Effect of coating on cleanability of glazed surfaces

The aim of this study was to establish the effects of different coatings on the cleanability of glazed ceramics. The surface properties were examined with a contact angle meter, a contact profilometer and a confocal microscope. The surfaces were soiled with three radiochemical model soils: inorganic particle soil, organic particle soil and oil soil. Soil adhesion on surfaces was measured with a quantitative radiochemical procedure. Generally, cleanability of the particles present in the model soil was found to be affected by the roughness of the surfaces; however, the cleanability of the oil in the model soils correlated with the contact angle of water on the surfaces. Coating of glazes, especially with fluoropolymer film, generally increased the contact angle values. The coatings affected the cleanability of ceramics somewhat: particle soils were removed most efficiently from glazes coated with TiO₂ and Zr. By contrast the oil soil residues of the fluoropolymer surfaces were the lowest. The cleanability results of the three model soils based on inorganic or organic particles or oil were different indicating differences between the cleanabilities of these main components of the soils.     

Effects of UV-radiation on the cleanability of titanium dioxide-coated glazed ceramic tiles

The effects of UV-radiation on the cleanability of three glazed tiles coated with ceramic sol–gel derived TiO₂ were evaluated. A quantitative radiochemical determination method was used to measure oil and organic particle soil residues on the surface. Surfaces were characterized with topography and contact angle measurements. The observed effects of UV-radiation were greatest on rough surfaces, implying that increasing roughness increases the surface area available for photo-induced phenomena in the TiO₂-surface. Organic particle soil was removed more efficiently after UV-radiation than without UV treatment, whereas UV-radiation did not affect the removal of oil soil. Contact angles decreased significantly after UV-radiation.     

The challenge of antimicrobial glazed ceramic surfaces

The resistance that microorganisms develop to antibiotics is a worldwide challenge. The antimicrobial agents as disinfectants for surface treatments are widespreadly used to prevent the proliferation of microorganisms, but their use should be repeated over time to ensure a complete microbe-free surface. Surfaces with permanent antimicrobial properties suppose a recent demand in materials science for functional polymeric coatings, metals, treated wood or ceramic glazed tiles. Whereas polymeric coating has been extensively studied, the antimicrobial functionality on ceramic glazed surfaces is not completely achieved. This work reviews glazed ceramic tiles developments in antimicrobial and virucidal surfaces. The main antimicrobial physical or chemical mechanisms have been described as the base to develop active glazed surfaces. The main tests required to evaluate the antimicrobial response in glazed ceramic tiles are also summarized. The high temperature required in the ceramic processing is the key point to achieve a micro/nanostructure that potentiates the antimicrobial and virucidal response of the glazed surfaces. A discussion on recent developments as well as the main routes and challenges to obtain permanent surfaces with antimicrobial and virucidal response is provided.     

Corrosion resistance and cleanability of glazed surface

This work aimed to study the effect of surface properties on the corrosion resistance and cleanability of glazed surface. The samples were zircon-containing raw glaze, zirconium-based frit glaze, double-glazed transparent glaze, and raw glaze coated with TiO₂ film. The corrosion resistance of the samples in acidic, alkaline, and household detergent solutions was investigated by the changes in contact angle and surface roughness. Besides, the cleanability of the samples before and after corrosion was also compared. It was found that the corrosion resistance of a glaze was affected by the presence of crystals and their distribution, while the corrosion resistance of TiO₂ film was closely related to itself and the nature of the substrate. The cleaning test showed that although adding a layer of transparent glaze reduced the surface roughness, it did not improve the cleanability. The TiO₂ film had excellent cleaning performance, especially after ultraviolet light irradiation, but it had weak alkali corrosion resistance. Therefore, a zirconium-based frit glaze is the right choice for sanitary ware in terms of durability and easy cleaning.     

Chemical resistance and cleaning properties of coated glazed surfaces

The effects of sol–gel-derived ceramic titania and zirconia coatings on staining resistance and cleanability of two matt and one glossy glazed tile were characterized. The surfaces were soaked in a weakly alkaline detergent solution in order to imitate the influence of normal household detergents on the surface properties. The soaking caused the water contact angle of the surfaces to decrease and also changes were observed in the average surface roughness. The surfaces were soiled with one color marked and two radiochemically labeled soil mixtures of oils and inorganic or organic particles. Under normal laboratory illumination conditions, the soils consisting of oil and inorganic particles were more easily cleaned from the surfaces than the soil with oil and organic particles. All surfaces soiled with the color marked mixture were also studied under exposure to UV light. The titania coating increased the cleanability and also showed self-cleaning capability after exposure to UV light, whereas exposure to UV increased the soil adherence to the zirconia-coated surfaces.     

Microstructural and mechanical changes by chemical ageing of glazed ceramic surfaces

In the present work, several ceramic tiles, characterised by different glazes, were considered in order to define the role played by the glassy and crystalline phases on the leaching mechanisms and the deterioration of the mechanical properties. The glazed working surfaces were subjected to chemical attack by using a strong basic solution and the chemical analysis of the leached solutions was performed. Before and after the chemical attack, the glazed surfaces of the samples were analysed from both the microstructural and mechanical point of view. In this context, the microstructure was observed by SEM and analysed by X-ray diffraction. In order to define other possible changes, roughness measurements, Vickers hardness and micro-scratch tests were also performed.The results made it possible to deepen the understanding of the mechanisms of elements release caused by the chemical attack and their implications on microstructural and mechanical degradation of the working surface of glazed ceramic tiles.     

Thermally stable and photocatalytically active titania for ceramic surfaces

The most photocatalytically active titania modification anatase must be stabilised to achieve high photocatalytic activity in ceramic processes at temperatures above 1000 °C. Thermally stable TiO₂ powders were prepared by the addition of silica and boehmite nanoparticles and deposited on corundum substrates and lead-free glazes. The powders and coatings were fired at increasing temperatures, and stabilisation of the anatase phase was achieved up to 1200 °C. In general, thermal stability was found to be lower when coated on substrates compared to the powder alone, and the extent of reduction depended on the chemical composition of the substrate. Only a slight modification of the titania electronic structure was found, indicating only weak interactions between silica and titania. Based on these results it is possible to assume an amorphous silica and alumina shell encases the titania particles which prevents grain growth and the anatase to rutile phase transformation.     

Wetting behavior of polymer melts on coated and uncoated tool steel surfaces

The wettability of steel and coatings used for tools and screws in polymer processing is often determined at room temperature. However, it has to be taken into account that polymeric materials are processed at higher temperatures. Contact angle measurements of melted PP, HDPE, PMMA, and PA 6.6 on steel and on TiN, TiAlN, CrN, DLC, and PTFE were performed in this work to investigate the wetting behavior under closer‐to‐processing conditions. The contact angle is dependent on time and the ambient atmosphere. Oxidation and degradation of the polymer melts influence wetting significantly. TiN, TiAlN, CrN, and DLC exhibit a rather good wettability, whereas the highest contact angle of the polymer melts was observed with PTFE. Higher roughnesses of the surfaces lead to an increase in the contact angle. It was also shown that a higher temperature causes a better wetting of the solid surfaces. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43469.     

Electrokinetic desalination of glazed ceramic tiles

Electrokinetic desalination is a method where an applied electric DC field is the driving force for removal of salts from porous building materials. In the present paper, the method is tested in laboratory scale for desalination of single ceramic tiles. In a model system, where a tile was contaminated with NaCl during submersion and subsequently desalinated by the method, the desalination was completed in that the high and problematic initial Cl⁻ concentration was reduced to an unproblematic concentration. Further conductivity measurements showed a very low conductivity in the tile after treatment, indicating that supply of ions from the poultice at the electrodes into the tile was limited. Electroosmotic transport of water was seen when low ionic content was reached. Experiments were also conducted with XVIII-century tiles, which had been removed from Palacio Centeno (Lisbon) during renovation due to damage of the glazing from the presence of salts. These tiles were severely contaminated with both chlorides and nitrates, and one of the tiles also contained sulphates though at a low concentration. The charge transfer was too low in the experiments to obtain full desalination, but promising results were obtained as significant decreases (>81% Cl⁻, ~59% NO₃ ⁻ and ~22% SO₄ ²⁻) were seen.     

Fracture behavior of coated/uncoated graphite-epoxy composites

The static delamination behavior of graphite/epoxy composite specimens subjected to mode I tensile opening (using UDCB

1 Uniform double cantilever beam.

specimens), and pure mode II shear loading (using ENF

2 End-notched flexural.

specimens) were studied. The graphite epoxy composites for the study were made from commercially treated fibers, with and without an electropolymerized interlayer. The mode I fracture energy (G_IC) was found to be significantly higher (more than 50 percent) for the coated fibers. However, this improvement was accompanied by a high reduction (more than 3 times) in the mode II fracture energy (G_IIC). This effect is apparently related to poor adhesion between the interlayer and the epoxy resin, which may be corrected by use of a “top layer” of appropriate composition to form chemical bonds between the phases. The fracture toughness (K_IC) of composites made with commercially treated fibers was also evaluated, using double side-notched specimens.     

Microstructure and permeability of porous zirconia ceramic foams prepared via direct foaming with mixed surfactants

The permeability performance of porous ceramics from particle-stabilized foams is closely associated with the connectivity between bubble-evolved pores. In order to regulate the connectivity of pore structure, the zirconia ceramic foams were fabricated by direct foaming with mixed surfactants of cetyltrimethyl ammonium bromide (CTAB) and sodium N-lauroyl sarcosinate (SLS). Different solid loadings and CTAB:SLS mixing ratios were used in this study. The results indicate that the pore structures of zirconia ceramic foams were interconnected by open windows on the cell walls, and the porosity and average size of cell and cell windows could be tailored by adjusting the solid loading and CTAB:SLS mixing ratio. The decrease in solid loading and CTAB:SLS mixing ratio caused larger porosity and size of cells and cell windows, and thus resulted in the obvious augment of Darcian (k₁) and non-Darcian (k₂) permeability constants. The ranges of k₁ and k₂ of the as-fabricated zirconia ceramic foams are 6.92 × 10^?13-4.05 × 10^?10 m² and 2.09 × 10^?5-3.19 × 10^?9 m respectively.     

Functionalization and metallization of fluoropolymer surfaces through reduction1,2

Fluoropolymer films, such as Teflon?-TFE [poly(tetrafluoroethylene)], Teflon?-FEP [copolymer of tetrafluoroethylene and hexafluoropropylene], Teflon?-PFA [copolymer of tetrafluoroethylene and perfluoro(propyl vinyl ether)], and PCTFE [poly(chlorotrifluoroethylene)], are reduced by the mild reducing agent benzoin dianion/DMSO, while Teflon?-AF [copolymer of tetrafluoroethylene and perfluoro-2,2-dimethyl-1,3-dioxole] is unreactive. The reduction makes the films adherable toward epoxy resins, the adhesive strength decreasing in the order PCTFE>PFA≥FEP>PTFE. Surprisingly, Teflon?-AF films are totally inert except when the TFE content is high, and in these cases the adhesive strength of Teflon?-AF is close to that of PTFE. The surfaces of PTFE, FEP and PFA films are further modified by first treating these films with the benzoin dianion/DMSO reagent and then with an excess of sodium salts of mercaptans. Reactive PTFE films that are light colored with a metallic luster are formed rather than the dark, metallic color typical of PTFE surface reduction without mercaptan treatment. These films have poor adhesion toward epoxy resins but good adhesion toward gold applied by sputtering. FEP and PFA films behaved similarly. These results are attributed to the incorporation of sulfur onto the reduced surface. Unreduced fluoropolymer films reacted with only sodium mercaptan fail to show C—S bond incorporation. This newly developed method can be used to selectively metallize the fluoropolymer film surface with gold layers and affords very high conductivity of the metallized regions. © 1995 John Wiley & Sons, Inc.     

Functionalization of fluoropolymer surfaces with nanopatterned polyelectrolyte brushes

We present a strategy to combine the excellent bulk properties of fluoropolymer substrates with the wide range of functionalities of surface-grafted polyelectrolyte brushes. Patterns of radicals serving as initiators were created by irradiation with extreme ultraviolet light (EUV) in an interference setup at the Swiss Light Source. From these initiators, brushes of poly(methacrylic acid) or poly(4-vinylpyridine) were grafted in one step by free-radical polymerization. Brushes carrying primary or secondary amines, i.e. poly(vinylamine), poly(allylamine) and poly(N-methyl-vinylamine), were obtained by grafting vinylformamide and acrylonitrile followed by hydrolysis or reduction. Periodic patterns with a resolution of 200 nm were achieved, while the thickness of the brushes in unpatterned areas could be controlled over a range of several hundred nanometers by variation of EUV dose and grafting parameters. The maximum dry brush thickness was used to estimate the average molecular weight of the polymer chains.     

Catalytic upgrading of biomass fast pyrolysis vapors with titania and zirconia/titania based catalysts

Fast pyrolysis of poplar wood followed with catalytic upgrading of the pyrolysis vapors was performed using analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The catalysts applied in this study were three commercial meso- or macroporous catalysts (TiO₂ (Rutile), TiO₂ (Anatase) and ZrO₂&TiO₂) and their modified ones with incorporation of Ce, Ru or Pd. These catalysts displayed different catalytic effects on the pyrolytic products. The TiO₂ (Rutile) based catalysts, especially the Pd/CeTiO₂ (Rutile), were effective to convert the lignin-derived oligomers to monomeric phenolic compounds, with the phenols increasing from 25.6% in the non-catalytic products to 37.2% after catalyzed by the Pd/CeTiO₂ (Rutile). The ZrO₂&TiO₂ based catalysts were the most effective to change the pyrolytic products. They significantly reduced the phenols, acids and sugars, and meanwhile, increased the hydrocarbons, linear ketones and cyclopentanones. The highest hydrocarbon content of 13.1% was obtained by the ZrO₂&TiO₂, compared with only 0.1% in the non-catalytic products. The catalytic effects of the TiO₂ (Anatase) based catalysts were between that of the TiO₂ (Rutile) and ZrO₂&TiO₂ based catalysts.     

Fabrication and electrochemical properties of SOFC single cells using porous yttria-stabilized zirconia ceramic support layer coated with Ni

A porous yttria-stabilized zirconia (YSZ) ceramic supported single cell with a configuration of porous YSZ support layer coated with Ni/Ni–Ce_0.8Sm_0.2O_1.9 (SDC) anode/YSZ/SDC bi-layer electrolyte/La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ cathode was fabricated. The porosity, mechanical strength, and microstructure of porous YSZ ceramics were investigated with respect to the amount of poly(methyl methacrylate) (PMMA) used as a pore former. Porous YSZ ceramics with 56 vol.% PMMA showed a mechanical strength of 24 ± 3 MPa and a porosity of 37 ± 1%. The electrochemical properties of the single cell employing the porous YSZ support layer were measured using hydrogen and methane fuels, respectively. The single cell exhibited maximum power densities of 421 mW/cm² in hydrogen and 399 mW/cm² in methane at 800 °C. Moreover, at a current density of 550 mA/cm², the cell maintained 91% of its initial voltage after operation in methane for 13 h at 700 °C.     

谈陶瓷颜色釉人物绘画的艺术魅力

一、概念的界定在景德镇陶瓷中,颜色釉、青花、粉彩、玲珑是闻名世界的“四大名瓷”。“颜色釉”是指在釉中掺入不同金属氧化物的着色剂,施在瓷器的坯胎上,再将坯胎放进1300℃以上的高温窑炉中焙烧,     

Thermally grown oxide in water vapor on coated and uncoated SiC

Coupons of Hexoloy^®, CVD SiC, and SiO₂ were thermally cycled in a flowing steam atmosphere of 90%/10% H₂O/O₂ at 1426°C in order to simulate the water vapor partial pressure of a turbine environment. The paralinear model for oxidation and volatilization is examined and a condensed version is provided that allows for extraction of the oxidation (k_p) and volatilization (k_l) rates from only a few measured data points across a small time window. Due to high Si(OH)₄ (g) volatility rates, SiO₂ scale thickness approached nearly invariant paralinear limiting values (~3-6 μm) for all conditions, including cycle frequency or material. However, a disparity still exists between weight changes measured and the thickness of the resulting oxide as well as the contribution from the material properties to the oxidation and volatilization rates. Comparisons are made for the oxidation and volatilization rates, specific weight changes, and oxide thicknesses for a number of cycle times for both uncoated and environmental barrier coated SiC.     

Processing,structural, and biological evaluations of zirconia scaffolds coated by fluorapatite

Highly porous zirconia (ZrO₂) scaffolds fabricated by the replication method were coated with fluorapatite (FA). The FA coating was obtained by dipping the ZrO₂ scaffolds into stabilized aqueous FA slips having different viscosity values (≤5.0 mPa.s). The influence of the FA slip viscosity and the immersion time on the reduction in the scaffold porosity and microstructure of the coated scaffolds were investigated. Cell spreading and survival of bone marrow‐derived stromal cells (BMSC) and pre‐osteoblastic MC3T3‐E1 cells on the uncoated and coated scaffolds were examined using fluorescence and SEM microscopy, and MTT assay.The FA slip with the lowest viscosity value did not lead to a continuous film along the strut network and the macropores remained uncoated. The slips with the highest viscosity value produced a partial blocking of macropores. The porous structure obtained after coating with slips of 2.2 mPa.s viscosity for 2 seconds exhibited a low reduction in porosity and pore size (400‐420 μm), due to the formation of the FA layer, and a continuous film distributed along the strut surfaces. Morphology, spreading, and survival of BMSC and MC3T3‐E1 cells over a 7‐day culture period evidenced good biocompatibility of FA‐coated ZrO₂ scaffolds processed by dip coating.     

云母钛珠光颜料的研制

探讨了云母钛液相包膜的多条工艺路线,其中对沸腾水解法的工艺条件进行了详细的研究。最佳工艺条件为：以硫酸溶液为介质,酸质量分数为１．５％～２．５％,反应时间为２～４ｈ。制备出金红石型钛含量较高的云母钛珠光颜料。