Papers by Keyword: Dipping

Abstract: The aim of this study was to characterize and evaluate the performance of two wood species, pine (Pinus sylvestris L.) and spruce (Picea abies Karst.) used for wooden furniture in outdoor coated with a water based ecological paint and subjected to artificial weathering. Another task of this research was to investigate the potential of the application of paint using dipping method in alternative to traditional brush or spraying coating application methods, since, if wood samples are grouped in stacks, the processing time can be reduced, compared to samples painted singularly. From the analysis of the dipping parameters, such as time and paint concentrations, more practical and specific knowledge was obtained regarding this painting method.From the characterization of the painted samples and from the measurements of color changes during artificial weathering it was observed that coated wood surfaces have similar optical properties also in case of different dipping times, although the type of wood could affect the performance of final product during artificial weathering test as in case of spruce wood samples, specifically those prepared with the shortest dipping time: for these samples a lower resistance to weathering and higher color changes were observed.

Abstract: SiC crystals are grown using a Si-Cr-based solvent by a top-seeded solution growth (TSSG) method by changing the dipping time after when the growth temperature is reached. Step-flow-like curve morphologies were observed for a dipping time after 15 min, while polycrystallization occurred at the periphery for that after 120 min, which corresponded to the dipping under unsaturated and supersaturated carbon in the solvent, respectively. Furthermore, the solution growth of SiC with dipping under unsaturated carbon was easily realized by the growth from the crucible bottom, step-flow-like growth was achieved. Using this technique, dominant polytypes of SiC in various growth conditions after stable seed dipping under the unsaturation in the solvent can be demonstrated.

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.

Abstract: The neutron absorption ball for High Temperature Gascooled Reactor contains 25wt% B4C, dispersed in graphite matrix. Good compressive strength, wear resistance and thermal shock resistance are essential to absorption ball. B4C and graphite were selected as the filler, and phenolic resin was chosen as the binder. A certain amount of phenolic resin and silane coupling agent were used for the surface preparation of inorganic aggregate. Results showed that the residual weights of pretreating powders after carbonizing were higher than that of powders without pretreatment. The compressive strength of the neutron absorption ball was studied. Dipping can effectively improve the strength. Within a certain range, the compressive strength increased with the increase of dipping times. Compared with the thermoplastic resin, higher compressive strength sample was obtained when the thermosetting resin was used as impregnant. The average crushing force of the absorption ball prepared by the optimal process was up to 612 N.

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.

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.

Abstract: Modified bamboo-charcoal (MBC) was prepared by Ferric sulfate dipping and microwave radiation with 20～30 mesh bamboo-charcoal (BC) pretreated by water boiling as the support. The original and modified BC were characterized by SEM, FTIR, XRD, BET and BJH. Fluoride removal from simulated drinking water containing fluoride was probed into with MBC. The results indicated that MBC took on minor average pore diameter (1.172nm), major microspores and greater specific surface area (99.891 m2/g). Loaded iron combined with BC by bonds from BC such as H-O-H bond, C-O bond and O-H bond. The increase of fluoride removal after BC being modified suggests that MBC is a more potential defluorinate agent.

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.

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.

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.