Ceramic acid

Ceramics Acid gases Change in surface appearance... 

A solid acid calcined at temperatures above 1000 °C is termed a Ceramic Acid . Ceramics are made by calcination of inorganic materials at elevated temperatures and they possess favorable stability. Brick, usually produced by calcination at temperatures above 1000 °C, is a typical example of one of these materials. Solid acids are generally prepared by calcination at temperatures around 500 °C to generate the highest acidity on the surface, and it is known that the treatment with temperatures above 500 °C causes the surface acidity to reduce. A solid acid prepared by calcination at similar temperatures to a ceramic, would be highly desirable in terms of green chemistry, as a result of the corresponding stability of acid sites. 

The above results led to the synthesis of a ceramic acid, 5-10 wt% W-added Sn02 materials calcined at 1000-1100 °C. The surface acidity determined by the heat... 

The above studies resulted in novel ceramic acids, l-5wt%W-added aluminas calcined at 1000-1200 °C. The surface acidity determined by the heat of adsorption of Ar and the catalytic activity for decompositions of toluene, ethylbenzene, and cumene were higher than those of sihca-alumina. The crystallographic phase was 0- or a-Al203. 

Use Special glasses, ceramics, acid cleaner, dehydration catalyst. 

The use of acids and bases to control interiDarticle forces in oxide (ceramic)-water suspensions is an example of... 

Tellurium improves the machinability of copper and stainless steel, and its addition to lead decreases the corrosive action of sulfuric acid on lead and improves its strength and hardness. Tellurium is used as a basic ingredient in blasting caps, and is added to cast iron for chill control. Tellurium is used in ceramics. Bismuth telluride has been used in thermoelectric devices. 

The ablated vapors constitute an aerosol that can be examined using a secondary ionization source. Thus, passing the aerosol into a plasma torch provides an excellent means of ionization, and by such methods isotope patterns or ratios are readily measurable from otherwise intractable materials such as bone or ceramics. If the sample examined is dissolved as a solid solution in a matrix, the rapid expansion of the matrix, often an organic acid, covolatilizes the entrained sample. Proton transfer from the matrix occurs to give protonated molecular ions of the sample. Normally thermally unstable, polar biomolecules such as proteins give good yields of protonated ions. This is the basis of matrix-assisted laser desorption ionization (MALDI). 

Table 6. Analyses of Ceramic- and Acid-Grade Fluorspar, wt...

Uses. Lithium fluoride is used primarily in the ceramic industry to reduce firing temperatures and improve resistance to thermal shock, abrasion, and acid attack (see Ceramics). Another use of LiF is in flux compositions with other fluorides, chlorides, and borates for metal joining (17) (see Solders). 

Hexafluorozirconic acid is used ia metal finishing and cleaning of metal surfaces, whereas the fluorozirconates are used in the manufacture of abrasive grinding wheels, in aluminum metallurgy, ceramics industry, glass manufacturing, in electrolytic cells, in the preparation of fluxes, and as a fire retardant (see Abrasives Metal surface treati nts). 

Tetraethylene glycol may be used direcdy as a plasticizer or modified by esterification with fatty acids to produce plasticizers (qv). Tetraethylene glycol is used directly to plasticize separation membranes, such as siHcone mbber, poly(vinyl acetate), and ceUulose triacetate. Ceramic materials utilize tetraethylene glycol as plasticizing agents in resistant refractory plastics and molded ceramics. It is also employed to improve the physical properties of cyanoacrylate and polyacrylonitrile adhesives, and is chemically modified to form polyisocyanate, polymethacrylate, and to contain siHcone compounds used for adhesives. 

Lead Tetroxide. Lead tetroxide (red lead minium lead orthoplumbite), Pb O, is a brilliant orange-red pigment which accounted for U.S. shipments of 17,780 t ia 1977, mainly to the ceramics and storage battery iadustries (40). U.S. shipments ia 1993 amounted to approximately 12,000 t. The decrease ia usage siace 1973 (19,000 t) is attributable to discontinued use ia the paint and coatings (qv) iadustry, and alterations ia mbber and ceramics (qv) markets. It is iasoluble ia water and alcohol, and dissolves ia acetic acid or hot hydrochloric acid. Red lead is manufactured by heating lead monoxide ia a reverberatory furnace ia the preseace of air at 450—500°C uatil the desired oxidative composition is obtaiaed. 

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