Jiansen NI
,
Hui XU
,
Mingyuan ZHU
,
Qiang LI
,
Bangxin ZHOU
,
Yu
,
a DON
材料科学技术（英文）
Nd8.5Fe74Co5Cu1Nb1Zr3Cr1B6.5 bonded magnets were prepared by melt-spun and subsequent heat treatment. Magnetic properties of Br=0.68 T, JHc=716 kA/m, (BH) max=77 kJ/m3 were achieved. The addition of Cr element shows to be significantly advantageous in reducing grain size and increasing the intrinsic coercivity.
关键词:
null
,
Nanocrystalline
,
Melt-spinning
,
Ma
Xuehua ZHANG
,
Yuanbin KANG
,
Sipeng LIU
,
Qiang LI
,
Ying YANG
材料科学技术（英文）
TaN/NbN multilayered coatings with nanoscale bilayer periods were synthesized at different Ar/N2 flow rate by r.f. magnetron sputtering. XRD and nano indenter were employed to investigate the influence of Ar/N2 flow rate on microstructure and mechanical properties of the coatings. The low-angle XRD pattern indicated a well-defined composition modulation and layer structure of the multilayered coating. All multilayered coatings almost revealed higher hardness than the rule-of-mixtures value of monolithic TaN and NbN coatings. At FAr:FN2 =10, the multilayered coating possessed excellent hardness, elastic modulus, internal stress, and fracture resistance, compared with ones synthesized at other Ar/N2 flow rates. The layered structure with strong mixture of TaN (110), (111), (200) and Nb2N (101) textures should be related to the enhanced mechanical properties.
关键词:
RF magnetron sputtering
,
TaN/NbN多层膜
,
纳米尺度
Jiaqi ZHU
,
Jiecai HAN
,
Songhe MENG
,
Qiang LI
,
Manlin TAN
材料科学技术（英文）
The microstructure and properties of tetrahedral amorphous carbon (ta-C) films deposited by the filtered cathodic vacuum arc technology has been investigated by visible Raman spectroscopy, AFM and Nano-indentor. The Raman spectra have been fitted with a single skewed Lorentzian lineshape described by BWF function defining coupling coefficient, which characterizes the degree of asymmetry and is correlated with the sp3 content. When the substrate bias is -80 V, the sp3 content is the most and simultaneously the coupling coefficient is the least, following with the minimum root mean square surface roughness (Rq=0.23 nm) and the highest hardness (51.49 GPa), Young’s modulus (512.39 GPa), and critical scratching load (11.72 mN). As the substrate bias is increased or decreased, the sp3 content and other properties lower correspondingly.
关键词:
Tetrahedral amorphous carbon
,
null
,
null
Shixi ZHAO
,
Hanxing LIU
,
Qiang LI
,
Shixi OUYANG
材料科学技术（英文）
Orthorhombic LiMnO2 cathode materials were synthesized successfully at lower temperature by sol-gel method. When LiMnO2 precursor prepared by sol-gel method was fired in air, the product was a mixture of spinel structure LiMn2O4 and rock-salt structure Li2MnO3, whereas in argon single-phase orthorhombic LiMnO2 could obtain at the range of 750℃ to 920℃. The substitution of Mn by Zn2+ or Co3+ in LiMnO2 led to the structure of LiMnO2 transiting to α-LiFeO2. The results of electrochemical cycles indicated that the discharged capacity of orthorhombic-LiMnO2 was smaller at the initial stages, then gradually increased with the increasing of cycle number, finally the capacity stabilized to certain value after about 10th cycles. This phenomenon reveals that there is an activation process for orthorhombic LiMnO2 cathode materials during electrochemical cycles, which is a phase transition process from orthorhombic LiMnO2 to tetragonal spinel Li2Mn2O4. The capacity of orthorhombic LiMnO2 synthesized at lower temperature is larger than that synthesized at high temperature.
关键词:
Orthorhombic LiMnO2
,
null
,
null
,
null
