RU2272271C1 - Method for etching tin bronzes - Google Patents

Abstract

FIELD: technology for researching prepared sections made of tin bronzes by means of chemical effecting on researched surface of material.

SUBSTANCE: method for etching tin bronzes for detecting structure of section includes preliminarily grinding and polishing of section surface. Etching of section is performed by 1% solution of chlorine copper in hydrochloric acid. Section is dipped into tub with etching agent for 40-80 seconds, then pulled out and dipped into tub with water, pulled out of water and dried by blotting paper and again dipped into etching agent, but with lesser exposure of 1-10 sec, repeating procedure with lesser delay until producing monotonously dark color of matrix.

EFFECT: simplified procedure, lower costs.

4 dwg

Description

The invention relates to the field of chemical effects on the studied surface of the material, in particular for the study of prepared thin sections of tin bronze.

A known method for detecting a structure on a pre-polished and polished surface of metallographic sections before it is examined with the naked eye using a magnifying glass or a microscope, which consists in acting on the surface with a gaseous reagent as an ozone-air mixture from a gas generator and directing the used mixture to discharge through an azone-absorbing solution or ozone destructor. RF patent No. 94017974, cl. G 01 N 1/28. A significant disadvantage of this method is the complexity of the procedure, its high cost.

A method is proposed for etching metallographic thin sections made of tin bronze, based on a quantitative assessment of the distribution and size of the hardening phase, a eutectoid. In this method, thin sections are subjected to deep etching using a 1% solution of perchloric copper in hydrochloric acid. The etching method consists in dipping the polishing section into the bath with the etchant for 40-60 seconds, then pulling out and dipping into the bath with water. Dry the sample with blotting paper and again dip it into the etchant, but with a shorter exposure time of 1-10 seconds. After each etching procedure, the samples are examined under a microscope, the color of the matrix becomes darker and more uniform. If prior to etching, its color was inhomogeneous in FIG. 1, after conventional etching, in FIG. 2, the matrix also has a non-uniform color, and after etching in accordance with the proposed method, it acquires a monotonously dark color, FIG. 3. The hardening phase - the eutectoid is not etched, but is located in the form of light almost white inclusions of various sizes, after the end of the etching, the samples are photographed and entered into the computer. If the sample is etched, the matrix is heterogeneous, figure 4, hence the number and size of structural components is calculated incorrectly. Computer program, computer image processing - CFI calculates the volume fraction and average particle size of the structure, provided that the thin section is etched to a monotonously dark color of the matrix and light spots of the hardening phase - eutectoid.

Claims (1)

A method of etching tin bronzes to identify the structure of a thin section, namely, that the surface of the thin section is pre-ground and polished, characterized in that the etching is performed with a 1% solution of perchloric copper in hydrochloric acid, while the thin section is dipped in a bath with an etchant of 40-80 s, then pulled out and dipped in a bath of water, pulled out of the water and dried with blotting paper and again dipped in the etchant, but with a lower shutter speed for 1-10 seconds, repeating the procedure with a lower shutter speed until the matrix is monotonously dark in color.

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