A Raman study of diamond film growth on Co-cemented tungsten carbide

Phase purity and crystallinity of diamond films grown by hot filament chemical vapor deposition on ISO-grade K10 cemented carbide [94.2 weight percent (w/o) WC-5.8 w/o Co] were studied by Raman spectroscopy as a function of substrate temperature, gas phase composition, and substrate pretreatments. High-quality diamond films were grown using 0.5% CH4/H-2 in a rather narrow range of substrate temperatures (750 to 760 degrees C). In all the deposited coatings, the first-order Raman band of diamond is detected at 1337 cm. This fact indicates that a 2 GPa residual compressive stress is present in the diamond phase. The linewidth of the diamond Raman peak increases with deposition temperature. This effect has been ascribed to a higher density of defects in diamond crystallites. It has been observed that Co removal from the substrate surface by wet chemical etching before deposition is less effective than a careful selection of deposition parameters to reduce the codeposition of nondiamond carbon phases. This finding has been attributed to the fast diffusion of the binder from the bulk to the substrate surface, even for the etched substrates

Co-sintering of dense electrophoretically deposited YSZ films on porous NiO-YSZ substrates for SOFC applications

An original process for the preparation of YSZ dense films with a thickness lower than 10 μm over NiO-YSZ substrates is presented. This process involves the preparation of a green membrane of NiO-YSZ and subsequent electrophoretic deposition (EPD) of commercial YSZ powder on this polymer-rich membrane. A single thermal treatment allowed removal of the organic compounds, sintering of the layers and full densification of the electrolyte. © 2005 Materials Research Society

Electrochemical characterization of anode supported SOFC prepared by co-firing technique

One of the main problems in the fabrication of anode supported solid oxide fuel cells is related to the sintering of electrolyte layer on anodic substrate, because differential densification of the layers may result in cracks during thermal process. Co-firing approach consists of simultaneous sintering of both electrolyte and anode. In this way, shrinkage of porous layer is compatible with the densification of electrolyte film. In this work co-firing technique was used for the sintering of YSZ thick films deposited on green NiO-YSZ layers by electrophoretic deposition (EPD). EPD is a colloidal process based on the motion of charged particles in the electric field in the direction of the electrode with opposite charge, thus forming a compact layer. With respect to other techniques, EPD has several advantages: short formation times, little restriction in the shape of substrates, simple deposition apparatus, possibility to have a mass production, low cost, easy control of the thickness of the deposited film through simple regulation of applied potential and deposition time. The EPD/co-firing combined process allowed to obtain a dense, 10 μm thick, crack free electrolyte layer with a good bonding to the anode. A slurry was prepared starting from a commercial NiOYSZ anodic powder (Praxair), polyvinylidene fluoride (PVDF binder SOLEF 6020, Solvay), a nanometric carbon powder (super P, Carbon Belgium), dispersed in N-methyl-2-pyrrolidone. A green membrane was obtained after evaporation of the solvent. A suspension of YSZ powder was prepared starting from commercial YSZ (TZ8Y, Tosoh) in methanol and deposited by EPD on a green NiO-YSZ membrane using a planar EPD cell setup. Co-firing parameters were assessed from the results of TG-DTA analysis performed on green bodies. Figure 1 shows the results of Hg porosimetry performed on sintered anodes for the determination of residual porosity and surface area. Green and fired samples were characterized in terms of morphology by scanning electron microscopy (FE-SEM), as reported in Figure 2. EDS linescan performed on the cross section of the cell did not show nickel diffusion in the electrolyte layer. A cathode layer was deposited on fully sintered half cells via spray-powder technique, using a suspension of commercial LSFC powder (Nextech), followed by a low temperature sintering process. Electrochemical characterization was performed on button cells in hydrogen in the temperature range 600-800 degrees C. Data of the electrochemical characterization will be presented at the conference

SUMMER SORES SECONDARY TO A HOOF CRACK IN AN ANDALUSIAN STALLION

Cutaneous habronemosis in horses is caused by larvae of the spirurid nematodes Habronema microstoma and Habronema muscae. These lesions, also known as "summer sores'', are often severe and disfiguring. Although Habronema-caused lesions at the coronary grooves have been described, cases of hoof cracks with secondary summer sores have never been reported. The present case describes clinic-pathological and surgical features of a quarter crack case complicated by cutaneous habronemosis at the dermal layers. A 15-year-old, Andalusian stallion was referred to the Veterinary Teaching Hospital of the University of Teramo because of a mass of the hoof and a severe lameness. The clinical examination revealed an exuberant granulation tissue protruding from a full thickness vertical quarter crack. The mass was surgically removed, and subjected to histopathological, microbiological, and parasitological analyses. A copromicroscopic examination was also performed. The feces scored PCR positive for H. muscae, while the skin for both H. microstoma and H. muscae, thus confirming the primary role of Habronema in causing the hoof mass. This is the first description of a hoof wall crack complicated by summer sores, with simultaneous gastric habronemosis. This case confirms that a prompt diagnosis during fly activity is imperative for an efficacious treatment and a timely prevention of disfiguring summer sores

Mixed trichuroid infestation in a dog from Italy

Background: Capillaria aerophila, Capillaria boehmi and Trichuris vulpis are trichuroid nematodes affecting wild and companion animals all over the World. The canine intestinal whipworm, T. vulpis, is the most common and wellknown in veterinary practice, whereas the respiratory C. aerophila and C. boehmi have been rarely reported in pets as a likely consequence of overlapping morphometric and morphological features of the eggs, which impair a correct etiological diagnosis. Findings: In December 2011, a mixed infestation by T. vulpis, C. aerophila and C. boehmi was diagnosed in an asymptomatic dog living in central Italy. Morphometric and morphological findings and pictures of the eggs found at the copromicroscopic analysis are herein reported. Conclusions: The present work demonstrates that when trichuroid eggs are found in a faecal sample from a dog, a careful morphological and morphometric analysis of individual parasite elements is mandatory. Key diagnostic features (i.e., size, wall surface pattern and aspects of plugs) should be carefully examined when eggs with overlapping shape and appearance are detected. In conclusion, given the importance in clinical practice of canine trichuroids and the zoonotic potential of C. aerophila, these nematodes should be included into the differential diagnosis of intestinal and respiratory parasitoses of dogs by a thorough microscopic analysis of all trichuroid ova present in microscopic fields

Microstructural and morphological properties of homoepitaxial (001)ZnTe layers investigated by x-ray diffuse scattering

The microstructural and morphological properties of homoepitaxial (001)ZnTe layers are investigated by x-ray diffuse scattering. High resolution reciprocal space maps recorded close to the ZnTe (004) Bragg peak show different diffuse scattering features. One kind of cross-shaped diffuse scattering streaks along directions can be attributed to stacking faults within the epilayers. Another kind of cross-shaped streaks inclined at an angle of about 80deg with respect to the in-plane direction arises from the morphology of the epilayers. (abridged version