidated by vacuum sintering at 1450°C for 1 h to obtain WC−Ni cemented carbides.The microstructure and properties of the as-consolidated CM-WCN were investigated.The average grain size of WC in the consolidated CM-WCN was calculated to be in the range of 3.0−3.8μm and only few pores were observed.A relative density of 99.6%,hardness of HRA 86.5 and bending strength of 1860 MPa were obtained for the CM-WCN−10wt.%Ni,and the highest impact toughness of 6.17 J/cm^(2 )was obtained for the CM-WCN−12wt.%Ni,surpassing those of the hand mixed WC−Ni(HM-WCN)cemented carbides examined in this study and the other similar materials in the literature.CM-WCN cemented carbides possess excellent mechanical properties,due to their highly uniform structure and low porosity that could be ascribed to the intergranular-dominated fracture mode accompanied by a large number of plastic deformation tears of the bonding phase.In addition,the corrosion resistance of CM-WCN was superior to that of HM-WCN at the Ni content of 6−12 wt.%.展开更多
The laser-induced fluorescence excitation spectrum of CoC was recorded in the spectral region from 13500 cm^-1 to 22000 cm^-1, in which the CoC molecules were produced by the reaction of sputtered cobalt atoms with me...The laser-induced fluorescence excitation spectrum of CoC was recorded in the spectral region from 13500 cm^-1 to 22000 cm^-1, in which the CoC molecules were produced by the reaction of sputtered cobalt atoms with methanol under supersonic jet cooled conditions. Much of the visible spectrum was assigned to transitions between the X2∑^＋ ground state and F2∑^＋ state. The 11 bands assigned as （v＇=3-13, 0） transitions of the F^2∑^＋-X^2∑^＋ band system were observed and rotationally analyzed. Equilibrium constants for the F^2∑^＋ state were Te=13628 cm^-1, We=669 cm^-1, ωeХe=4.3 cm^-1, Be=0.546 cm^-1, and Re=1.758A. Some new bands were observed.展开更多
The lifetime of roll-bits with inserted tooth will be obviously decreased while drilling in strata and the tungsten carbide can be integrally separated from the roll-cone,which will need more trip out time to replace ...The lifetime of roll-bits with inserted tooth will be obviously decreased while drilling in strata and the tungsten carbide can be integrally separated from the roll-cone,which will need more trip out time to replace the roller bit.This study provides an entire analysis on stress as well as strength for teeth and tooth holes in loaded conditions.Qualities of tooth drop from matrix within roller bit.The optimized interferences of teeth inserted into the bit can be reasonably obtained by the critical interference derived from some relevant influence factors on the tooth-fixing quality of roller bits.展开更多
基金Project (51074189) supported by the National Natural Science Foundation of ChinaProject (20100162110001) supported by Research Fund for the Doctoral Program of Higher Education of ChinaProject (2011BAE09B02) supported by the National Key Technology R&D Program of China
文摘WC-6MoxC-0.47Cr3C2-0.28VC binderless carbide was prepared by hot pressing （1700 °C, 20 MPa）. The sample was observed and analyzed by scanning electron microscopy, energy dispersive X–ray spectroscopy and X–ray diffraction. The results show that during the hot pressing process, W atoms dissolve substantially into the MoxC crystal lattices; whilst, the reverse dissolution of Mo atoms into the WC crystal lattices takes place. Consequently, the main phase and binder phase structure are formed. The phase compositions of the main phase and binder phase are a WC-based solid solution containing Mo and a Mo2C-based solid solution containing W, respectively. The isotropic dissolution and precipitation of W and Mo atoms do not result in substantial carbide coarsening. The mechanism for the densification was discussed.
文摘Through systematically theoretical analysis and experimental research,the failure mechanism,of CVD(chemical vapor deposition) coated carbide tools in wear and fracture conditions was studied.On the basis of mechanism analysis,the specific suitability of the coated tools for cutting conditions was revealed and clarified.
基金the financial supports from the National Natural Science Foundation of China (Nos. 51778213, 52078189)the Fundamental Research Funds for the Central Universities, China (No. B200202073)。
文摘WC powders were uniformly coated by Ni nanoparticles through a combined chemical co-precipitation and subsequent high temperature hydrogen reduction strategy(abbreviated as CM-WCN),and then were consolidated by vacuum sintering at 1450°C for 1 h to obtain WC−Ni cemented carbides.The microstructure and properties of the as-consolidated CM-WCN were investigated.The average grain size of WC in the consolidated CM-WCN was calculated to be in the range of 3.0−3.8μm and only few pores were observed.A relative density of 99.6%,hardness of HRA 86.5 and bending strength of 1860 MPa were obtained for the CM-WCN−10wt.%Ni,and the highest impact toughness of 6.17 J/cm^(2 )was obtained for the CM-WCN−12wt.%Ni,surpassing those of the hand mixed WC−Ni(HM-WCN)cemented carbides examined in this study and the other similar materials in the literature.CM-WCN cemented carbides possess excellent mechanical properties,due to their highly uniform structure and low porosity that could be ascribed to the intergranular-dominated fracture mode accompanied by a large number of plastic deformation tears of the bonding phase.In addition,the corrosion resistance of CM-WCN was superior to that of HM-WCN at the Ni content of 6−12 wt.%.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20433080 and No.20673107）, the National Key Basic Research Special Foundation of China （No.2007CB815203）, and the Chinese Academy of Science （KJCX2-YW-N24）.
文摘The laser-induced fluorescence excitation spectrum of CoC was recorded in the spectral region from 13500 cm^-1 to 22000 cm^-1, in which the CoC molecules were produced by the reaction of sputtered cobalt atoms with methanol under supersonic jet cooled conditions. Much of the visible spectrum was assigned to transitions between the X2∑^＋ ground state and F2∑^＋ state. The 11 bands assigned as （v＇=3-13, 0） transitions of the F^2∑^＋-X^2∑^＋ band system were observed and rotationally analyzed. Equilibrium constants for the F^2∑^＋ state were Te=13628 cm^-1, We=669 cm^-1, ωeХe=4.3 cm^-1, Be=0.546 cm^-1, and Re=1.758A. Some new bands were observed.
文摘The lifetime of roll-bits with inserted tooth will be obviously decreased while drilling in strata and the tungsten carbide can be integrally separated from the roll-cone,which will need more trip out time to replace the roller bit.This study provides an entire analysis on stress as well as strength for teeth and tooth holes in loaded conditions.Qualities of tooth drop from matrix within roller bit.The optimized interferences of teeth inserted into the bit can be reasonably obtained by the critical interference derived from some relevant influence factors on the tooth-fixing quality of roller bits.
