Papers by Keyword: Whisker

Abstract: Hydroxyapatite whiskers were prepared with diammonium hydrogen phosphate, calcium nitrate, nitric acid, sorbitol, HAP seed and carbamide by hydrothermal homogeneous precipitation. The HAP seeds served as whiskers nuclei and sorbitol served as template. The prepared hydroxyapatite whiskers were characterized by XRD,SEM and FTIR. It was indicated that hydroxyapatite whiskers with high crystallinity grew alone Z axis with carbonated trend, and the appearance of HAP was smooth, less magazine and no reunion, the length-diameter ratio of the whiskers was in range of 125-8 with the average is 32.78.

Abstract: Hydroxyapatite is well used as bone repair materials, due to its properties that can be combined with strontium to improve mechanical property and degradation property. In this article, hydroxyapatite whiskers with different amount of doped strontium were prepared with diammonium phosphate, calcium nitrate and strontium nitrate at 94 °C. Fourier transform infrared spectroscopy (FTIR) was used to identify the functional groups. X-ray diffraction (XRD) analysis was carried out to study the phase composition and crystallinity of the whisker. The morphology of the whiskers was characterized by scanning electron microscope (SEM). It was indicated that strontium can be doped in hydroxyapatite with proper process and then the strontium-doped hydroxyapatite whiskers were produced successfully.

Abstract: In-situ composite of Al2O3/Fe-Al with Al2O3 fibers were prepared by partial oxidation of oxygen to Fe powder and Al power, crystal phase composition and elemental composition were analyzed by XRD, NORAN. The results indicated that, the crystal composition is determined by Aluminum content, when the content is enough, FeAl3, Al and Al2O3 will be gain, on the contrary, Fe2Al, FeAl, Fe3Al and Al2O3 will be gain; Al2O3 fibers were synthesized via VLS process, the quantity of Al2O3 fibers increased with the Al content, the whisker’s diameter was improved with increasing of sintering temperature.

Abstract: Rutile titanium dioxide whiskers with diameter around 2μm and length up to 45μm have been successfully synthesized via a facile flux method, using anatase titanium dioxide as raw material and a mixture of ZnSO₄7H₂O and Na₂SO₄ as flux. The products were characterised by X-ray diffraction (XRD), scanning electron microcopy (SEM) and energy dispersive spectroscopy (EDS). It turned out that the calcined temperature and the type of flux addition affected the crystal phase and morphology of the final product greatly. The results showed that rutile titanium dioxide whiskers obtained at 850 °C for 4 hours had the most uniform morphology. The possible growth mechanism was briefly discussed.

Abstract: Well dispersive and single crystal calcium titanate (CaTiO₃) whisker with a length of 50-100μm was synthesized by sintering the mixture of calcium chloride and titanium dioxide with improvement of adding the mineralization agent of Pb(Ac)₂.3H₂O. The as-prepared samples were characterized by XRD, SEM. The optimum synthesis condition and the effect of the mineralization agent were discussed respectively. In the end, the possible reaction process was given and a LS growth mechanism was proposed.

Abstract: The effect of surface film on the Al whisker fabrication by utilizing stress migration was investigated. The sample was a thin aluminum film deposited on an oxidized silicon substrate and covered with a surface film. Aluminum oxide layer, silicon oxide layer and Cu oxide layer were used as the surface films. Al whiskers were obtained only in the samples with aluminum oxide layer and silicon oxide layer after heat treatment. It was found that both the brittle surface films and compressive stress determined the Al whisker growth.

Abstract: This article took the sodium sulfate and calcium chloride as the raw material and prepared calcium sulfate whiskers by hydrothermal method. The experimental results show that the calcium sulfate precursors are prepared by the reverse feed mode in which the sodium sulfate solution drop into the calcium chloride solution under the solution concentration 0.6 mol/L and the molar ratio of Na2SO4 to CaCl2 at 1:1.8. The precursors were placed in pH=6.12 hydrothermal environments and treated in the autoclave at 140 °C for 4 h to obtain the calcium sulfate whiskers having for the ratio of length to diameter at 97.5 and the better morphology.

Abstract: Sodium hexatitanate (Na₂O•6TiO₂) whiskers with an average diameter and aspect ratio of 1-3 µm and 10-20 respectively were synthesized by calcinating mixtures of industrial grade sodium carbonate (Na₂CO₃), anatase TiO₂ and potassium fluoride (KF). The growth of sodium hexatitanate whiskers was obtainable in a range of TiO₂/Na₂CO₃ molar ratio from 4 to 6, heating temperature from 940 °C to 1000 °C and content of KF from 5 wt.% to 7 wt.% with different morphologies and aspect ratio of the products. The role of KF on the growth behavior of Na₂O•6TiO₂ whiskers was demonstrated by structural and morphological observation.

Abstract: Using tetraethyl orthosilicate and anhydrous aluminum chloride as precursors, ethyl ether as oxygen donor, LiF as mineralizer, and Na2SO4-NaCl as compound molten salt, mullite whisker was synthesized in the low temperature by nonhydrolytic sol-gel process combined with molten salt method. The phase transformation of mixed powder composed of mullite xerogel and molten salt during the heat treatment and the microstructure of mullite whisker corresponding to different temperature were characterized by means of DTA-TG, XRD SEM and TEM. The results show that mullite crystal phase can be formed via non-hydrolytic sol-gel process combined with the molten salt method at 750°C. The synthetic effect of mullite get better as the temperature increased to 850°C, while NaAlSiO4 crystal phase is also detected. Mullite whisker, with diameters ranging from 300~500 nm and lengths of 3~5μm, is prepared at the temperature of 850°C.

Abstract: Ba2B5O9Cl whiskers with uniform morphology were synthesized by a simple flux method, using BaCl2•2H2O, H3BO3 as the starting materials, and KCl as the flux. The products were characterized by X-ray diffraction (XRD) and scanning electron microcopy (SEM), and the optimum conditions for preparing high quality Ba2B5O9Cl whiskers were studied. Results show that a sintering temperature around 700 °C, an Ba/B mole ratio of 1:3 and a raw materials to flux mass ratio of 1:2 lead to uniform orthorhombic Ba2B5O9Cl whiskers with a diameter of 0.4-1.0 µm and a length of 10-25 µm.