Sample preprocessing method of impurities in steel for scanning electron microscope observation

Abstract

The invention discloses a sample preprocessing method of impurities in a steel for scanning electron microscope observation, which comprises the following steps of: taking a to-be-tested sample as an anode and a stainless steel barrel as a cathode, inserting the to-be-tested sample and the stainless steel barrel into the same electrolyte solution, electrolyzing for 1-8h at room temperature on thecondition that current density is 20-50mA / cm<2>, reducing the thickness of the surface of the to-be-tested sample, after electrolyzing, taking out, cleaning and drying to obtain a sample for scanningelectron microscope observation, wherein the electrolyte solution comprises the following constituents in mass percentage concentration: 1-10% of electrolyte, 0.5-5% of complexing agent, 0.5-3% of acid and water for the rest. According to the invention, an electrolytic etching method is employed, a base body is decomposed while the impurities are conserved by impressed current through the difference of electrochemical properties of the base body and the impurities, so that the impurities are effectively protected from being corroded and destroyed by the acid and the shapes of the impurities in the sample are more really and objectively reflected. According to the invention, the operating steps are simplified, the preprocessing method is more objective and the electrolyzing efficiency is high.

Description

technical field [0001] The invention relates to a sample pretreatment method for scanning electron microscope observation, in particular to a sample pretreatment method for scanning electron microscope observation of inclusions in steel. Background technique [0002] Inclusions in steel are the main factor affecting the quality of billet. Its existence destroys the continuity of steel, causes uneven structure of steel, reduces the physical and chemical properties of steel, and brings great harm to product quality. Moreover, a lot of research work has shown that the composition, size, quantity and distribution of inclusions are closely related to the quality of steel. Therefore, it is important to analyze the morphology and composition of inclusions in steel. [0003] At present, the methods used to analyze inclusions in steel mainly include electrolytic method and metallographic method, and the emphases of these two analysis methods are different. The electrolysis method i...

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Problems solved by technology

[0005] When observing the morphology and composition of inclusions in steel with scanning electron microscope-energy dispersive spectrometer, the traditional sample pretreatment method has the following deficiencies: First, in the corrosion stage of the sample, 5% nitric acid-ethanol solution will interact with some in the steel Some inclusions or reducing substances in steel react, such as nitric acid can oxidize MnS precipitates in silicon steel, 3MnS+8HNO 3 = 3MnSO 4 +4H 2 O+8NO↑, destroys the original appearance of the sample; second, the sample is only handled by experience in the grinding and corrosion stages, and it is easy to cause over-corrosion or insufficient corrosion; third, for the thickness less than 1mm or the length greater than 5cm The sample cannot be mounted by the mounting machine, and other means of auxiliary treatment are required, which increases the difficulty of sample pretreatment; Fourth, there are many steps, time-consuming, and poor reproducibility; Fifth, scanning electron microscope analysis requires the sample to be conductive, so the conductivity of the mounting material high performance requirements