Study On Arc Ion Plating Film Coated On H13 Steel For Magnesium Alloy Die-Casting Die

Magnesium alloy die-casting is a high temperature, high pressure, and high-speed process, for which magnesium alloy die-casting mold with high resistance to shock, high temperature oxidation, and thermal fatigue is required. During the magnesium alloy die-casting process, adhesion on the surface, impact of shock loss and other failure modes often take place on the mold. Therefore, modification of mold surface is necessary. Arc ion plating technology, a surface treatment method with less environmental pollution, high ionization rate, high plating speed, and high-quality coating characteristics, is an advanced technology widely used in mold surface coating.According to the comparison of surface morphology, phase composition, micro-hardness, base-binding capacity and high temperature oxidation resistance between pre-nitrided and non-nitrided H13 steel, it is concluded that:1) Effects of pre-nitriding on the performances of TiN film. Compared with TiN/non-nitrided H13 steel, TiN/pre-nitrided H13 steel is smoother and higher in quality, with less white light particles and pits. The surface microhardness increased from 1031.4HV0.025 to 1073.8HV0.025, and the base-binding capacity is doubled, from 44N to 78N. Moreover, high temperature oxidation resistance of TiN/pre-nitrided H13 steel is not significantly changed.2) Effects of pre-nitriding on the properties of CrN film. Compared with CrN/non-nitrided H13 steel, CrN/pre-nitrided H13 steel is smoother and denser, with less white light particles and pits. The surface microhardness increased from 1092.8HV0.025 to 1351.6HV0.025, and the base-binding capacity improved nearly 3 times, from 18N to 62N. High temperature oxidation resistance has not significantly changed.3) The properties of CrAlN film. The surface of CrAlN film is rough with honeycomb-like particles. Its microhardness is up to 1895.5HV0.025, and the base-binding capacity is also larger, about 62N. After high temperature oxidation test for 6h, 12h, 18h, XRD curves of the coating layer change little, indicating its good resistance to high temperature oxidation.In summary, it is shown that mechanical properties of arc ion plating film is greatly improved after pre-nitridation of H13 steel; addition of Al can also improve the coating quality of CrAlN film; the properties of H13 steel is greatly improved by arc ion plating coating, which reduces the loss of the die failure, and extends the service life. Therefore, arc ion plating is a desirable mold modification technology.