Metal conductors, why can mica rich in various metals be used as insulating materials? Synthetic mica powder price

Mica is a silicate mineral rich in metals such as potassium, aluminum, magnesium, iron, and lithium. Metals are conductors, why do many conductors together insulate?

Mica is a good insulating material, because these metal elements do not exist in mica as monomers, but in the form of valence bonds, which can be understood as the existence of a state similar to oxides. Mica is insoluble in water, and its metal ions It is not easy to ionize in water, so mica is insulating.

How to judge the insulation performance of mica?

Mica is a layered silicate mineral with continuous layered silicon-oxygen tetrahedral structure. It is a very common rock-forming mineral and is divided into three subclasses: muscovite, biotite and lepidolite. It has high electrical insulation strength, corona resistance, heat resistance and good mechanical properties, and is widely used as an insulating material in the electronics and power industries.

The color characteristics of mica can usually be used to judge its insulating properties, and industrial mica is generally better in light color. Muscovite and phlogopite have good electrical insulation and thermal conductivity, acid resistance, alkali resistance and pressure resistance, while biotite has very poor insulation properties.

What are the raw materials for preparing mica insulating materials?

Mica insulating material is mainly composed of three parts: dielectric material, reinforcing material and binder. Mica used as an insulating material must have the conditions of low iron content, smooth surface, no ripples and wrinkles, and no inclusions. Therefore, muscovite, phlogopite and synthetic mica are mainly used for electrical insulation.

The characteristics of muscovite are insulation, high temperature resistance, luster, stable physical and chemical properties, good heat insulation, elasticity and toughness. In industry, its insulation and heat resistance, as well as acid resistance, alkali resistance, compression resistance and peeling resistance are mainly used as insulating materials for electrical equipment and electrical equipment.

The appearance of phlogopite is light green, light brown, light yellow or orange-yellow, with vitreous or semi-metallic luster. Phlogopite as an insulating material has strict requirements on the content of iron, not too much. Light-colored phlogopite has high heat resistance and can be used as insulating material below 1000°C.

Synthetic mica is similar to phlogopite, but has higher crystalline stability, and the maximum operating temperature can reach 1100 ° C. However, due to the difficulty of industrial production and the reasons for price, the production application in the electrical industry is still relatively small.

In industrial production, the first raw material is thin mica, but as the amount of mica increases, it is gradually replaced by powder mica paper with good integrity and high electrical strength, which can reduce the thickness of motor insulation. Mica crushed and mica powder can be processed into mica paper, and can also replace mica sheet to manufacture various insulating materials with low cost and uniform thickness.

In mica products, the binder plays the role of adhering the sheet mica or powder mica paper to the reinforcing material to make it a whole. In addition to determining the electrical and mechanical properties of mica products, the binder also determines the heat resistance of mica products. Different mica products have special requirements for binders. The adhesive used for mica tape and soft mica board should have good softness and thermal elasticity, such as alkyd mica glue and epoxy mica glue. The adhesive used for commutator mica board or liner mica board must have certain hardness and wear resistance after curing, such as polyimide glue. The binder for molding mica plates or mica foils requires a certain degree of thermoplasticity. The binder for heat-resistant mica products must have a corresponding heat-resistant grade, such as tungsten anhydride epoxy mica glue.

In recent years, with the continuous development of large and medium-sized high-voltage motors to large capacity and high parameters, the requirements for the insulation level of mica products are also getting higher and higher. The general development trend of large and medium-sized high-voltage motor insulation is to require mica insulation materials to develop in several directions such as high performance, high heat resistance level, thin insulation thickness and low cost, which requires increasing mica content, thermal mechanical strength and resistance. Electrothermal aging life, and continuous improvement of insulation manufacturability.