Lead-free phosphate sealed glass for electrothermal tube and its preparation method

Abstract

The invention discloses an electrothermal tube leadless microcosmic salt sealing glass, which comprises the following parts: 35-50% P2O5, 30-50% ZnO, 0-15% B2O3, 0-10% SiO2, 30-10% Al2O,0-10% Na2O, 0-8% MgO, 0-3.5% Li2O, 0-2% Fe2O3 and 20-2.5% MnO. The preparing course comprises the following steps: (1) producing mixture; (2) preventing heat 1-3 h under 200-250 deg.c; (3) melting 0.5-2 h under 1050-1250 deg.c; (4) cooling and hardening the melting liquid.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, in particular to a lead-free phosphate sealing glass for an electric heating tube and a manufacturing method thereof. [0002] Background technique [0003] Existing electric heating tube sealing glass contains a large amount of metallic lead, such as the lead content of existing electronic sealing glass brand DH-704 is 77%, and the lead content of DB-435 is 34%. We know that the heavy metal lead is harmful to the human body, the poisoning dose of lead is only 1 mg, and the lethal dose is 1 g. Therefore, the use of lead-free sealing glass to replace lead-containing sealing glass has attracted the attention of developed countries, and has become a green trade barrier in developed countries to a certain extent. The research on lead-free low-melting sealing glass has certain practical and economic benefits. . [0004] U.S. Patent US20020019303 proposes a sealing glass of phosphorus-tin-z...

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Problems solved by technology

[0003] U.S. Patent US20020019303 proposes a sealing glass of phosphorus-tin-zinc system, the sealing temperature is 430℃~500℃, but because it contains a large amount of SnO, it needs to be reduced The production and sealing under the atmosphere are not conducive to industrial application, and the cost of SnO is relatively expensive, so the application of this sealing glass has great limitations

[0004] US Patent P5153151 discloses a phosphate sealing glass with a transition temperature of 300-340°C and a thermal expansion coefficient of 135-180×10-7 / °C, the thermal expansion coefficient of this glass is relatively large, so it cannot be used for sealing with medium and low expansion coefficients

[0005] Hitachi, Ltd. published a vanadium oxide (V2O5) system For sealing glass, the sealing temperature is less than 400°C, and the thermal expansion coefficient is below 90×10-7 / °C. However, lead oxide is a necessary component in this glass, which cannot meet the requirements of lead-free. At the same time, it also contains highly toxic thallium oxides

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