SU929357A1 - Method of soldering in fusable element vapour - Google Patents

Description

The invention relates to soldering, in particular, to soldering methods with the introduction of one of the cocktails from the gas phase, and can be used in various fields of engineering.

A known method of soldering products using vapors of easily evaporating elements consists in that the floated products with solder blanks and an additionally easily evaporating element are placed in the volume of soldering, and then they are heated in a vacuum, neutral or reducing atmosphere. When heated, the easily evaporating element evaporates, binds the oxidizing components in the soldering volume, interacts with the oxide film on the soldered surface and provides flux-free soldering.

One of the possible mechanisms for the action of vapor is the formation of a liquid phase when vapors interact with the base metal. When vapors of the evaporation element interact with the solder blanks during the soldering process, solder is formed with a certain content of the evaporation element (11.

The properties of the resulting solder joint depend on the content of this element, in the solder, and, consequently, in the joint of the joint. However, the content of the steam element in the resulting solder depends on the parameters of the soldering process and is not adjustable.

There is also known a method of soldering in pairs of an easily evaporating element of the element, which includes the placement of soldered products and solder blanks in a closed volume with subsequent heating by the presence of an element which is easily evaporated.

15 in an inert or reducing environment or in vacuum. The method is implemented as follows.

Brazed products, solder and magnesium blanks are placed in a vacuum furnace.

20 and then heat up. When heated, the magnesium evaporates and provides flux-free soldering. To increase the pressure in p.i. and to reduce evaporation of at least part of the magnesium in

A non-oxidizing gas 2 is introduced into the vacuum chamber of the furnace.

Claims (2)

This method makes it possible to influence the content of a highly vaporizing element in the solder by reducing the rate of vapor supply to the solder blanks and diffusion saturation from the vapor phase. However, saturation from the vapor phase goes to an indefinite concentration. As a result, the composition of the solder joint and the properties of the solder joints are uncertain and unstable. Moreover, the method does not allow one to obtain the desired composition of the solder joint With the necessary mechanical and physical properties. The purpose of the invention is to provide the required content in the solder of an easily evaporating element. This goal is achieved in that according to the method, the pressure in the volume of the soldering is maintained equal to the pressure of the strong vapor of the easily evaporating element over the alloy of the required composition of solder at the soldering temperature. The specified pressure is determined using data on the vapor pressure of a purely vaporised element and the activity of a vaporizing element in the alloy of the required composition according to the formula RPD l. p - с - У1 А f where Р J is the saturated vapor pressure of a highly vaporizing element dissolved in solder at a given temperature; P is the pressure of the vapor deposition of the clean volatilizing element at a given temperature; the activity of easily evaporating the state element in the solder. In case of absence, the activity data can be considered approximately equal to the molar fraction of the evaporation element in the solder and be refined when developing the technology. By varying the pressure of the evaporating element in the soldering volume, it is possible to change its limiting content in the solder. The vapor pressure of the vapor element in the soldering volume tends to pressure the vapor at this temperature, but it cannot be higher than the total pressure in the system. According to the proposed method, the total pressure in the system is equal to the saturated vapor pressure of the easily evaporated element dissolved in the solder, therefore, lower than the saturated vapor pressure of the clean easily evaporated element. The interaction of the workpiece of the solder with the vapor of the easily evaporating element proceeds to the production of an alloy, the vapor pressure of the highly evaporating element above which is equal to the pressure maintained in the container. The degree of approximation to equilibrium depends on the time of delivery with a sufficient amount of evaporated element. The rate of propagation of vapors and their supply to the solder blanks is greater than with the introduction of non-oxidized gas into the soldering zone, which intensifies the processes of interaction with the solder blanks. The method makes it possible to adjust the composition of the solder and thereby obtain the specified properties of the solder joints. Example 1 High mechanical properties are required for steam joints of 40X steel. Brass was chosen as solder. The highest mechanical properties (maximum strength and high plasticity) possess of. + P brass with zinc content (about 42%) from 39 to 45%. Flux-free soldering is conducted in zinc vapor to obtain brass solder by reacting copper solder billet with zinc vapor. The melting point of brass of the required composition is 900-910 ° C. The temperature of the soldering chosen 915 ° C. At this temperature, the vapor pressure of zinc is PZV. ffl L09 kg / cm Zinc activity in brass at the soldering temperature is assumed to be equal. 0.25, taking into account the increase in zinc activity in copper-zinc alloys with increasing temperature. The vapor pressure of zinc over the alloy of the required composition P7I A2: „- Rgi 0,25.1,09 0,27 at (kg / cm). Float samples, copper solder blanks and evaporator with zinc are heated in a sealed container in a nitrogen atmosphere. With the help of a back-pressure balloon having a volume 10 times larger than the working volume of the container in which soldering takes place, and communicating with this volume, the pressure was maintained at a level of 0.27-0.31 at. The exposure time at the soldering temperature was 15 minutes After cooling and unloading, a 4OX steel is obtained from the obtained solder joint and a metallographic analysis of the solder is carried out. The structure and microhardness of the brazed joint corresponds to oL + (brass (39-45% Zn), which has good mechanical properties. Example 2. Samples from 4OX steel, copper solder blanks and zinc evaporator are heated in an airtight container with nitrogen at 1.0 -1.06 atm. The reamer at the soldering temperature is 15 minutes. After cooling and unloading, a cut of the obtained solder compound is made. The microstructure and microhardness along the length of the weld seam are heterogeneous and correspond to phases from (A + to dg. Consequently, the properties the pair connection is uncertain examples 3. For products that are not subjected to impact, bending and vibration brass alloys with a high content of zinc, such as PMts48 and PMts54, are used. Their advantage is a lower brazing temperature. For the flux-free soldering of steel 3 in zinc vapor, choose a temperature 880s Vapor pressure of pure zinc 5902. Ti 736 ° ® Accept the activity of zinc at a required composition of approximately equal to A2у, 4. The vapor pressure of zinc above the alloy of the required composition P OH 0.8 0.32 kg / cm. Brazed samples of steel 3, copper solder blanks and a zinc evaporator are heated in an airtight container under nitrogen atmosphere. With a booster cylinder having a volume 10 times the volume of the container in which soldering takes place and the volume connected with this volume is maintained the level of 0.32-0.36 atm. The exposure time at is 20 min. After cooling and unloading, a solder pad was manufactured and a metallographic analysis of the joint was performed. The structure and microhardness of the weld seam corresponds to f-brass (47-51% 2p), which has sufficient mechanical properties for parts not subjected to impact, bending, and vibration. The proposed method expands the soldering capabilities in pairs of readily evaporating elements. The method allows to adjust the properties of the solder joints by changing the content of the easily evaporated element in the solder. By. Compared with the known method, the proposed method allows to obtain a predetermined composition of solder during the soldering process. In addition, the interaction of the easily evaporated element with the solder blank is accelerated. The invention of the method of soldering in pairs of a lightly evaporating element, including the placement of soldered products and solder blanks in a closed volume with subsequent heating in the presence of a lightly evaporating element in an inert or reducing medium or in vacuum, characterized in that in order to provide the required content in the solder the evaporation element, the pressure in the volume is maintained equal to the saturated vapor pressure of the evaporation element above the alloy of the required solder composition at the soldering temperature. Sources of information taken into account in the examination 1.Lashko N.F., Lashko S.V. Soldering metals. M., Mechanical Engineering, 1977, p. 167-171. 2. The patent of the USA 1 3673678, cl. 29-494, pub. 04.07.72 (prototype).