填料对电机用轻量化导热灌封胶性能的影响

以端乙烯基硅油、含氢硅油为原料,添加填料、催化剂等制得有机硅灌封胶,探讨了α-氧化铝、球形氧化铝、氮化硼、有机蒙脱土对灌封胶性能的影响。结果表明,单纯采用α-氧化铝作填料时,灌封胶的流动性较差、排泡时间过长;采用相同粒径的球形氧化铝替代α-氧化铝能降低灌封胶的黏度,提高流动性和排泡速度,但会降低热导率,且胶料密度过高;添加氮化硼能降低灌封胶密度;添加有机蒙脱土能有效提高灌封胶的抗沉降性能和阻燃性能,但同时会增强胶料的触变性,降低流动性和热导率;当氮化硼、平均粒径5μm的球形氧化铝和平均粒径30μm的球形氧化铝按质量比17∶15∶68复配的填料用量为250份、有机蒙脱土用量为2份时,制得的灌封胶综合性能较佳,黏度为4527 mPa·s,热导率为1.51 W/(m·K),密度为1.81 g/cm³,阻燃等级为V-0级,流动性为9.4 cm/min,抗沉降性能较好,可作为汽车电机用轻量化灌封胶使用。

Effect of Fillers on the Performance of Lightweight Thermal Conductive Potting Adhesive for Electric Motor

Silicone potting adhesive was prepared with vinyl silicone oil,hydrogen polysiloxane,fillers and catalyst.The effects ofα-alumina,spherical alumina,boron nitride and OMMT on the properties of the potting adhesive were investigated.The results show that the potting adhesive has poor flowability and the defoaming performance while usingα-alumina as filler alone;while spherical alumina with the same particle size instead reduces the viscosity of the potting adhesive,it not only improves the flowability and defoaming performance,but also reduces the thermal conductivity,and has a rather high density of compounds;the density of potting adhesive can be reduced by boron nitride.The addition of OMMT improves the flame retardancy of potting adhesive and prevents precipitation,however enhances the thixotropy,decreases the flowability and thermal conductivity.The potting adhesive has a better comprehensive property with 2 phr of OMMT and 250 phr of composite filler compounded by boron nitride,5μm spherical alumina and 30μm spherical alumina with mass ratio of 17∶15∶68.The potting adhesive meets the specification of the lightweight automobile electric motor,with viscosity of 4527 mPa·s,thermal conductivity of 1.51 W/(m·K),density of 1.81 g/cm³,flame retardant grade of V-0,flowability of 9.4 cm/min and good settlement resistance,and can be used as lightweight potting adhesive for automoble motor.