For the part of the cavity surface of the die-casting mold, which is prone to sticking and all the cores, nitriding, carbonitriding, KANUC in Japan, vapor deposition (PVD physical vapor deposition, CVD chemical vapor deposition), and nitriding should be used. Surface strengthening treatment by evaporation, laser, etc. to reduce sticking or erosion.
At present, there are more treatments using KANUC in Japan. If nitriding is required, the total depth of the nitrided layer of the profile should be smaller than the previous 0.2-0.3mm, and should be controlled from 0.04 to 0.08 to 0.12 mm depending on the thickness of the casting, and there should be no compound white bright layer. Prevent excessive cracking of the white bright layer and cause premature cracking of the mold. The higher the nitridation temperature, the higher the nitrogen potential concentration and the thicker the nitride layer, the more likely the white bright layer is to be produced. For parts that are easy to stick to the mold, a surface treatment such as nitriding can be performed once per 10,000 to 20,000 molds.
After the mold is die-casted from 8 to 100,000 times, the nitriding treatment can also be performed when the mold is easily formed due to the decrease in hardness. Note that the mold surface should be polished accordingly before and after annealing and nitriding. In order to prevent oxidation rust before the mold cavity is mass-produced, after the mold is passed, the mold should be oxidized in the electric furnace for 530-560 for 1 to 1.5 hours.