Silver, copper, palladium and gold alloy brazing wire and preparation method thereof

Abstract

The invention relates to a silver, copper, palladium and gold alloy brazing wire and a preparation method thereof. A silver, copper, palladium and gold alloy comprises, in weight percent, 25-35% of copper, 20-30% of palladium, 0.1-5% of gold and the balance silver. The preparation method includes the steps: selecting high-purity silver, oxygen-free copper, high-purity palladium and high-purity gold, calculating the demanded quantity of the silver, the copper, the palladium and the gold according to a matching range, and preparing materials; placing the matched furnace materials into a crucible of a vacuum melting furnace, heating the furnace materials in high vacuum, refining the materials after the furnace materials are completely molten, adjusting the temperature to reach 900 DEG C to 1000 DEG C, and casting the materials; performing multi-pass rotary forging and vacuum annealing for a cast ingot; further drawing the wire and performing vacuum annealing, scalping and washing, finally, drawing the wire to obtain the finished brazing wire after burning a head by the aid of hydrochloric acid and passing a die. The diameter of the cast ingot is rotatably forged from phi 15mm to phi 3.4mm, the diameter of the finished brazing wire is phi 0.5mm, the melting point of the brazing wire ranges from 870 DEG C to 880 DEG C, the flow point of the brazing wire ranges from 890 DEG C to 910 DEG C, the temperature difference between the melting point and the flow point is small, the brazing temperature approximately ranges from 910 DEG C to 930 DEG C and approaches that of AuCu20 (with the melting point of 910 DEG C), and the AuCu20 can be partially replaced when electric vacuum devices with base materials such as oxygen-free copper, nickel, stainless steel and a nickel alloy are welded.

Description

technical field [0001] The invention relates to a silver alloy brazing material for electric vacuum devices and a preparation method thereof, in particular to a silver-copper-palladium-gold (AgCuPdAu) quaternary alloy wire-shaped brazing material and a preparation method thereof. Background technique [0002] The work of vacuum electronic devices requires long-term maintenance of high vacuum, and the devices are usually brazed in a hydrogen furnace or a vacuum furnace. Therefore, the brazing filler metal must meet the following requirements: 1) general brazing filler metals cannot contain high vapor pressure elements such as Zn, Cd, Bi, Mg, Li; No splashing during brazing; 3) The solder must be clean, otherwise the welding surface will turn black when the solder melts, seriously affecting the normal use of the device; 4) The melting point should be at least 60°C lower than that of the base metal; The flow distribution of the material (wettability, spreadability, ability to ...

AI Technical Summary

Problems solved by technology

Especially in the temperature range of 900 ℃ ~ 950 ℃, AuCu20 is the best gradient solder, its melting point and flow point are both 910 ℃, there is no temperature difference in melting flow to affect the flow of solder, it has good welding performance, low vapor pressure, plasticity Good, wide range of welding base materials, etc., but because AuCu20 involves precious metal gold raw materials, the raw material cost and price are high, making the welding cost of electric vacuum devices expensive, so the research on replacing gold-based solder is particularly important