Cements acid-resisting

Cement, Acid-Resistant, See under Acid-Resistant Materials in Vol l,pp A92-A93 of this Encyclopedia... 

Cast-iron flanges (ANSI B16.1, 125-lb bolt spacing) are permanently attached to the porcelain with high strength acid-resistant cement. Flanged chemical-porcelain 90° and 45° elbows, tees, crosses, reducers, caps, and globe valves of the Y pattern are available. Armored chemical porcelain is furnished with 1.5- to 2.4-mm- (Mfi- to... 

High-alumina cement is very quick setting, but its acid resistance is only slightly better than Portland cement, and it is rapidly attacked by alkalis. Super-sulfated cement is used for liquors high in sulfates. It is resistant to acidic conditions down to a pH of 3.5 and has alkali resistance similar to Portland cement [50]. 

Epoxy resin cements are specifically intended for resistance to caustic alkalis and organic solvents, but they also have fair acid resistance. They have excellent bond strength to other materials including ceramic and concrete. The corrosion resistances of the cements described above are given in Table 3.40. 

Phosphate and polyelectrolyte AB cements are resistant to attack by boiling water, steam and mild acids and this suggests that they could be employed in technologies where these properties are important. 

After 1950 some serious attempts were made to improve dental silicate cement. Notable were those of Manly et al. (1951) and Rockett (1968) also, Pendry reported an acid-resistant cement containing indium (Pendry Cook, 1972 Pendry, 1973). None of these experimental materials went into production. These attempts came too late in view of progress made in other directions, and the picture of dental silicate cement remains one of an essentially traditional material which has changed little since the original developments made mainly by German chemists prior to 1914. 

In neutral solution when fully hardened, dental silicate cements are resistant to aqueous attack. Before they have fully hardened, set cements contain soluble reaction intermediates - soluble sodium salts, acid phosphates and fluorides - which render them vulnerable to attack even by neutral solutions including saliva (Wilson, 1976). 

The ability of a cement to resist aqueous attack depends on the nature of the acid anion. 

High-quality bricks and tiles are used for lining vessels, ditches and to cover floors. The linings are usually backed with a corrosion-resistant membrane of rubber or plastic, placed behind the titles, and special acid-resistant cements are used for the joints. Brick and tile linings are covered in a book by Falcke and Lorentz (1985). 

Nukem Acid-resistant resin cements Amercoat Corp. 

Acid-Resistant Materials. As acid plants are usually attached to plants manufg expls, it is important to have some knowledge of acid-resistant materials, such as metals, bricks, plastics, gaskets, paints, cements and putties, etc.Basic info on this subject may be found in the refs listed below. A common type of acid-proof putty is one consisting of powd red iron oxide and asbestos fiber in a petroleum grease. During WW II, this type of putty was used at many US Ord Plants, including Wabash Ordnance Works... 

Aplastic rubber cement which resists most acids may be prepd by dissolving, with gentle heating and stirring, 1 p of rubber (reclaimed) or caoutchouc in 2 ps linseed oil and then adding 1 p of clay... 

Acid resisting cements), pp 1461-152< (Acid resisting construction materials) pp 1526 ... 

Acid resistant metals and alloys) pp 1534-36(Acid resistant carbon, graphite, cement, mortar, putty, ceramics and plastics)... 

Ethylsilicate-32 is widely used in various spheres of economy, e.g. as a cementing and impregnating agent in the production of molds for precision molding, etc. For example, the cement obtained by mixing ethylsilicate with various fillers (quartz flour, cinder) solidifies in the cold. It is resistant to acids and weak alkali. Water only improves its mechanical properties. After baking at 300°C, the cement becomes resistant to concentrated alkali as well. 

Washing tanks for the final washing of nitro compounds with water (the water from the operation is slightly acid) are made either from stainless steel or from wrought iron lead lined or they may be constructed of bricks bonded by an acid resistant cement and lined with sheet lead and with acid resistant tiles (Fig. 83). 

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