Principle and application of zinc-chromium coating protection technology

Zinc-chromium coating technology is a brand-new surface treatment technology. It is also known internationally as Dake Le, Dake Rust, Zinc Chrome Film, Duckman, etc. It was invented by the Americans in the early 1970s and transferred to the United States around 1976. The MCⅡ company, DACRAL company of France and NDS company of Japan are producing. With the development of the global economy, environmental protection has increasingly become an important part of social economy and trade. In 19%, the former Ministry of Machinery Industry listed the zinc-chromium coating process as a key development project funded by the sustainable development of cleaner production in the machinery industry, which is a kind of "green electroplating." In developed countries, zinc-chromium-coated metal surface anti-corrosion technology has been

It replaces many traditional anti-corrosion treatment processes such as electro-galvanizing, hot-dip galvanizing, cadmium electroplating, zinc-based alloy coating, phosphating, etc., which are seriously polluting, and is a new process to radically reduce environmental pollution.

Anti-corrosion mechanism

The appearance of the zinc-chromium coating is matt silver-gray (other colors abroad), and it is composed of extremely fine flake metal zinc, aluminum and chromate. After pretreatment, such as degreasing and shot blasting, the workpiece is dip-coated

(1) Based on the actual quenching oil tank used in the heat treatment workshop as a prototype, a mathematical model for solving the flow field of the quenching medium in the tank was established. Using Fluent software, according to the actual quenching oil data, the three-dimensional turbulence of the quenching tank after no-load and loaded with typical workpieces is effectively numerically calculated.

(2) When the quenching tank is unloaded, the medium flow rate in the working area is relatively uniform, forming a large area of "effective quenching zone"; after loading 3 disc-shaped workpieces, the medium flow rate field in the quenching oil tank has a significant change compared with the unloaded , There is no large eddy current around the workpiece, but a relatively uniform flow velocity field is formed around the workpiece.

(3) The simulation results of the medium flow field in the quenching tank show that the structure and size of the flow-sharing device have a great influence on the uniformity of the medium flow rate in the quenching oil tank, which has great influence on the control of the quenching process and the design and production of the quenching tank. Certain guiding significance.