SU1641504A1 - Method for joining powder bronze-graphite layer with steel foundation - Google Patents

Abstract

The invention relates to powder metallurgy, in particular to methods for combining a bronze-graphite layer with a steel base. The purpose of the invention is to improve the quality of the connection of layers by reducing the distortion of their geometry. A bronze-graphite powder is applied to the corrugated steel surface with an electroplated by the underlayer and an intermediate layer, heated at a speed of not more than 100 ° C / h to a temperature of 10 to 30 ° C below the initial melting point of the powder material, sintering at this temperature, after which it is cooled at a rate not exceeding 100 ° C / h. 1 ill., 1 tab.

Description

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The invention relates to a powder method, in particular, to the manufacture of a product from powder materials.

The purpose of the invention is to improve the quality of the connection of layers by reducing the distortion of their geometry,

The drawing is a diagram of the connection of the powder layer with a metal base.

Metallic base 1 with a galvanically applied sublayer 2 is applied with sublayer 3 of an intermediate composition, onto which the main powder layer 4 is pressed. The connection of the main powder layer with the metal base is fixed by sintering.

Sintering operations are illustrated by a specific example.

Example. In the manufacture of a bogie billet, an anti-friction powder layer of bronze-grained PA-BrONGrZ should be connected with a metal base, which is a steel galvanically copper strip with an intermediate layer (about 0.5 mm) of bronze powder PA-BrO, which was previously applied to the tape by the method of free filling and baking at 800 ° C.

Priming of the main layer of bronzografit is carried out in a chamber furnace, in a container with an atmosphere of hydrogen.

The temperature conditions of sintering and the results obtained are tabulated.

Limiting the heating rate contributes to a longer stay at high temperatures, which, due to the diffusion bonding of the layers and the removal of the resulting stresses (relaxation), reduces

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mutual displacements of the powder layer and the metallic,., 51c, caused by the difference in thermal-expansion of foreign materials. The absence of melting prevents the powder layer and the metal base from moving in the liquid phase and the formation of uncontrolled and uneven shrinkage of the powder layer. Limiting the cooling rate and intermediate exposure during cooling reduces the stresses due to differences in the thermal contraction coefficients of foreign materials.

The data in the table shows that the use of the proposed technology allows, while maintaining the high adhesion strength of the layers, to eliminate the distortions of their geometry, as a result of which there is no need for a known method (prototype).

Heating the product by additional machining.

Claims (1)

DETAILED DESCRIPTION OF THE INVENTION A method for combining a bronze-graphite powder layer with a steel base, including corrugation and electroplating of the surface of the base, applying an intermediate and bronze-graphite layer, heating to sintering temperature and cooling, in order to improve the quality of the layer by reducing its geometry , heating is carried out at a rate of not more than 100 ° C / h, sintering is carried out at a temperature of fO-30 ° C below the initial melting point of the bronze-graphite layer, and cooling is ut at a rate not exceeding 100 ° C / h.