Gray oxide

A rapid method to determine the calcium content of lead alloys is a Hquid-metal titration using lead—antimony (1%) (9). The end point is indicated by a gray oxide film pattern on the surface of a sohdifted sample of the metal when observed at a 45° angle to a light source. The basis for the titration is the reaction between calcium and antimony. The percentage of calcium in the sample can be calculated from the amount of antimony used. If additional calcium is needed in the alloy, the melt is sweetened with a lead—calcium (1 wt %) master alloy. 

Lead Monoxide. Lead monoxide (litharge), PbO, occurs as a reddish alpha form, which is stable up to 489°C where it transforms to a yellow beta form (massicot). The latter is stable at high temperatures. The solubihty of a-PbO ia water is 0.0504 g/L at 25°C the solubihty of the p-PbO is 0.1065 g/L at 25°C (40). Lead monoxide is amphoteric and dissolves ia both acids and alkahes. In alkahes, it forms the plumbite ion PbO - The monoxide is produced commercially by the reaction of molten lead with air or oxygen ia a furnace. Black or gray oxide is manufactured by the Barton process, by the oxidation of atomized molten lead ia air, as well as by the ball mill process, ia which metallic lead balls of high purity are tumbled ia the mill to form partially oxidized lead particles. 

Rough ingot iron 1700-2040 0.87-0.95 Galvanized sheet iron, gray oxidized 75 0.276... 

The production of the active material for positive and negative electrodes starts with the same substance, a mixture of lead oxide (PbO) and metallic lead called gray oxide or lead dust. It is a fine powder that contains 20-30 wt.% of lead (Pb). The size of the primary particles is in the range of 1-10 /an. Larger agglomerates are usually formed. 

Gray oxide can be produced by a milling process, which, strictly speaking, does not mill the material. A rotating drum is filled with solid balls or ingots of lead. 

The production of tubular positive plates is in principle similar to that of pasted plates. A number of manufacturers use the same gray oxide as the basic filling substance. Sometimes the share or red lead or minium (Pb304) is increased above 25 or even to 100wt.%. The latter is more economic when the manufacturer runs his own minium plant then the expense of the chemical oxidation of lead oxide (PbO) to minium (Pb304) may be compensated by reduced formation cost. Furthermore, curing is not required, because of the high oxidation state, and the battery starts with full capacity when formed. 

Sodium. Soft, silvery white sticks, pellets, wire, or granules normally coated with a gray oxide or hydroxide skin.1... 

When all the metal appears as the dull gray oxide, half-cover the crucible and gently heat with a small Bunsen flame. Over a period of 5 min., gradually adjust the intensity of the flame until it is at its hottest, then heat the crucible to the cherry red color for 5 min. 

The method requires the use of a reference standard sample in order to set the sensitivity level before an unknown sample is tested for discontinuities. The type of reference discontinuities used in a particular application has been specified by the American Society for Testing Materials and the American Petroleum Institute. Some reference standards are depicted in Figure 2.10. Some of the discontinuities detected are seams, laps, cracks, slivers, scabs, pits, slugs, open welds, miswelds, improperly or misaligned welds, black or gray oxide weld penetrators, pinholes, hook cracks and surface cracks. 

Cobalt oxide 4250 CoO Asbolite black oxide of cobalt cobalt black cobalt monoxide cobaltouc oxide gray oxide of cobalt oxide of cobalt protoxide of cobalt. 

Mercurous oxide 4143 Hg20 Black oxide of mercury Black precipitate dioxide of mercury gray oxide of mercury protoxide of mercury suboxide of mercury. 

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