Steel structure part surface protective coating and preparation method thereof

Abstract

The invention relates to a steel structure part surface protective coating and a preparation method thereof. The preparation method comprises the following steps that Zn / Al / Mg alloy powder is directly sprayed on the surface of a steel structure part through high-speed airflow, so that the Zn / Al / Mg alloy powder is deposited on the surface to form the protective coating. The Zn / Al / Mg alloy powder is formed by mixing 5 wt%-15 wt% of aluminum powder, 0.01 wt%-0.02 wt% of magnesium powder and the balance zinc powder. The spraying technological parameters are as follows, the spraying distance is 25-50 mm, the air pressure is 3.5-5.0 MPa, the air temperature is 580-800 DEG C, and the air flow is 35-50 g / s. According to the preparation method, the uniformly distributed Zn / Al / Mg coating with the ideal thickness can be prepared on the surface of the steel structure part, the corrosion resistance of the steel structure part in the marine environment is remarkably improved, and the service life is prolonged.

Description

technical field [0001] The invention relates to the field of metal anticorrosion, in particular to a protective coating on the surface of steel structural parts and a preparation method thereof. Background technique [0002] The environment around the ocean contains highly corrosive electrolytes. Over the years, countries have made unremitting efforts to prevent the corrosion of steel materials in the marine environment. As early as the 1930s, the long-term anti-corrosion technology of spraying a certain thickness of zinc, aluminum or their alloys on the steel surface to form a dense coating has been used. In various typical environments, the protection life exceeds 20 years without maintenance. The 19-year test of the American Welding Society on the thermal sprayed zinc (aluminum) layer shows that the coating thickness is 80-150 μm, which can ensure that the base metal will not be corroded in the harsh marine atmosphere; the tests of the former Soviet Union also show that,...

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Problems solved by technology

Hot-dip galvanizing is to immerse the workpiece to be coated in the molten zinc solution, so that the surface of the workpiece is bonded with a layer of zinc coating. It is currently the main means of anti-corrosion tower rods. However, the preparation process of this method requires high temperature, and the coating cannot be repaired after damage. Moreover, the thickness of the coating is limited, and its anti-corrosion life is short; thermal spraying uses oxygen-acetylene as a heat source for heating metal materials (flame spraying) or an electric arc as a heat source (arc spraying), and atomizes the molten metal with a high-speed airflow and High-speed spraying to the surface of the workpiece to form a coating. Due to the use of a high-temperature heat source, the wire or powder particles are heated to a molten state, and the metal will inevitably undergo a certain degree of oxidation, phase change, decomposition, evaporation, and grain growth during the spraying process. In addition, the coating also has shortcomings such as high porosity and high residual stress. For zinc-aluminum coatings, high porosity means that the corrosion loss of the coating itself is accelerated, and the formed corrosion products will cause the coating to bubble. lead to failure, and the zinc and aluminum vapors produced during the spraying process are harmful to the human body, and there are unsafe factors such as fires when used for on-site repairs

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