Tunnel furnace (pushing plate furnace) sintering varistor

Since its invention, tunnel furnace zinc oxide varistor has been widely used in overvoltage protection of power electronic circuits due to its excellent nonlinearity and surge resistance. The manufacturing process is similar to that of general electronic ceramics. The main parameters of ZnO varistor are varistor voltage, leakage current, nonlinear coefficient, 8/20 wave flow capacity and so on. The consistency of these electrical properties determines the cost and quality level of the product and is the key to large production. The electrical properties of the ZnO varistor are mainly determined by the ceramic sheet preparation process, and the assembly process plays a secondary role. The preparation process of ZnO ceramics includes the following four factors: a. formulation; b. slurry preparation process; c. molding process; d. For the varistor that has been mass-produced, the formulation is fixed; the slurry preparation process can also be adjusted to maintain the uniformity of the formulation components and the smooth progress of the spray granulation. The process is fixed. Constant; the molding process can be fixed for secondary effects. Thus, the effect of the firing process on electrical properties is decisive. The tunnel furnace zinc oxide varistor is in the sintering process, so that the low melting point of the product near the inner wall of the crucible is lost in the crucible wall, which causes the product performance to deteriorate, and the dispersion of the center product is biased. The reason should be the same as above, that is, the loss of the low melting point of the green sheet during firing is still too much.

According to the sintering characteristics of the tunnel furnace zinc oxide varistor, we designed a tunnel type zinc oxide varistor sintering furnace, the main technical parameters:

1. Thermal parameters

(1) zui high temperature: 1300 °C.

(2) Common temperature: 1200 °C.

(3) Number of temperature control groups: 14 zones for heating, 20 points for temperature control, and 7 points for temperature measurement. (14 temperature zones in the whole furnace, temperature control zone 5 zone 5 points temperature control, high temperature section 6 zone 12 points temperature control, cooling zone 3 zone 3 points temperature control)

(4) Furnace temperature stability: ± ≤ 1 ° C (the meter display shall prevail).

(5) Temperature uniformity: ≤ ± 5 ° C (based on the measurement of the inlet temperature measurement ring)

(6) External temperature rise of the furnace: ≤60 °C (based on the surface thermometer)

(7) Heating power: ≤ about 190 KW.

(8) Insulation power: about ≤110KW.

(9) Working power: 3-phase 4-wire, 380V.

(10) Temperature control mode: Adopt Japanese Fuji strap 485 communication interface, thyristor module phase shift voltage regulation, automatic temperature control according to P, I, D principle.

(11) Speed ​​adjustment mode: precision speed control valve (Rexus) adjustment

By subdividing the temperature zone, the furnace structure is improved, and the atmosphere requirement of the varistor sintering is ensured, thereby achieving the consistency of the electrical properties of the product.

Epichlorohydrin (ECH)

Epichlorohydrin, 3-Chloro-1, 2 - epoxypropene, chloropropylene oxide ,ECH .

Molecular Formula: CH2OCHCH2Cl, C3H5OCl

Properties: It is a volatile, unstable colorless liquid with irritating odor similar to chloroform and ether. Molecular weight is 92.85, density, 1.1806g/cm3, boiling point, 116.11°C, freezing point, -57.2°C, refractive index (nd20), 1.4382, flash point (open cup), 40.6°C, and ignition point, 415°C. It is slightly soluble in water, miscible with many organic solvents, and able to generate azeotrope with a variety of organic liquids.

Main Applications:
Epichlorohydrin is an important organic industrial chemical and a chlorine-consuming product in fine chemicals, mainly for producing epoxy resin, synthetic glycerin, epichlorohydrin rubber, nitroglycerine explosives, glass fiber reinforced plastics, and electrical insulation products, which are widely used in the chemical industry, light industry, transportation, medicine, electronics and other fields. It also can be used as solvent for cellulose ester, resin, and cellulose ether, and the raw material of plasticizer, stabilizer, surfactant, and chloroprene rubber.

Toxicity and Protection: It is highly toxic, absorbed through the skin, and irritating to skin and mucous membranes. In higher concentrations, it has the function of narcotism. When poisoning occurs, there will be eye irritation, conjunctivitis, rhinitis, lacrimation, cough, fatigue, gastrointestinal disorders, nausea and other symptoms. Serious poisoning may lead to anesthesia or even lung, liver or kidney damages. Lethal concentration of human beings is 20ppm. Lethal dose of rat is 5090mg/kg. The maximum allowable concentration in air is 5ppm (18mg/m3). Production equipment needs to be closed, air, circulating, and the operator, wear protective equipment. In addition, due to intense auto polymerization, epichlorohydrin can not be heated in the fire in case of container burst. As for reaction as reagent, it is appropriate to be diluted with inert solvent and slowly added.

Packaging, Storage and Transport:
As ferric chloride or stannic chloride can promote auto polymerization, epichlorohydrin should be stored in dry, clean iron barrel, 200kg each, and kept in a cool, ventilated, and dry place, away from fire and heat. Store and transport in accordance with the provisions of flammable toxic substances.

EPICHLOROHYDRIN SPECIFICATION DATA SHEET

Epichlorohydrin (Ech),Epichlorohydrin 106-89-8,99.9% Epichlorohydrin,High Quality Epichlorohydrin

Shandong Tiancheng Chemical Co., Ltd. , https://www.tianchengchemical.com