Maria Cannio

Synthesis of chromium containing pigments from chromium galvanic sludges

In this work the screening results of the scientific activity conducted on laboratory scale to valorise chromium(III) contained in the galvanic sludge as chromium precursor for ceramic pigments are reported. The valorisation of this waste as a secondary raw material (SRM) is obtained by achievement of thermal and chemical stable crystal structures able to color ceramic material. Two different pigments pink CaCr(0.04)Sn(0.97)SiO(5) and green Ca(3)Cr(2)(SiO(4))(3) were synthesized by solid-state reactions using dried Cr sludge as chromium oxide precursor. The obtained pigments were characterized by X-ray diffraction and SEM analysis. Furthermore the color developed in a suitable ceramic glaze was investigated in comparison with the color developed by the pigments prepared from pure Cr(2)O(3). The characterization carried out corroborates the thermal and chemical stability of the synthesized pigments and, especially for the Cr-Sn pink pigment, the powders develop an intense color that is very similar to the color developed by the pigments obtained starting from pure Cr(2)O(3).

Service life prediction for refractory materials

Ultrasonic pulse velocity testing and image analysis were used to predict the thermal stability of cordierite–mullite refractories. Two compositions used as substrates in fast firing of porcelain whiteware, characterized by different microstructure and crack propagation behavior, were investigated. Fracture strength and fracture toughness values were obtained from three point bending test and chevron notched specimen technique, respectively. The measurement of the ultrasonic velocity was used to assess the material degradation with increasing number of thermal-shock cycles and specimen damage was monitored using image analysis to obtain further evidence of material degradation. The correlation between thermo-mechanical properties, ultrasonic velocity, microstructure, crack-propagation behavior and thermal-shock resistance was discussed. A remarkable similarity was found between the variation of ultrasonic velocity (when measured through the length of the refractory plates) and fracture strength with number of thermal shock cycles. On the other hand, the development of surface microcracking, as monitored by image analysis, is in good agreement with the variation of KIC with the number of thermal-shock cycles. The variation of the

The Electrophoretic Deposition of Bioglass®/Carbon Nanotube composite layers for bioactive coatings

\frac{d\sigma_{\rm f}}{dE_{\rm dyn}}

Effect of low-temperature high-pressure sintering on BiFeO3 density, electrical magnetic and structural properties

ratio with number of thermal-shock cycles shows the highest gradient of the investigated trends and it is proposed as a promising parameter to differentiate refractory materials regarding their different thermal shock behavior. Service life prediction models for refractory plates, from measured values of ultrasonic velocity and surface damage analysis, were proposed and validated.

Prediction of Service Life of Cordierite‐Mullite Refractory Materials by Non‐Destructive Methods

Abstract Equimolar amounts of trans -[ReOX 2 (OEt)(PPh 3 ) 2 ] (X=Cl, Br, I) precursors and potentially bidentate N , S -donor pyrimidine-2(1 H )-thione (pymSH) react in refluxing acetone to give mononuclear octahedral paramagnetic trans -[Re III X 2 (pymS)(PPh 3 ) 2 ] (X=Cl, Br, I) species. Starting from a metal–ligand molar ratio of 1:3, in the presence of N(C 2 H 5 ) 3 as deprotonating agent in refluxing ethanol, the same reaction proceeds stepwise, affording octahedral [ReO(pymS) 3 ] or [ReO(pymS) 3 ] and pentagonal-bipyramidal [Re(pymS) 3 PPh 3 ] complexes as a function of the reaction time. The compounds were characterized by elemental analysis, magnetic susceptibility, UV–Vis–NIR, IR and 1 H NMR spectroscopy and by cyclovoltammetric measurements. Reaction pathways and physico-chemical properties of the complexes are discussed.

Substituent Effects in the Reduction Behaviour of Thio- and Oxopyrimidines in Non-Aqueous Solvents

The feasibility of using Electrophoretic Deposition (EPD) to produce Carbon Nanotube (CNT) films on 45S5 Bioglass® coatings deposited on stainless steel substrates was investigated. The optimal experimental conditions were determined using a trial-and-error approach by varying the relevant EPD parameters. SEM observations confirmed that sequential EPD led to the formation of thick (up to 40µm) and uniform Bioglass® coatings covering the metallic substrate entirely and a porous network of CNTs ordered uniformly on the Bioglass® structure. The novel bioactive and nanostructured composite coatings are intended for applications in the biomedical field (ortophaedic implants and bone tissue engineering scaffolds).

Quality Control and Thermal Shock Damage Characterization of High‐Temperature Ceramics by Ultrasonic Pulse Velocity Testing

Reaction of 4,6-dimethylpyrimidine-2(1 H )-thione (Me 2 pymSH) with mer -[ReOCl 3 (Me 2 S)(OPPh 3 )] synthon in 1:1 molar ratio in refluxing acetone, results in the replacement of the Me 2 S ligand to form the mer -[ReOCl 3 (Me 2 pymSH)(OPPh 3 )] species. X-ray diffraction shows that the structure of the title compound consists of monomeric units with a distorted octahedral coordination around the rhenium(V) centre which includes the axial ReO and ReOPPh 3 bonds, and in which three Cl − ions and a S-monodentate neutral Me 2 pymSH ligand act as equatorial ligands. The compound was also characterised using electrochemical measurements and UV–Vis–NIR and IR spectroscopy.

Substitution of sodium silicate with rice husk ash-NaOH solution in metakaolin based geopolymer cement concerning reduction in global warming

Single-phase multiferroic BiFeO3 (BFO) powders were prepared by hydrothermal microwave synthesis and dense BiFeO3 ceramics were fabricated for the first time by the low-temperature high-pressure (LTHP) sintering technique. Effect of sintering temperature ranging from 400 to 800 °C (3 min and 10 min) and pressure of 3–8 GPa on structural, microstructural, electric and magnetic properties were investigated through X-ray diffraction, scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS), density and magnetic measurements. The results highlighted that LTHP sintering method, thanks to the high pressure involved, requires lower temperature and shorter time than other techniques, avoiding BiFeO3 phase degradation. SEM images show that for short experimental time (t = 3 min) the average grain size of the sintered samples was approximately the same size of raw powder. Extending the sintering time up to 10 min the grain growth phenomena occurred. Moreover the results indicate that the best obtained density value was around 98% of theoretical density. The dielectric behavior of BiFeO3 ceramics was not significantly influenced by the LTHP sintering conditions. Magnetic measurements showed that ceramic BiFeO3 is weakly ferromagnetic at room temperature.