Metallographic corrosive agent and corrosion method

A metallographic corrosion and etchant technology, which is applied to instruments, analytical materials, measuring devices, etc., can solve the problem of inability to complete the metallographic corrosion of the martensitic steel matrix and the coating at the same time, and achieve the coating structure and precipitation phase. The effect of clear imaging, clear observation and analysis

Pending Publication Date: 2021-02-12
HUANENG POWER INTERNATIONAL +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a metallographic etchant and a corrosion method to solve the corrosion problem that the existing metallographic etchant cannot simultaneously complete the metallographic imaging of the martensitic steel substrate and the coating

Method used

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  • Metallographic corrosive agent and corrosion method
  • Metallographic corrosive agent and corrosion method
  • Metallographic corrosive agent and corrosion method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] 1) Preparation of corrosion samples

[0043] The original martensitic steel aluminide coating sample was hot-mounted along the coating cross-section direction and marked on the sample with an electric engraving pen; , 1200# and 2000# water-grinding metallographic sandpaper to grind step by step; finally, use polishing cloth or flannelette on the polishing machine to polish the sample until the surface reaches the mirror-level brightness without visible coarse scratches to the naked eye; among them, the mounting powder is Conductive mounting powder, polishing paste is 1.5μm diamond spray polishing agent, and the grinding and polishing directions are perpendicular to the coating direction.

[0044] 2) Preparation of metallographic etchant

[0045] First measure the pure water of 39mL concentrated nitric acid (mass fraction 68.0%), 44mL, 9mL phosphoric acid (mass fraction 85%) and 8mL glycerol respectively according to volume percentage, take by weighing 4g iron trichlori...

Embodiment 2

[0049] 1) Preparation of corrosion samples

[0050] Hot mount the martensitic steel aluminide coating sample in service state along the coating cross-section direction and mark on the sample with an electric engraving pen; then use 280#, 800# #, 1200#, 2000# Water-grinding metallographic sandpaper is ground step by step; finally, the sample is polished on a polishing machine with a polishing cloth or flannelette until the surface reaches a mirror-level brightness without visible coarse scratches to the naked eye; among them, the mounting powder It is conductive mounting powder, the polishing paste is 1.5μm diamond spray polishing agent, and the grinding and polishing directions are perpendicular to the coating direction.

[0051] 2) Preparation of metallographic etchant

[0052] First, measure 40mL of concentrated nitric acid, 40mL of pure water, 8mL of phosphoric acid and 12mL of glycerin according to the volume percentage, weigh 2g of ferric chloride and 10g of oxalic acid;...

Embodiment 3

[0056] 1) Preparation of corrosion samples

[0057] The original martensitic steel aluminide coating sample was hot-mounted along the coating cross-section direction and marked on the sample with an electric engraving pen; , 1200# and 2000# water-grinding metallographic sandpaper to grind step by step; finally, use polishing cloth or flannelette on the polishing machine to polish the sample until the surface reaches the mirror-level brightness without visible coarse scratches to the naked eye; among them, the mounting powder is Conductive mounting powder, polishing paste is 1.5μm diamond spray polishing agent, and the grinding and polishing directions are perpendicular to the coating direction.

[0058] 2) Preparation of metallographic etchant

[0059] First measure respectively the pure water of 35mL concentrated nitric acid (mass fraction 68.0%), 48mL, 7mL phosphoric acid (mass fraction 85%) and 10mL glycerol according to volume percentage, take by weighing 3g iron trichlor...

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Abstract

The invention discloses a metallographic corrosive agent and a corrosion method. The method comprises the following steps: mixing 30-40% by volume of nitric acid, 37-48% by volume of ultrapure water,4-10% by volume of phosphoric acid and 6-15% by volume of glycerol to obtain a liquid phase, adding ferric trichloride and oxalic acid, and uniformly mixing to obtain the metallographic corrosive agent; carrying out hot inlaying and labeling on a martensitic steel coating sample in an original state or a service state in the coating section direction, and then carrying out step-by-step grinding and polishing; and washing the surface of the sample with a metallographic corrosive agent for erosion corrosion treatment, and cleaning and blow-drying the sample after the surface loses smoothness. The corrosion method is mainly used for simultaneously developing organizational structures of martensitic steel and aluminide coatings on the surfaces of the martensitic steel, and the effect of simultaneously developing a matrix and a coating structure in the original state and the service state is remarkable.

Description

technical field [0001] The invention belongs to the technical field of metallographic inspection of metal materials, and in particular relates to a metallographic etchant and a corrosion method. Background technique [0002] 9Cr series martensitic heat-resistant steel is gradually developed on the basis of 9Cr1Mo heat-resistant steel. Due to its low coefficient of thermal expansion, high thermal conductivity and excellent fatigue resistance, it has become the material of choice for the main steam pipes, headers and sockets of 600°C ultra-supercritical coal-fired boilers and has been widely used. However, the upper limit of the service temperature of martensitic heat-resistant steel is only 600°C steam temperature, beyond this temperature, martensitic steel will face the serious problem of insufficient steam oxidation resistance. Therefore, it is the focus of current work to seek a technical path that can overcome the high-temperature oxidation problem faced by the martensit...

Claims

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Application Information

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IPC IPC(8): G01N1/32G01N21/84C23F1/28
CPCG01N1/32G01N21/84C23F1/28
Inventor 黄锦阳鲁金涛张醒兴杨征党莹樱张捷袁勇谷月峰
Owner HUANENG POWER INTERNATIONAL
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