A Ni layer with a thickness of about 100 nm was sputtered on Cu substrates,followed by an ultrasonic seeding with nanodiamond suspension.High-quality diamond film with its crystalline grains close to thermal equilibri...A Ni layer with a thickness of about 100 nm was sputtered on Cu substrates,followed by an ultrasonic seeding with nanodiamond suspension.High-quality diamond film with its crystalline grains close to thermal equilibrium shape was deposited on Cu substrates by hot-filament chemical vapor deposition（HF-CVD）,and the sp2 carbon content was less than 5.56%.The nucleation and growth of diamond film were investigated by micro-Raman spectroscopy,scanning electron microscopy,and X-ray diffraction.The results show that the nucleation density of diamond on the Ni-modified Cu substrates is 10 times higher than that on blank Cu substrates.The enhancement mechanism of the nucleation kinetics by Ni modification layer results from two effects：namely,the nanometer rough Ni-modified surface shows an improved absorption of nanodiamond particles that act as starting points for the diamond nucleation during HF-CVD process;the strong catalytic effect of the Ni-modified surface causes the formation of graphite layer that acts as an intermediate to facilitate diamond nucleation quickly.展开更多
Diffusion bonding of Si3N4 ceramic to itself was performed using Ni interlayer. A flat Si3N4/Ni interface was found at a lower temperature （ 1 273 K）. Whereas at a higher temperature （ 1 473 K）, a porous zone loca...Diffusion bonding of Si3N4 ceramic to itself was performed using Ni interlayer. A flat Si3N4/Ni interface was found at a lower temperature （ 1 273 K）. Whereas at a higher temperature （ 1 473 K）, a porous zone located at the Si3N4/Ni interface and some petal-like Ni3 Si compounds precipitated in the Ni interlayer were observed. The formation mechanism of the porous zone was investigated based on a fracture analysis. An additional stress （O＇add ） generated at the Si3NJNi interface played an important role in the formation of the porous zone, which was resulted from the aggregation of nitrogen during the bonding process. A calculation equation of the O＇aaj was derived to analyze its effects. The results indicated that %~ was directly in dependent with diffusion bonding temperature and dwell time.展开更多
基金Project(20110933K) supported by the State Key Laboratory of Powder Metallurgy,ChinaProject(2012QNZT002) supported by the Freedom Explore Program of Central South University,ChinaProject(CSUZC2012024) supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University,China
文摘A Ni layer with a thickness of about 100 nm was sputtered on Cu substrates,followed by an ultrasonic seeding with nanodiamond suspension.High-quality diamond film with its crystalline grains close to thermal equilibrium shape was deposited on Cu substrates by hot-filament chemical vapor deposition（HF-CVD）,and the sp2 carbon content was less than 5.56%.The nucleation and growth of diamond film were investigated by micro-Raman spectroscopy,scanning electron microscopy,and X-ray diffraction.The results show that the nucleation density of diamond on the Ni-modified Cu substrates is 10 times higher than that on blank Cu substrates.The enhancement mechanism of the nucleation kinetics by Ni modification layer results from two effects：namely,the nanometer rough Ni-modified surface shows an improved absorption of nanodiamond particles that act as starting points for the diamond nucleation during HF-CVD process;the strong catalytic effect of the Ni-modified surface causes the formation of graphite layer that acts as an intermediate to facilitate diamond nucleation quickly.
文摘Diffusion bonding of Si3N4 ceramic to itself was performed using Ni interlayer. A flat Si3N4/Ni interface was found at a lower temperature （ 1 273 K）. Whereas at a higher temperature （ 1 473 K）, a porous zone located at the Si3N4/Ni interface and some petal-like Ni3 Si compounds precipitated in the Ni interlayer were observed. The formation mechanism of the porous zone was investigated based on a fracture analysis. An additional stress （O＇add ） generated at the Si3NJNi interface played an important role in the formation of the porous zone, which was resulted from the aggregation of nitrogen during the bonding process. A calculation equation of the O＇aaj was derived to analyze its effects. The results indicated that %~ was directly in dependent with diffusion bonding temperature and dwell time.
