Preparation Of Conductive Grease And The Analysis And Calculation Of Its Contact Resistance

Electrical contact exists in modern power system, automatic control system and information transmission system. The stability and reliability of the electric energy and signal transmission are directly affected by the quality of electrical contact. Conductive grease can improve the quality of electrical contact. It can reduce the contact resistance and the heat, and prolong the life of electrical contact. The conductive grease which works under current carrying, take the responsibility of friction reducing, wear resistance, energy and signal transmission. Therefore, it requires the conductive grease has excellent tribological properties and conductive capacity. In order to solve this problem, the main research contents and conclusions of this paper are as follows:(1) The vapor grown carbon fiber (VGCF) was used as the conductive additive, and the Ag and Cu were used as the contrastive additives. The polyepoxyethane polyoxypropylene monobutyl ether (PAG660) and the teflon (PTFE) were used as base oil and thickner, respectively. A series of conductive greases were prepared and we investigate the conductive capacity and tribological properties in detail. The results show that the VGCF can reduce the volume resistivity of grease and improve the conductive capacity at room temperature and 100℃. When then concentration of VGCF is 1.5wt%, the VGCF grease has a better tribological properties than that of Ag and Cu greases.(2) The Ketjen black was used as the conductive additive, and the acetylene black and carbon black were used as the contrastive additives. The Oil soluble polyether (OSP320) was used as base oil to prepare a series of conductive lithium complex grease. The conductive capacity and tribological properties were investigated in detail. The results show that the ketjen black which possess special branch structure can form a better conductive network than acetylene black and carbon black. The conductive lithium complex grease has an excellent conductive capacity at room temperature,100℃ and 150℃.The ketjen black also can improve the tribological performances. When the concentration of ketjen black isl.8wt%, compared with acetylene black and carbon black, the conductive grease prepared with ketjen black has better friction reducing and wear resistance.(3) According to the theory of electrical contact, we calculated the relationship between the contact resistance and the contact pressure, the concentration of conductive particles. Contact resistances of conductor were measured at different contact pressures. A formula was got by fitting the experimental data. The result shows that:with the contact pressure and concentration of the conductive carbon black increasing, the contact resistance decreases. There is a numerical relationship between the contact resistance and contact pressure, concentration of conductive particles. The further experiments prove the correctness of the calculation model.