Study On The Characteristics And Mechanism Of Muscovite Type Mineral In Insulating Pouring Sealant

Having an extremely high insulation property and a lower dielectric loss, muscovite minerals were widely used in insulating materials. In order to overcome the existing shortcomings that using non-metallic mineral insulating to fill the pouring plastic and to provide the scientific basis for new insulation pouring sealant preparation, application and so on, using the PC68 digital high resistance meter, WE-100 hydraulic universal testing machine, Japan Science 5530 scanning electron microscope and spetrum one type of fourier transform infrared spectroscopy, focus on researching the microcrystalline muscovite, crushed mica, muscovite, silicate and other minerals muscovite plastic infusion's new functional materials, insulation resistance and compressive strength characteristics and mechanism. At the same time, focus on the minerals and other small samples of solid insulating materials resistivity of the test methods and influencing factors, and obtained the following results:(1)Design and application of a small electrode experimental installation for resistivity measurement of mineral and solid insulating material: According to the Chinese National Standard (GB/T1410-2006) and features of digital high resistance meter, a small electrode experimental installation was developed; it can work with current high resistance meter; the sample decreases to 18 mm from standard size 100 mm in diameter and reduces by 30.86 times in area. A three-electrode system is supported and precisely positioned by two insulating bases whose diameter is 60 mm and height is 20 mm, which ensures accuracy of device structure and reliability of measuring results. The key technological parameters are as follows: diameter of high voltage electrode is 18mm; diameter of measuring electrode is 14.6 mm; internal diameter and external diameter of guard electrode are 16 and 18 mm, respectively; the gap between guard electrode and measuring electrode is set at 0.6 mm. These parameters are adequate for the measurement of flat specimen of mineral and solid insulating material whose diameter is 18 mm. According to the confirmatory experiment on the volume resistivity and surface resistivity, the measuring results are almost the same, using a small electrode experimental installation and a standard electrode.(2)Some basic factors that influence insulating materials of mineral bulk resistivity the sample of the test: Clean and dry bulk micro-crystal muscovite samples placed in the air will continue to adsorbed water and impurities in the air, Thereby resulting in significant decline in insulation resistance,volume resistivity decreased from 2.35×10¹²Î©Â·cm to 7.50×10¹⁰Ω·cm, surface resistivity decreased from 4.79×10⁹Ωto 5.93 10⁸Ω, as storage time increased, this decreasing became gently, at last volume resistivity stable at 3.49×10¹⁰Ω·cm,which decreased two magnitude, surface resistivity stable at 3.49×10⁸Ω, which decreased one magnitude; untreated mica insulation resistance of ceramics will increase with the beginning of the increase of drying time. However, when the drying time was extended to 2h, the insulation resistance will incline to stable,volume resistivity increased from 2.38×10¹¹Î©Â·cm to 2.25×10¹²Î©Â·cm, surface resistivity increased from 2.11×10⁸Ωto 2.10 10⁹Ω, all of them increased one magnitude; rough surface will have no effect on the ceramic insulation resistance,normal samples can be used by more than 80 # sandpaper for polishingwhen the resistivity is tested.(3)The influences on the epoxy resin potting compound resistivity and compressive strength of the curing agent : When the 593 curing agent is 25phr, the cured product of the compressive strength, volume resistivity and surface resistance rate reaches the maximum, respectively 128.42Mpa, 8.93â…¹10¹⁵Ω·cm, 1.21â…¹10¹⁵Ω; When 650 polyamide reaches the number of 120phr, the cured product of the compressive strength, volume resistivity and surface resistance rate reaches the maximum, respectively 56.77Mpa, 1.04â…¹10¹⁶Ω·cm, 2.96â…¹10¹⁵Ω; When the Methpa curing agent was 70phr, the cured product of the compressive strength, volume resistivity and surface resistance rate reaches the maximum, respectively 113.45Mpa, 1.78â…¹10¹⁶Ω·cm, 8.55â…¹10¹⁵Ω.(4)Effect of microcrystal muscovite on the resistivity and compressive strength of insulating pouring sealant: the results show that: micro-crystal muscovite has no disadvantageous effects on the volume resistivity of insulating pouring sealant virtually, while it can improve the surface resistivity of insulating pouring sealant. When the amount of micro-crystal muscovite is 40phr, its surface resistivity reaches up to 7.53â…¹10¹⁴Ω, and compressive strength increases while the amount of micro-crystalline muscovite is under 100phr, on the contrary, it decreases rapidly when the amount of micro-crystalline muscovite exceeds 100phr. The optimized amount of microcrystalline muscovite is 80phr according to the insulating property, mechanical property and viscosity glue and so on.(5)The influence on the insulation resistance and compressive strength of the Muscovite minerals: Preliminary results show that under the circumstance of the Muscovite minerals reach 40phr comparing, Muscovite, crushed mica, muscovite microcrystalline silica minerals as filler ratio, the traditional mineral corundum powder has better insulation properties, Muscovite system in which the overall performance (volume resistivity 9.81â…¹10¹⁵Ω·cm, surface resistivity 2.35â…¹10¹⁵Ω, compressive strength (113.24Mpa) is more excellent. But the premise is not appropriate because of its relatively optimal amount of minerals, the issue needs to be further deepened.(6)The influence of the surface modification of ceramic insulation resistance and compressive strength of the muscovite:Preliminary results show under the circumstance of microcrystalline muscovite 80phr, after the modifying of the 3#, the insulation system (volume resistivity 2.10â…¹10¹⁶Ω·cm, surface resistivity 2.35â…¹10¹⁵Ω) and compressive strength (119.71Mpa) are more excellent, but study the issue needs to be further deepened; when microcrystalline muscovite powder reach saturated adsorption, the volume resistivity(8.53â…¹10¹⁴Ω·cm) and surface resistivity(4.33â…¹10¹⁴Ω) of unmodified cured product decreased an order of magnitude which compared with the volume resistivity(7.65â…¹10¹⁵Ω·cm) and surface resistivity(3.55â…¹10¹⁵Ω) of modified cured product, but the issue needs to be further deepened.