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Jin Y.,University of Sichuan | Jin Y.,The Key Laboratory of Material Corrosion and Protection of Sichuan colleges and Universities | Ye F.,University of Sichuan | Liu C.,University of Sichuan | Yang R.,University of Sichuan
Advanced Materials Research | Year: 2012

Ultrafine Cr 3C 2 powders with globular-like particle of ~0.3-0.8 μm were synthesized by a new precursor method, namely carbothermal reduction of complex chromium oxide-carbon mixture, which was made initially from salt solution containing chromium and carbon elements by air drying and subsequent calcining at 400 °C for 1 h. Phase composition of reaction products was discussed by X-ray diffraction (XRD), and microstructure of the calcined powders and final products was studied by scanning electron microscopy (SEM). The results show that the synthesizing temperature of Cr 3C 2 powders was reduced greatly by the new precursor method. Thus, the preparation of ultrafine Cr 3C 2 powders is at only 1000 °C for 2 h. The lowering of synthesizing temperature is mainly due to the homogeneous chemical composition of the complex oxide-carbon mixture. There is a coarsening tendency of Cr 3C 2 powders with the increase of reaction temperature and time. © (2012) Trans Tech Publications, Switzerland. Source


Yue P.P.,University of Sichuan | Jin Y.Z.,University of Sichuan | Jin Y.Z.,The Key Laboratory of Material Corrosion and Protection of Sichuan colleges and Universities | Hu X.D.,University of Sichuan | And 2 more authors.
Advanced Materials Research | Year: 2014

Ni-P ultra-black films having conical pores with the diameter of ~ 10-30 μm and the depth of ~ 15-30 μm were prepared by chemical etching of electroless plated Ni-P films using 8 mol/L nitric acid at 40 °C for 60 s. The phase composition and microstructure of the film samples were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results show that the diameter and depth of the etching pores become larger and the flat top regions bounded by etching pores become smaller by the coalescence of adjacent pores with the increase of etching time. The surface morphologies of the etched Ni-P films are characterized by the distribution of conical pores. © (2014) Trans Tech Publications, Switzerland. Source


Jin Y.,University of Sichuan | Jin Y.,The Key Laboratory of Material Corrosion and Protection of Sichuan colleges and Universities | Ye F.,University of Sichuan | Zeng X.,University of Sichuan | Yang R.,University of Sichuan
Advanced Materials Research | Year: 2013

Cr3C2-WC-Ni nanocomposite powders with ~50-100 nm were synthesized from precursors by vacuum-aided carbothermal reduction at only 750 °C for 2 h. The phase composition and microstructure of the synthesized products were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The present study shows that Cr3C2-WC-Ni nanocomposite powders contain two kinds of solid-solution phases, namely Ni and (Cr, W)3C2 solid solution, respectively. WC and W2C phases do not appear inreaction products due to the dissolution of tungsten atoms into Ni and Cr3C2 unit cells. Especially, there is a change of the crystalline structure for (Cr, W)3C2 phase from 750 °C to 800 °C. © (2013) Trans Tech Publications, Switzerland. Source


Jin Y.Z.,University of Sichuan | Jin Y.Z.,The Key Laboratory of Material Corrosion and Protection of Sichuan colleges and Universities | Yang K.,University of Sichuan | Zen X.G.,University of Sichuan | And 3 more authors.
Applied Mechanics and Materials | Year: 2014

Ni-P ultra-black films were prepared by ultrasonic chemical etching of electroless plated Ni-P films using 8 mol/L nitric acid at 40 °C for 20 s with different ultrasonic power ranging from 0 to 195 W. Scanning electron microscopy (SEM) was used to study topographic characteristics of the films. The results show that ultrasonic oscillation plays an important role during ultrasonic chemical etching of electroless plated Ni-P films. The enhanced pore features with higher porosity through coalescence of adjacent isolated pores have been observed at 0-105 W. The increase in pore size of Ni-P etched films with the ultrasonic power (from 105 to 195 W) has been confirmed by SEM characterization. Generally, the dependences of relative etching rate on ultrasonic power are closely associated with pore size, pore shape and the distribution of etching pores. © (2014) Trans Tech Publications, Switzerland. Source

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