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A preparation method of chromium-rich high-temperature corrosion-resistant coating deposited by slurry method

A high-temperature, corrosion-resistant technology, applied in the field of preparation of chromium-rich high-temperature corrosion-resistant coatings, can solve the problems of toxic gas emissions endangering human health, limitations in the applicability of chromizing efficiency, and low powder utilization, and achieve excellent steam resistance Oxidation properties, short sintering time, and high production efficiency

Active Publication Date: 2021-04-27
HUANENG POWER INT INC +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The powder embedding method is to embed the metal workpiece in the chromizing agent powder and keep it warm for a long time (more than 4 hours) at high temperature. This method is simple in process, but the powder utilization rate is low, the efficiency is low, the cost is high, and the dust pollution is serious. And other issues
Vapor-phase chromizing is to suspend the workpiece on the chromizing agent powder, pass in chlorine gas, etc. to react with the chromium powder to generate chromizing gas, which will adhere to the surface of the workpiece to form active chromium atoms and penetrate into the substrate to form a chromizing layer; this method avoids Dust pollution and other issues have been solved, but the process is complicated and requires to be carried out under vacuum, and the emission of toxic gases is harmful to human health
The liquid phase method usually puts chromium powder into molten salt, and forms a chromizing layer through high temperature insulation, but the molten salt is volatile at high temperature in this method, which is extremely harmful to the workpiece and the environment.
In addition, there are a variety of other new chromizing methods such as mechanical energy assisted chromizing, high-frequency electric spark chromizing, etc., but these chromizing processes are limited in chromizing efficiency and applicability to large workpieces such as pipelines, special-shaped parts, and complex parts. Therefore, there is a need for a new type of chromizing coating material and preparation process suitable for various complex workpieces.

Method used

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  • A preparation method of chromium-rich high-temperature corrosion-resistant coating deposited by slurry method
  • A preparation method of chromium-rich high-temperature corrosion-resistant coating deposited by slurry method
  • A preparation method of chromium-rich high-temperature corrosion-resistant coating deposited by slurry method

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preparation example Construction

[0027] The preparation method of chromizing slurry is as follows: according to mass percentage, weigh 10-30% sodium silicate, 40-60% chromium powder, 2-10% sodium chloride, 5-20% filler oxidation Aluminum and 10-30% distilled water, and divide the distilled water into three parts; Distill the first part of sodium silicate solution in distilled water to obtain sodium silicate solution, dissolve sodium chloride in the second part of distilled water to obtain sodium chloride solution, then add the chromium powder into the sodium silicate solution and stir evenly, then add the sodium chloride solution into the mixed solution and mix thoroughly, then add the alumina powder into the above mixed solution, stir evenly, and then add the second Three parts of distilled water, adjust the slurry to a suitable viscosity according to the needs; finally put the mixed slurry into a planetary ball mill tank for 5-10 hours, rotate at a speed of 350-400r / min, and obtain a rapid chromizing slurry ...

Embodiment 1

[0039] 1) Clean the surface of the pipe

[0040] Use alcohol / acetone to clean the oil stains and dust on the surface of the pipe, and use a steel brush to remove the surface oxide skin.

[0041] 2) Slurry coating on the surface of the pipeline

[0042] After preheating the pipeline at 60°C for 30 minutes, apply the slurry to a suitable thickness at one time by spraying (or brushing, etc.) ~5mm.

[0043]Wherein, the slurry is obtained through the following process: according to the mass percentage, respectively weigh 12% sodium silicate, 58% chromium powder, 5% sodium chloride, 15% filler alumina and 10% distilled water, And divide the distilled water into three parts; Distill the first part of sodium silicate solution in distilled water to get sodium silicate solution, dissolve sodium chloride in the second part of distilled water to get sodium chloride solution, then add chromium powder to silicic acid After stirring evenly in the sodium solution, add the sodium chloride s...

Embodiment 10

[0055] 1) Pipe surface cleaning

[0056] Use alcohol / acetone to clean the oil stains and dust on the surface of the pipe, and use a steel brush to remove the surface oxide skin.

[0057] 2) Pipe surface slurry coating

[0058] After preheating the pipe at 60°C for 60 minutes, apply the chromizing slurry to a suitable thickness at one time by spraying, and do not apply multiple layered layers; the thickness of the coating slurry layer is 0.1-5mm.

[0059] Wherein, the slurry is prepared through the following process: according to the mass percentage, respectively weigh 10% sodium silicate, 60% chromium powder, 5% sodium chloride, 5% filler alumina and 20% distilled water, And divide the distilled water into three parts; Distill the first part of sodium silicate solution in distilled water to get sodium silicate solution, dissolve sodium chloride in the second part of distilled water to get sodium chloride solution, then add chromium powder to silicic acid After stirring evenl...

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Abstract

A method for preparing a chromium-rich high-temperature corrosion-resistant coating deposited by a slurry method. After the workpiece is preheated, the chromizing slurry is applied to the surface of the workpiece, and the thickness of the coated slurry layer is 0.1 to 5 mm; and then dried and solidified , and finally sintered to obtain a chromium-rich high-temperature corrosion-resistant coating; wherein, the chromizing slurry includes 10-30% of an adhesive, 40-60% of an infiltration source, 2-10% of an activator, 5-20% filler and 10-30% diluent. The chromium-rich high-temperature corrosion-resistant coating deposited by the slurry method and its preparation method can be applied to metal parts such as various carbon steels, austenitic stainless steels, and high-temperature alloys, and are especially suitable for large-scale pipeline metal parts, heterosexual metal parts and Complicated parts, etc., have strong practicability, wide application range, high chromizing efficiency, low pollution, moderate thickness, good metallurgical bonding with the base, and are not easy to fall off.

Description

technical field [0001] The invention belongs to the technical field of material surface coatings, and in particular relates to a preparation method of a chromium-rich high-temperature corrosion-resistant coating deposited by a slurry method. Background technique [0002] Thermal power generation accounts for more than 70% of my country's total power generation. With the development of thermal power generation towards higher steam temperature and pressure (620-650°C / 30-35Mpa), the corrosion problem of the heating surface of boiler heat-resistant steel pipes will become more prominent ;In the actual production process, accidents caused by corrosion failure of boiler pipes occur from time to time, causing huge economic losses and potential safety hazards to the country and individuals. Therefore, under the new operating parameters of boiler units, the development of boiler pipes suitable for power plants Anti-corrosion technology has important practical significance. [0003] At...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C10/20
Inventor 黄锦阳鲁金涛杨珍周永莉党莹樱尹宏飞袁勇谷月峰
Owner HUANENG POWER INT INC
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