Lead - a metal of a bluish hue, has a large specific gravity and a practically minimal hardness (it can be cut with a knife). Lead melting point is such that it can be melted on a fire or at home. In pure form, lead is quickly covered with oxide film and dims. At normal temperature, lead is inert to most acids.
The melting point of lead that does not haveimpurities, about 328 degrees. In the molten form, the metal has good casting qualities. When pouring lead into the sand form, it is necessary that the metal possess good fluidity, for this purpose the melt is brought to a temperature exceeding the melting point by approximately 100-120 degrees. It is easy to machine, forge, high plasticity of the metal allows you to easily roll it to the minimum thickness of the sheet.
The boiling point of lead is within 1,749 degrees.
In the molten form has a noticeable volatility,which increases with increasing temperature. Lead dust, a pair of oxides and lead itself is a poison for the human body. The presence in the body of 0.3 g of lead or its components leads to severe poisoning. In the process of crystallization, lead is subject to high shrinkage, it is usually about 3.5%. In the earth's crust, lead is most often contained in the form of compounds, in the pure form it is quite rare.
It is established that mainly it occurs in the form of sulfides in various rocks.
As impurities in it can be suchelements like antimony, copper, iron, tin, bismuth, arsenic, sodium, etc. Most of the impurities are undesirable, especially in the manufacture of critical parts, because they lead to a modification of the chemical and mechanical properties of the metal. Zinc and bismuth reduce the resistance of lead to acids. The presence of magnesium or calcium leads to an increase in strength, and a metal doped with antimony is characterized by a multiple increase in hardness.
Copper increases the resistance of the product from lead toThe effects of sulfuric acid, barium and lithium increase the hardness. The melting point of lead in the presence of impurities does not undergo significant changes. The range of applications of lead products is quite wide. The main consumers of this material are cable and battery production, where it is used as a cable sheath and for the production of battery plates.
Of the lead, shot and bullets are made. The low melting temperature of lead allowed hunters to make bullets and pellets in the past.
Anticorrosive ability of lead allowsApply it to apply a protective layer on items made of iron. In addition, this property of lead is widely used in the manufacture of paint and varnish products. The main component of the ship's surrey, which paint the underwater part of the ship, is a pigment, which is based on lead.
The lead sheath of the cable is able to protect againstcorrosion electrical and telephone cable, laid under the ground and water, in an aggressive environment. At what temperature lead, tin, bismuth and cadmium are melted, account is taken of the manufacture of electrical fuses. To this day, lead batteries are in demand in the automotive, defense and a number of other industries. True, in recent years, cadmium-nickel batteries have been actively used.
Lead in the composition of alloys is widely used in theproduction of babbitt bearings, solder of tin and lead, printing alloys. Sheets made of lead shield X-rays and radioactive radiation. The accident that occurred in 1986 at the Chernobyl nuclear power plant was accompanied by intensive radioactive radiation, in order to stop the process in the reactor, bags with shot and lead dies were used.
To protect people who are on helicopters, who serve this load, lead sheets were used. The unique properties of lead in this case proved to be indispensable.
