română L. YU , Q. S. PU, J. YUAN, X. D. ZHANG, J. X. GAO, S. M. LIU
Abstract
Superhydrophobic Co3O4 surfaces with a micro-nanostructure on glass slides were successfully prepared using a simple solvothermal synthesis process at 160℃and dip-coatings with stearic acids to reduce the surface energy. Such surfaces showed surperhydrophobic with a contact angle as high as approximately 169° and a low sliding angle of less than 3°. Further investigations indicated that the surfaces exhibited extraordinary self-cleaning performance and stable anti-icing property. For a spherical water droplet placed on the surfaces at -5℃, icing cannot occur for more than 70 min, implying wide applications on various industrial aspects.
Keywords
Superhydrophobic; antiicing; contact angle
MIHAI EFTIMIE, ANA FILIP , CRISTINA TODAȘCĂ, LAURA ȘERBAN
Abstract
Iron ions can change the properties of bottled foods and beverages in terms of taste, flavour, smell and colour. The paper deals with the chemical stability and the releases of Fe3+, Na+, Mg2+ and Ca2+ ions from commercial glass containers as well as from our own recipes, similar to the industrial ones. Even if, regarding the considered ions, the released amounts cannot lead to food toxicity, the Fe3+ migration from the elaborated glass recipes is in the range where a release – resorption mechanism could be used in the wine stabilization stage, thus making the process of wine production more efficient.
Keywords
iron ions migration, glass containers, food degradation potential
A.MELINESCU, G.IONIȚĂ, R.TRUȘCĂ, M.PREDA
Abstract
In this paper, the synthesis and physico-chemical characterization of some porous ceramic materials were studied using the geopolymer processing route. Samples were synthesized to contain as mineralogical component the mullite. For the synthesis, metacaolin and a NaOH solution were used. The samples were heat treated at temperatures between 1100 and 12000C. It resulted that in this temperature range samples with low density are obtained, this decreasing with increasing temperature and at 12000C the density is below 1 g/cm3. The mineralogical composition of the samples was examined by X-ray diffraction and the presence of mullite, cordierite, α-quartz and nepheline as crystalline phases was found. Also, the presence of the vitreous phase was observed, which increases with the increase of the heat treatment temperature. Through scanning electron microscopy studies it was observed that the samples contain pores of different shapes, closed and non-communicating, which explains the low density of the samples.
Keywords
geopolymer route, metakaolin, alkaline solution, XRD, SEM
TAHA H. ABOOD AL-SAADI, ABDULRAHMAN SALEH IBRAHIM, HAZIM FALEH
Abstract
Foaming geopolymers (light-weight porous inorganic materials) were successfully synthesized by alkali activator of mixed color waste glass powder without/with pure graphite powder (0.1 wt%) and dry intercalated graphite powder(0.1 wt%) as foaming agents; the specimens were thermally treated at 500,600,700 and 800ºC for 1hour. An important volume increase was recorded (-11.8-240.68%), (68.25-146.64%) and (43.79-968.54%) for MG-N5, MGG-N5 and MGIG-N5 respectively after thermal treatment. A sharp increase in volume (important swelling) and shape deformation was recorded for the specimens with intercalated graphite (MGIG-N5 pastes) at temperature 600ºC. The microstructure and mechanical properties of these materials were also studied. The foaming geopolymers containing glass and graphite powder (G or IG) which were obtained from this work are strong candidates mostly for the applications demanding thermal insulation with favorable combination of light weight, porosity, mechanical strength and performance to produce construction materials.
Keywords
Glass waste; graphite; foam geopolymers; thermal treatment
SIMONA ELENA BEJAN, EDUARD PISCANU, ALINA MELINESCU
Abstract
This work is dedicated to studying the synthesis of some ceramic materials, based on aluminum titanate and magnesium oxide addition so that the composition could be found in the binary pseudosystem Al2TiO5-MgTi2O5.
,br>The chemically pure raw materials used for synthesis were TiO2, Al2O3 and MgCO3 and the synthesis took place by the solid state reaction method. The powders were heat treated at temperatures between 1200°C-1400°C. The real mineralogical composition of the samples was determined by X-ray diffraction, being observed that, at 1400°C a solid state solution of aluminum titanate structure was formed. The microstructural analysis of the synthetized samples showed that, after the heat treatment process, different shape and size crystals were formed, with dimensions ranging between 4 and 8 micro m. The formation of bridges between particles was observed due to the sintering of the samples and the presence of both closed and open pores. Measurement of thermal expansion coefficients showed that they increase with increasing MgTi2O5 content.
Keywords
aluminum titanate, AT-MT2 solid solution, SEM, XRD
ASAD ALI, SARIR UDDIN, ABID ZAMAN, ABID AHMAD, MUHAMMAD KAMRAN, ZAFAR IQBAL
Abstract
Solid solution of Tin- doped barium tetra titanate Ba(Ti1-xSnx)4O9 (with x = 0.0, 0.5) composition prepared through mixed oxide conventional method and calcined at 1100˚C for 3 h with heating/cooling rate 5˚C/min. The structural, optical and microwave dielectric properties were studied by X-ray diffraction, Scanning electron microscopy, Fourier transform infra-red, photoluminescence spectroscopy and vector network analyzer respectively. An intense and broad band spectrum was observed at around the red color emission region. Optimum dielectric properties i.e. high dielectric constant (ϵr = 57.3) and low dielectric loss (0.00013) have been observed.
Keywords
Mixed oxide route, Optical properties, Dielectric properties