Weld surface protection method for aluminum alloy storage tank storing N2O4 for a long time

Abstract

The invention relates to a weld surface protection method for an aluminum alloy storage tank storing N2O4 for a long time, and belongs to the technical field of aluminum alloy weld corrosion protection. According to the method, weld surface accumulated tumors are removed through mechanical grinding; the diameters of holes with the diameters being smaller than 0.5 mm are expanded by 2-5 times; the height difference between a weld and a base body material fusion line is smaller than 0.8 mm; aluminum powder and 2024 aluminum alloy powder or 2219 aluminum alloy powder are mixed with Al2O3 powder respectively, then the powder is sent into a cold spray gun to prepare an aluminum alloy composite coating, and weld surface coarsening and oxide removal are achieved synchronously; and when welding slag and / or black gray oxidized layers exist on the weld surface, before the aluminum alloy composite coating is deposited through cold spraying, the Al2O3 powder or SiC powder is sent into the cold spray gun so as to carry out sand blasting on the weld surface, and after treatment, residual welding slag and residual black gray oxidized layers do not exist through visual inspection. By means of the method, corrosion protection on the weld of the inner wall of the aluminum alloy storage tank storing N2O4 for a long time can be achieved, and deformation of a large-size thin-wall tank body is controlled.

Description

technical field [0001] The present invention relates to a long-term storage N 2 o 4 The surface protection method of aluminum alloy storage tank welds, specifically, involves a long-term storage of strong oxidants N 2 o 4 The corrosion protection method of the inner surface weld seam of an aluminum alloy storage tank, the method is by depositing a composite coating containing aluminum alloy on the surface of the weld seam, adjusting the spray powder material, size and proportion, so as to realize the welding seam in strong oxidant N 2 o 4 long-term corrosion protection; the method can simplify the preparation steps, realize the oxide cleaning of the weld surface, the roughening treatment of the base material surface and the deposition of the coating in one step, and effectively solve the problem of long-term storage of strong oxidant N in the storage tank. 2 o 4 The problem of intergranular corrosion and pitting corrosion; belongs to the technical field of corrosion prote...

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Problems solved by technology

However, anodizing treatment is sensitive to the shape of the base material, and it is prone to discontinuous coverage at the joint between the weld and the base metal and in the pores, and is limited by the size and shape of the tank, so its application in full-size tanks is restricted; Coating protection materials are difficult to withstand the long-term chemical corrosion of fuel and strong corrosive agents in the storage tank, and are prone to premature failure of welds; while thermal spraying, laser cladding and surfacing welding are used due to excessive heat The input will easily lead to the secondary heat degradation of the base material and weld properties, and will cause serious deformation for thin-walled storage tanks. Therefore, it is urgent to find a new protection method to meet the protection requirements of the inner wall welds of the storage tank.

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