Tin is a metal element, element symbol: Sn, belongs to the main group metal of IVA group, atomic number 50, relative atomic mass 118.71, belongs to IVA group metal, melting point: 231.89 ℃, boiling point: 2260 ℃, density: 7.28g/cm3 . Pure tin is soft, has good ductility at room temperature, stable chemical properties, is not easy to be oxidized, and often maintains a shiny silver luster. The content of tin in the earth's crust is 0.004%, almost all in the form of cassiterite (tin oxide), in addition to a very small amount of tin sulfide minerals.

1. Compounds of tin

The compound of tin and oxygen - tin dioxide, is a white powder insoluble in water, which can be used to make enamel, white glaze and opal glass. Tin dioxide can also be used as a catalyst to prevent air pollution - automobile exhaust gas often contains toxic carbon monoxide gas, under the catalysis of tin dioxide, at 300 ℃, most of it can be converted into carbon dioxide. Tin compounds can also be used in industries such as dyes, rubber, plastics, and pesticides.

2. Chemicals

Tin chemicals are another major end use of tin. In recent years, the consumption of tin in the chemical industry has been increasing. Chemical tin is mainly concentrated in five areas: PVC heat stabilizers, pesticides, catalysts, agricultural fertilizers and glass coatings.

3. Other applications

1. Materials for electronic industry, used as high-purity reagents.

2. Reagents for the determination of arsenic and phosphate as reducing agents, and also used in organic synthesis.

3. It is used in the manufacture of electric carbon products, friction materials, oil-impregnated bearings and powder metallurgy structural materials. For the determination of phosphate and organic synthesis, also used as a reducing agent. High-purity copper is an indispensable and valuable material in atomic energy, rockets, missiles, aviation, aerospace and metallurgical industries. High-purity copper has strong heat absorption capacity, stable mechanical properties, high melting point and high temperature resistance, and is a good material for the neutron reflection layer of atomic reactors. In the metallurgical industry, it is an additive of alloy steel, and is also used in many aspects such as refractory materials and special glass, integrated circuits, and antennas.

4. For the preparation of low melting point alloys. High-purity tin is used in the electronics industry for tin plating and diffusion doping processes.

5. The application prospect of tin and its substitute products

In 2013, Dr. Jeremy Pearce, director of the China Technology Department of the International Tin Research Association, said that due to the continuous advancement of technology, there may be a technological revolution in the application field of tin in the future. In less than 20 years, he said, the world will see a new "solderless" technology that consumes less energy, has stronger solder joints, and better reliability, which will provide tin The application of metal will bring unprecedented benefits, and its application in tablet computers, smartphones and other fields will change with it. At the same time, some analysts believe that the market demand for tin is expected to increase by 2% annually in the future. This is mainly due to the growth of downstream industries and the expansion of tin application fields, such as the substitution of tin for anode carbon in the field of lithium batteries, the substitution of chromium-nickel in the field of stainless steel, and the substitution of lead in the field of PVC. These are expected to contribute new forces to the growth of tin demand.

But at the same time, in some other fields, tin is also replaced by other materials. For example, in the production of containers such as metal cans, aluminum, glass, paper, plastic and tin-free steel can all replace tin; epoxy resin can replace tin in welding; aluminum alloy, copper-based alloy and plastic can be used in production Bronze is a substitute for tin; plastics can also replace tin in the production of bearing alloys; lead compounds and sodium compounds can also replace part of tin compounds.