Lead-free high-insulating ceramic coating zinc oxide arrester valve and preparation method thereof

A method for preparing a zinc oxide surge arrester valve block having a lead-free insulating ceramic coating, the method comprising:

• preparing an initial powder from starting materials with the following mass percentages:
• ZnO:
• 86-95%;
• Bi2O3:
• 1.0-3.0%;
• Co3O4:
• 0.5-1.5%;
• Mn3O4:
• 0.2-1.0%;
• Sb2O3:
• 3.0-9.0%;
• NiO:
• 0.2-1.0%;
• and SiO2:
• 1.0-3.0%;
• preparing a ceramic coating powder by mixing the initial powder, deionized water and first agate grinding balls, loading the mixture into a polyurethane ball mill jar, ball milling the mixture, and oven-drying and pulverizing a slurry resulting from the ball milling, wherein a ratio of a mass of the initial powder to a mass of the deionized water to a mass of the first agate grinding balls is 3:2:4;
• preparing a ceramic coating slurry by mixing a PVA solution, the ceramic coating powder and second agate grinding balls, loading the mixture into a polyurethane ball mill jar and ball milling the mixture, wherein a ratio of a mass of the ceramic coating powder to a mass of the PVA solution to a mass of the second agate grinding balls is 1:0.6:3;
• and
• spreading evenly the ceramic coating slurry on a side of a ZnO varistor element formed by pressing, once the slurry is dry, it is put into a heating furnace with a green body and integral debinding is performed, a resistor element resulting from debinding is sintered, the sintered green body undergoes abrasive disk processing and heat treatment;
• an end face of the heat-treated resistor element undergoes aluminum electrode spraying, to obtain the zinc oxide surge arrester valve block having a lead-free insulating ceramic coating.