Coating sinter

ITottinen et al. [44,45] used htanium sintered meshes as DEs on the cathode side of a PEMEC because the porosity of these metal sheets does not reduce when in compression. It was demonstrated that in order ter the cell to achieve the required performance, the sintered meshes had to be coated with platinum. However, the results showed that a cell with CEP (SIGRACET GDEIO-BB) as the DE shll performed slightly better (especially at high current densities) than the cell with the Pt-coated sintered Ti mesh. Cisar et al. [46 presented another example in which a DE consisting of sintered metal fibers was used on the cathode side of a PEMEC. Once put together, these fibers were rmified or bonded to the EE plate (made out of metal) in order to combine the two components into one. 

The slip coating-sintering procedure can be used to make membranes with pore diameters down to about 100-200 A. More finely porous membranes are made by sol-gel techniques. In the sol-gel process slip coating is taken to the colloidal level. Generally the substrate to be coated with the sol-gel is a microporous ceramic tube formed by the slip coating-sintering technique. The solution coated onto this support is a colloidal or polymeric gel of an inorganic hydroxide. These solutions are prepared by controlled hydrolysis of metal salts or metal alkoxides to hydroxides. 

Figure 3.31 Slip coating-sintering and sol-gel processes used to make ceramic membranes...

Oxide-metal composite anodes consist of a mixed ruthenium dioxide and titanium oxide coating sintered onto a commercially pure titanium substrate. These expanded-mesh anodes also are used for protecting reinforcing steel in concrete [37]. 

Fig. 16. Sol-gel and simple slip-coating-sintering process used to make ceramic membranes.

Ceramic Membranes. A number of companies have developed ceramic membranes for ultrafiltration and microfiltration applications. Ceramic membranes have the advantages of being extremely chemically inert and stable at high temperatures, conditions under which polymer films fail. Most ceramic membranes are made by the slip-coating-sintering or sol-gel techniques outlined in Figure 16 (56-58). 

The slip-coating-sintering process is the most widely used. In this process, a porous ceramic support tube is made by pouring a dispersion of a fine-grain ceramic material and a binder into a mold and sintering at high temperature. The pores between the particles that make up this support tube are large. One surface of the tube is then coated with a suspension of finer particles in a solution of a cellulosic polymer or PVA which acts as a binder and viscosity enhancer to hold... 

The water absorption decreased as the density and uniformity of coating improved, and the water absorption of coating sintered at 1400X3 is as low as 2.6%. 

Everaert K, Mathieu M, Baeyens J, Vansant E. Combustion of Chlorinated Hydrocarbons in Catalyst-coated Sintered Metal Eleece Reactors. J Chem Technol Biotechnol 2003 78 167-172. 

Figure 19-18. Corrosion behavior of sol-gel coated galvanized steeL Polarization curves reveal the protective properties depend on coating sintering conditions.

Microfiltration and ultrafiltration membranes can be made from organic polymers or inorganic materials such as ceramic, glass, or metal or organic polymers. Materials used in MF and UF membrane fabrication are shown in Table 6.1. A number of different techniques are employed to prepare synthetic MF/UF membranes the most important are phase inversion, coating, sintering, and track etching. 

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