| There were three types of insulating coating which included heat-resistant organic insulating coating,heat-resistant inorganic insulating coating,and heat-resistant organic-inorganic composite insulating coating on metal wires.The heat-resistant organic-inorganic composite insulating coating had both coating properties of organic materials and heat resistance of inorganic materials,and had received extensive attention and research.In order to improve the heat-resisting temperature of the insulation coating on the surface of the metal wire and make the coating having a certain ability to deform with metal,this paper prepared low melting point lead glass powder,talcum powder,etc.dispersed in organic solvents such as xylene and butyl titanate.The method of adjusting the thickness of Pb-Si-Mg-Ti-O heat-resistant insulating coating was studied.And the micro-structure,insulation at room temperature and high temperature,the insulation of the coating as the nickel plate is flexed and thermally impacted,and the level of adhesion between the coating and the nickel substrate were examined and analyzed.The suspension stability of heavy lead glass composite slurry was studied.Lead glass was prepared powder by high-energy ball milling.The particle size of lead glass powder was adjusted by sieving through 400 mesh.And lead glass powder was modified by KH-570.The suspension slurry was prepared by mixing modified lead glass powder,talcum powder,and montmorillonite into 3:1:4 volume ratio of acetylacetone:butyl titanate:xylene through high speed stirring.The effects of 25wt%~50wt%solids content and 0wt%~9wt%montmorillonite content on viscosity,Zeta potential and stability of suspension slurry were studied respectively.The results showed that with the solid content increasing from 25%to 50%,the viscosity and Zeta potential increased from 83mPa·s and 23.14mV to 778mPa·s and 30.96mV respectively.Suspension stability of slurry after standing for 24h from 46%increased to 93%.At 35%solids content,with montmorillonite increasing from 1%to 9%,the viscosity and Zeta potential increased from 172mPa·s and 20.96mV to 663mPa·s and 31.06mV respectively.Suspension stability of slurry after standing for 24h from 60%increased to 96%.With the total solid content is 30%~35%and montmorillonite 5%,the prepared suspension slurry had the characteristics of low solid content and high viscosity,and had better regulation of coating thickness.Basing on the above slurry,a coating was prepared on the surface of the nickel substrate by the dip method and sintering at a temperature of 600?to 800?for 1 minute to 30 minutes.And the preparation process of lead-containing ceramic coatings was studied systemly.The results showed that the thickness of ceramic coating prepared from 25%-50%solids slurry increased from 10?m to 18?m with sintered at 700?for 5min.The ceramic coating of 30%total solid content thickness increased from 12?m to 19?m with the dip was increased from1 time to 3 times through 700?sintering for 5 minutes.Multiple dipping and rapid sintering can reduce the single coating microcrack and improve the insulation performance of the ceramic coating?The effects of solid content and sintering method on the insulation of ceramic coating at room temperature and high temperature,the insulation after bending of nickel coating,and the insulation after thermal shock were studied.The combination of coating and nickel substrate was tested and analyzed.With the increase of sintering temperature,the insulation of ceramic coating increased first and then decreased.The resistance between the nickel plate and the coating surface at room temperature was 2000 M?,and the coating resistivity was58.68×10~9?·cm by sintering at 700?for 5 min.The resistance between the nickel plate and the coating surface decreased to 128 M?at room temperature by sintering at 750?for 5 min and ceramic coating loses insulation when sintered at 800?.High-temperature insulation test showed that the coating with 35%solid content and sintered at 700?for 5 minutes can maintain the 551M?resistance between the nickel substrate and the coating surface at 360?.The 10?m thick ceramic coating prepared by sintering at 700?for 5 min thickness had an insulation resistance of 316M?after the nickel was flexed 8 times.Then the 14?m thick ceramic coating prepared by sintering at 700?for 5 min thickness had an insulation resistance of 566M?after the nickel was flexed 10 times.Furthermore,the 19?m thick ceramic coating prepared by sintering at 700?for 5 min thickness had an insulation resistance of 239M?after the nickel was flexed 4 times.All kinds of ceramic coatings from35%solids content and 700?sintering for 5 minutes had a scratch rating of 1 to 2 and all had a good bond with the nickel substrate. |
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