CN87106949A

CN87106949A - Air heat exchanger is with brazing material and brazing flux

Info

Publication number: CN87106949A
Application number: CN87106949.0A
Authority: CN
Inventors: 唐仁辉; 余强中; 童康年; 胡建时
Original assignee: SHANGHAI MATERIALS INST COMMISSION ON MACHINE BUILDING
Current assignee: SHANGHAI MATERIALS INST COMMISSION ON MACHINE BUILDING
Priority date: 1987-10-20
Filing date: 1987-10-20
Publication date: 1988-07-13
Also published as: CN1006046B

Abstract

Air heat exchanger brazing material of the present invention is to be the alloy that base contains Al, Sn element with Zn, and it is Zn91-93% that its weight percent is formed, Al3.5-5.5%Sn3.5-4.5%, with the supporting use brazing flux of this solder be ZnCl ₂, NH ₄The saturated aqueous solution of Cl and KCl, 372 ℃ of solder fusing points, solder joint intensity height, brazing manufacturability is good, and alloy element resource is abundant, and this brazing material price only is 1/10 of a pure tin solder.

Description

The invention relates to air heat exchanger with brazing material and brazing flux, specifically a kind of Zn base ternary alloy that contains Al, Sn element.

The radiating tube of air heat exchanger generally is to make with red copper, bronze, but the manufacturing of also useful ferrous metal, the radiating tube of ferrous metal manufacturing uses pure Z _nCan soldering.The radiating tube that red copper or bronze are done is to do solder with pure tin or high tinalloy traditionally.Air heat exchanger is refrigeration and the every heating of common apparatus, the oven dry that heat in the modern project technology, it is wet to lower the temperature, fall, fermentation, freezing, all extensive uses of air-conditioning.Need to use brazing material quantity very big in the production of air heat exchanger, domestic consumption is more than kiloton.And tin resource is very short both at home and abroad, and influence is produced and normally carried out.Research and develop new brazing material, do a lot of work both at home and abroad.Now, states such as American and Britain, day used solder in this field is generally pure tin or high tin, and high metal contains Ag, I in some composition _nNoble metal.The solder alloy of relevant document record is exemplified below: 95%Pb-5%In; 97.5%Pb-1%S _n-1.5%Ag; 93.5%Pb-5%S _n-1.5%Ag; 91%Pb-5%S _n-4%Sb.In these alloying components, lead content is very high, and plumbous steam is poisoned greatly during soldering, contains precious metal element, cost height not only, and there is the resource difficulty greatly equally in use amount.

The brazing material that domestic air heat exchanger uses has following several: 60%Sn-40%Pb according to the literature; 85%Zn-15%Sn; 40-60%Sn-60-40%Pb.

Above-mentioned brazing material, the content of tin be still than higher, and the highest by 60%, minimum also reaches 15%.In addition, lead content is also higher.

The Soviet Union treats the research work of tin brazing material and carries out early, published in 1963 "

" two kinds of zinc-base brazing materials of report, its alloying component such as table 1:

Table 1

The trade mark

Composition

Solidus (℃)

Liquidus curve (℃)

Zn

Al

Cu

Sn

Pb

B63

89

7

4

－

377

No. 7

74－77

19－21

4－5

377

395

It is said that above-mentioned brazing material can be used for copper, copper alloy and mild steel soldering, its supporting brazing flux is: NaF5%, ZnCl ₂37%, LiCl16%, KCl31%NaCl6%, NH ₄Cl5%.But practical application in producing, the solder spreading character is poor, can not use in the soldering of air heat exchanger radiating tube.

Deng Jianzhu " soldering " report aluminium cored solder, its alloy composition such as table 2

Table 2

Composition			Solidus (℃)	Liquidus curve (℃)
					Zn	Al	Cu	Ag
95	5									282	382
			93	5	1	1		380	385
94	4	2								377	395

Above-mentioned prescription can not be used for brazed copper, more can not be used for many, the complex-shaped air heat exchanger radiating tube of soldered seam.

The objective of the invention is to develop a kind of brazing material that the air heat exchanger radiating tube is used that is suitable for, require alloy element resource abundant, low price, fusing point are not higher than 400 ℃, and brazing manufacturability is good, the weld strength height.

The present invention is that a kind of that air heat exchanger is used is the alloy that base contains Al, Sn element with Zn, and the percentage by weight of alloying element is Zn91-93%, Al3.5-5.5%, and Sn3.5-4.5%, optimized percentage is Zn92%, Al4.5%, Sn3.5%.In the alloy, Zn, Sn element are strong to the affinity of Cu, improve weld strength, and the Al element can reduce alloy melting point.The Al constituent content is controlled at 3.5-5.5% near eutectic composition, if exceeding this range alloys fusing point raises on the contrary, the Al constituent content surpasses 7.5%, and scum silica frost appears in liquid level, influences the immersion plating workpiece quality.The Sn constituent content is high more, certainly alloy flowability is good more, and weld strength also can improve, but purpose of the present invention will reduce the Sn constituent content exactly to greatest extent, can be principle to satisfy the soldering processes requirement again simultaneously, so the Sn constituent content is controlled between the 3.5-4.5%.

The fusing point of solder of the present invention is 372 ℃, and viscosity is little, and active strong, surface tension is little, and favorable manufacturability is arranged.Do not contain poisonous elements Pb in the alloying component, reduced the murder by poisoning smog pollution during immersion plating; Do not contain precious metal In, Ag etc., alloy element resource is abundant.The air heat exchanger spiral is around chip radiating tube weld shape complexity, fin is that wire contacts with pipe basically, requirement soldering strength height, good manufacturability, solder of the present invention can satisfy the specification requirement of air heat exchanger radiating tube soldering fully, weld strength 20-27.16Kgf, solder thermal conductivity factor=0.227.Solder of the present invention and domestic used several solder performances are to such as table 3.

Table 3 data declaration, its fusing point of solder of the present invention is higher 140 ℃ than pure tin fusing point, and is higher 190 ℃ than Pb-Sn solder alloy fusing point, use the radiating tube of this solder welding under than higher temperature, to work, thermal conductivity factor is big, and good heat-transfer has improved the technical indicator of air heat exchanger complete machine.

In general, brazing flux and solder are matching used, and different solders need use different brazing fluxes.Before the immersion plating of air heat exchanger radiating tube, general greasy dirt is more, and these greasy dirts and oxide on surface must be removed totally.The brazing flux of aforementioned Soviet Union bibliographical information, the wherein toxic pollution of LiCl, HCl corrosivity is strong, and constituent is many.With the matching used brazing flux of solder of the present invention by ZnCl ₂, NH ₄The saturated aqueous solution of Cl and KCl is formed.Its percentage by weight is: ZnCl ₂55-65%, NH ₄Cl13-23%, KCl17-27%, its best proportioning is: ZnCl ₂60%, NH ₄Cl18%, KCl22%, wherein, ZnCl ₂Have the radiating tube surface and oil contaminant of removing and oxide-film, and suppress the workpiece effect of oxidation once more, improve solder wetting, NH ₄Cl improves flux activity, and KCl reduces brazing flux cohesive force, increases mobile.Brazing flux of the present invention and Zn base Al, the collocation of Sn solder alloy have appropriate melting point, wetability the most, can realize very effectively 400 ℃ of left and right sides solderings.

The manufacture method of solder of the present invention and brazing flux.

The smelting technology of solder is as follows:

Raw material: smart zinc ingot metal contains zinc 99.995%, and special No. 1 metallic aluminium contains aluminium 99.7%, special No. 1 metallic tin stanniferous 99.97%.

Adopt the iron crucible furnace, coal gas adds heat refining.Crucible is cleaned out, and warms to about 100 ℃, will once add in the stove according to aluminium ingot, zinc ingot metal order by the load weighted furnace charge of solder proportioning of the present invention, is warming up to 680 ℃, when all melting, drops into tin slab, fully stirs, and skims, and adds refining agent ZnCl ₂Refining is stirred at last and is skimmed.Be cooled to 390-410 ℃ and can carry out soldering.Perhaps be cast into ingot, use for the user.

The brazing flux manufacturing process is as follows:

By brazing flux formula rate of the present invention, take by weighing technical pure level ZnCl ₂, NH ₄Cl, KCl are positioned in the Plastic Drum, add to prepare saturated aqueous solution from the beginning, and promptly till the adularescent precipitation, this moment, solution proportion was about 1.62.

Embodiment.By weight being Al 4.5%, Zn 92%, the ingredient composition of Sn 3.5%, and cored solder is made in melting in the iron crucible furnace, and example is gone in the solder slots, and insulation between 390-410 ℃ is prepared the soldering spiral around chip red copper air heat exchanger radiating tube.Before the soldering, the red copper radiating tube that is wound with the red copper corrugated plate is immersed in ZnCl ₂In the solution about 1-2 minute, dry subsequently, immerse again by in the solution of brazing flux formula rate preparation of the present invention about 1-2 minute, take out and get rid of excessive brazing flux, radiating tube is kept wet.Clip the radiating tube two ends with instrument then, immerse in the solder, swing is three times below alloy liquid, takes out in second at 2-4, promptly obtains the high-quality workpiece.The work weld strength is near using pure tin brazing product weld strength.Use this solder, brazing flux and soldering processes can 24 cun radiating tubes to 78 cun all size length of soldering.Qualification rate reaches more than 95%.

The metallographic structure of accompanying drawing 1 solder of the present invention is that (with Zn is the solid solution of base to primary crystal

) the metallographic structure figure of ten eutectics.

The metallographic structure figure of the air heat exchanger radiating tube weld seam section of accompanying drawing 2 and accompanying drawing 3 solder welding of the present invention.Black part is divided into solder in the weld seam, and the white band shape between solder and the mother metal is a diffusion layer, and Dark grey partly is the matrix red copper.As seen a series of physics and course of reaction chemistry taken place on solder and parent material interface, formed inseparable soldered seam just because of this process.

Brazing material alloy resource of the present invention is abundant, and it is low to contain the Sn amount, and its price only is the pure tin pricker About 10% of material. According to incompletely statistics, the soldering tin of District of Shanghai similar applications, annual more than 300 tons. The whole nation is annual more than 1000 tons. If apply solder of the present invention, only District of Shanghai can be economized on the use of funds more than 8,000,000 yuan in 1 year, and of paramount importance is to have reduced to greatest extent the Sn metal consumption.

Claims

1, air heat exchanger use a kind of be the brazing material that base contains the Al element with Zn, it is characterized in that it is Zn, Al, Sm alloy, the percentage by weight of alloying element is Zn91-93%, Al3.5-5.5%, and the Sm3.5-4.5% optimized percentage is Zn92%, Al4.5%, Sm3.5%, Zm in the alloy, Sn element are strong to the affinity of Cu, improve weld strength, the Sn element improves solder spreading character and wetability, and the Al element reduces alloy melting point.

2, a kind of by NH ₄Cl, ZnCl ₂With the brazing flux that KCl forms, it is characterized in that it is ZnCl that its weight percent is formed ₂55-65%, NH ₄Cl 13-23%, the saturated aqueous solution of KCl 17-27%.

3, brazing flux as claimed in claim 2 is characterized in that its optimum weight percentage composition is ZnCl ₂60%, NH ₄Cl 18%, the saturated aqueous solution of KCl22%.