Low-melting-point and high-strength low-silver cadmium-free manganese-free multi-element silver solder and preparation method thereof

Abstract

The invention relates to a low-melting-point and high-strength low-silver cadmium-free manganese-free multi-element silver solder and a preparation method thereof. The multi-element silver solder is composed of 19%-23% of silver, 32%-35% of zinc, 1.0%-3.0% of tin, 0-2.0% of nickel, 0-3.0% of indium, 0.01%-1.0% of alloying elements and the balance of copper, wherein the alloying elements are one ormore of phosphorus, lanthanum and cerium; and the alloying elements are composed of the following components in percentage by mass: 0.2%-1% of phosphorus, 0-0.02% of lanthanum and 0-0.01% of cerium.The preparation method of the multi-element silver solder comprises the following steps: S1, heating copper in Cu-X alloy in a medium-frequency smelting furnace crucible to be completely molten, and then adding alloy metal X till the Cu-X alloy is completely molten; S2, adding silver, zinc, tin, nickel and indium with the purity being at least 99.99% and the remaining part of the Cu-X alloy from which copper is removed into the medium-frequency smelting furnace crucible containing the molten Cu-X alloy to be smelted and cast according to the component proportion of the low-silver cadmium-freemanganese-free multi-element silver solder; and S3, carrying out subsequent treatment. The silver solder is easy to prepare, the total content of cadmium, manganese, silver and indium is low, the solid phase line temperature, the liquid phase line temperature and the welding performance are proper, and the machinable performance is high.

Description

technical field [0001] The application relates to a low-melting-point, high-strength low-silver, cadmium-free, manganese-free multi-component silver solder and a preparation method thereof. Background technique [0002] Silver-based brazing filler metal is a medium-temperature hard brazing filler metal widely used in low-carbon steel, stainless steel, copper alloy and other alloys. It has excellent process performance, suitable melting temperature, good gap filling ability and wettability. With the increase of silver price, the cost of silver-based solder is also rising. High-performance low-silver solder has always been the goal pursued by enterprises. Among the traditional low-silver solders, the performance of cadmium-containing silver solders is the most prominent, mainly because as the silver content in the solder decreases, its melting temperature will continue to rise, and the spreading performance will also decrease. At this time, the addition of cadmium can effectiv...

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Problems solved by technology

The silver content of the solder involved in the above three patent documents is < 20 wt.%, but the soldering temperature is high, and it cannot replace mature low-silver solder products such as BAg25CuZnSn and BAg26CuZnSnIn

CN10494247B recommends a cadmium-free silver solder containing tin, silicon, zinc and praseodymium and its preparation method. The silver content is 30 wt.%, the solidus temperature is 670°C, and the liquidus temperature is 765°C. The advantage is that after adding the rare earth element Pr, the spreading performance and the tensile strength of the brazed joint are effectively improved, and it can be used to replace BAg45CuZn with high silver content. The brazed brass joint can reach 320MPa-370MPa, but the silver content is relatively high. Its cost is still "on the high side"

CN103418933A discloses a cadmium-free silver solder for connecting brass and stainless steel. The silver content is 18-22wt.%. It is alloyed with In, Sn, Ni and lanthanum-cerium mixed rare earth elements, and has good properties with brass and stainless steel. It is used to replace the silver-copper-zinc solder with a silver content of 25 wt.% and above, but only two of its examples have a solidus line lower than 680°C and a liquidus line lower than 790°C, The proportion of silver and indium in its composition formula is about 25~26 wt.%. Considering that the price of indium is comparable to or even higher than that of silver, it cannot be used to replace the solder with a silver content of 25~26 wt.% to reduce costs

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