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Gel Coatings (gel + coating)
Selected AbstractsSol,Gel Coatings as Active Barriers to Protect Ceramic Reinforcement in Aluminum Matrix Composites,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2004J. Rams Silica obtained through a sol,gel process is used as a coating for ceramic reinforcements (SiC) in aluminium matrix composite materials. The interaction between molten aluminium and the coated particles during material casting can be controlled by means of the thermal treatment given to the coating. Wettability is increased because the coating reacts with molten aluminium, and the formation of the degrading aluminium carbide is inhibited. [source] Application of Inhibitor-Loaded Halloysite Nanotubes in Active Anti-Corrosive CoatingsADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Dmitri Fix Abstract Halloysite particles are aluminum-silicate hollow cylinders with a length of 0.5,1,µm, an outer diameter of ca. 50,nm and a lumen of 15,nm. These nanotubes are used for loading and sustained release of corrosion inhibitors. The inhibitor is kept inside the particles infinitely long under dry conditions. Here, halloysite nanotubes filled with anticorrosive agents are embedded into a SiOx,ZrOx hybrid film. An aluminum plate is dip-coated and immersed into 0.1,M sodium chloride aqueous solution for corrosion tests. A defect in the sol,gel coating induces pitting corrosion on the metal accompanied by a strong anodic activity. The inhibitor is released within one hour from halloysite nanotubes at corrosion spots and suppresses the corrosion process. The anodic activity is successfully restrained and the protection remains for a long time period of immersion in NaCl water solution. The self-healing effect of the sol,gel coating doped with inhibitor-loaded halloysite nanotubes is demonstrated in situ via scanning vibrating electrode technique measurements. [source] Hydrophilic and Antimicrobial Zeolite Coatings for Gravity-Independent Water Separation,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2005Abstract Condensing heat exchangers onboard manned spacecraft require hydrophilic fin surfaces to facilitate wetting and wicking of condensate to achieve gravity-independent water separation in the zero- or micro-gravity environment of space. In order to prevent the proliferation of microbes, the coating must also be biocidal. Here we show for the first time that zeolite,A and ZSM-5 coatings deposited via in-situ crystallization on stainless steel and aluminum alloys have excellent hydrophilicity, biocidal properties, and adhesion. Water contact angles below 5° were obtained on most substrates tested. When silver-ion exchange is carried out on the zeolite,A coating, it becomes highly antibacterial. This biocidal capability of zeolite,A is regenerative by repeated ion exchange. All coatings exhibit the highest rating of 5B as determined by adhesion test ASTM D-3359-02 (American Society for Testing and Materials). These properties, in addition to zeolite coating's low-temperature crystallization process and demonstrated corrosion resistance, make zeolite coatings advantageous over the current sol,gel coatings and well suited for use in condensing heat exchangers onboard manned spacecraft. [source] Synthesis and Characterization of Magnetic NanocontainersJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2008Christos Tapeinos Magnetic hollow spheres were synthesized through a two-step process and were evaluated by Fourier transform infrared spectroscopy, scanning electron microscopy, super quantum interference device, vibrating sample magnetometry and Mössbauer spectroscopy methods. First, polystyrene spheres (PS) were produced using emulsion polymerization. Second, the PS spheres were coated via the sol,gel method to form an iron oxide layer. The size of the PS spheres was controlled by the concentration of the monomer (styrene), the initiator (potassium persulfate), and the emulsifier (sodium dodecylsulfate). The sol,gel coatings were prepared by controlled hydrolysis of aqueous solutions of FeCl3 in the presence of PS latex, polyvinylpyrrolidone, and hydrochloric acid. The composite was treated in air to burn off the PS latex. Temperature treatments were optimized after extensive differential thermal analysis and thermo gravimetric analysis characterization of the samples. Treatments under hydrogen atmosphere at various temperatures gave control over the formation and extend of magnetic phases in the nanocontainers such as a Fe, hematite (Fe2O3), and magnetite (Fe3O4). The size of the containers ranged between 300 and 400 nm. [source] | ||||||||||