Papers by Keyword: Dipping

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Authors: S.Y. Brou, G. Bonnet, Jean Luc Grosseau-Poussard
Abstract: TiAl, TA6V and titanium coupons were treated by a phosphoric acid solution by dipping. They were then submitted to a heat treatment and, in the case of TiAl and TA6V, to high temperature discontinuous oxidation under laboratory air. The H3PO4 treatment allowed to decrease the mass gains for TiAl and TA6V, in particular during the first 100 hours. XRD analyses demonstrated for the three substrates the formation of a pyrophosphate layer during the heating period. This pyrophosphate evolved towards TiO2 with oxidation time increase, quicker for smaller aluminium content (or higher titanium content) in the metallic substrate. The decrease of mass gains was attributed to a diffusion barrier effect of the pyrophosphate layer as long as it was present.
Authors: Hamidah Harahap, Elmer Surya, Indra Surya, Baharin Azahari, Hanafi Ismail
Abstract: Alkanolamide-modifed kaolin was added into natural rubber latex (NRL) pre-vulcanization system at 70°C and the products were formed into films by coagulant dipping method. The dipped films then were dried at 120°C for 15 and 30 min. The effect of drying time on properties of NRL films such as crosslink density, tensile strength, tensile modulus, and elongation at break was observed in this study. Results showed that longer drying time improved the properties of NRL films due to the additional formation of crosslink process in the NRL films. The longer drying time swelled the particles more in matrix as confirmed by Scanning Electron Microscopy (SEM) micrograph.
Authors: Begoña Ferrari, Isabel Santacruz, María Isabel Nieto, Rodrigo Moreno
Authors: Gabriel Ferro, Maher Soueidan, Olivier Kim-Hak, François Cauwet, Yves Monteil
Abstract: Growing good quality SiC epitaxial layers at temperature lower than 1400°C is a challenging problem which could help reducing the costs, increasing the safety of the process or even give new perspectives. Toward this aim, liquid based growth techniques have been used. The Si-based melts should be carefully chosen considering several criteria. Furthermore, the implementation of a liquid phase for growing SiC epilayer can be performed in various manners (dipping or VLS mechanism) so that one has to choose the more appropriate technique. The discussion is illustrated with several results showing that the growth of SiC from a liquid phase at low temperature can address various important technological points such as experimental safety, ptype doping, on-axis or selective epitaxy. The recent demonstration of single-domain 3C-SiC heteroepitaxial layers on hexagonal SiC substrates confirms that liquid based growth has still unexpected qualities.
Authors: Guo Qing Wang, Li Ping Niu
Abstract: Hydroxyapatite (HAP) is known as a kind of bioactive and biocompatible material, HAP coatings are used to improve the biocompatibility of substrate by some researchers. In this paper, homogenous precipitation of hydroxyapatite was formed in the system of CaNa2EDTA -(NH4)2HPO4-NH4OH-H2O, and HAP powder was obtained after calcinations at 800 and grinding. Add HAP in UHMWPE o-xylene solution to get dipping solution and prepare HAP/UHMWPE-coated titanium by dipping coating process. Scratch test demonstrated that Ti-HAP/UHMWPE material started to shine metallic luster under 1.03 N, and adhesive strength is 32MPa. UHMWPE not only simplified the process of preparing HAP-coated material, but also enhanced the adhesive strength, which shows great potential in biomedical areas.
Authors: S.Y. Brou, G. Bonnet, Jean Luc Grosseau-Poussard
Abstract: Gamma-TiAl samples were treated by phosphoric acid solutions at different concentrations. With 15 mol/dm3, a viscous deposit was left on the surface leading, after drying and high temperature oxidation, to a very heterogeneous surface aspect. Concentrations below 0.5 mol/dm3 were then used and allowed to greatly ameliorate the homogeneity of the superficial layer. After heating from ambient to oxidation temperature, however, cracks were always observed, due to the departure of gaseous molecules. Isothermal oxidation tests come out at 800°C and 900°C under reconstituted air showed that weight gains were strongly reduced when TiAl had been treated. A compound containing titanium, oxygen and phosphorus was detected at the end of the heating period, identified as titanium pyrophosphate, TiP2O7. This compound remained the only one detected for 100 h when oxidation was come out at 800°C, but evolved towards TiO2 when oxidation time was increased. In the case of oxidation at 900°C, the evolution from TiP2O7 to TiO2 also happened but appeared to go faster.
Authors: Kyeong Sik Cho, Hghn Joon Choi, Jung Goo Lee, Yung Woo Park
Authors: Yvan Houbaert, Tanya Ros-Yáñez, Pablo Rodriguez-Calvillo, José Barros, Leo Kestens
Abstract: Crystallographic texture has an important effect on the magnetic quality of electrical steel: a specific texture parameter A is defined and used to estimate the magnetic quality of texture components. It is shown that obtaining the best possible texture in non oriented electrical steel can reduce the losses with 1,5 W/kg. Two production schemes for high silicon electrical steel are described: a conventional processing through hot and cold rolling with adequate temperatures and cooling rates and an immersion-diffusion process by hot dipping in a Si- and Al-rich bath followed by diffusion annealing. The texture evolution in these experimental materials is under study and first results are reported for conventional alloys (rolling procedure) and for immersion-diffusion alloys, which are annealed after dipping in order to obtain a controlled concentration gradient with high Si and/or Al at the surface or a homogeneous Si and/or Al-content over the thickness.
Authors: Jian Er Zhou, Xue Bing Hu, Hui Li Li, Yan Xiang Wang, Yong Qing Wang, Xiao Zhen Zhang
Abstract: The mullite sol was prepared using tetraethyoxysilane (TEOS) as raw materials. Aluminum titanate (AT) powders were coated with the sol by dipping. The influence of the concentration of the mullite sol and pH value on the microstructure of the coated AT powders was studied. The results showed that AT powders are coated homogeneously and the thickness of the mullite film is about 0.15 μm when the concentration of the mullite sol is 0.18 mol·L-1 and pH value is 3.0.
Authors: Zhang Fang, Qiu Nan Li, Hui Min Wang, Guang Hua Zhao
Abstract: Porous SiC foamed ceramics used raw material of SiC were prepared by adjusting slurry viscosity at 1400°C. Formed technology was dipping organic precursors. The result showed that the section of the sample presents three-dimensional net structure, wall of hole thickness is proper, the distribution of the hole are homogeneous, and have high porosity, apertures are small than 30 μm, the main crystal appearance is SiC. The strength of samples is been improved by dealing organic precursors. The slurry on the ribs is been increased.
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