Authors: Li Juan Zhou, Yong Ting Zheng, Shan Yi Du
Abstract: BN-AlN-TiB2 compound conductive ceramics from powder mixtures of BN, Al, and TiB2 was
fabricated by self-propagating high temperature synthesis (SHS) and hot isostatic pressing (HIP). The
powder mixtures were shaped by isostatic cool pressing at 5-10MPa and the combustion reaction was
carried at 100-200 MPa N2 by an ignitor. XRD experiments confirmed that the reaction was complete and
only AlN, BN and TiB2 were detected. Optical microscopy as well as SEM with an electron probe
microanalysis was used for microstructural analysis and revealed a relatively uniform distribution of
particulates. The temperature-dependence and composition-dependence of the electrical resistivity of
BN-AlN-TiB2 ceramics were studied. The results showed that the optimum composition was 5-10wt%
BN, 30-55wt% Al and 60-40wt% TiB2, and the products had the density of 90% of the theoretical,
resistivity of 80-1000 μ⋅cm and bending strength of 100-200 MPa.
786
Authors: Min Zhou, Jing Feng Li, Jing Liu
Abstract: The Bi2Te3 compound was synthesized by mechanical alloying (MA) of highly pure
constituents of Bi and Te powders, and then was consolidated by spark plasma sintering (SPS) method.
The MA-derived alloy formation was characterized by X-ray diffraction (XRD), and the microstructure
change was investigated through scanning electron microscopy (SEM). The thermoelectric properties
were measured using a Seebeck Coefficient/Electrical Resistance Measuring System. The influence of
MA time on the thermoelectric properties of the SPS-sintered samples was investigated to find the
optimal MA condition for the powder synthesis and thermoelectric properties. The obtained results
showed that the sample with the MA time of 6 h exhibited the optimal electrical transport properties. The
maximum power factor of over 2.0 × 10-3 W/m K2 was obtained between 323 K and 423 K.
538
Authors: Atsunori Kamegawa, Toru Iwaki, Masuo Okada
Abstract: Effects of hydrogenation process of the microstructure, electrical conductivity and mechanical properties for the Cu-(1~3) mass%Ti alloys were investigated. During hydrogenation process at 350°C, 7.5 MPa for 48 h, the disproportionation reaction occurred with forming of Ti hydrides in the alloy. It is found that remarkable simultaneous improvements of mechanical strength of 1094 MPa and electrical properties of 21%IACS are obtained in the hydrogenated Cu-3mass%Ti alloy.
1319
Authors: Bai Ping Lu, Can Cheng Liu, Hui Xu
Abstract: Cu-11Ni-2W alloys have been prepared by vacuum non-consumable arc-melting and high-frequency induction melting injection moulding. The effects of melting processes on the resultant microstructure were studied. The results show that the grain of Cu-11Ni-2W alloy prepared by vacuum non-consumable arc-melting is coarse and the microstructure includes α solid solution and W particles. As for the sample prepared by high-frequency induction melting injection moulding, the grain is superfine and the microstructure is α solid solution. Moreover, the thermal conductivity coefficient for the sample prepared by vacuum non-consumable arc-melting is 67.2 W/(m•K), while that for high-frequency induction melting injection moulding is 47.8 W/(m•K). The melting point of Cu-11Ni-2W alloy prepared by vacuum non-consumable arc-melting is 1157.27°C.
508
Authors: Jie Yan, Kai Yong Jiang
Abstract: TiC/Cu composites were prepared by means of high-energy ball mill and cold-press sintering. Confirming the better process parameters, the effects of the milling time and sintered temperature on microstructure, mechanical properties and electric conductivity of TiC/Cu composites was discussed. The shape of the composite grains changed from laminar to spherical and lattice distortion increased with the milling time increasing. The increase of the sintering temperature and TiC contents help to decrease porosity and density of the composites. With increasing of TiC mass fraction the bend strength increased first and then decreased，the peaks both appear in 10wt. %. The increasing of the sintering temperature is beneficial to improve the bend strength. Ball milled 15h the electric conductivity performs at optimum level. When the milling reached 24h, fine particles appear agglomeration and it shows a low level of the electric conductivity.
318
