High-conductivity nanometer composite anti-corrosive earthing product
Excellent conductive property of nano-coating
Conductive coating is filled in a container with inner diameter of Φ6mm and length of 50mm and copper lead is implanted at both ends; after the coating is cured, the copper lead is taken from the container and electric resistance at both ends is measured as 0.02Ω with the ohm gauge whose precision is 0.01Ω; the volume resistivity is calculated as follows:
In the above equation:
ρ – volume resistivity at standard temperature;
R – resistance of sample with gauge length at standard temperature;
A – sectional area of sample at standard temperature;
L – gauge length of sample at standard temperature.
The volume resistivity of steel at the standard temperature is 0.98×10-6Ω·m and the resistivity of domestic soil ranges from 100 to 5, 000Ω·m. The resistivity of conductive coating is only 1ppm of soil resistivity. As the intermediate layer between metal ground body and soil, the resistivity of environmentally-friendly nanometer conductive and anti-corrosive coating is close to ordinary metal and the conductive performance is excellent.
Satisfactory anti-corrosive performance
For acid earthing environment, alicyclic amine acts as the curing agent in the coating and alicyclic is directly with N atom and enters the 3D structure of coating as the cross-linking agent; thus, cross-linking density of coating is increased and diffusion of acid media is hindered; in the meantime, the cyclic structure reduces the density of electron cloud on nitrogen atom, which makes formation of complex compound become difficult by hindering the attack of H+; however, acid resistance property of the coating is improved. For alkaline medium, the curing of resin is the process where thermoset resin goes through irreversible change through chemical reactions such as condensation, closed-loop, addition or catalysis; alkali resistance property of curing coating mainly depends on the difficulty of combination of condensate molecules with ionized molecule OH-. Since alkaline amine type curing agent is applied in this coating, the cyclic structure will definitely reduce the electron cloud density on nitrogen atom or lone pair electron will definitely occur to nitrogen atom; as a result, the system after curing will present electronegativity and repel each other with OH-radical. Therefore, compared with its acid resistance, this curing coating performs better in the aspect of alkaline resistance.
Excellent surface bonding property
This coating adopts epoxy materials as base materials and epoxy resin is the general name for all resins that contain epoxy group; since there are epoxy group, hydroxyl group and ether group in its molecular structure, it has strong polarity, which makes epoxy resin molecules cause electromagnetic pressure with the vicinal plane;
as a result, epoxy group reacts chemically with the free group on the medium surface and chemical bond is generated; so the adhesive force of epoxy resin is extremely strong and as coating, epoxy resin has excellent performance.
The epoxy resin group at the end of epoxy resin molecular chain acts as the active site during cross-linking in thermoset polymer and the chemical medicine reacts with theses epoxy groups is called the curing agent which usually contains the active hydrogen atom that is connected with nitrogen, oxygen or sulphur and the cured epoxy resin is obtained from the reaction. Direct addition reaction between epoxy resin and curing agent or the ring-opening polymerization of the epoxy group in resin molecule makes the cross-linking of molecular chain happen to form hard body-type macromolecular compound – the curing agent; this system has excellent mechanical property. In addition, during curing reaction, no water or other volatile by-products are produced; compared with unsaturated polyester resin and phenolic resin, they show weak contractibility (less than 2%) during curing, so that the internal stress produced is small and this also helps to increase the bonding strength.
This product can be widely applied to equipment site, ac and dc working ground and safety protection place of industries and fields such as communication industry, electric power system, building system, military facilities, railway system and radio & broadcast system; moreover, it is especially applied to the place where the surface environment is harsh. This product has promising application prospect for the earthing works with high corrosion resistance requirement.
On-site construction technology of high-conductivity nanometer composite anti-corrosive coating
Inspection items and requirements prior to construction
Steel surface cleaning
Steel surface of ground body shall be wiped to remove impurities such as moisture, sediment and grease; if the steel is seriously corroded, the surface rust shall be removed by using steel brush or sand paper; moreover, welding slag at welding point must be removed strictly to guarantee the adhesion strength of the coating.
Good ventilation at construction site
High-conductivity nanometer composite anti-corrosive material contains flammable solvent, so that construction shall be carried out in well-ventilated site and open fire, direct skin and eye contact shall be avoided.
The coating shall be fully mixed before use
High-conductivity nanometer composite anti-corrosive material belongs to polyurethane coating and requires no dilution. Too dense coating can be diluted by using dedicated organic solvent. The composition of coating will be separated to some extent after storage and it shall be adequately mixed before the use.
The whole coating surface of ground body steel can be brushed from top to bottom by using hair brush and during construction, protective clothing and dedicated protective gloves shall be worn to operate; the omitted places can be brushed at any time and the hair brush shall not be used until it is cleaned in dimethylbenzene; coating on hands and skin can be first wiped with dimethylbenzene and then be washed with clean water; the surface will be dried three hours after the brushing and will be dried out after 24h.
In the factory, the coating shall be processed according to the surface painting process of standard work piece.
Ground body steel shall be covered with materials such as soil or resistance reducing agent 24h after being coated and if the construction period is short, the coating must be dried for more than 5 hours.
JHY high-conductivity nanometer composite anti-corrosive earthing material is the efficiency conductivity coating produced through strict material optimization and optimal proportion of dosage based on the raw materials such as conductive filler including nano carbon and graphite powder, modified epoxy resin, organic solvent and coupling agent. The composite components obtained through covering such product on galvanized steel plate or raw steel uniformly have excellent conductivity and corrosion resistance against acid, alkali and salt; the conductive and anti-corrosive effect are obvious.
Schematic diagram of product
See Figure 1 for JHY high-conductivity nanometer composite anti-corrosive earthing material (galvanized round steel is adopted as the base material)