Heat-Resistant Ceramic Pigments on the Base of Waste Vanadium Catalyst and Alumina

Ceramic pigments on the base of technogenic silica-containing material—waste vanadium catalyst were obtained in this work. Corundum is identified along with the predominant mullite phase in the composition of pigments. The ions of nickel, chromium, and iron are embedded in the structure if the concentration of the corresponding oxide in the initial mixture does not exceed 10 wt.%. In this case, the oxide is not identified in a free form according to the results of X-ray diffraction analysis. Spinel CoAl2O4 is formed in cobalt pigments. The developed pigments keep the firing temperature up to 1200°C. The obtained pigments may be recommended for ceramic paints and colored glazes for building materials

Multi-technique investigation of archaeological pottery from Parma (Italy)

A ceramic factory with at least three kilns, active from the 14th century until the 17th century, was recently found close to the city walls of Parma (Italy). A series of measurements by different techniques was performed on pottery fragments belonging to the first and last production period. Micro-Raman spectroscopy and scanning electron microscopy–energy dispersive spectroscopy were used to study the glazes and the painting materials, while time-of-flight neutron diffraction and X-ray diffraction were used to characterize the ceramic bodies. The bodies are mainly composed by quartz, diopside, Na- and K-rich alkali feldspars, gehlenite, calcite, and silica-alumina glass; the red coloration is due to hematite. The glazes were obtained using a lead-silica glass, with a fictive temperature of about 600 ◦C. The main pigments were identified. The ceramics were produced from illitic calcareous clays and annealed in an oxidizing atmosphere at an estimated temperature of 900–1000 ◦C. Different amounts of magnesium in ceramics of the 14th and 17th century suggest the use of different quarries. The white pigment in the 17th century ceramics, showing the Raman spectrum of nearly pure anatase, is due to a titanium-bearing clay

The effect of functional ions (Y3+, F-, Ti4+) on the structure, sintering and crystallization of diopside-calcium pyrophosphate bioglasses

The effects of three functional ions (yttrium Y3+, fluorine titanium Ti4+) on the glass forming ability, sintering, crystallization, and thermo-physical properties of glasses and glass-ceramics were studied in a diopside-calcium pyrophosphate (90% CaMgSi2O6-10% Ca2P2O7) system. Three different percentages (1, 3 and 5 wt%) for each additive were tested. The structural features of glasses were assessed through FT-IR (Fourier Transform infra -red spectroscopy) and Si-29 and P-31 NMR (nuclear magnetic resonance), showing that the silicate network in all the investigated glasses is predominantly coordinated in Q(2) (Si) units, while phosphorus tends to remain in the orthophosphate (Q) environment. All glasses exhibited fast rates of biomineralization, making them promising candidates for biomedical applications. The sintering and crystallization behaviours of the glass powders were studied by differential thermal analysis (DTA), while the coefficient of thermal expansion (CTE) was determined by dilatometry. Glass transition temperature (Tg) values of all doped glasses were lower than the parent glass, while CTE values decreased with initial addition (1 wt%), of dopants before exhibiting an increase with further addition. In Y-doped glasses, a gradual increase was seen in the values of maximum crystallization peak temperature, Tp, up to 3 wt%, while an opposite trend was observed in Ti-doped glasses, showing an enhancement of the stability of the Y-doped glasses against devitrification. F-doped glasses exhibited a similar trend. Crystalline phase evolution was analysed by X-ray diffraction (XRD), and amorphous glass were obtained by sintering powder compacts from all the glasses at 800 degrees C for 1 h. (C) 2016 Elsevier B.V. All rights reserved