Vidriados cerámicos fotoactivos

El estudio de la capacidad fotocatalítica de precursores cerámicos como el silicato de circonio y tres tipos de fritas de uso común en la producción industrial (monoporosa, bicocción y porcelánico). Conocida la capacidad fotodegradativa de estos materiales, se ha pretendido preparar vidriados cerámicos mediante metodología sol-gel, analizando: (i) rutas monofásicas o polifásicas, (ii) efecto del dopado con metales colorantes, (iii) efecto de la introducción de nuevos componentes a una base silícea introducida como TEOS, con el objetivo de obtener un vidriado sol-gel viable con capacidad fotocatalítica óptima. Obtenido este vidriado óptimo se estudia su modificación mediante: (i) adición de agentes modificadores del band-gap (vanadio, niobio, estaño, antimonio...) (ii) agentes inductores de la desvitrificación (ZrO2, Al2O3, ZnO, MoO3, TiO2...) (iii) y se realiza un análisis comparado de la fotoactividad de vidriados convencionales que desvitrifican fases cristalinas en su cocción sobre sustratos tales como ZrO2, ZrSiO4, CaTiSiO5 frente a los vidriados sol-gel y los propios precursores analizados con anteriorida

New chromium doped powellite (Cr–CaMoO4) yellow ceramic pigment

A new chromium doped powellite (Cr–CaMoO4) yellow ceramic pigment alternative to yellow of praseodymium-zircon has been synthesised and characterised in order to analyse: (a) the stoichiometry of the solid solution, (b) the effect of the dopant concentration under the pigmenting properties, (c) the effect of the chromium precursor and mineralizers addition, (d) the effect of the synthesis method. The composition CrxCaMo1−xO4x=0.075 using K2Cr2O7 or Cr2O3 as chromium precursors fired at 1000–1100 °C produces a yellow colour, slightly lower in intensity than the commercial praseodymium-zircon yellow pigment in double (1000 °C) or single firing (monoporosa—1080 °C or porcelainized stoneware—1200 °C) ceramic glazes. By a coprecipitation method with ammonia, and firing at 950 °C, the yellow ceramic pigment glazed in a conventional CaO–ZnO–SiO2 glaze (monoporosa glaze, 1080 °C) shows a yellow colour similar to the commercial praseodymium-zircon yellow pigment. However the release and possible mobilization of the Cr (VI) should be controlled in order to get its industrial implementation.Authors acknowledge the financial support given by MEC (MAT2012-36988-C02-01 project)

Photocatalytic Glazed Tiles

A parent glass in the SiO2–CaO–ZnO–B2O3–K2O–Al2O3 system, deposited and processed by the monoporosa firing method (1085 °C), was coated using a sol–gel procedure and by serigraphy with silica, bismuth oxide, zirconia, and anatase with thermal treatment at 600 °C. The photocata- lytic activity of the samples determined by degradation in the Orange II dye test shows that a first-order reaction according to the Langmuir- Hinshelwood model is followed. From the UV-Vis-NIR results the band gap calculated is around 3.5 eV for the parent glass and that with a silica coating, and slightly lower for the other coatings. The needle-shaped microstructure of the parent glass shows the best photocatalytic results in agreement with the literature. The preserved zircon microstructure can explain the relatively high results for the silica coating, which unexpect- edly showed better results than both the anatase and tetragonal zirconia coatings. Finally, the interaction with the parent glass can explain the relatively high results of the bismuth oxide sampl

New chromium-calcium titanate red ceramic pigment

Synthesis and characterization of a new chromium- calcium titanate red ceramic pigment is described in this communication. The pigment is based on the solid solution of chromium (IV) in calcium titanate and was characterized as red-brown pigment in a CaO- ZnO-SiO2 transparent glaze used for ceramic tiles (1080oC). XRD, UV-Vis-NIR spectroscopy and CIE-L*a*b* techniques of characterization have been employed. The L*a*b* valour of the optimal pigment with 0,015 mol/mol of chromium fired at 1100oC with a soaking time of 3 hours and 5% weight added to the transparent glaze is 59.3/12.5/9.5. Likewise 5%w. addition of NHCl used as flux agent increase b* and decrease L* valour (L*a*b*=45.2/15.3/5.3)

Iron and chromium doped perovskite (CaMO3 M = Ti, Zr) ceramic pigments, effect of mineralizer

Solid solutions Ca(DxM1−x)O3 (M = Ti, Zr and D = Fe,Cr), have been studied as ceramic pigment in conventional ceramic glazes using 0.5 mol/mol of NH4Cl as flux agent by solid state reaction and by ammonia coprecipitation route. Ca(CrxTi1−x)O3 compositions obtained without addition of NH4Cl as mineralizer, produce pink color in glazes at low x but CaCrO4 crystallizes when x increases, producing undesired green colors. The crystallization of chromates can be avoided using NH4Cl as mineralizer, giving a complete solid solution that produce pink color in glazes at low x and dark blue shades at high x. Coprecipitated sample produce blue colors at low x and at low temperature than ceramic sample (1000 °C instead 1200 °C for CE sample). Cr4+ ion acts as red chromophore, but at higher x values (blue samples) Cr3+ ion entrance affects the color. Ca(FexTi1−x)O3 system crystallizes perovskite CaTiO3 and pseudobrookite Fe2TiO5 together with rutile as residual crystalline phase, glazed samples change from a yellow to a pink color associated to the increase of pseudobrookite with firing temperature. Ca(FexTi1−x)O3 and Ca(CrxZr1−x)O3 systems crystallize perovskite CaZrO3 and zirconia (ZrO2) in both monoclinic and cubic polymorphs, but iron or chromium oxides are not detected in the powders. Coprecipitated sample stabilises cubic form. The solid solution is not reached completely in these samples and is not stable in glaze

Photocatalysts in ceramics

Advanced oxidation processes (AOPs) are oxidation processes based on sufficient concentrations of hydroxyl radicals to degrade dissolved organic compounds present in water or those that are dispersed in air to mineral forms or at least toharmless organic compounds. It is a safe and clean technology and, in certain processes, solar radiation can be used as process initiator. Titanium oxide is currently the reference as photocatalytic material, given its high activity, relative stability, low cost, and low toxicity. In this study, the use of ‘ceramic’ photocatalysts (ceramic composites) in treatment processes for specific pollutants in urban environments (VOCs and NOx ) and waste waters (persistent, bioaccumulative and toxic (PBT) organic compounds) is analysed, as well as their use ‘in ceramics’ on glazed ceramic tiles as substrates for photocatalytic layers or photocatalytic glaze

Obtención de pigmentos cerámicos de perovskita CaTiO3 dopada con cromo y vanadio por descomposición metal-orgánica (MOD)

The Metal Organic Decomposition (MOD) route based on the chelation of a solution of metallic salts (usually nitrates) by policarboxylic acid (oxalic and citric), applied to the synthesis of ceramic pigments based on chromium and vanadium doped CaTiO3 perovskite, is presented in this paper. MOD synthesis allows preparing ceramic inks using the raw emulsioned materials directly or the nanostructured charried powders at 500ºC dispersed in DEG, and also stable ceramic pigments in glazes when the particle size and crystallization are sufficiently. In the CaTiO3 perovskite 20% molar modified with vanadium in the Ti position, ceramic inks using charried powders produce adequate orange shades and the fired powders at 1000ºC produce adequate orange colours in glazes. Samples of 1.5 molar addition of policarboxylic acids show the best pigmenting properties. In the case of CaTiO3 perovskite 1% molar modified with chromium in the Ti position, ceramic inks using charried powders produce adequate pink shades and the fired powders at 1000ºC produce adequate pink colours in glazes. Samples of 0.25 molar addition of policarboxylic acids show the best pigmenting propertie

Documentación necesaria para la introducción de un difractómetro de rayos X en una empresa

Treball Final de Màster Universitari en Prevenció de Riscos Laborals (Pla de 2013). Codi: SIS017. Curs acadèmic: 2018/2019.El objetivo del presente Trabajo Fin de Máster es el de exponer como se estudiaría y prepararía la documentación necesaria para la obtención de la autorización de alta de instalación radiactiva para el caso hipotético de la compra de un difractómetro de rayos X destinado a la medida de tensiones residuales por parte de una empresa. La autorización de alta de instalación radiactiva es un trámite que se realiza en la Secretaría de Estado de Energía (o en el respectivo departamento de Energía de cada Consejería de Industria en el caso de instalaciones de 2ª y 3ª Categoría en aquellas Comunidades con la transferencia adquirida). En el caso de la Comunitat Valenciana incluye los siguientes documentos (10): - Memoria descriptiva de la instalación. - Estudio de seguridad. - Verificación de la instalación, incluyéndose una descripción de las pruebas a que ha de someterse la instalación, y en caso necesario el plan de mantenimiento previsto. - Reglamento de funcionamiento. - Relación prevista de personal, la organización proyectada y la definición de las responsabilidades de cada puesto de trabajo. - Plan de emergencia interior. - Plan de protección física, en el caso de que el plan cuente con fuentes radiactivas incluidas en el ámbito de aplicación de la normativa relativa a la protección física. - Previsiones para la clausura y cobertura económica prevista para garantizar la misma en condiciones de seguridad. - Presupuesto económico de la inversión a realizar

In situ synthesis of orange rutile ceramic pigments by non-conventional methods

Different precursor-mixtures of orange Cr,Sb-TiO2 ceramic pigment have been obtained by non-conventional methods (heterogeneous ammonia coprecipitation, urea homogeneous coprecipitation, PECHINI polyester method and an original aqueous-organic coprecipitation method in water-diethylenglycol medium) in order to produce in situ the pigment through the ceramic body firing. The pigmenting performances of powders were appraised in two cases: (a) as ceramic pigment for glazed porcelain stoneware and (b) as ceramic inks for screen printing of porcelain stoneware. Samples were characterised by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), UV-vis-NIR spectroscopy by diffuse reflectance method, CIE-L*a*b* colour parameters, BET specific surface area and crystallite size measured by the Scherrer method. The colouring performance of raw powders obtained by non-conventional methods in glazed porcelain stoneware improves that of the ceramic samples fired at 1100 °C used as reference. TEM observations indicate nanostructured powders with pigmenting performance depending on factors such as their specific surface area (BET), the crystalline phases detected by XRD (e.g. anatase-rutile presence) and their crystallite size (Scherrer measurements). Ammonia coprecipitated samples, both in water and in water-diethylenglycol medium without surfactant addition, or modified by the addition of sodium dodecyl sulphate as surfactant, stand out by their colouring performance. © 2009 Elsevier Ltd and Techna Group S.r.l