Hydrothermal coating process

A. Razmjou, J. Mansouri, V. Chen, M. Lim, and R. Amal, Titania nanocomposite poly-ethersulfone ultrafiltration membranes fabricated using a low temperature hydrothermal coating process. Journal of Membrane Science 380 (2011) 98-113. 

Thin zeolite membranes can also be prepared through a spin-coating process of a nanoparticle suspension. Yan and coworkers synthesized silicalite-1 and silicalite-2 in a nanoparticle suspension using a two-stage hydrothermal process.[138,139] First, the precursor... 

A process has been developed by J. M. Huber Co. to treat kaolin clay pigments using a hydrothermal process (see Clays) (25). The products, called synthetic alkah metal aluminosihcates (SAMS), have superior pigmentary quahties for paper (qv) coating. 

Hydrothermal Method. Iron [Fe(III)], barium, and the dopants are precipitated as their hydroxides and reacted with an excess of sodium hydroxide solution (up to 6 mol/L) at 250-350 °C in an autoclave. This is generally followed by an annealing treatment at 750-800°C to obtain products with the desired magnetic properties. Many variations of the process have been described [5.36]-[5.40], the earliest report being from 1969 [5.41], In later processes, hydrothermal synthesis is followed by coating with cubic ferrites, a process resembling the cobalt modification of iron oxides (see Section 5.1.2). The object is to increase the saturation magnetization of the material [5.42]-[5.44],... 

It is evident that the ceramic membrane, which is represented in the XRD pattern (see Figure 10.6) by the amorphous component of the XRD profile, was covered by the AlP04-5 molecular sieve, since the crystalline component of the obtained XRD pattern fairly well coincides with the standards reported in the literature [107]. Consequently, the porous support was successfully coated with a zeolite layer, which was shaped by the hydrothermal process as previously described. Thus, a composite membrane, that is, an AlP04-5 molecular sieve thin film zeolite-based ceramic, was produced. 

Thin hexagonal monocrystalline AI2O3 flakes can be produced by hydrothermal processes [5.150-5.152]. The thickness of the resulting flakes is not uniform. Therefore, the resulting coated pigments merely assume a dull pearlescence. 

It is possible that inorganic cell prototypes were created in hydrothermal systems. Iron sulfides are abundant in oceanic hydrothermal systems and are one of the main products of high-temperature vents. Russell and Hall (1997) and Martin and Russell (2003) proposed that iron monosulfide bubbles, created in an oceanic hydrothermal setting formed a template for the structure of the first cells. In this model the FeS membrane acted as a catalytic chamber within which organic synthesis could take place. As this process evolved, the sulfide membrane became coated with abiotic organic polymers which eventually took over from the sulfide and replaced their function. 

The mesoporous silicates MCM-41 and MCM-48 are members of the family M41S, which are of interest for adsorption and catalysis because their textural properties, i.e., pore size between 35 and 50 A and surface areas of about 1000 m /g [1-2]. These materials are being investigated as supports and catalysts for the processing of complex hydrocarbons, but they exhibit some drawbacks, such as a low hydrothermal stability and structural degradation in the presence of water. Thus, this work explores the structural reinforcement of the silicate walls of mesoporous MCM-41 materials by means of the coating with polymeric carbon, which can also modify their physicochemical properties... 

Han, Y. et al. Evaluation of nanostructured carbonated hydroxyapatite coatings formed by a hybrid process of plasma spraying and hydrothermal synthesis. /. Biomed. Mater. Res., 2002,60 511-16. 

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