SU856719A1 - Flux for high-temperature soldering - Google Patents

Description

(54) FLUX FOR HIGH-TEMPERATURE SOLDERING

I

This invention relates to solo production, in particular to fluxes for high-temperature soldering, used mainly for induction brazing of carbide tools.

Known flux for high-temperature soldering 1, containing, in weight. about:

Bura12.

Bourne Acid 78

Calcium fluoride10

The main disadvantage of this flux is the poor quality of the joint when brazing carbide tools. One of the reasons for the poor quality of carbide soldering tools is the poor wettability of the surface of hard alloys with solders. In addition, the presence of free and chemically bound carbon on the surface of a hard alloy prevents the solder from forming reciprocal metal bonds at the interface between the solder and the hard alloy and, thus, to ensure the mechanical strength of the solder joint.

To increase the flux activity with respect to free and chemically bound carbon of a hard alloy, oxides of transition metals, such as cobalt and tungsten, are introduced into the flux, their chemical affinity with oxygen at the soldering temperature is relatively small.

The closest in its composition and effect to be achieved is flux 2, containing, by weight. %: Potassium fluoride 5,0-8,0

Sodium fluoride 2.0-4.0

Cobalt oxide 0.1 -1.0

Tungsten oxide1.0-10.0

Cobalt tungstate0.1-8.0

Oxygen Compound C

In the process of soldering, the elimination of the harmful effect of carbon on the wettability of the surface of a hard alloy is achieved by the fact that at 850-1200 ° C oxides of cobalt and tungsten thermally decompose and produce oxygen, which is used for oxidation of carbides with subsequent sublimation of carbon in the form of carbon monoxide and carbon dioxide the atmosphere.

However, in the known flux, at the interface between the solder and the hard alloy, there are slag and gas inclusions, which reduces the density of solder joints and, consequently, worsens their operational properties.

properties. This flux deficiency is most pronounced when induction soldering of cutting tools from among hard alloys of systems tungsten carbide - titanium carbide - cobalt, tungsten carbide - tantalum carbide - cobalt and tungsten carbide - cobalt, containing a relatively low percentage of cobalt.

The purpose of the invention is to create a flux for high-temperature soldering, ensuring the density of the solder joints.

This goal is achieved by the fact that the flux additionally contains transition metal borides and silicides with the order numbers 21-28 and 39-42 in the following ratio of components, weight. /about;

Fluorides

alkaline earth

Metals4,2-8,8

Transient borides

metals0.12-12.6

Transitional silicides

metals0,2-8,2

Oxygen compound

bora the rest

Oxygen-free boron and silicon compounds from the number of transition metals with serial numbers 21-28, for example iron groups (Fe, Co and Ni), are oxidized to form a borosilicate mass, the film of which has sufficient strength, density and elasticity, which allows reliably Isolate the solder joint from the external environment: in the process of soldering with induction heating by high frequency currents, the heat generated in the surface layers of the metal is primarily spent on coalescing the separated low-melting boron compounds. During this period, oxygen, boron compounds are formed due to oxygen adsorbed on the surfaces of the substrate, carbide plates, solders and, to a lesser extent, on the surfaces of their own particles. This period of fluxing in the range of 150-650 ° С ensures the solidity of carbides on the surface of the hard alloy.

The solidity of the carbide component of the hard alloy surface at the exit to

the soldering temperature before melting the solder is ensured by the fact that oxides, for example, iron groups (Fe – B – Si, CO – B – Si and

N1-B-Si) are able to increase the density of the protective cover at the interface of the flux-hard alloy by creating

The "exclusion zone" for the diffusion of chemically free oxygen and the surface of a hard alloy, while boron and its oxygen compounds are inhibitors (conversion) of the conversion of chemically bound and free carbon into volatile compounds.

Moreover, it is surface-inert with respect to chemically bound and free carbon and has relatively limited mutual solubility of Fe-B-Si, on the one hand, and WC-TiC-Co, on the other, borosilicates iron at the flux-hard alloy interface can inhibit the mass transfer of oxygen carbon compounds, the transition of KOTOpi ix to slag and gaseous products leads to a breakdown of the solidity of metal bonds at the solder-hard alloy interface.

In tab. 1 presents examples of the composition of the proposed flux.

In tab. 2 - some indicators of the quality of paired compounds.

Table 1

Surface Separate pure pores in the metal solder

SameMetalNormal Wear.

solder The resistance of the incisors to the interdense is repeated by applying the flux of the proposed composition to reduce the amount of adsorbed oxygen as the temperature increases in the range of 150-300 ° C by preheating the burned compound; reduce to a minimum the amount of adsorbed oxygen at 350 ° C and above by treating the paired surface with low-melting boron materials; to prevent corrosion damage during the soldering process by isolating the surface of the hard alloy from the environment with strong and elastic borosilicate transition metal compounds; provide a uniform volumetric heat input to the carbide plate prior to melting the solder; reduce the possibility of overheating of the carbide plate in the process of heating and soldering; to provide a constant viscosity of borosilicate collar, an ity film by thermal decomposition and exchange reactions of oxygen-free compounds of boron and silicon; minimizing the dissolution of the metal forming its carbides, the molecular and atomic carbon of the surface of the hard alloy in the flux components, which makes it possible to preserve the geometrical dimensions of the plate; by complex processing of the melt by soldering with such reducing agents as hydrogen, calcium and silicon in a paired seam and a transitional zone of the paired compound, to obtain a dense metal; to ensure the formation of metallic bonds of the type of solid solutions at the interface between hard alloy and solder

table 2

Between 1-2 sharpening chipping occurs cutting edge. The durability of the cutters between the next sharpening 125 min

Coy I85 min

Same Normal Wear.

Durability of cutters between the next sharpening 182 min

both in the process of wetting with the liquid solder the surface of the plate, and at the stage of their joint crystallization.

Thus, the process of induction brazing of a carbide cutting tool is implemented, where the proposed composition is used as a flux, which ensures the solidity of carbides, reduces hardness and increases the density of metal bonds at the solder-hard alloy interface.

In addition, the likelihood of cracking and the development of cracks on a cemented carbide substrate is reduced.

40

Claims (1)

Invention Formula The flux for high-temperature soldering, mainly induction brazing of carbide tools containing oxygen boron and alkaline earth metal fluorides, characterized in that, in order to increase the density of solder compounds, the flux additionally contains transition metal borides and silicides with sequence numbers 21 -28 and 39-42 in the following ratio of components, weight%: Transient borides metals Silk-earth fluorides Metals4,2-8,8 transient borides metals0.12-12.6 7 856719 „ /about Transitional silicides1. Khr pin V. E. and Lacedaemon A. metals 0,28,2Platnik handler. M., “Mashinostroystroi Oxygen Compound, 1974, p. 115, tab. 1Y9, flux number 4. boron Else2. USSR author's certificate Sources of information, No. 338332, CL. In 23 K 35/362, 1970 (prototype taken into account in the examination of the type).