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Titanium dioxide (TiO2) is used primarily as an opacifier in solid dosage forms and is present in the majority of tablet and capsule dosage forms on the market. The IQ* TiO2 Working Group has previously shown that titanium dioxide has unique properties which are necessary for its function in these formulations and noted that, as the potential replacements lack the semi-conductor properties, high refractive index and whiteness of E171, it might be hard to replicate these properties with alternative materials. In this paper we detail the results of readiness surveys and practical assessments that have been conducted with alternative materials by IQ member companies. A range of technical challenges and regulatory hurdles were identified which mean that, in the short term, it may be difficult to replace titanium dioxide with the currently available alternative materials while readily achieving the same drug product quality attributes, especially for some of the marketed formulations that titanium dioxide is currently used for. We note the higher technical complexity, due to the variability, color fading and identified scale up risk, of E171 free film coatings and the likely impact on development costs and timelines. We also highlight several regulatory hurdles that would have to be overcome if a titanium dioxide replacement was required for some markets but was not mandated by others. [ABSTRACT FROM AUTHOR]

Abstract Micronized zircon (ZrSiO4) is used as an opacifier in the production of engobes, opaque glazes, and floor tile bodies. Elevated price levels incentivize researchers to develop alternative engobe formulations with reduced zircon ratios. In this study, new engobes with low zircon content were developed with varying SiO2-Al2O3 mixtures. The effect of the SiO2/Al2O3 ratio on the performance and opacity of the wall and floor tile engobes was investigated. It has been observed that the amount of zircon in the sample compositions could be reduced up to 40% by optimizing the refractoriness-water absorption balance of the engobe with the SiO2/Al2O3 ratio while keeping the opacity in the preferred levels. The color difference (∆E) value relative to the standard surface was below 1, which is acceptable for visual perception for all the samples. Other measurements such as water absorption and firing shrinkage of the floor tile samples were found to be compatible with the standard composition.

SiO2 aerogel attracts much interest as thermal insulation material due to ultra-low density and excellent thermal performance at room temperature. However, the poor mechanical property and a mass of heat transfer by radiation in high temperature limit application of aerogels. Herein, a novel aerogel composite multiscale reinforced by glass fibers felt with SiC nanowhiskers (SiCnw) (AFS) was prepared. SiCnw were evenly distributed in glass fibers felts by freeze-drying method to form a uniform multiscale felt. The SiCnw inside felts provided more contact point with aerogel to increase the interfacial adhesion force so that compressive stress of aerogel composites with 4% volume fraction SiCnw was increased to 0.29 MPa. SiCnw blocked infrared radiation to decrease the heat transfer. Therefore, thermal conductivity at 500℃ of aerogel composite with 4% volume fraction SiCnw was only 0.040 W/(m·K). In a word, SiCnw reduced the sensitivity of thermal conductivity to temperature. AFS showed potential in the field of medium and high temperature insulation. [ABSTRACT FROM AUTHOR]

Micronized zircon (ZrSiO4) is used as an opacifier in the production of engobes, opaque glazes, and floor tile bodies. Elevated price levels incentivize researchers to develop alternative engobe formulations with reduced zircon ratios. In this study, new engobes with low zircon content were developed with varying SiO2/Al2O3 mixtures. The effect of the SiO2/Al2O3 ratio on the performance and opacity of the wall and floor tile engobes was investigated. It has been observed that the amount of zircon in the sample compositions could be reduced up to 40% by optimizing the refractoriness-water absorption balance of the engobe with the SiO2/Al2O3 ratio while keeping the opacity in the preferred levels. The color difference (E) value relative to the standard surface was below 1, which is acceptable for visual perception for all the samples. Other measurements such as water absorption and firing shrinkage of the floor tile samples were found to be compatible with the standard composition. [ABSTRACT FROM AUTHOR]

On-site pXRF analysis in various French collections (Musée du Louvre, Musée national des Arts asiatiques-Guimet, Paris) of porcelains decorated with painted enamels from the Qing Dynasty, in particular porcelains bearing an imperial mark, identifies the types of enamels/glazes, the ions and coloring phases or the opacifier. The study of the elements associated with cobalt (nickel, manganese, arsenic, etc.) and of the impurities of the silicate matrix (yttrium, rubidium and strontium) differentiates the use of 'Chinese/Asian' raw materials from ones imported from Europe by the initiative of the European missionaries (chiefly Jesuits) present at the Court (Beijing). Particular attention is paid to the analysis of the blue color of the marks and to the elements associated with the use of gold or copper nanoparticles as well as to the compositions of the pyrochlore phases (tin yellow, Naples yellow). The comparison is extended to pXRF and Raman microspectroscopy measurements previously made on other Qing imperial porcelains as well as on Cantonese productions (on porcelain or metal) from different Swiss and French museums and blue-and-white wares of the Ming and Yuan Dynasties (archaeological and private collections). [ABSTRACT FROM AUTHOR]

Zirconium silicate (ZrSiO4) is widely used commercially as an opacifying agent in the ceramic tile industry. But due to the high price of ZrSiO4, its alternatives are being discovered. In this research, a novel approach of replacing zirconium silicate with talc [Mg3Si4O10 (OH)2] in ceramic floor tile glaze has been investigated to make the glaze cost effective. Zirconium silicate is gradually replaced by six different weight percentages of talc in glaze compositions. All the prepared compositions were fired in a roller kiln under industrial conditions. After firing, all the samples were collected from the kiln exit and were subjected to various quality check tests like water absorption, bending strength, chemical test, thermal expansion and shrinkage. The color index for the fired samples is measured by CIELEB color space, and it is concluded that better opacity can be achieved by totally replacing zirconium silicate with talc. Resistance of the fired sample tiles to the chemicals attack is also studied, and no significant changes are observed on the surface of the sample tiles. The surface morphology of all the glazed sample tiles is analyzed by SEM and EDX. At the end, both opacifying agents, i.e., zirconium silicate and talc are economically analyzed, and it is concluded that the replacing of zirconium silicate with talc can reduce the cost of opacifier by 82%. [ABSTRACT FROM AUTHOR]

Resumen: Dado el interés histórico, artístico y tecnológico de las opalinas de la Real Fábrica de Cristales, se han formulado vidrios opales utilizando como opacificantes CaF2 y P2O5. El objetivo es obtener una composición compatible con el proceso de fabricación de la Fundación Centro Nacional del Vidrio usando el vidrio sonoro regularmente utilizado para la reproducción de piezas históricas. Los vidrios opales obtenidos se han caracterizado por espectrofotometría visible, difracción de rayos X, microscopia electrónica de barrido de emisión de campo y microanálisis de dispersión de energías de rayos X. Además, en los vidrios se ha medido la densidad, el coeficiente de dilatación térmica, la temperatura de transición vítrea y el índice de blancura. Los resultados indican que la opacificación que tiene lugar está directamente relacionada con la nucleación de microcristales y la separación de fases líquida. En los vidrios opacificados con CaF2 se produce la nucleación de microcristales de fluorita, mientras que en los opacificados con P2O5 tiene lugar un proceso combinado de nucleación de difosfato de silicio y silicato de calcio y de separación de fases. La opacificación inducida por CaF2 es más intensa que la que proporciona el P2O5, y adecuada para incorporar Co2+ a fin de obtener una opalina de color azul. Abstract: Due to the historic, artistic and technological interest of opalinas from the Royal Glass Works of San Ildefonso (Spain), several opal glasses have been formulated in which CaF2 and P2O5 were the opacifiers. The objective is the obtaining of a composition that will be compatible with the production process of the National Glass Centre Foundation starting from the crystal glass commonly used for the historic pieces reproduction. The opal glasses obtained were characterized by visible spectrophotometry, X-ray diffraction, field emission scanning electron microscopy and dispersive X-ray microanalysis. Likewise, measurements of density, thermal expansion coefficient, glass transition temperature and whiteness index have been carried out. The results showed that opacification is directly connected with microcrystals nucleation and phase separation. In glasses containing CaF2 the nucleation of fluorite microcrystals takes place, while in those opacified by P2O5 a combined process of silicon diphosphate/calcium silicate nucleation plus a phase separation occurs. The opacification induced by CaF2 is more intense that those of P2O5. Moreover, in the CaF2 containing composition the incorporation of Co2+ to obtain blue opalinas works correctly.

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• Heat transfer mechanisms of alumina aerogel-fiber-opacifier composites were studied. • An analytical thermal conductivity model of composites was developed. • Solid-gas coupling heat transfer in aerogels was found to be a dominant mechanism. • Contribution of gaseous conduction was comparable to solid conduction and radiation. • The optimal diameters and volume fractions of fibers and opacifier were obtained. As compared with silica aerogels, alumina aerogels have excellent high-temperature stability, and hence, are regarded as a promising candidate for high-temperature thermal insulation materials. However, heat transfer mechanisms for such materials remain insufficiently explored. In this study, based on real material microstructures, an analytical thermal conductivity model for alumina aerogel-fiber-opacifier composites is developed via a modified parallel-series equivalent electrical circuit approach. The model takes into account solid, gaseous, and solid-gas coupling heat conduction in aerogels, solid heat conduction in both fibers and opacifier particles, and radiation in aerogels, fibers, and opacifier particles. The model is validated by comparing its predictions with measured thermal conductivity data. The model predictions reveal that there are two kinds of solid-gas coupling heat transfer mechanisms, which occur in the corner regions between interconnected secondary particles and in the slit regions between adjacent chains, respectively. Because of this coupling, the contribution of gaseous heat conduction is comparable to that of solid heat conduction and radiation of aerogels, fibers, and opacifier particles, which is well supported by experimentally measured data of thermal conductivity. The model is also used to analyze effects of various parameters on the thermal insulation performance of the composites, such as diameters and volume fractious of both fibers and opacifier particles. [Display omitted] [ABSTRACT FROM AUTHOR]

The reduction of radiation heat transfer in VIPs is an important issue. In VIPs, the radiation heat transfer is reduced by the use of opacifier. However, the amount of opacifier also significantly affects the cost of VIP. In this study, the effect of different types and sizes of opacifiers on VIP thermal conductivity was investigated. For this purpose, 6 VIP samples containing different opacifiers (SiC, graphite and calcium aluminate in 3 different grain sizes) were produced. Fumed silica, glass fiber and opacifier were used as fillers in VIP cores at 65%, 20% and 15% (by mass), respectively. VIP samples were vacuumed up to 0.1 Pa, and their thermal conductivity coefficients were measured according to TS EN 12667 standard. In addition, transmittance ratios (%T) of fumed silica, glass fiber, opacifiers and core samples were measured by FTIR spectrophotometer and the mass extinction coefficients of each sample were calculated. The silicon carbide (F1000) as the opacifier (e: 399 m2 kg−1) and the graphite-containing core among the VIP core samples (e: 149 m2 kg−1) exhibited the highest mass absorption coefficient. In addition, the thermal conductivity of the core samples without barrier was measured under 1 Pa vacuum and then the radiation conductivities were calculated from the obtained data. F800 type SiC significantly reduced radiation heat transfer, while the solid conduction of the core was increased due to its relatively coarse grain size. VIP sample with SiC (F1200) provided the lowest thermal conductivity at 0.1 Pa (3.94 mW mK−1). As a result, F1200 type SiC was found to be the most efficient type of opacifier among the investigated opacifiers. [ABSTRACT FROM AUTHOR]

In August 2014, a pit containing more than 10000 porcelain shards was excavated in the southwestern area of the Palace Museum. Reign marks and other stylistic criteria dated the manufacture of these fragments from the reign of Hongwu in the Ming Dynasty (1368–98 CE) to the Guangxu reign in the Qing Dynasty (1875–1908 CE). A famille rose (fencai, 粉彩) bowl decorated with a red-ground peony pattern and having the reign mark of Qianlong (1736–96 CE) on the base was studied using several non-destructive analytical methods to determine the variation in overglaze compositions, the colorants, the application sequences, the thickness of the colored layers and the high-temperature porcelain glaze, and the identification of the surface weathering products that formed during burial. The methods include non-destructive X-ray fluorescence, Raman spectroscopy, optical stereomicroscopy, and laser confocal microscopy, as well as X-ray diffraction. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Unit cell model was modified and developed for nanocomposite silica aerogel. • A novel class of silica/clay mineral nanocomposite aerogel was synthesized. • The effective thermal conductivity of nanocomposite aerogel was predicted. Abstract The crucial effect of the morphology of nanocomposite aerogel on its effective thermal conductivity caused the presence of comprehensive theoretical investigation. Classic unit cell model provided an analytical relationship between microstructure and thermal conductivity of pristine silica aerogels, but the predicted results showed more than 250% deviation from the experimental results. In this work, the classic unit cell model was modified for nanocomposite aerogel by considering the effect of phonon scattering, secondary porosity, and clay mineral presence. The modified classic unit cell model (MCUM) acted as a powerful tool in the analysis of thermal conductivity mechanism of silica/clay mineral nanocomposite aerogels. Clay mineral was utilized to improve thermal radiation insulation properties of nanocomposite aerogels. Experimental results revealed that addition of 7 wt% clay mineral to silica aerogel led to a 55% reduction in thermal radiation heat transport at 700 °C. MCUM showed good agreement with experimental results with a less than 10% deviation for neat and nanocomposite aerogel. [ABSTRACT FROM AUTHOR]

Abstract Expanded PolyStyrene (EPS) foams are very widely used as thermal insulators, especially for the Building insulation. Therefore, the heat transfer in these materials has been extensively studied and optimised. Nevertheless, due to their very low density, the IR thermal radiation propagating through their porous structure still contributes significantly to the total heat transfer. In order to increase their insulation performances even more, the addition of particles strongly interacting with IR radiation in the polymer matrix is very promising. We have investigated this solution from the theoretical and experimental points of view. The influences of the presence of particles on both the conductive and radiative properties of the opacified foams have been modelled. A parametric study allows us to highlight the key properties required to make the opacifying particles efficient and to evaluate the corresponding potential savings. Alongside, several powders have been tested experimentally by incorporating them into polystyrene thin films. Spectrometric measurements conducted on these films allow us to identify their radiative properties, evaluate the reduction of equivalent conductivity and confirm the efficiency of the solution. This investigation then constitutes a useful tool for selecting appropriate opacifiers. [ABSTRACT FROM AUTHOR]

Surface smoothness of ceramic glazes is always an important characteristic of ceramic glazes as a point of surface engineering studies. Surface roughness affects chemical resistivity, glossiness and stainabiliy of glazes. In fact, less surface roughness improves cleanability of the surface by the least usage amount of detergents. In this investigation, surface topography of two common opaque glazes, zirconia and titania-based, has been investigated. Crystallinity of the surface has been studied from SEM images, and comparison of EDS elemental results with phase analysis results of XRD. Surface roughness profile measured by Marsurf M300, shows that titania-based glaze is almost 24% percentage more smooth than zirconia based glaze. Surface smoothness is in relation with crystallinity of glaze surface, crystal type and crystal distribution in amorphous matrix phase

Due to their high-porosity, nanoporous structure and pores, aerogel materials possess extremely low thermal conductivity and have broad potential in the thermal insulation field. Silica aerogel materials are widely used because of their low thermal conductivity and high temperature resistance. Pure silica aerogel is very fragile and nearly transparent to the infrared spectrum within 3-8 µm. Doping fibers and opacifiers can overcome these drawbacks. In this paper, the influences of opacifier type and content on the thermal conductivity of silica fiber mat-aerogel composite are experimentally studied using the transient plane source method. The thermal insulation performances are compared from 100 to 750 °C at constant pressure in nitrogen atmosphere among pure fiber mat, fiber mat-aerogel, 20% SiC-fiber mat-aerogel, 30% ZrO2-fiber mat-aerogel and 20% SiC + 30% ZrO2-fiber mat-aerogel. Fiber mat-aerogel doped with 20% SiC has the lowest thermal conductivity, 0.0792 W/m⋅K at 750 °C, which proves that the proper type and moderate content of opacifier dominates the low thermal conductivity. The pore size distribution indicates that the volume fraction of the micropore and mesopore is also the key factor for reducing the thermal conductivity of porous materials. [ABSTRACT FROM AUTHOR]

Fibrous aerogel composites have attracted considerable attention in the field of insulation materials due to their low thermal conductivity and elasticity. However, they cannot meet the thermal insulation performance under practical application conditions due to their high infrared radiation transmittance and limited thermal stability. A novel strategy for embedding anatase TiO 2 nanoparticles in SiO 2 nanofibers was reported herein. TiO 2 nanoparticles embedded in SiO 2 nanofibers with bead-on-string structures were prepared through electrospinning, which leads to enhanced binding force between nanofibers and opacifier nanoparticles and uniform dispersion of opacifier in nanofibrous aerogel composites. Combined with freeze-drying technology, nanofibrous aerogel composites with the lamellar structure were prepared, which possessed ultra-low density of 5.8 mg/cm3 and superior compression strength (6.71 kPa at 40% strain) and fast recovery after compression. In addition, the obtained aerogel composites exhibited low infrared transmittance (60% at 3 µm), thermal conductivity (0.0257 W/mk at room temperature), splendid flame-retardant properties, and thermal insulation properties. The combined structural stability and low infrared transmittance offer an ideal candidate for thermal insulation under extreme conditions. • TiO 2 nanoparticles embedded in SiO 2 nanofibers with bead-on-string structures. • Uniform dispersion of opacifier in nanofibrous aerogel composites. • Lamellar structure offers superior compression strength and fatigue-resistance. • TiO 2 nanoparticles opacifier provides lower infrared transmittance. • Nanofibrous aerogel composites with excellent flame retardant performance. [ABSTRACT FROM AUTHOR]

Vacuum insulation panel (VIP) is known to be the most effective insulation material. However, the usage areas of VIPs are restricted because of their high production costs. The core of VIP is the most important item affecting the cost of VIP. In this study, to obtain VIPs, which are provided with minimum thermal conductivity resistance value (R=5 m2 K/mW), was aimed for the optimal thickness of the panel (

To improve the high-temperature thermal insulation characteristics of silica aerogels, it is important to reduce the radiative heat transfer. This can be achieved by Y 2 O 3 doping in the silica sol to opacify the infrared radiation of silica aerogels. The purpose of the present work was to study the effect of Y 2 O 3 incorporation on the structural and physicochemical properties of opacified silica aerogels prepared by a simple ambient pressure drying method. The influence of Y 2 O 3 addition on specific extinction coefficient and high temperature thermal insulation of prepared aerogels were investigated. The synthesized aerogels were lightweight and crack-free, with a granular, nanoporous morphology. The specific surface area, pore diameter, and bulk density of the prepared samples were 917.5–937.6 m 2 /g, 5.64–6.58 nm, and 0.047–0.076 g/cm 3 , respectively. The thermal conductivity of opacified silica aerogel at 1000 K was 0.080 W/(m.K), which was lower than the unopacified silica aerogel and it was around 0.104 W/(m.K) at same temperature. [ABSTRACT FROM AUTHOR]

Due to pure silica aerogel is fragile and nearly transparent to 3–8 μm infrared beam, reinforced fiber and opacifier are composited with silica aerogel to optimize its performance. The suppression of radiative heat transfer is related to opacifier type, size and content. However, the addition of opacifier will enhance solid conduction inevitably. In addition, the influence of doping opacifier will also be affected by temperature since thermal radiation is temperature and wavelength dependent. Therefore thermal conductivities of 10 fiber and opacifier doped silica aerogel composites are studied experimentally and theoretically. Transmittances of silica aerogel doped with opacifier of different type, size and content are measured within 1.4–25 μm by FTIR. The spectral extinction coefficient of fiber/opacifier loaded silica aerogel composite is obtained by considering the practical absorption of KBr diluents. The thermal conductivity of silica aerogel composite is measured by transient plane source method at different temperature and gas pressure. Effective model with considering heat conduction via gaseous molecules, matrix skeleton, fiber, opacifier and thermal radiation via skeleton, fiber and opacifier is developed for fast predicting the thermal conductivity of fiber/opacifier doped silica aerogel composite. It is found that the silica aerogels doped with SiC or TiO 2 particles has lower radiative thermal conductivity than that doped with ZrO 2 particles with volume fraction of 3.75% and diameter of 3.5 μm. Silica aerogel doped with 3.75%, 3.5 μm SiC particles has the lowest thermal conductivity at temperature less than 1000 K. [ABSTRACT FROM AUTHOR]

Aerogel containing ceramic fibre insulations represent a newly developed high performance insulation material applied in industrial installations and recently expanding rapidly into the construction industry to reduce the heat transfer through walls and ceilings. As a rather expensive material they are preferentially used in cases where slim layers of insulation are needed mainly in refurbishing of existing buildings especially those under heritage protection. The reaction to elevated temperatures in case of fire is a decisive property for building applications. The present article investigates the reaction to fire of an aerogel containing ceramic fibre insulation already available on the market. This reaction was monitored experimentally by means of temperature sensors at different depth in the material when subjected to the standard ISO fire. The measured temperature evolutions are discussed with respect to radiative heat transfer in an optically thick medium, temperature induced changes in density because of mass loss and the occurrence of endothermic and exothermic reactions detected by thermal analysis and compared with simulation results. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper deals with the effect of thermal shock treatment on grindability and grinding characteristics of zircon minerals and the overall energy saving achieved. This attempt is made due to a fine dry grinding of zircon minerals to produce zircon flour is an energy intensive operation. The effect of grinding time on grinding of zircon minerals in a continuously agitated rod mill indicate that the time required is 170 minutes for obtaining 75% of particles passing 45 µm size for natural zircon mineral whereas for thermally treated zircon it is only 100 minutes to achieve the same. Hence, 70 minutes of grinding time is saved. The work index test results show that 13.3% of the total energy can be saved when a sample is preheated to 850 °C and subjected to thermal shock treatment. The effect is due to the development of numerous micro-cracks and fractures in samples subjected to thermal shock.

The present research was conducted to assess the feasibility of using two kinds of industrial wastes as opacifiers in porcelain tile bodies, as well as to define what pre-treatment would be required to prepare the wastes for such use. The characteristics of the wastes were analysed, first, to determine their chemical and mineralogical composition, as well as their behaviour when subjected to heat, in order to identify any undesirable substances and to establish suitable conditions for removing these with simple methods. This allowed suitable materials to be obtained for use in porcelain tile compositions. The effects were then studied of the incorporation of these pre-treated waste materials on porcelain tile characteristics. The results obtained indicate that the two waste materials used in this research have a significant opacifying capability, which makes them of great interest as possible raw materials for products that are not required to have maximum whiteness values. The only drawback detected in one of these wastes was that the porcelain tile composition needed to be slightly adjusted in order to ensure that its behaviour during firing did not change.La investigación se ha realizado con el objetivo de evaluar la viabilidad de utilizar dos residuos industriales como opacificantes para pastas de gres porcelánico, así como definir los tratamientos previos que serían necesarios para efectuar dicha incorporación. Inicialmente se han caracterizado los residuos, determinando la composición química y mineralógica, así como el comportamiento térmico, con el objeto de identificar las sustancias indeseables y establecer las condiciones adecuadas para eliminarlas mediante tratamientos simples. De este modo fue posible obtener materiales aptos para su incorporación a las composiciones de gres porcelánico. Posteriormente se han estudiado los efectos de la incorporación de los residuos tratados sobre las características del gres porcelánico. Los resultados obtenidos indican que los dos residuos investigados poseen un poder opacificante apreciable, lo que les confiere interés como posible materia prima en productos donde no sean necesarios valores máximos de blancura. La única desventaja detectada con uno de ellos es la necesidad de realizar cierto reajuste en las composiciones de gres porcelánico para mantener invariable su comportamiento durante la cocción.

Plasmonic nanoparticles are doped in silica aerogels for high-efficiency photothermal conversion of solar energy in seawater desalination and so on. However, this suffers from remarkable heat loss problem via near-infrared radiation. The present work proposes a novel aerogel composited with both plasmonic nanoparticles and opacifiers. The radiative characteristics of the aerogel composite were numerically investigated by coupling the T-matrix method and Monte Carlo method. The opacifiers promote the extinction characteristics in the infrared wavelength range and reduce the radiative thermal conductivity, while the plasmonic nanoparticles enhance the absorption efficiency in the solar spectrum. Moreover, silica aerogels doped with both silver nanoparticles and indium tin oxide (ITO) particles were prepared and tested. It is found that the optimal radius and volume fraction of ITO particles are 1000 nm and 1% at 300 K, respectively, based on the silica aerogel (particle radius of 5 nm and porosity of 95%) doped with silver plasmonic nanoparticles (particle radius of 10 nm and concentration of 5%). They can achieve an absorption efficiency of 87.65% in the solar spectrum and a low transmittance in the infrared range with reduced heat loss. The present work paves a new way to design full-spectrum absorption aerogels for high-efficiency photothermal conversion. • A new aerogel composited with opacifiers and plasmonic nanoparticles is prepared. • The proposed aerogel composite achieves 87.65% solar absorption efficiency. • The low transmittance in the infrared range reduces the radiative heat loss. • Optimum diameter and concentration of opacifiers are determined. • The enhancement mechanism of solar-thermal conversion is revealed theoretically. [ABSTRACT FROM AUTHOR]

Radiative heat transfer at high temperature deteriorates the insulating capability of silica aerogel due to its poor extinction characteristics for wavelength below 8 μm. Both the infrared opacifier doping and fiber doping can reduce the heat transfer and improve insulating capability of silica aerogel efficiently at high temperature. We determine the optimal temperature-dependent size for typical opacifiers and silica fibers by combining the spectral extinction coefficient with blackbody radiation. The optimal temperature-dependent doping amount is obtained by minimizing the effective thermal conductivity. Based on the obtained temperature-dependent optimal parameters and the graded temperature distribution in silica aerogel, four solutions of multi-layer graded doping are presented and the insulating capability is improved effectively. The measured back temperature curves of doped silica aerogel in the experiment qualitatively verify the optimization predictions. [ABSTRACT FROM AUTHOR]

The paper presents a historical evolution of compositions and applications of glazes on various ceramics (majolica, facing tile, glazed pottery, porcelain). The origin and development of artistic and industrial enameling processes for metals are described. The effect of additions in glazes and enamels on the color and transparency of decorative, artistic, and technical vitreous coatings on metallic and nonmetallic materials is exemplified by objects created in different historical epochs. [ABSTRACT FROM AUTHOR]

Surface smoothness of ceramic glazes is always an important characteristic of ceramic glazes as a point of surface engineering studies. Surface roughness affects chemical resistivity, glossiness and stainabiliy of glazes. In fact, less surface roughness improves cleanability of the surface by the least usage amount of detergents. In this investigation, surface topography of two common opaque glazes, zirconia and titania-based, has been investigated. Crystallinity of the surface has been studied from SEM images, and comparison of EDS elemental results with phase analysis results of XRD. Surface roughness profile measured by Marsurf M300, shows that titania-based glaze is almost 24% percentage more smooth than zirconia based glaze. Surface smoothness is in relation with crystallinity of glaze surface, crystal type and crystal distribution in amorphous matrix phase. [ABSTRACT FROM AUTHOR]

This paper faces the problem of acquiring archaeological artifacts using triangulation based 3D laser scanners and focusing on reflective/refractive surfaces. This kind of artifacts are mostly made of glass or polished metal, and the properties of their surfaces violate most of the fundamental assumptions made by vision algorithms. Also, the unique and fragile nature of archaeological artifacts adds an extra constraint to the acquisition process: the use of industrial whitening sprays has to be avoided, due to the physicochemical processes required to clean the surface after scanning and because the chemical properties of these sprays may damage the original object. As an alternative to them, a new way to use a common conservation material is proposed: the use of cyclododecane as a whitening spray. Thanks to its chemical stability and to the fact that it sublimes at room temperature, together with its good film-forming capabilities, a set of evaluation tests is presented to prove that the error introduced by the opaque thin layer created on the surface of the artifact is smaller than the accuracy of the 3D scanner and, thus, no acquisition errors are introduced. A comparison with general-purpose industrial whitening sprays is also presented, and achieved results show no significant differences in the quality of the resulting 3D models. [ABSTRACT FROM AUTHOR]