Dacromet is the transliteration and abbreviation of DACROMET, referred to as Dacromet. The domestic name is zinc-chromium coating, which is a new type of anti-corrosion coating. Compared with traditional electro-galvanizing: zinc-chromium coating has strong corrosion resistance, 7-10 times of galvanizing, anaerobic brittleness, especially Suitable for high-strength parts, high heat resistance, heat-resistant temperature of 300 °C, especially suitable for high-strength components of wind turbines, automobiles, motorcycle engine parts, high permeability, high adhesion, high wear reduction, High weather resistance, high chemical stability and non-polluting.
Dacromet's range of base materials: steel products and non-ferrous metals such as aluminum, magnesium and their alloys, copper, nickel, zinc and other alloys, and no pollution during the coating process, in the history of metal surface treatment is a The revolution is a representative of high-tech in the world of metal watches.
First, Dacromet technology anti-corrosion mechanism
1. Controlled electrochemical expansion of zinc on the substrate.
2. Passivation of chromic acid: The usual passivation is only to form a very thin passivation film on the metal surface to be treated, such as electroplating, hot plating, and numerous tiny zinc flakes in the Dacromet solution. After the chromic acid passivation reaction, after the coating is baked, the zinc sheets are layered to form a myriad of passivation films. The mechanical shielding shielding protection of the zinc sheet aluminum sheet and the composite chromium salt coating and the "elution" effect of the aluminum inhibiting zinc.
Second, Dacromet's technical holding point
1. Superior corrosion resistance
The etched galvanized layer etched 1-3 um thick Dacromet-treated metal surface in the salt spray test for 10 hours, and corroded 1 um in 100 hours after salt spray test, which is more resistant than conventional metal surface treatment. Corrosion is improved by 7-10 times, salt spray test can reach more than 1000 hours, and there is a high technical index against sulfur dioxide, showing stronger rust resistance.
2, superior heat corrosion resistance
When the conventional galvanized layer is higher than 70 ° C, micro cracks will occur, and it will change color under the condition of 200-300 ° C, and the corrosion resistance is also greatly reduced. Dacromet anti-corrosion film curing temperature is 300 ° C, so even if the surface metal is placed under high temperature conditions, its appearance is unchanged, and the hot corrosion resistance is excellent.
3, no hydrogen brittleness
Hydrogen embrittlement is a drawback that cannot be overcome by traditional galvanizing processes. During the Dacromet treatment, no pickling, no pickling, no hydrogen is used to erode the steel substrate, and at high temperatures, the Dacromet coating is absolutely free of hydrogen embrittlement. It is especially used for anti-corrosion treatment of high-strength parts with tensile strength Rm>1000N/sq·mm, such as high-strength bolts and springs. 4, high permeability
Metal parts processed by Dacromet can form a film in fine voids, a corrosion-resistant coating with good penetration, a uniform coating on the tubular part, and a water-soluble solution of Dacromet solution. , so its permeability is very good.
5, high adhesion
The brazing, aluminum sheet and composite salt coating formed after high temperature baking have good adhesion to the steel substrate.
6, high weather resistant land
Dacromet can withstand sulfur monoxide, acid rain, soot and dust at a given coating thickness. Its resistance to SO2 test can reach 3 cycles. Suitable for workpieces, sea wheels, etc. in maritime climate. In addition, it is also resistant to chemical corrosion, and has good corrosion resistance in gasoline and engine oil.
7. Optimized the protective function of aluminum electrochemical element corrosion
In general, when two metals or alloys with different electrode potentials are in contact, electrochemical corrosion and corrosion inhibition of galvanizing result in anti-corrosion effect, and the anticorrosion mechanism of Dacromet is based on the passivation of Cr acid. And the controlled sacrificial protection of zinc, so the mechanism is optimized, the consumption of zinc is suppressed, and the safety of corrosion resistance is greatly improved.
8, low friction
The Dacromet coating after the addition of the lubricant can be subjected to an appropriate treatment to produce an ultra-low friction of a coefficient of 0.06 to 0.12, and a general treatment yields a medium friction of 0.12-0.18.
9, good coordination accuracy
Generally, the Dacromet coating can be controlled between 6-8um, so the matching precision of the fastening body can meet the accuracy requirement of 6g/6n.
10, beautiful Yaxing silver gray coating appearance
The metal surface of the workpiece or part processed by Dacromet technology is matt silver grey, beautiful and generous, and the Dacromet coated surface has strong adhesion to paints and coatings, and can form a variety of colors.
Third, Dacromet's inevitability, necessity and benefit analysis
1. Because electroplating not only causes serious pollution to the atmosphere, land, and water sources, it is also very harmful to operators. The state has already adopted a new green industry to replace it, so the demise of the electroplating industry is an inevitable result, and the conversion of electroplated parts to Dacromet is inevitable. In the production process of Dacro, there is no pollution, which is encouraged by the state. The real green industry of development.
2. It is also necessary to use Dacromet technology for various metal surface coatings. It is because the original electroplated parts have poor corrosion resistance, easy rust, poor thermal corrosion resistance, easy deformation; poor surface stability of the coating, easy hydrogen embrittlement; secondly, because Dacromet technology overcomes these shortcomings of electroplating, it can be done for ten years. The above does not rust, can adapt to the requirements of users, and adapt to the requirements of export products.
3. For individual parts with high water content, such as automobiles, motorcycles, aerospace, highway bridges, electrical and electronic parts, etc., electroplating technology cannot be satisfied. It can only be solved by Dacromet technology. This is electroplating. incomparable. The emergence of Dacromet technology is a high-tech of metal surface treatment in the world today. It has been praised by experts as a revolutionary product and green engineering with epoch-making significance in the international metal surface treatment industry.