Iron-based nanocrystalline composite coating for protecting boiler tail heating surface and laser-cladding forming process of iron-based nanocrystalline composite coating

Abstract

The invention discloses an iron-based nanocrystalline composite coating for protecting a boiler tail heating surface and a laser-cladding forming process of the iron-based nanocrystalline composite coating. The iron-based nanocrystalline composite coating comprises the following components in percentage by weight: 49.9-62.8% of Fe, 14.2-20.4% of Cr, 9.0-16.3% of Mo, 2.9-4.1% of B, 0.6-1.3% of C, 1.0-2.4% of Mn, 3.4-8.0% of W, 1.0-1.9% of Si and 0-3.9% of RE, wherein RE is a rare earth element. The forming process comprises the following steps: preparing alloy powder of the iron-based nanocrystalline composite coating; treating the surface of the boiler tail heating surface; preparing the iron-based nanocrystalline composite coating through a simultaneous powder feeding method and a laser-cladding method, wherein the laser cladding is performed for multiple times. The formed iron-based nanocrystalline composite coating is 1 mm above in thickness. The iron-based nanocrystalline composite coating can obviously enhance the wear resistance and corrosion resistance of the boiler tail heating surface, and reduce maintenance costs of worn and corroded parts and consumption of raw materials of a power plant.

Description

technical field [0001] The invention belongs to the field of power plant boiler surface protection, and specifically refers to an iron-based nanocrystalline composite coating and a laser cladding molding process for protecting the heating surface of the boiler tail. Background technique [0002] The situation that my country uses coal as the main primary energy source is difficult to change for a long time. The pollution caused by coal burning and the emission of greenhouse gases are one of the main problems affecting my country's sustainable development. There are many types of coal in my country, including lignite, bituminous coal, lean coal, anthracite, etc. The calorific value of coal varies greatly, and the sulfur content is generally high (56% contain sulfur <1%, 32% contain sulfur 1%-2%) %, sulfur content > 2% accounted for 12%). Therefore, coal power generation becomes the main source of coal combustion pollutants. It is an important aspect of my country's ene...

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Problems solved by technology

[0006] Nanocrystalline alloys have excellent corrosion resistance. The coatings prepared by the existing thermal spraying method have limitations such as low bonding strength between the coating and the substrate (mechanical bonding), and the thickness of the coating is generally less than 500 μm. , It is easy to fall off under the action of alternating thermal stress, which cannot meet the comprehensive protection requirements of boiler tubes with both erosion resistance and low-temperature sulfuric acid dew point corrosion resistance

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