| Contact components are pivotal element of switch wiring. To great extent the service life and major properties of switch wiring are decided by contact materials. With the improvement of the electric contact manufacture and the increase of variety, especially meeting the need of saving silver and other noble metals, people attach importance to the research of copper-based contact materials instead of silver.Perfect electrical contact materials must meet the various needs of synthetic performance, such as physical performance, mechanical performance, electrical contact performance, chemic performance, manufacture performance and so on. These demands are diversiform, and some performance needs are contradiction to each other, so only one material is impossible to content these requirements. Therefore, generally adopting powder metallurgy technology, by this method two or more kinds of metals or alloys which have different performances and can't dissolve in each other or solubility is little can be combined to produce composite materials. In this way the material can accord the above-mentioned demands of major properties, and achieve optimal synthetic performance.This article based on the requirements of electric contact's performance, added many elements to copper-base, adopted powder metallurgy technology and made a new type copper-based electric contact composite material which has excellent performance with no silver. This material that possess upper conductivity, preferable oxidation resistance and anti-welding, lower tangent resistance and fine mechanics performance can meet the usable requirements of electric contact in low-voltage and substitute silver-based electric" contact materials which has been used extensively. Meanwhile it also can advance the use properties of switch wiring, and reduce the cost of electric contact element.Contact materials are demanded to have finer electric erosion resistance and anti-welding properties, but pure copper can't meet the requirement easily. So it is necessary to choose an element with low melting point, which can be more easily oxidized, burnt or vaporized than copper under the melting point and the oxide of which can be easily break up. When the oxide is decompounding, the electric arc's energy would reduce and extinguish easily. When the electric arc goes out, the cupreous molten would curdle. And the superfluous oxygen is expelled, forming small or tiny orifice. Thislacunaris structure is in favor of the contact's anti-welding properties. Choosing Sn, Cd, Zn, Bi and Sb as low-melting point elements, by doing electric performance and oxidation experiments on the materials, the result revealed that the electric performance of electric contact materials which used Cd as low-melting point elements is prime. However, Cd steam is poisonous. Through other low-melting point elements, the integrated performance of Bi as low-melting point element was better in conductance and tangent resistance. Consider the effect of Bi as low-melting point element to multifarious performances into accord, the added quantity of Bi is 2%.To improve copper-base's mechanical performance, enhance its hardness, simultaneously, advance its anti-wear, it is need to add high-melting point and high-hardness elements, which would compound with copper-base. And that would possess well electric performance and mechanical performance. Choosing WC, TiC and B4C as high-melting point and high-hardness elements, and the composite which was added B4C crystal granules has best properties through the comparison among samples' electric performance and hardness. Meanwhile the content of B4CS influence on material performance was researched. In copper-base composites materials, adding B4C can improve material's hardness and anti-wear. But if the added quantity exceeds 3%, the sample's hardness would have degressive trend, but then, its anti-wear would enhance as the increase of the added B4C quantity. The added quantity below 2% has little influence on oxidation resistance, however, the added weight of oxidation is severe when the added quantity exceeds 2%. Found the mathematic formulas of oxidation performance and electric performance which is quadratic function and simple function to the content of B4C. In the composites materials, when the molar percent of B4C between 0 and 5, it can be calculated that the composites materials' oxidation resistance and conductance by using mathematic relation. Synthetically take the influence of B4C as high-melting point and high-hardness element to holistic properties into account, the added content of B4C is confirmed about 2% at last. Thus the loss of its electric performance and oxidation resistance would be less at the base of improving the materials' hardness and anti-wear.The article researches the influences of cupreous alloy with rare earth and different content of it on the electric performance, mechanical performance and anti-welding of the copper-based contact composite materials. Through contrastive experiments it was found that rare earth could advance the conductivity of copper-based contact composite material sample when the content of rare earth didn't reach 0.05%. Materials' mechanicalperformance would be improved because of the adding rare earth. When the added content of rare earth is below 0.1%, the hardness of cupreous alloy with rare earth can increase quickly. When the added content of rare earth is below 0.2%, its anti-welding is better as the more rare earth. Rare earth can improve the materials' tangent performance and enhance its oxidation resistance and base's intensity. Considering the effect of rare earth on materials' synthetic properties, the optimal proportion of rare earth is about 0.1%. Found the mathematic formulas between the resistance and temperature of new materials adding 0.1% rare earth and without rare earth. The mathematic formulas indicate that added rare earth could stabilize resistance well at high temperature. Meanwhile analyze its mechanism. The reason is that rare earth can improve the interfacial property, enhance the based combinative performance with granules, and reduce the resistance of disfigurements as impurities and digital error in copper-base, which can increase its electrician performance.Through the testing of the samples' electric, oxidation and mechanical performance which are made by ball grind machining technology and ordinary powder mix technology, the influence of ball grind machining technology on electric contact performance was studied. Raw materials of contact materials are machining by ball grind machining technology, whose anti-wear and hardness would improved greatly. The reason is that bases can be mixed sufficiently with intensifier in the process of ball grind. Meanwhile the high energy which was produced in the process of ball grind makes the systemic activeness enough highness, and interfacial rise of temperature which was produced because of instantaneous mutual collision between the balls and powder grains leads to chemic reaction here. So the samples' mechanical performance would be enhanced greatly.. In addition, the influence of ball grind machining technology on electric performance and oxidation performance is mainly that intensifier can be distributed symmetrically on the surface of bases, thereby affect electric performance and oxidation performance.Comparing the vacuum hot-press technology with general cold-press technology, with the rise of press temperature, the scleroses speed of alloy powder reduces and plastic ability of alloy powder advanced. Moreover, this technology can promote effectual pressure, and enhance the roughcast's uniformity and density. Because it was pressed in the condition of vacuum, roughcast's simple relative density could reach above 90%, and its holes' proportion was less than 10% after the hot-press. The plastic of contact materials augmented, and its holes' proportion reduced, so this couldpromote its density and uniformity.The optimal components proportion of the studied new type electrical copper-based composite materials was decided: Bi is 2%, B4C is 2%, rare earth (mixed rare earth with abundant La) is 0.1%, and the other is copper or other unavoidable impurities. Besides, the major parameters of the hot-press sinter were basically decided: the temperature is 750°C, keeping the temperature about 30 minutes, and the pressure is 25 MPa. Finally the new material's specific resistance can reach 2.40~2.80uIXcm, its hardness can be 57~65 HB, and its density can get 8.30~8.40g/cm3.The article discussed the relationship between the electric contact composite materials' microcosmic structure and its various properties in theory, studied the designed electric contact materials' electric performance, physic performance, mechanical performance and so on, and analyzed its structure and principle.By analyzing metallic electric theory and the factors which affect metallic conductance, the uppermost factor of those is the constituted phases' granularity and its dispersion degree. The finer the constituted phases are, the bigger the odds of electrons' dispersion on the crystal boundaries is, and its resistance is also higher. Through the contrast of the samples' real conductance with academic conductance which was calculated by some experiential formulas, it was found that multiphase copper-based composite materials' real conductance is lower than calculated conductance. When a suitable quantity of rare earth is added, copper-based composite materials' real conductance is more close to the calculated conductance. Discussed the new type materials' tangent resistance in theory, analyzed the formed theory of tangent resistance simply, set up simple model in perfect conditions, found generic model and formulas in practical conditions, qualitatively analyzed the new type materials' tangent resistance using formulas, and analyzed several primary factors affecting the new type materials' tangent resistance.Analyzed the contact materials' surface appearance and substantial components after intensified experiments, through the energy spectrum analysis, it can be observed that copper-based surface contains Bi and rare earth, which can illuminate that the two substances have obvious anti-welding effect in the process of fusion and welding. Besides, the contrastive experiments on oxidation resistance were carried. Because of the added rare earth and B4C, the new material's oxidation resistance is better than the CuCr25 electric contact material, and is close to 95Ag-5C electric contact material.This shows new material has overcome the trait that copper and cupreous alloy can easily form oxidation pellicle.The article discusses the new material's hardness and anti-wear, and analyzes its microcosmic structure. The major reason of the new material's advance in hardness and anti-wear is the adding of B4C which has the effect of dispersion intensify and digital error intensify. Consequently, the new materials' anti-wear and hardness can meet the need of materials' properties.The research of new materials' various properties and the analysis in theory shows that the new material has overcome the deficiency that copper surface can easily shaped with oxidation pellicle, the anti-wear is obviously higher than copper-based and silver-based contact materials in common use. In conclusion, new type copper-based electric contact composite material is a kind of material with excellent synthesis performance and cheap cost.
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