Papers by Keyword: In Situ Synthesis

Abstract: Al2O3 matrix composites reinforced with Ba-b-Al2O3 phase were synthesized through reactive sintering using Al2O3 and BaCO3 as starting powders. Dense Al2O3/Ba-b-Al2O3 composites can be obtained by spark plasma sintering from Al2O3/BaO•Al2O3 powder, which was prepared by calcining Al2O3/BaCO3 powder mixture. The Ba-b-Al2O3 reinforcing phase exhibited an elongated morphology due to preferred diffusion of Ba cations. The existence of Ba-b-Al2O3 phase as well as low sintering temperature and short holding time during reactive sintering inhibit grain growth and thus result in small grain sizes of the Al2O3 matrix.

Abstract: To synthesize morphology- controlled nano- copper with excellent lubrication properties as lubricant’s additive, chemical reduction synthesis method was used coalescing in situ via liquid paraffin as resolvent and modification with polyethylene glycol (PEG-2000). The as- prepared Cu nanopieces with 35.59 nm average length and 21.03 nm average width were characterized by X-ray diffraction (XRD), and transmission electron microscopy (TEM). The tribological behavior of Mobil 1 5W-30 lubricating oil with nano- Cu were measured by ball- on- disk UMT- Ⅱ tribometer and analyzed by SEM and EDS. It is found that the tribological performance of Mobil 1 5W- 30 with nano- Cu is improved, and the optimization addition is 0.4% (Cu wt) with the lowest friction coefficient.

Abstract: nanosize hydroxyapatite/polyacrylonitrile composite bead was prepared via in-situ synthesis method. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), particle size measurement and X-ray diffraction (XRD) were used to characterize the HAp/PAN composite bead. XRD curve indicates low crystallinity of HAp. Particle size and SEM analysis demonstrates that decreased partical size of synthesized HAp as well as good distribution with the addition of PAN is found. The HAp is well-distributed and the combination between HAp and PAN is well. FTIR showed that there was no shift of characteristic peaks of synthesized HAp in PAN, which proves the physical interaction between PAN and HAp. The approximate HAp content of 28.6% calculated from thermal analysis curves means high conversion ratio of HAp. The adsorption amount of cadmium ions onto composite beads is lower than HAp particles.

Abstract: The emphasis of this study was in-situ synthesis of carbon nanotubes (CNTs) on Mg matrix at 480°C. The process involves homogeneous deposition of Co catalyst onto Mg by deposition-precipitation route with low Co content (1.0 wt.%) and in situ synthesis of CNTs by chemical vapor deposition. The morphologies and microstructure of the as-obtained CNTs/Mg composite powders was characterized by SEM, TEM, Raman spectrum, and XRD. The results indicated that CNTs were well graphitized and uniformly distributed on the surface of Mg powders, which would be beneficial to the mechanical property of CNTs/Mg composites.

Abstract: Iron matrix composite reinforced with VC reinforcements was produced by in situ synthesis technique. The microstructure of the composites was characterized by X-ray diffraction and scanning electron microscopy. The micrographs revealed the morphology and distribution of the reinforcements. The results show that the composite consists of VC carbide as the reinforcing phase and α-Fe as the matrix. The distribution of spherical VC particulates in iron matrix is uniform, and the matrix microstructure of Fe-VC composite is pearlite.

Abstract: Titanium and its compounds are one of the most frequently used reinforcing particles in iron ceramic composite materials. These materials have special characteristics because they are quenchable, their hardness can be increased by heat treatment and they can be quite easily machined. The point of the technology developed in the Bay Zoltán Institute of Materials Sciences and Technology is to form the reinforcing layer on the surface of the sample in an in situ way by melting the surface of the low carbon steel and the laminar carbon felt using laser beam while the titanium metal powder is simultaneously added to the melt. Several methods (metallographic examinations, selective area hardness measurements, SEM, and XRD) were applied to answer the questions about the optimal conditions for the in situ synthesis of a wear resistant layer.

Abstract: The in-situ synthesized TiC particle reinforced high chromium Fe-based ceramics composite coating was fabricated on the substrate of Q235 steel by plasma cladding process using Fe-Cr-Ti-C composite powder as reactive material. Microstructure of the coating was observed by scanning electron microscope (SEM), the phases were determined by X-ray diffraction (XRD), and the wear resistance was evaluated under dry sliding wear test conditions at room temperature. Results indicate that the composite coating consists of the reinforcing TiC carbide, (Cr,Fe)7C3 eutectic as well as austenite, and is metallurgically bonded to the Q235 steel substrate. The gradient distribution of TiC carbides is observed. TiC particles present in the granular shape in the fusion zone and central zone while present in the dendritic shape on the surface of the composite coating. Hardness of the coating from surface to fusion zone varies a little; the average hardness of the coating is about HV0.2750 which is 3.2 times as much as that of the base. The wear mass loss of Q235 base material is 13 times higher than that of the composite coating.

Abstract: This article describes the in-situ synthesis and immobilization of iron nanoparticles on several substrates at room temperature using NaBH₄ as a reducing agent and ascorbic acid as capping agent. The method is very effective in protecting iron nanoparticles from air oxidation for more than 30 days. Substrates used to immobilize iron nanoparticles are spherical polymer resins (size of 100–200 mesh) and novel carbon substrates prepared from high temperature carbonization of e-spun nylon and polyacrylonitrile fabrics. Iron nanoparticles (40–100nm) immobilized sample showed higher activity for the reductive removal of hazardous hexavalent Cr (VI) compared to free floating iron nanoparticles at ambient temperature. Iron immobilized substrates has a great potential to be used not only for the removal of Cr (VI) in waste stream but also for oxygen scavenger for food packaging.

Abstract: A TiCN cermet composite coating was fabricated on 45# steel substrate by reaction nitrogen arc welding cladding technique. The mixture powder of titanium and graphite was preplaced onto the 45# steel substrate after intensive mixing by star ball-mill and gluing with starch binder. The microstructures and phase of the coatings, interracial behavior between coatings and the substrate were investigated by scanning electronic microscope, X-ray diffractometer. The microhardness distribution of the coating section, frictional coefficient, abrasion loss and wearing surface morphology were investigated by microhardness tester, abrasion machine and scanning electronic microscope. The results show that an excellent bonding between the coatings and the 45# steel substrate is ensured by the strong metallurgical interface and phase of the coatings are mainly composed of TiCN. The highest microhardness of the coatings reaches HV _0.5 810, which is about 3 times more than that of the 45# steel substrate. The anti-abrasive test results show the coating has better anti-abrasive performance than the 45# steel substrate.

Abstract: In-situ Al3Ti /A356 composites were synthesized by direct melt reaction method in Al-K2TiF6 system. The preparation techniques was discussed and the effects of Si, Mg, La (0.30%), Ce (0.30%) and multiple rare earth (0.15% La + 0.15%Ce) addition on microstructures of Al3Ti /A356 composites were investigated by X-ray diffraction and scanning electron microscope. The results show that the morphology and size of Al3Ti reinforcement are influenced significantly by Si, Mg and the optimal preparation process is composition with latter Si, Mg alloying. The Al3Ti precipitations during solidification process are restrained by 0.30% La addition or 0.30% Ce addition and lead in the uniform of Al3Ti size and morphology. The radial growth of Al3Ti is strongly restrained by rare earth composite addition, and the main morphology is slender-spherical like.