Basic Study Of Preparing Insulating Pouring Sealant Of The Silica Powder

Non-metallic mineral filler is important component of insulating pouring sealant,which improves it heat resistance, thermal conductivity, mechanical properties and soon. The fillers commonly used are quartz silica powder, aluminum hydroxide, alumina,wollastonite, etc.. Silica and alumina have good performance, and they are the mostcommonly used fillers. Micro silica has good performance, is rich in mineral resourcesand cheap, and it is widely used fillers in insulating pouring sealant. Quartz silicapowder has a great influence on the mechanical properties and electrical resistivity ofinsulating pouring sealant. In order to clearly understand the reasons,using the PC68digital high resistance meter, WE-100hydraulic universal testing machine, Japan5530scanning electron microscope, SNB-1rotational viscometer, Z323K refrigeratedcentrifuge produced by Germany Hermle company, BT-9300H laser particle sizedistribution analyzer, BT-600type cycle dispersion equipment, study insulationproperties and compressive strength of quartz silica powder in insulating pouringsealant, and test their particle size distribution in epoxy resin, the dispersibility andsettleability, then analysis its mechanism. The results have been made as follows:(1)The influence on the insulation resistance and compressive strength of the400mesh quartz silica micro powder: Preliminary results show that volume resistivity ofthe silica powder on the insulating pouring sealant is basically no adverse effect, whilehave a certain degree on the surface resistivity, and the resistivity values remained inthe same order; compressive strength increase while the amount of micro silica isunder100phr,on the contrary, it decreases rapidly when the amount of silica powderexceeds100phr.(2) The influence on the insulation resistance and compressive strength of the400mesh active quartz silica micro powder: Preliminary results show that volume resistivity of the silica powder on the insulating pouring sealant is basically no adverseeffect, while have a certain degree on the surface resistivity, and the resistivity valuesremained in the same order; compressive strength increase while the amount of quartzsilica powder is under120phr,on the contrary,it decreases rapidly when the amountof micro silica exceeds120phr. Compared with the same amount of unmodified quartzsilica powder active silica has always larger compressive strength. Surfacemodification has a positive effect on the compressive strength.(3)The dispersibility of the electrician-level quartz400quartz silica powder andactive quartz silica micro powder in epoxy resin: The result showed that thedispersibility of quartz silica micro powder modified by coupling agents in epoxy resinis better than that of silica micro powder at the ordinary temperature and60°C, thedispersibility of the-modified is better than the unmodified in the epoxy resin.Temperature and modified micro silica have influence on dispersibility.(4)The settling properties of electrical grade400mesh quartz silica micro powderand active micro silica in the epoxy resin: according to centrifugal stratified distancemethod, testing the settling time of the micro silica. The results show that theunmodified micro silica will take140.8days to settle completely and the active microsilica will take207.6days to settle completely in epoxy resin, settling time mainly dueto the particle size, the particle size of active micro silica is mainly concentrated in the0.1um to0.4um, the particle size of unmodified micro silica is mainly concentrated inthe10um to100um. The settling properties of unmodified micro silica is worse thanthe active micro silica.(5) Modification of the quartz silica powder by using a silane coupling agent, andmeasure its hydrophobicity: the results show that,the micro silica after thesurface-modified is measured hydrophobicity than3hours according to the nationalstandard, the modification can improve the filling performance among the micro silicaparticles and the epoxy resin. According to SEM images of insulating pouring sealant,it is clear that the surface-modified micro silica is very closely contact with epoxy resin.