Large power tube lead-free sealed glass powder and its preparation method

Abstract

The invention discloses a larger power tube leadless seal glass and preparing method, which comprises the following steps: (1) allocating raw material with molar percentage rate at 20-60% P2O5, 25-55%ZnO,3-23% SiO2 and 3- 13% Na2O; adding B2O3, CuO and Li2O; blending these raw materials together; (2) loading the raw materials into quartz crucible under 200 deg.c; insulating 1.5 h; (3) melting under 1050-1250 deg.c; insulating 1-3 h; obtaining seal glass with bulking factor at 65-140*10-7 deg.c and seal temperature at 420-570 deg.c.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, in particular to a lead-free sealing glass powder for high-power tubes. Background technique [0002] The existing high-power tubes often use low-melt sealing glass. In the low-melt sealing glass, the lead-containing sealing glass has high resistance, low dielectric loss, high refractive index and dispersion, and absorbs high-energy radiation, and has a low softening temperature. With a series of characteristics such as good chemical stability, it has a wide range of applications in low-melt sealing. PbO-SiO2, PbO-B2O3, PbO-B2O3-SiO2, PbO-ZnO-B2O3 and other systems are often used in the preparation of lead-containing sealing glass at home and abroad. The poisoning dose of lead is only 1 mg, and the lethal dose is 1 g. However, the PbO content in most low-melting sealing glasses is even as high as 60-80 mol%. The heavy metal lead contained in such products will cause serious harm to the...

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Problems solved by technology

[0004] U.S. Patent P5153151 discloses a phosphate sealing glass whose molar composition is Li 2 O: 0-15%, Na 2 O: 0~20%, K 2 O: 0-10%, ZnO: 0-45%, Ag 2 O: 0-25%, Tl 2 O: 0-25%, PbO: 0-20%, CuO: 0-5%, CaO: 0-20%, SrO: 0-20%, P 2 o 5 : 24~36%, Al 2 o 3 : 0~5%, CeO 2 : 0~2%, BaO: 0~20%, SnO: 0~5%, Sb 2 o 3 : 0~61%, Bi 2 o 3 : 0~10%, B 2 o 3 : 0 to 10%, the transition temperature of the glass is 300 to 340°C, and the coefficient of thermal expansion is 135 to 180×10 -7 / °C, the disadvantage of this glass is that Tl 2 The toxicity of O is very high. At the same time, the thermal expansion coefficient of glass is relatively large, so it cannot be used for sealing with medium and low expansion coefficients.

[0005] The mole percentage of the glass composition disclosed in Japanese Patent No. H7-69672 is: P 2 o 5 : 25 to 50%, SnO: 30 to 70%, ZnO: 0 to 25%, adding B on this basis 2 o 3 、WO 3 , Li 2 O, etc., the transition temperature of the glass is 350-450°C, and the coefficient of thermal expansion is greater than 120×10 -7 / °C, the method of using fillers in the patent reduces the expansion coefficient of the glass, but affects the fluidity and airtightness of the glass when sealing

[0006] USP: 20020019303 proposes a sealing glass of phosphorus-tin-zinc system, the sealing temperature is 430°C~500°C, which is not conducive to industrial application because it needs to be produced and sealed in a reducing atmosphere, and because it contains a lot of cost More expensive SnO, so the application of this sealing glass has great limitations

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