Overview of Conductive Coatings

Conductive coatings are coatings that are coated on non-conductive substrates, and the coating itself has certain ability to conduct current and dissipate electric charge. According to its conductive type, it can be divided into resistive coatings, wave shielding coatings, wave absorbing coatings, heat generating coatings, anti-static coatings, electric field mitigation coatings, etc.

The main film-forming material of conductive coatings is polymer, so its conductive principle is mainly to study the conductivity of polymers. Conductive polymers can be divided into two categories: doped additive conductive polymers and intrinsic structure type conductive polymers. The conductive polymer itself does not have conductivity, and its conductivity is achieved by incorporating conductive particles; the intrinsic structure of the conductive polymer itself has inherent conductivity, and the polymer molecular structure provides conductive carriers. Due to the synthesis of intrinsic conductive coatings, construction has many difficulties, the cost is also higher, the performance is not satisfactory, has not yet reached the stage of mass production, so the actual application of conductive coatings are mostly doped conductive coatings.

Conductive coatings for different purposes, the required conductivity is also different. The table shows the resistivity of conductive coatings for several purposes.

Compared with other technical means of obtaining conductive films such as plastic plating and vacuum sputtering, conductive coatings have the advantages of simple equipment, easy construction, low cost and suitable for complex surface coating.

Application of Conductive Coatings

Conductive coatings are widely used in the modern electronic industry, such as TV picture tube coated with conductive coatings, after the power off can exclude the remaining energy. In radio electronic devices, wave shielding, electrode terminal lead wires, tuning device of tape recorder, TV antenna, outer surface of cathode ray tube, wave conductor, radio reflector, reflector of radar intercepting paraboloid and other parts need to be coated with conductive coatings.

Using the conductive ability of conductive coatings, electrical energy can be converted into heat. Electric heat coating can be used to heat residential, industrial and agricultural buildings, and can also be made into food heaters, frost, snow and water mist removal for rear glass windows of automobiles. When used for indoor heating, electric mattress, electric foot warmer, because of the large coating area and low resistance, low voltage current can be used and there is no danger of contact. Electric heat paint can also be used as an anti-freeze device for oil pipelines and ship hulls in cold areas, and anti-icing on roof roads.

Conductive coatings can be used for anti-static and dissipative purposes. In industrial systems to transport gases, liquids and solid powder often use glass pipes, as an insulator of the glass in the process of conveying the material and the wall of the pipe friction will generate static electricity, resulting in the inner wall of the pipe caused by adsorption and blockage. If the inner wall of the pipe coated with cheap doping type (such as amorphous graphite as a conductive filler) coating, the minimum surface resistance of 110Ω-cm, static voltage reduced to the original 1/4 ~ 1/5. In addition, the surface of the conveyor belt, the outer surface of the aircraft shell, the surface of the video tape, printing press guide roller surface, etc., are also coated with conductive coatings to eliminate static electricity.

Conductive coatings can be used as insulation shielding. High-voltage plastic power cables treated with semi-conductive coatings have high dielectric strength and corona resistance level (i.e., suppressing dendrite discharge), which can act as insulation shield. Good shielding coating should have a specific volume resistance of ρv = 105Ω-cm. cable with a large amount of semi-conducting coating, so generally use inexpensive doped semi-conducting materials.

Electromagnetic shielding, anti-electromagnetic strike, in the current national defense construction has a very important significance, in the prevention of leaks, to prevent interference, to prevent the enemy's electromagnetic pulse impact damage means of protection, the coating is a convenient material to use, in the conductive coating based on the development of electromagnetic shielding coating is very meaningful work.