Something about steel vacuum coating

With vacuum technology and materials technology development and the development of new iron and steel industry an urgent requirement of steel, strip steel strip vacuum coating surface treatment is becoming an important technology, with good prospects for development. At present, become mature and can quickly realize the industrialization of the strip electron beam vacuum coating technology is the steel vacuum coating. Practice has proved that steel vacuum electron beam coating has many advantages: (1) choice of coating material melting point without much restriction. High energy density electron beam can make the coating material in a very short time to reach 3000 ℃ ~ 6000 ℃. Therefore, in addition to common galvanized hot dip galvanized, aluminum, tin, zinc oxide, almost all of the metal materials can be deposited, but also a wide variety of plated metal nitride film, metal oxide film and metal carbide and a variety of composite membrane . This strip material for the development of new offers great freedom. (2) coating of high material utilization, environmental pollution. Vacuum coating is a dry coating, no harmful liquids, gases. (3) strip coating quality, access to uniform, smooth and very thin coating, coating of high purity, corrosion resistance and adhesion. Strip coating by electron beam warm-up prior to surface activation, coating of high purity, no intermediate brittle alloy layer can be a metal forming, and even rolled into a small tube rather than directly by the coating off. (4) process flexible, easy to change varieties, according to product requirements to achieve a flexible steel plating on single-sided, double-sided, single layer, multilayer, plated two materials can reach plated mixed film. Coating thickness is easy to control, and ultra-thin films can be coated.
However, the strip is still in the vacuum coating the whole early stages of development, the share of the strip surface is still far and hot-dip, plating compared. Hinder the development of vacuum coating strip is mainly due to low productivity, high cost. The most effective solution is developed high-speed, high power and stable evaporation source.
The development of high-power electron gun and vacuum coating with a strip of key technologies. General vacuum evaporation coating resistance heating can be used and induction heating. Its equipment is relatively simple, but the heating temperature and the evaporation rate is low. Industrial production to meet the continuous need for vacuum coating steel strip, you must use heating speed, high melting temperature of the heat source. Home and abroad proved that high-power electron gun belt continuous vacuum coating process is the ideal heat source. This is because (1) electron gun emitted after electron beam can be achieved by focusing a high energy density, bombardment crucible coating material titanium dioxide, so the temperature can reach 3000 ℃ or more, than the high temperature arc. (2) electron beam energy conversion rate of 80% -90%, using the magnetic deflection system can be easily e-beam focusing and scanning, uniform heating. (3) electron beam bombardment only the surface coating material, not because of the incorporation of other materials caused by mixed problems. (4) use of the electron gun beam diameter, electric power, plus beam voltage, scan path, frequency and other parameters are easy to implement regulation. (5) use an electron gun can also be coated in the production process of steel-plated steel vacuum was warm, clean and strip electron gun is used, to bombard the surface activation. Stop by the electron beam scanning, strip surface temperature at 200 ~ 550 ℃, the steel coating and preheating is necessary to improve coating adhesion.