| With the rapid development of modern science and technology, all kinds of electrical equipment is more and more widely used in the fields such as military, communications, medical, industrial and agricultural application, the electromagnetic radiation it produced is becoming more and more strong. Increasingly serious electromagnetic radiation can produce electromagnetic interference, electromagnetic information leaks and electromagnetic pollution of the environment.Electromagnetic shielding coating as a kind of high cost performance shielding materials play an important role in the electromagnetic pollution prevention. But the traditional electromagnetic shielding coatings use metal as conductive filler which has excellent electrical conductivity but more the high cost, such as, silver, copper, nickel and other metal powder or lower cost nonmetal powder but poor electrical conductivity such as carbon black, graphite, tourmaline, carbon fiber, etc. Glass fiber is a new type of functional and structural material in inorganic non-metallic materials. Glass fiber has series of excellent properties, but it’s poor electrical conductivity. Conductive glass fiber prepared by electroless plating, can improve the conductivity of the glass fiber, to achieve broaden its use, to improve its cost performance. Compared with the traditional carbon fiber, brass fiber, aluminum and other metal fibers, the surface coated with metal glass fiber has better conductive, low metal proportion and low cost. So the research and development new type of conductive glass fiber has a certain engineering significance and economic value.In this paper, based on the previous research, we chose copper with good conductivity and nickel with good corrosion resistance, oxidation resistance as glass fiber plating metal. Ni-Cu covered glass fiber is prepared by using electroless plating technology, through the degreasing cleaning, activating and sensitization pretreatment. Nickel sulfate(Ni S04·6H20) and copper sulfate(CuS04·5H20) are used as the metallic main salt, Sodium hypophosphite(NaH2PO2·H2O) is used as the reducing agent, and Nitrilotriacetic acid N((CH2COOH)3) is used as the complexing agent. The conductive glass is analyzed and tested by scanning electron microscopy(SEM), X-ray diffraction(XRD), infrared spectrum(IR). A new kind of Ni-Cu-coated glass fiber/nickel powder/epoxy resin electromagnetic shielding composite coating is developed by preparation methods of paints, using the treated Ni-Cu-coated glass fiber and nickel powders in a certain proportion as composite fillers and using epoxy resin as binder. It is tested by the electrical conductivity and shielding effectiveness and other physical and chemical properties. This paper gives a new way to improve the cost performance of glass fiber and broaden its application in order to research and develop a new type of cheap electromagnetic shielding materials. The main results of the research are as follows:Pretreatment technology of glass fiber are as follows: deoiling treated with acetone, surface modificated with 1% of gamma ammonia propyl triethoxy silane solution, coarsening processed with 60-65% nitric acid solution, sensitizing treatment with 12g/L Sn Cl2·2H2O and 30 g/L HCl mixed solution, activating treated with 0.5 g/L PdCl2 and 1 mL/L HCl, restore treated with 1.0-3.5% of sodium phosphite solution.The basic formula of plating solution of electroless plating Ni-Cu glass fiber: 30~40 g/L nickel sulfate and 5~10 g/L copper sulfate as the metallic main salt, 25~50 g/L sodium hypophosphite(Na H2PO2·H2O)as stabilizer, 30~50 g/L Nitrilotriacetic acid N((CH2COOH)3) as complexant etc. Among them, the solution of the p H value is 4.8, chemical plating temperature is 88 ℃, the plating time is 1 ~ 2 h.The analysis Result of EDS of glass fiber before and after the chemical plating nickel copper indicates: The weight percentage of Ni, Cu in Ni-Cu-coated class fiber is increased from 0.13% and 0.68% to 17.39% and 1.91%. The atomic percentages of Ni、Cu in Ni-Cu-coated glass fiber is increased from 0.05% and 0.22% to 5.77% and 0.59%. That means electroless plating technique successfully surface metalized of glass fiber. The resistance of Ni-Cu-coated fiber glass measured by the digital multimeter is 0.85 ? and the pure glass fiber is insulator. This means the chemical plating Ni-Cu improves the glass fiber composition and electrical conductivity.A new kind of Ni-Cu-coated glass fiber/nickel powder/epoxy resin electromagnetic shielding composite coating was developed by preparation methods of paints, using the treated Ni-Cu-coated glass fiber and nickel powders in a certain proportion as composite fillers and using epoxy resin as binder. In the Ni-Cu-coated glass fiber/nickel powder/epoxy resin electromagnetic shielding composite coating, the optimum addition amount of Ni-Cu-coated glass fiber is 5 wt% of the filler content; the resistivity of the coating is 1.32 ? ?cm reduced by 1.08 ? ?cm compared with the nickel powder/epoxy resin coating when the coating layer thickness is 0.3 mm; in the frequency range of 300 k Hz-1.5 GHz, the shielding effectiveness(SE) of the coating is 35.822-41.924 d B increased by 1.17-8.79 d B compared with the nickel powder/epoxy resin coating; and the electrical conductivity and shielding effectiveness(SE) of the coating are significantly improved; the properties of the coating achieve conformity to product requirements of the SJ/T 10674-1995 < General Technical Specifications of Paint Coating >. |
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