Method for preparing protective coating material of boiler tube

Abstract

The invention discloses a method for preparing a protective coating material of a boiler tube. The coating material consists of the following components in percentage by weight: 12 to 14 percent of Cr, 0.4 to 0.6 percent of Mn, 2 to 3 percent of Ti, 3 to 5 percent of Al, 2 to 4 percent of Si, 1 to 2 percent of Nb, 8 to 12 percent of Fe, 1 to 3 percent of Co, 3 to 5 percent of Mo, less than or equal to 0.025 percent of S, less than or equal to 0.035 percent of P and the balance of Ni. The method for preparing the protective coating material comprises the following steps of: 1) smelting waste steel, intermediate alloy and nickel ingots according to the components and refining to prepare coating material alloy ingots; 2) placing the prepared alloy ingots in a crucible for prepare powder through atomization, heating and melting, and atomizing to prepare powder by taking helium as atomization gas; and 3) screening the prepared atomization powder to obtain the coating powder with the diameter of -200 meshes.

Description

technical field [0001] The invention relates to the field of preparation of coating materials, in particular to a preparation method of a protective coating material for boiler pipes. Background technique [0002] In coal-fired power plants, boilers are exposed to high-temperature environments for a long time. Due to the action of flue gas or ash suspended in it, high-temperature corrosion will occur to varying degrees, including high-temperature oxidation, high-temperature sulfate corrosion, sulfidation corrosion, and high-temperature chloride corrosion. The high-temperature corrosion phenomenon of the "four tubes" of high-temperature and high-pressure boilers (that is, water-cooled wall tubes, superheater tubes, reheat tubes, and economizer tubes) and the resulting series of serious consequences such as tube bursts have always been urgently needed by the power industry. A problem solved. [0003] Using thermal spray technology to prevent boiler tubes is an effective means...

AI Technical Summary

Problems solved by technology

In China, the main spraying protection technologies currently used are: aluminum spraying protection, because the melting point of aluminum is as low as 660.4°C, it works well in low temperature environments, its creep resistance is low, and its wear resistance is poor. High temperature and high pressure boiler "four tubes" These factors make the protective effect after spraying aluminum unsatisfactory; spray welding Ni-W alloy coating, although the spray welding layer is well bonded, wear and corrosion are slight, but its technology is not enough. The problem is that the remelting temperature is too high, causing the pipe to deform, and it is difficult to use it in a large area; in China, aluminizing and chromizing are also used for protection, but the hot dipping process is generally only suitable for coatings composed of a single element, and the method requires The higher working temperature (generally between 750-1100 ℃) will have a certain impact on the structure and performance of the matrix material, and the protection effect is not good

Although this patent has achieved a certain improvement effect, its chromium content is high, which easily leads to poor bonding performance of the coating, and it is easy to peel off after a period of use