The deposition of high-quality diamond films and their adhesion on cemented carbides are strongly influenced by the catalytic effect of cobalt under typical deposition conditions. Decreasing Co content on the surface...The deposition of high-quality diamond films and their adhesion on cemented carbides are strongly influenced by the catalytic effect of cobalt under typical deposition conditions. Decreasing Co content on the surface of the cemented carbide is often used for the diamond film deposition. But the leaching of Co from the WC-Co substrate leading to a mechanical weak surface often causes a poor adhesion. In this paper we adopted an implant copper layer prepared by vaporization to improve the mechanical properties of the Co-leached substrate. The diamond films were grown by microwave plasma chemical vapor deposition from CH4:H2 gas mixture. The cross section and the morphology of the diamond film were characterized by scanning electron microscopy (SEM). The non-diamond content in the film was analyzed by Raman spectroscopy. The effects of pretreatment on the concentrations of Co and Cu near the interfacial region were examined by energy dispersive spectrum (EDS) equipped with SEM. The adhesion of the diamond on the substrate was evaluated with a Rockwell-type hardness tester. The results indicate that the diamond films prepared with implant copper layer have a good adhesion to the cemented carbide substrate due to the recovery of the mechanical properties of the Co-depleted substrate after the copper implantation and the formation of less amorphous carbon between the substrate and the diamond film.展开更多
We review the fundamental properties and significant issues related to Cu/graphite composites.In particular,recent research on the interfacial modification of Cu/graphite composites is addressed,including the metal-mo...We review the fundamental properties and significant issues related to Cu/graphite composites.In particular,recent research on the interfacial modification of Cu/graphite composites is addressed,including the metal-modified layer,carbide-modified layer,and combined modified layer.Additionally,we propose the use of ternary layered carbide as an interface modification layer for Cu/graphite composites.展开更多
Crystal structure of Ti_(5)Al_(2)C_(3)was determined by means of X-ray powder diffraction(XRPD),transmission electron microscopy(TEM)and ab initio calculations.In contrast to the already known P63/mmc space group that...Crystal structure of Ti_(5)Al_(2)C_(3)was determined by means of X-ray powder diffraction(XRPD),transmission electron microscopy(TEM)and ab initio calculations.In contrast to the already known P63/mmc space group that the MAX phases crystallize,it was demonstrated that the R3_m space group could better satisfy the experimental data.The lattice parameters are a=0.30564 nm,c=4.81846 nm in a hexagonal unit cell.展开更多
In this study, the effect of heat treatment on the room temperature strength of W-core Si C fiber produced by chemical vapor deposition（CVD） was investigated. Thermal exposure in the temperature range of 900–1000？...In this study, the effect of heat treatment on the room temperature strength of W-core Si C fiber produced by chemical vapor deposition（CVD） was investigated. Thermal exposure in the temperature range of 900–1000？C decreases the strength of the Si C fiber. Fracture morphology analysis indicates that failure initiations predominantly take place at the W-core/Si C interface. A reaction layer that formed at the W-core/Si C interface during thermal exposure degraded the fiber strength and an empirical linear relationship of strength vs thickness of the reaction layer can be obtained. The kinetics of the growth of the W-core/Si C reaction layer were determined.展开更多
文摘The deposition of high-quality diamond films and their adhesion on cemented carbides are strongly influenced by the catalytic effect of cobalt under typical deposition conditions. Decreasing Co content on the surface of the cemented carbide is often used for the diamond film deposition. But the leaching of Co from the WC-Co substrate leading to a mechanical weak surface often causes a poor adhesion. In this paper we adopted an implant copper layer prepared by vaporization to improve the mechanical properties of the Co-leached substrate. The diamond films were grown by microwave plasma chemical vapor deposition from CH4:H2 gas mixture. The cross section and the morphology of the diamond film were characterized by scanning electron microscopy (SEM). The non-diamond content in the film was analyzed by Raman spectroscopy. The effects of pretreatment on the concentrations of Co and Cu near the interfacial region were examined by energy dispersive spectrum (EDS) equipped with SEM. The adhesion of the diamond on the substrate was evaluated with a Rockwell-type hardness tester. The results indicate that the diamond films prepared with implant copper layer have a good adhesion to the cemented carbide substrate due to the recovery of the mechanical properties of the Co-depleted substrate after the copper implantation and the formation of less amorphous carbon between the substrate and the diamond film.
基金Funded by Changsha Natural Science Foundation(No.kq2208270)。
文摘We review the fundamental properties and significant issues related to Cu/graphite composites.In particular,recent research on the interfacial modification of Cu/graphite composites is addressed,including the metal-modified layer,carbide-modified layer,and combined modified layer.Additionally,we propose the use of ternary layered carbide as an interface modification layer for Cu/graphite composites.
基金This work was funded by the NSFC under Grant No.50832008,Grant No.91226202 and the IMR innovative research foundation.
文摘Crystal structure of Ti_(5)Al_(2)C_(3)was determined by means of X-ray powder diffraction(XRPD),transmission electron microscopy(TEM)and ab initio calculations.In contrast to the already known P63/mmc space group that the MAX phases crystallize,it was demonstrated that the R3_m space group could better satisfy the experimental data.The lattice parameters are a=0.30564 nm,c=4.81846 nm in a hexagonal unit cell.
基金the Raman Spectroscopy Laboratory of Institute of Metal Research, Chinese Academy of Sciences for the support in the accomplishment of this paper
文摘In this study, the effect of heat treatment on the room temperature strength of W-core Si C fiber produced by chemical vapor deposition（CVD） was investigated. Thermal exposure in the temperature range of 900–1000？C decreases the strength of the Si C fiber. Fracture morphology analysis indicates that failure initiations predominantly take place at the W-core/Si C interface. A reaction layer that formed at the W-core/Si C interface during thermal exposure degraded the fiber strength and an empirical linear relationship of strength vs thickness of the reaction layer can be obtained. The kinetics of the growth of the W-core/Si C reaction layer were determined.
