Search

Ta-xZr (x = 90, 80, 70, 60 at.%) alloys with good mechanical properties and high density were prepared by powder metallurgy method and vacuum sintering technology. The surface morphologies and mechanical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS). The results showed that lamellar Ta was observed with no second phase during the sintering process. The tensile strength and the Young's modulus increased with the Ta contents firstly and then decreased, and varied with the Ta contents in the range of 60.5 ± 5.03~163.0 ± 10.11 MPa and 4.5 ± 0.47~11.8 ± 1.16 GPa, respectively. In conclusion, The Ta-70Zr alloy is potentially useful in the hard tissue implants for its mechanical properties and biocompatibility.

Coarse grained WC–9Co cemented carbides with 0–1.0% TaC (mass fraction) were fabricated by HIP-sintering and gas quenching. The effects of TaC on the microstructures and mechanical properties were investigated using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), X-ray diffractometry (XRD) and mechanical properties tests. The results show that the maximum values of hardness and strength are HV 1124 and 2466 MPa respectively when 0.4% TaC is added. When the content of TaC is more than 0.6%, the grain size of WC is no longer affected by the amount of TaC, and (W,Ta)C occurs as well. Moreover, the strength and fracture toughness increase and the (Ta+W) content decreases with the increase of TaC content. The dependence of (Ta+W) content on the mechanical properties indicates that (Ta+W) content in Co should be decreased as low as possible to improve the mechanical properties of coarse grained WC–TaC–9Co cemented carbides with the microstructure of WC+γ two phase regions.

The effect of preparation routes on the physical characteristics and activity of the Ag-MnOx/C composites toward the oxygen reduction reaction (ORR) in alkaline media were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy-dispersion spectroscopy (EDS) as well as scanning electron microscopy (SEM) and electrochemical techniques. The results show that more Ag and Mn species present on the surface of the Ag-MnOx/C composite prepared by two-step route (Ag-MnOx/C-2) compared to the one prepared by one-step route (Ag-MnOx/C-1), which contributes to its superior activity toward the ORR. The higher electron transfer number involved in the ORR can be observed on the Ag-MnOx/C-2 composite and its specific mass kinetic current at −0.6 V (vs Hg/HgO) is 46 mA/μg, which is 23 times that on the Ag/C. The peak power density of zinc–air battery with the Ag-MnOx/C-2 air electrode reaches up to 117 mW/cm2.

In this paper, the Fe-9Si-6Al soft magnetic composite has been prepared via powder particles coated with aluminum oxide and silicone. The magnetic properties and microstructure of Fe-Si-Al SMC has been investigated. Results showed that the powder particles surface contained a thin insulating layer made of aluminum oxide and silicone. After annealed at 800℃ for 60min, the particles of component are all by themselves and the insulating layer is not destroyed. The Fe-Si-Al SMC has excellent magnetic properties. The magnetic permeability is steady with the frequency changing at 5kHz-100kHz range.

Nanocrystals hydroxyapatite (nHA) was synthesized and modified chemically, and nanocrystals hydroxyapatite / poly(L-lactide)/poly(ethylene succinate)(nHA/PLLA/PES) composite was prepared by melt-blending using nHA, PLLA and PES as reactants in a stainless steel chamber. The obtained nHA was of high purity and high crystallinity as well, its mean sizes measured from TEM observations were 65±35nm (long axis) and 40±10nm (short axis), and are close to the endosteal needle hydroxyapatite crystals size ((15 ~ 20) nm×60 nm) in the human body. The mechanical properties of nHA/ PLLA/PES blends were determined by bending and tensile tests and the effects of nHA content on the mechanical properties of nHA/PLLA/PES blends were investigated. The blending modulus and tensile modulus increase with the nHA (0,5,10,15and 20 wt.%) content increase, while blending strength increases up to HA mass fraction of 10% and after that decreases. SEM images revealed that the surface changed from rough to smooth with increasing nHA content, especially with nHA content higher than 20%, which implied the failure mechanism of the material changes from ductile to brittle.

In this paper, the effect of heat treatment processing on magnetic properties of Fe-3.5Si soft magnetic composite has been investigated. The thermal treatment improved the magnetic properties of Fe-3.5Si SMC materials. With the treatment temperature increasing, the permeability and eddy loss of the composites increase and the core loss and hysteresis loss decrease. The magnetic properties would be deteriorated at too high temperature. Annealed temperature at 750℃ for 60min, the Fe-3.5Si soft magnetic composite has the optimum overall magnetic properties.