反应合成银氧化锡材料的电接触性能研究

【作者】 刘方方；

【导师】 陈敬超；

【作者基本信息】 昆明理工大学 ， 材料物理与化学， 2008， 硕士

【摘要】 AgSnO₂电接触材料作为最具有应用前景的电接触材料而备受关注,作为开关电器中承担接通和分断电路的元件,它对开关电器的安全运行起决定性作用。因此研究AgSnO₂材料的电接触性能非常重要。本论文研究了真应变分别为ε₁=5.9、ε₂=11.7、ε₃=17.6的反应合成AgSnO₂电接触材料在直流、阻性负载的工作条件下的电接触性能。依据实验结果,利用分子动力学方法对电弧侵蚀过程中触头表面的熔池行为进行了计算、模拟。实验结果表明,反应合成AgSnO₂材料在电压18V、电流5A～25A工作条件下,材料转移量＜120ng/次;在电压8.5V、电流4A～14A材料转移量＜50ng/次,表现出低的材料转移性能。在18V工作电压,电流值≤20A工作条件下,反应合成AgSnO₂材料的熔焊力曲线波动小,且数值较低,这表明反应合成AgSnO₂材料在该工作条件范围内抗熔焊性能良好。但电流值＞20A时,材料的抗熔焊性能明显下降。反应合成AgSnO₂触头材料在电压18V、电流5A～30A工作条件范围内,触头材料的转移方式有阴极转移、阳极转移两种,且发生阴极转移时材料转移量比发生阳极转移时增大。材料转移方式发生反转的电流临界值与材料的变形量有关。变形量越大,临界电流值越小。反应合成AgSnO₂触头材料在电压8.5V、电流4A～14A工作条件下,触头材料转移方式单一,只发生阴极转移。在开、闭频率分别0.8HZ、1.0HZ、1.2HZ条件下,反应合成AgSnO₂触点材料（ε₃=17.6）的转移方式有阳极转移、阴极转移两种,且材料转移方式发生反转的临界电流值都一致,为16A。随着频率的增大,反应合成AgSnO₂材料在材料转移方式发生反向后,阳极触点质量损耗量显著增大,而阴极触点质量增加量逐渐减少,从而导致一对触点的总质量损耗呈现增大的趋势。反应合成AgSnO₂触点材料的电弧侵蚀形貌特征表现为凸起和凹坑、气孔、裂纹、熔珠及网状结构。表明在电接触过程中,触头表面形成了熔池,网状结构表明触头表面发生的黏附是导致材料转移的一种重要方式。结合能谱分析得知,材料发生阴极转移时对材料的电弧侵蚀更严重。结合分子动力学计算结果和实验结果得知,当温度界于银基体的熔点和氧化锡的熔点之间时,团聚的氧化锡颗粒在银熔池中被不断分散、解离成较小的团聚颗粒,从而氧化锡在银液中的分布更加均匀,增大了熔体的粘度,这是反应合成AgSnO₂电接触材料具有较低的材料转移能力的重要原因。随着温度升高,当熔池温度达到氧化锡的分解温度之后,氧化锡发生分解,通过计算和分析得知,氧化锡的分解及银的汽化都大大消耗了电弧能量,是灭弧的主要原因,是降低材料转移量的重要因素。更多还原

【Abstract】 AgSnO₂ contact material is the most promising electrical contact material,as in the electrical switch connected to the circuit and breaking device,which switches the safe operation of electrical appliances play a decisive role.So the study of electrical contact materials AgSnO₂ performance is very important.This paper studies the true strain wereε₁=5.9、ε₂=11.7、ε₃=17.6 of AgSnO₂ Contact Materials which was made by Reactive Synthesis,when under DC,resistive load conditions of electrical contact properties,then use the Molecular Dynamics method to calculate and simulate the atomic motion in the melting pool because of arc erosion.The experimental results show that the RS-AgSnO₂ has good arc erosion resistance properties when working under 18V,5A-25A conditions,the material mass change less than 120ng per-time,while the mass change would less than 50ng per-time when the conditions change to 8.5V,4A-14A.Under the 18V,and the current less than 20A working conditions,the RS-AgSnO₂ has good welding resistance performance.But once the current value is more than 20A,the welding resistance properties would declined markedly.RS-AgSnO₂ contact material mass transfer including two ways,anode transfer and cathode transfer.Both of the two ways would happen under the 18V,5A-30A working conditions.And the critical current condition is the determining factor of the way of material transfer.The more the true train is,the less critical current value is.But when the RS-AgSnO₂ contact material works under 8.5V,4A-14A conditions,the single material transfer mode is cathode transfer,and the mass change is little.As the break-close frequencies were 0.8HZ,1.0HZ,1.2HZ conditions,the RS-AgSnO₂ contact material（ε₃=17.6）transfer mode including anode transfer and cathode transfer, and material transfer reversal of the way in which the critical current value unanimously for the 16A.With frequency increasing,the anode mass loss of RS-AgSnO₂ contact material is significant increase,and the mass increases in the quality of cathode contacts gradually reduced,resulting in a total mass loss of contact shows an increasing trend.The SEM characteristics of RS-AgSnO₂ contact material after arc erosion performance the uplift and pockmarks,pores,cracks,melting beads and reticular structure.These indicated the contacts surface had molten during electric-contacts.The network structure is the result of arc erosion.With the EDS results,it’s sure that the mass loss during cathode transfer is more serious than during anode transfer process.Combine the Molecular Dynamics calculation results with the experimental results,it shows that when the contacts materials surface temperature is between the melting point of silver and the melting point of tin oxide,the particle reunion of tin oxide particles in the pool were dispersed into smaller dissociation reunion particles.Thereby the viscosity of the RS-AgSnO₂ melting pool would increase.And this is one reason of why the RS-AgSnO₂ contact material has low material transfer performance.As the temperature increases,when the temperature of melting pool is higher than the sublimation temperature of silver,silver vaporization and tin oxide decomposition will occur,both of the two processes need energy consumption,it would consume arc energy. And the extinguished arc is an important factor to reduce the transfer of materials.更多还原