Advanced Materials Research Vols. 105-106

Abstract: In this paper, the new high temperature ceramic matrix coating of anti-oxidation for stainless steel was prepared by slurry method. With the research about oxidation resistance of ceramic matrix coating formed on stainless steel, the effect of initial melting temperature, melting temperature range and thermal expansion coefficients of ceramic sintering change on protective properties of high temperature coating prepared at 1250°C is investigated, and then high temperature sintering ceramic with high-performance is gained through optimization. Through the test of TG-DTA and XRD to the coating, study on high temperature oxidation resistance of ceramic coating and the structure changing of the scale with coating from SEM images and photos, it is shown that the ceramic coating has excellent oxidation resistant properties, the weight loss with coating decrease more than 85%.

Abstract: Ti-doped DLC films were synthesized from C2H2 and Ti by ion beam deposition and magnetron sputtering, and the influence of Ti target current on the structures and the friction coefficients of Ti-doped DLC films were studied by SEM, AES, XPS, a ball-on-disk friction tester. The Ti content in Ti-doped DLC films is below 1at% when Ti target currents rise up to 3.5 A; but when Ti target current exceeds 3.5 A, Ti content in the films is obviously increased with increasing Ti target current. Ti-doped DLC films have a smooth dense surface with several particles dispersed in it and the surface morphology deposited with different Ti target currents is similar. With the augment of Ti target current, the ratio of sp3-C to sp2-C is almost a constant first, and then an obvious rise followed by an abrupt decrease is found; but only when Ti target current is above 5A, the ratio of TiC-C to sp2-C is obviously increased with Ti target current. The lowest friction coefficients are obtained for the Ti-doped DLC films with the highest ratio of sp3-C to sp2-C and a low ratio of TiC-C to sp2-C.

Abstract: A Fe-Al/WC composite coating was fabricated by using high velocity arc spraying (HVAS) and cored wire. The elevated temperature erosion behaviors of the coating were investigated with a grit blasting type erosion tester. The coating microstructure and eroded surface morphologies were analyzed by energy dispersion spectroscope (EDS), X-ray diffraction (XRD), scanning electron microscope (SEM) , transmission electron microscope (TEM) and image analyzer. The effects of incidence angle and test temperature on the erosion behavior were determined.

Abstract: In this paper, Y2O3-Al2O3-ZrO2 nano-ceramic coatings were prepared on 316L stainless steel substrate at 600°C for 0.5 hour by sol-gel method, using Y(NO3)3•6H2O, ZrO(NO3)•2H2O and Al(NO3)3•9H2O as raw materials, hexamethylenetetramine as catalyst. Phases and morphology of these coatings were characterized by XRD, SEM and EDS. Effect of heat treatment temperature on microstructure of the coatings was studied. Y2O3-Al2O3-ZrO2 coatings with grain size about 50nm tightly integrated with metal substrate after densely sintering at 600°C. The grain sizes have grown up with increasing temperature.

Abstract: Yttrium silicates oxidation resistance coatings were deposited on SiC-C/C composites surface by a hydrothermal electrophoretic deposition process. The influence of deposition voltage on the yttrium silicates coatings and the deposition amount of coatings were particularly investigated. Results show that with the increase of deposition voltage, the deposition amount of coatings increase, the density and uniformity of the coating surface is improved. When the deposition voltage reaches 210V, dense yttrium silicates coatings are achieved. While increase the deposition voltage continually, the uniformity of coatings decrease. When the deposition voltage arrives to 240V, high deposition voltage will result in cracked coatings. There is a parabola relationship between the deposition amount of coatings and time.

Abstract: Monodispersed silica spheres have attracted much attention because of their widely applications in the areas of catalysis, adsorption, chromatography packing materials and advanced ceramics. This paper focused on its application as a packing material of function coatings for space applications. Nanosized monodispersed silica spheres can be fabricated by Stöber method. However, microsized monodispersed silica spheres are not easy obtained. In this paper monodispersed silica spheres with the size between 200nm to 2000nm were fabricated by hydrolysis of tetraethoxy silane (TEOS) in isopropyl alcohol solvent and using ammonia as catalyst through multi-step growth method. The influence of silica seed number density and TEOS concentration on monodispersity and size of silica sphere were studied. The result shows that monodispersed silica spheres could be obtained through control the concentration of TEOS and the silica seed number density during every growth step. The diameter of monodispersed silica spheres increased with the steps of growth.

Abstract: The experimental makes use of the liquid-phase reaction of self-assembly method, we immerse the functional glass substrates into the precursor solution to prepare SrTiO3 films, which makes (NH4)2TiF6, Sr(NO3)2, H3BO4 as raw materials, then study the growth status of SrTiO3 thin films under different pH values of precursor solution, the morphology and the phase of the films are characterized by OMS, XRD and SEM, it is shown that when the pH value of the precursor solution under 2.0, the SrTiO3 films are unable to grow, when the pH value above 3.0, a white emulsion liquid precursor solution occurred, as a result, SrTiO3 films deposition can’t be achieved. And when the pH value between 2.0 and 3.0(contain both), with the pH value increasing the deposition time of the SrTiO3 films decreases. After annealing treatment at 600°C, we can have a conclusion that under these conditions the phase of the films are pure SrTiO3 films, the surface is smooth and the grains grow uniformly.

Abstract: The La (S,C)-TiO2 oriented films with honeycomb ceramic wafers as carriers were prepared by template hydrothermal synthesis. The effects of the hydrothermal reaction temperature and the amount of template agents on the performances of nano-TiO2 films were studied. The films were characterized on the XRD, BET, EDS and SEM. The results showed that the TiO2 films with anatase phase were obtained when hydrothermal reaction temperature was 150 °C and the reaction time was 10h, and the oriented films were obtained when the molar ratio of PEO-PPO-PEO（P-123）to Ti was 0.03. The data also revealed that the specific surface area of particles in the film increased from 148 m2/g to 240 m2/g, and the oriented film could fully decompose methyl orange in water for 3 h.

Abstract: Functional TiB2 coating was prepared onto the surface of Cr-Zr-Cu electrodes by vibrating electrospark deposition in order to extend their service life during resistance spot welding of Zinc coated sheet steels. The microstructure and mechanical properties of the coatings have been characterized by scanning electron microscopy, energy dispersive analysis, X-ray diffraction and micro-hardness tests respectively. The results indicate that cracks appear in the coating due to the tensile stress accumulation and delamination of the coating is related to mismatch in the equivalent valence electron. Cu diffuses obviously from the substrate to the surface of the coating, forming a gradient distribution and making the bonding of the interface between the coating and the substrate an atomic one. TiB2 coating is oxidized during deposition under high temperature of electrosparking. The micro-hardness of the coating is approximately 500HV, which is much bigger than the hardness of the uncoated ones.

Abstract: Y3+ doped TiO2 coatings were successfully prepared on glass slide substrates. The phase structure, optical properties，microstructure and surface properties of the coatings were characterized by using XRD, FT-IR, UV-vis and SEM. The photoinduced super-hydrophilicity and photocatalytic activity of the films were evaluated by the water contact angle measurement and photocatalytic oxidation of Rhodamine B in air, respectively. The results indicated that the doping of Y3+ into TiO2 could improve the hydrophilicity and photocatalytic activity, and TiO2 thin films doped with Y3+ at 2-4 at.% and heat-treated at 450 oC were of super-hydrophilicity. The optimal Y3+ content for the photocatalytic activity was 4 at.% and larger film thickness was helpful to reduce the contact angle of the composite films.