Marble coating

Synthetic examples of super-hydrophobicity include covers for solar cells, satellite dishes, coatings for papers and microfluidics. A related example is provided by liquid marbles, which are non-stick droplets coated with microscale or nanoscale particles of low surface energy that exhibit very high contact angles (>150°) and extremely low friction when rolling on solid surfaces [37]. Some liquid marbles, coated with hydrophobic particles, will float on a pool of water. An example in nature is the conversion of honeydew droplets into liquid marbles by aphids [38]. 

Because of these characteristics, perlite light eight hollow spheres or bubbles have been found to be cost effective in a number of applications including the manufacture of adhesives, auto body putty, cultured marble, coatings, patching compounds and stucco... 

Although the use of simple diluents and adulterants almost certainly predates recorded history, the use of fillers to modify the properties of a composition can be traced as far back as eady Roman times, when artisans used ground marble in lime plaster, frescoes, and po22olanic mortar. The use of fillers in paper and paper coatings made its appearance in the mid-nineteenth century. Functional fillers, which introduce new properties into a composition rather than modify pre-existing properties, were commercially developed eady in the twentieth century when Goodrich added carbon black to mbber and Baekeland formulated phenol— formaldehyde plastics with wood dour. 

The weatherabihty and hydrolytic stabiUty of unsaturated polyesters based on neopentyl glycol have made it a popular intermediate for use in formulations exposed to severe conditions, eg, in gel coats for cultured marble and marine appHcations (see Coatings, marine) (13). 

Calcium carbonate, available both from natural sources and as precipitated forms (see Calcium compounds), is most useful in coating because of purity and high brightness, ie, 90—95%. Ground carbonates from marble deposits have high purity levels as do the carbonates from some chalk deposits. 

World production of unsaturated polyester resins in 1997 was of the order of 1.7 X 10 tonnes, with the USA accounting for about 45% and Western Europe 27%. Over 75% is used in reinforced plastics, with the rest being used for such diverse applications as car repair putties, cultured marble , wood substitution and surface coatings. The pattern of consumption in 1993 of reinforced polyesters in the USA was reported as ... 

Mortars are cements used for bonding together masonry units, such as stones or bricks. When a cement is used to conceal masonry, as a more or less smooth covering on walls, for example, it is referred to as plaster. A very fine plaster, known as stucco, is made of very thin sand or finely comminuted marble. Freshly prepared plasters and stuccos are spread on consolidated masonry to form more or less uniform and smooth layers stucco also provides a smooth and often flat outer coating. 

Example 12.5. The stabilizing effect of powders was impressively demonstrated by making liquid marbles in air [549], Liquid marbles (Fig. 12.11) are obtained by making a small amount of water (typically 1 mm3) roll on a very hydrophobic powder. The powder particles go into the interface and completely coat it so that, after spontaneous formation of the spherical drop, only the solid caps of powder particles come into contact with the solid support. 

Figure 9.38 (a) A 6,3-sheet of [Ag2(9.14b)3] (BF4)2 and (b) the 2D— 2D parallel Borromean interpenetrating network that it forms with the means planes of the 2D sheets coincidental. The Ag atoms (spheres) lie above each other, held by argentophilic interactions, (c) Borromean rings in black on white marble at the Cappella Rucellai in the Church of San Pancrazio, now the Marino Marini Museum, in Florence. The rings form part of the coat of arms of the Borromeo family and are also said to be a symbol of the Florentine de Medici family (photograph courtesy of Prof. L. J. Barbour).37... 

Calcium carbonate is the most commonly used extender. It is widely available and low in cost, and it provides for improvements in certain performance properties. The material is a mineral that is mined throughout the world. Common forms of calcium carbonate include limestone, marble, calcite, chalk, and dolomite. It is manufactured by precipitation processes and is commercially available from a number of sources. Calcium carbonate is available in many different particle sizes and in various grades. To improve dispersion in certain resins, the filler is often coated with calcium stearate or stearic acid. 

In addition, scientists are experimenting with coatings to protect marble from the acidic atmosphere. However, a coating can do more harm than good unless it breathes. If moisture trapped beneath the coating freezes, the expanding ice can fracture the marble. Needless to say, it is difficult to find a coating that will allow water to pass but not allow acid to pass, so the search continues. ... 

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