Bronze results

K. Grob, M. Biedermann and M. Bronz, Results of a contr ol of edible oils frauds by admixtures, contaminations , Mitt. Gebiete Lebensm. Hyg. 85 351-365 (1994). 

The atomic radii of Cu, Sn(1.45 A), and Zn(1.42A) are also nearly identical, allowing for a full gamut of Cu/Sn and Cu/Zn alloy concentrations to be produced, known as bronze and brass, respectively. Although the use of bronze dates back to at least 3,000 B.C., there are also early examples of brass artifacts that date back to ca. 2,200 B.C. in India. Most likely, the discovery of bronze resulted from the inquisitive mixing of available metals at the time, only to discover that Au/Sn alloys possessed a greater strength than iron steels were not developed until thousands of years later. Since zinc metal was not available until the mid-18th century, and tin was readily obtained, the widespread production of bronzes occurred at the expense of brasses. In the absence of pure zinc, early formulations of Cu/Zn alloys were most likely... 

Among leaden articles belonging to the Roman period are pipes, coffins, cists, etc. The Romans also used articles of pewter (p. 211), at that time an alloy of lead and tin in the ratio of 1 to 4. Probably the two metals were deliberately mixed to produce the pewter, for the Romans were familiar with solder. It is possible, however, that pewter may have been produced in the first instance from a natural mixture of tin and lead ores, just as bronze resulted from a mixture of tin and copper ores (p. 91). Professor Louis has recorded such an occurrence m the Far East, where he found the Chinese smelting a natural mixture of lead and tin ores obtained by washing certain alluvials in the State of Patain in the northern part of the Malay Peninsula. 

It may be prepared by the Ulman Condensation of o-iodobenzoic acid with 2, 6-dichloro-w-toluidine in the presence of copper-bronze resulting into the formation of meclofenamie aeid whieh on neutralization with equimolar proportion of sodium hydroxide yields meclofenamate sodium. 

Activated copper bronze. Commercial copper bronze does not always give satisfactory yields in the Ullmann reaction, but uniform results can... 

In the outdoor environment, the high concentrations of sulfur and nitrogen oxides from automotive and industrial emissions result in a corrosion having both soluble and insoluble corrosion products and no pacification. The results are clearly visible on outdoor bronze sculpture (see Airpollution Exhaust CONTROL, automotive Exhaust conthol, industrial). 

Another ak pollutant that can have very serious effects is hydrogen sulfide, which is largely responsible for the tarnishing of silver, but also has played a destmctive role in the discoloration of the natural patinas on ancient bronzes through the formation of copper sulfide. Moreover, a special vulnerabihty is created when two metals are in contact. The electromotive force can result in an accelerated corrosion, eg, in bronzes having kon mounting pins. 

A hard, mst-resistant shaft of at least 0.25 micrometer finish is usually required. Common shaft surfaces are hardened tool steel, chrome plate, high strength bronze, and carbide and ceramic overlays. Test results over a broad speed range from 0.05 to 47 m/s (10 to 9200 fpm) iadicate that a coefficient of friction of 0.16—0.20 and a wear factor of 14 X 10 m /N(70x 10 ° in. min/ft-lb-h) are typical for dry operation of weU appHed grades of carbon—graphite (29). 

Flexible Metal Hose Deeply corrugated thin brass, bronze, Monel, aluminum, and steel tubes are covered with flexible braided-wire jackets to form flexible metal hose. Both tube and braid are brazed or welded to pipe-thread, union, or flanged ends. Failures are often the result of corrosion of the braided-wire jacket or of a poor... 

Reduced copper powder and various grades of copper bronze were used with practically the same results. 

For a given amplitude of the quasi-elastic release wave, the more the release wave approaches the ideal elastic-plastic response the greater the strength at pressure of the material. The lack of an ideally elastic-plastic release wave in copper appears to suggest a limited reversal component, however, this is much less than in the silicon bronze. Collectively, the differences in wave profiles between these two materials are consistent with a micro-structurally controlled Bauschinger component as supported by the shock-recovery results. Further study is required to quantify these findings and... 

At elevated temperature and pressure hydrogen embrittlement can result Most metals when gas is moist. Galvanized pipe or brass or bronze fittings... 

Perfluoroalkylation can be accomplished via direct reaction of peifluoroalkyl halides and copper with aromatic substrates [232, 233, 234, 235, 236] Thus, perfluoroalkyl iodides or bromides react with functionalized benzenes m DMSO m the presence of copper bronze to give the corresponding perfluoroalkylated products directly in moderate to good yields [233] (equation 157) Mixtures of ortho, meta, and para isomers are obtained [232, 233], The use of acetic anhydride as solvent gives similar results [234, 235], Similarly, the direct reaction of perfluoroalkyl iodides and pyrroles with copper metal regiospecifically gives the 2-perfluoroalkylpyrroles [236] (equation 158). 

Cathodic protection with a sacrificial anode that is less noble than either member of the couple is frequently used to reduce the severity of bimetallic corrosion, particularly that resulting from the use of bronze propellers in steel ship hulls. 

The results of tests on copper alloys have been given by Tracy , Thompson , Mattsson and Holm and Scholes and Jacob , the first two of these investigations being made under the aegis of the American Society for Testing and Materials. The tests of Tracy, and Scholes and Jacob were both for periods up to 20 years in those of Thompson, and Mattsson and Holm specimens have been removed after 2 years and 7 years and further specimens remain exposed for removal after 20 years. The numbers of materials tested are given in Table 4.11 they included brasses, nickel silvers, cupro-nickels, beryllium coppers and various bronzes. Mattsson and Holm tested 14 alloys in the form of rod in addition to the sheet materials, the results for which are given in Table 4.11. 

Corrosion of. power-station condenser tubes by polluted, waters has been particularly troubles ome in Japan anil efforts have been made to,study the problem by, electrochemical methods and by exposing model condensers at a variety of bower station sites ., Improved results have been reported, using tin. brasses , or special, tin bronzes. . Pretreatment with sodium dimethyldithiOcarbamate is reported to give protective films that will withstand the action of polluted waters , though the method would be economic only in special circurtistapcies., , , . ... 

The fact that the composition of the speculum deposit must be closely controlled to obtain the best results has been a serious drawback to development. The coating finds uses on decorative hollow-ware, oil lamps and tableware. The bronze deposits with 10 or 20% tin are used lacquered in decorative metal-ware for domestic and personal ornament and, in thick layers to protect hydraulic pit props against corrosion and abrasion. They have also been used with success as undercoatings for nickel-chromium or tin-nickel alloy deposits. 

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