Substances & Homeopatic Remedies

Zincum metallicum

Requests: If you need specific information on this remedy - e.g. a proving or a case info on toxicology or whatsoever, please post a message in the Request area so that all users may contribute.

The world's consumption of zinc falls into five areas. The most important use, approaching 50 percent, is in the corrosion protection of iron and steel. About 15 to 20 percent is consumed both in brass alloys and cast-zinc alloys, and 8 to 12 percent is used both in wrought alloys and in miscellaneous uses such as chemicals and zinc dust.Corrosion protection The major method of applying zinc coatings to steel for corrosion protection is known as galvanizing. This protects steel in two ways. First, it provides a reasonably impermeable barrier between the steel and a corrosive atmosphere. Second, when the barrier protection fails, it provides sacrificial electrochemical action whereby the zinc, which is more electronegative than iron, corrodes instead of the steel. Hot-dip galvanizing is the most common procedure for coating steel with zinc. This may be a batch process known as general galvanizing or a continuous coating of coils of steel strip. In general galvanizing, steel is pickled in acid, treated with fluxing agents, and then dipped in a bath of molten zinc at about 450° C (840° F). Layers of iron-zinc alloy are formed on the surface, topped with an outer layer of zinc. Objects so treated range from small nuts and bolts to steel window frames and large girders used in construction. An ordinary grade of zinc containing up to 1.5 percent lead is normally used in this process. In continuous coating of steel strip, similar pretreatments are given to the steel, but the bath contains a purer form of zinc and 0.1 to 0.2 percent aluminum (Al), which, at these concentrations, suppresses the formation of brittle iron-zinc compounds and results in a coating that is more flexible and able to withstand greater deformation. Coating thicknesses can be controlled by varying such factors as the temperature and composition of the zinc bath, but a thickness of 25 micrometres (0.001 inch) is normal. The commercial use of coated strip has been widened by two additional bath compositions. Galvalume is a highly corrosion-resistant alloy of 55 percent aluminum, 43.5 percent zinc, and 1.5 percent silicon that is used in cladding and roofing in industrial environments. Galfan is high-purity zinc containing 5 percent aluminum and 0.1 percent misch metal; steel coated with this alloy has high corrosion resistance and better formability than conventionally coated steel. Continuously coated steel strip has growing application both in the cladding of industrial buildings and in car bodies. Some of this strip is coated on one side only, and electrogalvanizing (or zinc plating) is an alternative method of applying zinc when controlled thinner coatings are required. A continuous plating line, by depositing an electrocoat of zinc with 12 percent nickel, nickel, can provide the automobile industry with steel sheet that has high corrosion resistance and improved spot-welding capability. Other methods of applying zinc coatings to steel include (1) the spraying of atomized particles of molten zinc onto cleaned and roughened steel from a special gun fed with wire or powder (a process useful for applying protective coatings to structures that are too large for the dipping process), (2) the heating of small articles in a revolving drum of heated zinc powder, resulting in the formation of an alloy layer on the surface, and (3) the application of an electrically conducting dry film consisting of paint formulated with a high content of zinc dust (a coating that gives the same protection as galvanizing and is widely used both in protecting steel and in repairing damaged zinc coatings).

Zinc, cadmium, and mercury are all of considerable commercial importance. The main application of zinc is as a coating for the protection of steel against corrosion. Zinc itself forms an impervious coating of its oxide on exposure to the atmosphere, and, hence, the metal is more resistant to ordinary atmospheres than iron, and it corrodes at a much lower rate. In addition, because zinc tends to oxidize in preference to iron, some protection is afforded the steel surface even if some of it is exposed through cracks. The zinc coating is formed either by alloying or, to a lesser extent, by electroplating. In the alloying or galvanizing process the steel parts, after suitable cleaning, are dipped in a bath of molten zinc. Some alloying occurs at the interface (surface between the two metals), and the zinc coating adheres tenaciously to the steel. In a continuous galvanizing process developed in the 1930s and '40s, which is displacing the batch dipping process for sheet production, steel strip is passed continuously through a cleaning treatment to remove scale and then through a bath of molten zinc. The zinc coating so formed is firmly adherent and can withstand considerable deformation (change of form). In the rolled state, considerable quantities of zinc are used for roofing, particularly in Europe; small additions of copper and titanium improve creep resistance; i.e., resistance to gradual deformation. Alloyed with copper to form brass, zinc has been widely used since Roman times. Another important series of alloys are those formed by the addition of 4 to 5 percent aluminum to zinc; these have a relatively low melting point but possess good mechanical properties and can be cast under pressure in steel dies.