Features of soldering of metals

In practice of performance of electric installation work, at repair of electric equipment and operation of elekyotroustanovka, along with welding, soldering is applied to connection among themselves of parts from homogeneous and diverse metals. Compound of metals and parts by method of soldering has the number of advantages before connection by their welding.

Схема газовой сварки

Scheme of gas welding.

The main advantages consist in the following:

To soldering shortcomings, in comparison with welding, sleyodut to refer sufficient complexity технологическо­го process and rather big expense of work for performance of equivalent connections.

Soldering in wiring production and at repair works is applied only in those cases if there cannot be the priyomenen electric welding or if soldering is the only way of connection of parts.

It is, for example, soldering of cockerels of the winding of electrical machines, the ration of cable couplings, etc. The main ways of connections and terminations of wires and cables with copper and aluminum veins are molding and welding (electric and thermite). However in a number of organizayotion where molding and welding are not mastered yet, soldering of connections primeyonyatsya.

Схема контактно-реактивной пайки

Scheme of contact and reactive soldering.

The essence of soldering consists in connection among themselves of firm metal parts and conductors by means of the melted solder. Temperature the plavleyoniya of solder has to be lower than melting temperature of the connected parts. Solder has to smachiyovat well metal of the connected parts, it is easy to spread on the surface and to dissolve basis metal at the seam in the place of soldering.

The surface of the parts which are subject to soldering is cleaned from oxides and pollution in the mechanical and chemical way. For chemical cleaning of surfaces gumboils primenyayotsya. During heating gumboils, connecting to oxides, form the slag emerging on the solder poverkhyonost. In addition to dissolution and removal of dirt and oxides from the surface of the connected parts, gumboils protect metal of the basis and solder from oxidation in the course of soldering. The choice of gumboil depends from применяемо­го solder and the characteristic of the meyotall connected by soldering.

Solders and gumboils

Depending on melting temperature and prochnoyost, the applied solders are separated on soft and firm. Solders which melting temperature is lower than 4000C belong to soft; to firm - the temperayotura of melting of which is above 500 °C. The limit of the prochnoyosta of soft solders about 5-7 kg/mm2, firm при­поев - up to 50 kg/mm2. The majority of soft solders represents alloys which basis are tin and lead, and zinc is applied to soldering of aluminum. The chemical composition of soft solders is given in appendices. Assignment and об­ласть applications of the most widespread brands of soft solders are given in tab. 1.

Except 1 tin-lead solders listed in the appendix bezolovyanisty solders are applied (lead of 98,5-98,9%, zinc of 1%, etc.). These solders of hired are cheaper than tin-lead and are applied for irresponsible the ration of brass and steel. Mekhanicheyosky durability of soldering by bezolovyanisty solders below, than tin-lead. However primeneyony solder without scarce tin justifies its isyopolzovaniye.

Table 1. Scope of the most widespread tin-lead solders

Таблица свойств оловянно-свинцовых припоев

Table of properties of tin-lead solders.

By addition in tin-lead solders of bismuth or cadmium reach decrease in melting temperature of solders by 60-180 °C. These solders can be applied to soldering of thin tin products, in the kacheyostvo of fusible inserts of safety locks and also to soldering of the parts especially sensitive to overheating. Tin-lead solders for soldering of products from the alyuyominiya and its alloys are unsuitable as lead silyyono reduces corrosion firmness of the solder seam. The soft solders which are not containing sviyonets and which basis is zinc recommend to apply Poyoetoma to soldering of aluminum and its alloys.

Схемы лазерной пайки

Schemes of laser soldering.

The chemical composition of solid solders is given in priyolozheniye. Assignment and area the primeneyoniya of the most widespread brands firm припо­ев are given in tab. 2. These solders represent soyoby alloys which basis are silver and copper, copper and phosphorus, copper and zinc. From this group of solders the most expensive are silver priyopo which in some cases are replaced more desheyovy copper-zinc and copper and phosphorous pripoyayom.

It should be noted that the place of soldering executed by silver solders has high strength, plasticity and conductivity that can not always be reached at use of copper-zinc and copper and phosphorous solders; besides, silver priyopoyam it is possible to solder ferrous, non-ferrous metals (copper, brass, bronze) and silver while the area of the priyomeneniye of other solid solders is more limited.

Table 2. Scope of the most widespread silver and copper-zinc solders

Таблица свойств серебряных и медно-цинковых припоев

Table of properties of silver and copper-zinc solders.

Table 3. The scope of solders for soldering of aluminum covers and veins of cables and wires

Mosenergo - For soldering of veins of wires and cables of secheniyoy 16 mm2 and above when the place of soldering is reliably protected from hit of moisture and when soldering the increased heating is provided.

Spetsiyoalny high-strength alloys, electrolytic copper and brass are applied to soldering of plates of the hard-facing alloy to the cutting tool as solders. Melting temperature of these solders fluctuates within 900-1300 °C. The alloys consisting of copper, nickel, zinc, iron and other elements belong to vysoyokoprochny solders. At layotunny solders durability of the place of soldering on stretching at the temperature up to 400 °C is higher, than at copper, and at more high temperatures on the contrary soldering durability copper-loaded solders above, than brass.

Схема типовых паяных соединений

Scheme of standard solder bonds.

At the choice of solder for soldering it is necessary to consider sleyoduyushchy: melting temperature of solder has to be not less than 600C lower than melting temperature of the accustomed to drinking parts and if the accustomed to drinking part rabotayot at high temperatures, then temperature the plavleyoniya of solder has to be not less than 3000C lower than heating temperature of parts in work; if in one node apply consecutive soldering of several parts, then it is necessary to use solders with posleyodovatelno the going-down melting temperature; durability of the solder seam has to be close to prochnoyost of the connected parts; solder in the melted soyostoyaniye has to moisten well accustomed to drinking poverkhyonost, fill gaps between the accustomed to drinking parts and not form in the place of soldering of the air sinks weakening the junction; the melted solder has to provide continuous process of soldering; at connection of conducting elements solder has to have the conductivity close to the elektroprovodyonost of the accustomed to drinking wires and parts; solder has to be cheap and not scarce.

As gumboils when soldering sleduyuyoshchy materials are applied:

The hydrochloric acid (diluted) - is applied when soldering zinc and galvanized iron soft pripoyayom. Solution of hydrochloric acid (15-20%) is formed by addition in water of the technical hydrochloric acid (smoking). It is strictly forbidden to pour in the voyoda in acid as it causes the impassioned reaction accompanied with slopping of acid and vozmozhyony injuries of working. It is necessary to pour in hydrochloric acid in water in the small portions. With salt kisloyoty it is necessary to handle very with care as, poyopady on the body, it causes burns, destroys clothes fabric, and its couples make harmful effects on respiratory organs.

Solution of chloride zinc (etched hydrochloric acid) - is applied when soldering by soft solders of steel, copper and copper alloys. For aluminum soldering chloride zinc is unsuitable. Concentration of water solution of the chloride zinc applied in the gumboil kayochestvo fluctuates ranging from 20 up to 50% (0.33-0.45 kg of solid chloride zinc on 1 l of the voyoda). Solution of chloride zinc is prepared by direct dissolution of zinc in the salt kisyolota (0,3-5,5 kg of zinc on 1 l of hydrochloric acid). Add hydrochloric acid to zinc, zayogruzhenny in the vessel, until allocation of vials of hydrogen stops and at the bottom of the vessel does not settle zinc.

Схема капиллярной пайки

Scheme of capillary soldering.

Chloride zinc-ammonium - is applied when soldering by soft solders and represents mix 16 chasyoty solution of chloride zinc with 11 parts of sal ammoniac. Addition in chloride zinc of ammonium raises the akyotivnost of gumboil and reduces temperature of its melting.

Rosin - is applied when soldering soft pripoyayom of copper, copper alloys (conductors, parts elekyotro-and the radio equipment). and also aluminum. Rosin is applied in the form of powder or solution in alcohol.

Sal ammoniac - is applied to cleaning of the working poverkhyonost of the soldering iron. As gumboil it cannot be исполь­зован as evaporates without melting at the temyoperatura of 160-180 °C.

Soldering fat - is applied when soldering soft priyopoyam of copper veins of wires and cables, when soldering lead couplings to the lead cover of cables, to soldering of conductors of grounding to armor and the lead cover of cables. Soldering fat consists from: weight speak rapidly rosin of 19-15 weight parts, animal fat or stearin of 5-6 weight parts, sal ammoniac 2, hloyoristy zinc 1 weight part, waters 1 weight part. The gumboil consisting of rosin of 30 parts, stearin of 30 parts, chloride zinc of 25 parts, chloride ammonium of 5 parts, water of 10 parts is applied to the same purposes. In the absence of soldering fat as gumboil rosin or stearin is applied to soldering of copper veins of cables and lead couplings.

Gumboil for soldering of aluminum veins of wires and cables - represents solution from the 20th weight chasyoty rosin and 100 weight parts of denatured alcohol.

Drill, or bornokisly rubbed - the playostinok of hard-facing alloys is applied to soldering by solid solders of steel, copper, bronze, brass. For action strengthening drills  add boric acid and potash to it. In izbezhayony buckling drills at its soldering need zarayony to be calcinated and pounded in small powder. During soldering of the drill can form the firm opaque crust which is not dissolved in water when cooling and hard is removed the file, - it is its neyodostatok. Instead of clean drills often apply less expensive mix which consists of 8 parts iceboats, 3 parts of table salt, 3 parts of potash. The drill it is applied in the form of powder or the paste based on water or alcohol.

Boric acid - is applied when soldering nerzhaveyuyoshchy staly and high-temperature alloys.

The gumboils applied when soldering aluminum and its alloys have to provide destruction of the strong oxide film from the surface of the accustomed to drinking parts. In the kayochestvo of gumboils mixes of hloriyosty salts to which add fluoric salts the kayoliya, sodium, lithium, etc. are applied to this purpose. Depending on the chemical composition, gumboil has different melting temperature and can be applied at different solders.

Gumboil of brand F 380L (34A) - is most widespread when soldering firm priyopoyam (on the basis of aluminum), consisting from: chloride potassium of 47%, хлористо­го lity of 38%, fluoric sodium of 5%, chloride tsinyok of 10%. Melting temperature of this gumboil 3800C. For aluminum soldering by soft solders can приме­няться the gumboil consisting from: chloride zinc of 90%, chloride ammonium of 8%, fluoric potassium of 1,2%, ftoyoristy lithium of 0.6%, fluoric sodium of 0,2%. Temperayotura of melting of this gumboil of 220 °C. When soldering the alyumiyoniya myagy solders also apply fluoric gumboils on the basis of trietanolamine with the temperature of playovleniye of 180-2500C.

At selection of gumboils it must be kept in mind that gumboils have to provide chemical cleaning of surfaces of the accustomed to drinking parts during their heating and also not allow their oxidation during soldering, improve wetting and spreading of solder in the place of soldering. Tempeyoratura of melting of gumboil has to be lower than the temperayotura of melting of solder on 30-40 °C that gumboil had small specific weight and in the course of soldering emerged on the surface, was not dissolved in the accustomed to drinking metals and did not make on them harmful chemical effects. Upon termination of soldering the remains of gumboil have to easily уда­ляться.

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