Ceramic thermal stability

Plasma processing technologies ate used for surface treatments and coatings for plastics, elastomers, glasses, metals, ceramics, etc. Such treatments provide better wear characteristics, thermal stability, color, controlled electrical properties, lubricity, abrasion resistance, barrier properties, adhesion promotion, wettability, blood compatibility, and controlled light transmissivity. 

The solubilities of the various gases in [BMIM][PFg] suggests that this IL should be an excellent candidate for a wide variety of industrially important gas separations. There is also the possibility of performing higher-temperature gas separations, thanks to the high thermal stability of the ILs. For supported liquid membranes this would require the use of ceramic or metallic membranes rather than polymeric ones. Both water vapor and CO2 should be removed easily from natural gas since the ratios of Henry s law constants at 25 °C are -9950 and 32, respectively. It should be possible to scrub CO2 from stack gases composed of N2 and O2. Since we know of no measurements of H2S, SO, or NO solubility in [BMIM][PFg], we do not loiow if it would be possible to remove these contaminants as well. Nonetheless, there appears to be ample opportunity for use of ILs for gas separations on the basis of the widely varying gas solubilities measured thus far. 

In general most of the commercial polymers are not comparable to metals and ceramics in terms of load-bearing property, mechanical strength, and thermal stability. To overcome these difficulties the aromatic ether or sulfide (thioether) linkages in the polymer backbone... 

The discussion so far implies that membrane materials are organic polymers, and in fact most membranes used commercially are polymer-based. However, in recent years, interest in membranes made of less conventional materials has increased. Ceramic membranes, a special class of microporous membranes, are being used in ultrafiltration and microfiltration applications for which solvent resistance and thermal stability are required. Dense, metal membranes, particularly palladium membranes, are being considered for the separation of hydrogen from gas mixtures, and supported liquid films are being developed for carrier-facilitated transport processes. 

Metal Metal, ceramic, carbon, glass fibers Elevated temperature strength Electrical resistance Thermal stability... 

Ceramic composites, which use ceramic fiber or whisker reinforcement in a ceramic matrix, are less susceptible to brittle failure since the reinforcement intercepts, deflects and slows crack propagation. At the same time, the load is transferred from the matrix to the fibers to be distributed more uniformly. These ceramic composites are characterized by low density, generally good thermal stability, and corrosion resistance. 

Bulk ceramics are produced conventionally by the sintering of powders. The strength, toughness, thermal stability, and dielectric properties of the fired ceramic depend strongly on the size and uniformity of the precursor powder and on the chemical properties of the powder smface. 

Although hollow fibers are thought to be an excellent candidate to be used as support-they are cheap and have a very high surface area to volume (>1000 m m ) - very few reports on hollow-fiber-supported zeolite membranes exist in the open literature. For zeohte membranes, ceramic hollow fibers are preferred because of their mechanical and thermal stability. Recently, Alshebani... 

Classical commercial ceramic porous materials, as those obtained via sol-gel processes, generally have adequate permeabilities but could present some drawbacks They indeed have a limited thermal stability and are generally not permselective enough their pores are in the mesoporous range and maximum separation factors correspond to Knudsen diffusion mechanisms. 

Third, the introduction of crosslinks between chains confers insolubility and increased solid state rigidity, often accompanied by improved thermal stability. High degrees of crosslinking confer ceramic-type properties on the solid, whether the backbone atoms are carbon atoms or inorganic species. 

Yajima [6-8] reported further that heteroatoms such as titanium, zirconium or vanadium could be incorporated into the polymers and ceramic fibers to enhance their thermal stability. 

The apparent thermal stabilities of the two families, BaPb1 x BixOg and Ba K BiOg are quite different. Under the normal conditions of ceramic synthesis, the oxidation states desired in BaPb1.x-... 

Because of the close similarity of ionic radii, transition metal ions (M = Mn, Cu, Fe, Cr, Co, Ni) can be partially substituted for A1 ions. These transition metal ions can provide significant activity in combustion reaction.5 At low metal concentrations, the structural and morphological properties are not significantly affected by substitution, so that high thermal stability is maintained. Substituted hexaaluminates can be directly shaped in the monolith form required by the combustor, providing bulk active catalysts without need of ceramic supports. 

The use of TPX permits complete transfer of the toner from its initial carrier onto many other surfaces including of paper, card, cardboard, all of which may be uncoated or coated with many different types of finish, and of glass, ceramics, woods, metals, plastics, etc. TPX has sufficient thermal stability to be useful within the range of temperatures at which the material can be used for effecting image transfer. 

Thermal Properties. Many commercial glass-ceramics have capitalized on their superior thermal properties, particularly low or zero thermal expansion coupled with high thermal stability and thermal shock resistance properties that are not readily achievable in glasses or ceramics. Linear thermal expansion coefficients ranging from —60 to 200 x 10-7 j° C can be obtained. Near-zero expansion materials are used in applications such as telescope mirror blanks, cookware, and stove cooktops, while high expansion frits are used for sealing metals. 

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