Ceramic discharge tube low-temperature nickel metallization sealing method

Abstract

The invention discloses a ceramic discharge tube low-temperature nickel metallization sealing method comprising the steps: preparing a slurry from a nickel powder with the particle size of less than 0.6 micron, a low-temperature inorganic binder, a boron powder with the weight of about 5% and an organic binder according to a set proportion, carrying out ball milling, then coating the surface of a ceramic discharge tube with the mixture, placing the ceramic discharge tube in air, and curing under conditions of the temperature of 100-140 DEG C and the drying time of 30-80 min, wherein in the curing process, organic compounds are oxidized and volatilized, a glass powder starts to carry out a reaction and the nickel powder is not oxidized; then under a condition of the temperature of 350-700 DEG C, sintering into a metallized ceramic tube; and then under conditions of the temperature of 700-900 DEG C and a welding atmosphere of hydrogen or vacuum, welding the metallized ceramic tube with a copper electrode in a brazing furnace. The method ensures the welding strength and the rate of finished products without hydrogen or hydrogen atmosphere sintering equipment, without high temperature nickel metallization and only under the condition of the boron powder, and has the advantages of process simplification, raw material saving and low cost; the welding strength reaches the strength level of a ceramic discharge tube welded by a traditional method of sintering a pure nickel sample in a hydrogen atmosphere and at the temperature of 1000 DEG C.

Description

technical field [0001] The invention relates to a low-temperature nickel metallization sealing method for ceramic discharge tubes, in particular to a low-temperature nickel metallization sealing method for ceramic gas discharge tubes in the air, and belongs to the technical field of bonding ceramic fired products and metal products. Background technique [0002] In the manufacturing process of the ceramic gas discharge tube, it is necessary to weld the ceramic discharge tube and the copper electrode in the discharge tube. Since the ceramic cannot be directly welded to the copper electrode, a Mo-Mn metallization is usually used, but the Mo-Mn layer is also It cannot be welded with copper, and the method of secondary nickel metallization is used to achieve firm welding with copper electrodes, such as the invention patent "a sintered metallization process for ceramic parts" (2015104510690) and "a ceramic discharge tube sealing Process" (201410668555.3) disclosed steps. There a...

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Problems solved by technology

However, the nickel coating method is still the most widely used method at present, which is both environmentally friendly and relatively economical. The nickel coating method has been developed so far, but there are still the following problems: First, it is easy to appear black wall climbing on the side wall during the nickel metallization process of small porcelain parts Once climbing the wall, it will be a waste product; second, when sintering in a hydrogen atmosphere, the cost of hydrogen required is high and dangerous, and requires high equipment; third, the sintering temperature is relatively high, such as the temperature of nickel metallization in a hydrogen atmosphere is about 1000℃

However, this method of sintering nickel electrodes in air is not suitable for the nickel metallization sealing of ceramics, because the sealing of ceramic gas discharge tubes requires metal Ni to form a firm bond with the metallized Mo layer and to form a firm bond with the copper electrode. For welding, when using the existing method of firing nickel electrodes in air to metallize ceramic discharge tubes, glass powder will be precipitated and partially oxidized on the metallized surface, which will seriously affect the welding strength with copper electrodes

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