China high quality silicon metal industrial grade si metal

1. Overview/Silicon Metal

1). Metal silicon, also known as crystalline silicon or industrial silicon, is mainly used as an additive for non-ferrous alloys. It is a trade name that appeared in the mid-1960s. Its emergence is related to the rise of the semiconductor industry. At present, the international usage is to divide commodity silicon into metal silicon and semiconductor silicon. Silicon metal is a product smelted by quartz and coke in an electric heating furnace. The content of the main component silicon is about 98%, and the remaining impurities are iron, aluminum, calcium, etc. Silicon metal is expensive. 2). Industrially, metallic silicon is usually prepared by reducing silicon dioxide with carbon in an electric furnace. Chemical reaction equation: SiO2 + 2C → Si + 2CO The purity of metal silicon obtained in this way is 97~98%. It is then melted and recrystallized, and impurities are removed with acid to obtain metallic silicon with a purity of 99.7~99.8%.

2. Properties/Silicon Metal

Silicon is one of the semi-metals, formerly known as "silicon". The melting point is 1420°C, and the density is 2.34 g/cm3. Hard and brittle. It is insoluble in acid at room temperature and easily soluble in alkali. The composition of metal silicon is mainly silicon, so it has similar properties to silicon. The properties of metal silicon are similar to those of germanium, lead and tin, and have semiconductor properties. Silicon is extremely abundant in the earth's crust, second only to oxygen, accounting for a quarter of the total weight of the earth's crust, and exists in the form of silica or silicate. The purest silicon mineral is quartz or silica. There are two allotropes of silicon: one is a dark brown amorphous powder, which is active and can burn in the air; the other is a stable crystal (crystalline silicon). Generally, silica and quartz are used for glass and other building materials, and high-quality quartz is used to make alloys, metals and single crystals.

3. Classification/Silicon Metal

1). The classification of metal silicon is usually classified according to the content of three main impurities of iron, aluminum and calcium contained in the metal silicon component. According to the content of iron, aluminum and calcium in metal silicon, metal silicon can be divided into 553, 441, 411, 421, 3303, 3305, 2202, 2502, 1501, 1101 and other different grades.

2). Industrially, metallic silicon is usually prepared by reducing silicon dioxide with carbon in an electric furnace. Chemical reaction equation: SiO2 + 2C → Si + 2CO The purity of silicon obtained in this way is 97~98%, which is called metal silicon. It is then melted and recrystallized, and impurities are removed with acid to obtain metallic silicon with a purity of 99.7~99.8%.

3). The composition of metal silicon is mainly silicon, so it has similar properties to silicon. Silicon has two allotropes, amorphous silicon and crystalline silicon. Amorphous silicon is a gray-black powder that is actually a microcrystal. Crystalline silicon has the crystal structure and semiconductor properties of diamond, with a melting point of 1410°C, a boiling point of 2355°C, a density of 2.32-2.34 g/cm3, a Mohs hardness of 7, and a brittleness. Amorphous silicon is chemically active and can burn violently in oxygen. It reacts with non-metals such as halogen, nitrogen and carbon at high temperature, and can also interact with metals such as magnesium, calcium and iron to form silicides. Amorphous silicon is almost insoluble in all inorganic and organic acids including hydrofluoric acid, but is soluble in mixed acids of nitric acid and hydrofluoric acid. Concentrated sodium hydroxide solution can dissolve amorphous silicon and release hydrogen. Crystalline silicon is relatively inactive, it does not combine with oxygen even at high temperature, it is not soluble in any inorganic acid and organic acid, but it is soluble in mixed acids of nitric acid and hydrofluoric acid and concentrated sodium hydroxide solution.