New Clayey Deposit and Their Potential as Raw Material for Red or Structured Ceramics: Technological Characterization

Mineralogical and technological characterization of ceramic raw materials from a new deposit located at Caxias city, Maranhão State—Brazil, was accomplished to determine their potential as raw materials for the ceramics industry in northeastern Brazil. The ceramic raw materials were collected from three different locations on the site and characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), differential thermal analysis (DTA), and thermogravimetry (TG). The XRF analysis of the fraction < 2 μm revealed that most samples had SiO2 (35–51 wt%), Al2O3 (19–29 wt%), Fe2O3 (2–21 wt%), MgO (0.7 to 4.5 wt%) and K2O (0.9 to 5 wt%) as components. Quartz, kaolinite, illite, hematite and montmorillonite were the main mineral phases identified. DTA and TG analysis confirmed the mineral identification. The technological potential of the ceramic raw materials was investigated by: cation exchange capacity (CEC), plastic behavior (Atterberg Limits), linear shrinkage at 950 °C (LSF), flexural strength (FS), apparent porosity (AP), water absorption (WA) and bulk density (BD). The main experimental results—WA (9–17%), AP (19–31%), FS (2.0–23 MPa), and the Atterberg limits—indicated that the ceramic raw materials investigated have high potential to be used to develop mass for red or structured ceramics, such as bricks and roof tiles.

Optical and Electrical Properties of Nd3+doped Na2O-ZnO-TeO2 Material

Neodymium-doped Na2O-ZnO-TeO2 (NZT) glasses were prepared by the conventional melt quenching technique. DTA and TG were used to confirm glass preparation through the glass transition temperature at 447°C for the glass system. The analysis of FTIR spectra and X-ray diffraction described the samples' nature as ionic and amorphous, respectively. The optical band gap energy was estimated using absorption spectra and found to be decreased from 2.63eV to 1.32 eV due to the increase of doping concentration. The intensity of the emission spectra was enhanced for the higher concentration of Nd3+ ions. The dielectric constant of the glass samples was found to be constant for the large range of frequency (3 kHz to 1 MHz). The variation of conductivity with the temperature of the samples had shown the Arrhenius mechanism of conduction.

Ionically cross-linked chitosan–halloysite composite microparticles for sustained drug release

This study investigated the potential of halloysite nanotubes (HNTs) to improve the sustained release properties of chitosan (CS) microparticles cross-linked ionically with tripolyphosphate (TPP). Composite CS-HNTs microparticles were obtained by a simple and eco-friendly procedure based on a coaxial extrusion technique. Prior to encapsulation, a water-soluble model drug, verapamil hydrochloride (VH), was adsorbed successfully on HNTs. The microparticles were characterized by optical microscopy, Fourier transform infrared (FTIR) spectroscopy, differential thermal analysis/ thermogravimetric analysis (DTA/TG) and evaluated for encapsulation efficiency and drug-release properties. The composite particles had a slightly deformed spherical shape and micrometric size with average perimeters ranging from 485.4 ± 13.3 to 492.4 ± 11.9 μm. The results of FTIR spectroscopy confirmed non-covalent interactions between CS and HNTs within composite particle structures. The DTA and TG studies revealed increased thermal stability of the composite particles in comparison to the CS-TPP particles. Drug adsorption on HNTs prior to encapsulation led to an increase in encapsulation efficiency from 19.6 ± 2.9 to 84.3 ± 1.9%. In contrast to the rapid release of encapsulated model drug from CS-TPP microparticles, the composite CS-HNTs microparticles released drug in a sustained manner, showing the best fit to the Bhaskar model. The results presented here imply that HNTs could be used to improve morphology, encapsulation efficiency and sustained drug-release properties of CS microparticles cross-linked ionically with TPP.

The Influence of the Chemical Composition of Selected Waste Materials from the Production of Copper on the Final Environmental Assessment

This article presents qualitative and quantitative analysis of the waste produced by KGHM Polska Miedź. The waste has been analyzed according to its chemical composition and balanced in order to be reused and recycled. Special attention has been paid to mining industries producing the biggest amount of waste and ore enrichment businesses generating waste, which isn’t reused nowadays. Laboratory reseach has been conducted on floatation waste, different kinds of slags, waste gases and water slag extracts. Attention has been drawn to the possibility of using a computer program SLAG - PROP for analyzing physicochemical features, technological features and the refining of the acquired waste. Consequently, the further way of utilization of waste has been shown. From this point of view, analyses of DTA and TG slags in an oxide coating seem especially interesting. Having a particular composition they can be successfully utillised in the refining processes of copper pyrometallyrgy.

Synthesis and Characterization of Pseudoboehmite and Gamma-Alumina

Pseudoboehmite (PB) were synthesized through the sol-gel process, using aluminum nitrate as precursor. The pH adjustment of the precursor solution was made by using ammonium carbonate. After the precipitation, the material was dried at 70°C before characterization. The pseudoboehmite obtained were characterized by x-ray diffraction, scanning electron microscopy and afterwards by thermal analysis (DTA and TG). The pseudoboehmite was also calcined at 500oC to obtain gamma-alumina. The specific surface area measurements through the BET process and the desorption-absorption of nitrogen as well the t plot in order to evaluate the pore volume of the calcined samples was realized. Finally, the results showed that the synthesized pseudoboehmite can be used to produce high specific surface material with a crystal structure of gamma-Al2O3(around 324m2/g).

Study of Gamma Alumina Synthesis – Analysis of the Specific Surface Area

Different samples of pseudoboehmite (PB) were synthesized through the sol-gel process, using aluminum nitrate as precursor. The influence of variables on the synthesis and calcinations of the PB on the specific area of the obtained gamma-Alumina were studied. The variables were the ageing temperature (25 and 130o C), addition or not of polyvinyl alcohol to the precursor solution and the ageing time of the PB. The pH adjustment of the precursor solution was made by using ammonium carbonate. The products, which were obtained on different conditions, were then characterized by x-ray diffraction, specific area measurements through the BET process, and by thermal analysis (DTA and TG). After characterization, the synthesis products were calcined at 500°C; during this process the gamma-Alumina transformation was observed. The calcination products were characterized by the same methods (x-ray diffraction, BET, DTA and TG) and the desorption-absorption curves were obtained as well, in order to measure the pore volume of the samples. Finally, the results were analyzed through an experimental factorial planning, which showed that high specific surface area gamma-Al2O3 (around 330m²/g) can be obtained through this process.

Study of the Thermal Stability and Mechanical Characteristics of MAX Phases of Ti-Al-C(N) System and their Solid Solutions

The DTA and TG study in air of Ti2Al (C1-xNx) and Ti3AlC2 synthesized under Ar 0.1 MPa pressure and densified in thermobaric conditions at 2 GPa, 1400 °C, for 1 h showed that the increase of the amount of TiC layers in Ti-Al-C MAX phases structures leads to the increase of their stability against oxidation: 321 MAX phase Ti3AlC2 are more stable than Ti2AlC and Ti2Al (C1-xNx) solid solutions both before and after thermobaric treatment. The oxide film formed on the surface of the highly dense (ρ=4.27 g/cm3, porosity 1 %) material based on nanolaminated MAX phase Ti3AlC2 (89 % Ti3AlC2, 6 % TiC, 5 % Al2O3) manufactured by hot pressing (at 30 MPa) made the material highly resistant in air at high temperatures: after 1000 hours of exposition at 600 °C it demonstrated a higher resistance to oxidation than chromium ferrite steels (Crofer GPU and JDA types). Due to the surface oxidation self-healing of defects took place. Besides, the Ti3AlC2 material demonstrated resistance against high-temperature creep and after being kept in H2 at 600 °C for 3h its bending strength reduced by 5 % only. At room temperature the Ti3AlC2 bulk exhibited microhardness Hμ = 4.6 GPa (at 5 N), hardness HV50 = 630 (at 50 N ) and HRA = 70 (at 600 N), Young modulus was 140 ± 29 GPa, bending strength =500 MPa, compression strength 700 MPa, and fracture toughness K1C=10.2 MPa·m0.5.

Recycling of Automotive Laminated Waste Glass in Ceramic

Reducing the environmental impact is an important factor for the sustainability of environment. This paper discusses the characterization of white ceramic bodies with an industrial waste produced in the automotive industry. The use of laminated glass residue as a raw material of a ceramic body was endeavor to make a positive impact on the environment. The laminated safety glass was ground to promote separation of glass from poly (vinilbutiral). Then, the powdered glass was used as starting material in the ceramic mass and PVB was used to confer plasticity to the ceramic mass. The fired ceramic body was analyzed using thermal analysis (DTA and TG). The specimens were tested to obtain the flexural resistance and water absorption. The data shows that PVB addition improved mechanical properties and that the grinded glass powder reduced the water absorption and increased the mechanical strength of ceramic bodies after firing.

Preparation of Hydrotalcites Derived Ni/Co/Cu/Fe Nanocomposite Oxides and their Catalytic Activities for Thermal Decomposition of Ammonium Perchlorate

Ni/Co/Cu/Fe nano-composite oxides (Ni/Co/Cu/Fe–NCOs) were prepared by calcination of Ni/Co/Cu/Fe hydrotalcites (Ni/Co/Cu/Fe–HTs) precursors. Ni/Co/Cu/Fe–NCOs were used as new catalysts on improving thermal decomposition of ammonium perchlorate (AP). Their catalytic activities were investigated using DTA and TG–MS. The results revealed that Ni/Co/Cu/Fe–NCOs exhibited NiO and spinel phase with high specific surface areas of 90–120 m2 g–1. They have homogenous particles with average crystallite size in the range of 50–60 nm. The thermal decomposition process of AP can be accelerated by the addition of Ni/Co/Cu/Fe–NCOs. Ni/Co/Cu/Fe–NCOs achieved the purpose of improving thermal decomposition of AP based on the presence of superoxide ion (O2–) on the surface of Ni/Co/Cu/Fe–NCOs.