Coated metal mold and method for manufacturing same
The purpose of the present invention is to provide a coated metal mold having superior durability and adhesion resistance over a usage range from cold to warm/hot; and a method for manufacturing the coated metal mold. The coated metal mold is characterized by having a hard coating on a surface, wherein the hard coating includes an A layer formed from a nitride and having a film thickness not smaller than 5 μm, and a B layer formed of a diamond-like carbon coating, the B layer is disposed closer to the outer surface side than the A layer, the surface of the B layer has an arithmetic mean roughness Ra≤0.2 μm, a maximum height Rz≤2.0 μm, and a skewness Rsk<0.
1. A coated metal mold for warm/hot working comprising:
a metal mold, and
a hard coating disposed on a surface of the metal mold, the hard coating comprising an A layer formed from a nitride and having a film thickness of 5 μm or more, a B layer formed from a diamond-like carbon coating and having a film thickness in a range of from 2 μm to 15 μm, and, between the A layer and the B layer, a coating film having a composition different from that of the A layer, wherein:
the A layer is a laminated film comprising alternating layers of (a) a layer comprising a nitride containing chromium and (b) a layer comprising a nitride containing vanadium;
the coating film contains titanium carbide; and
the A layer is disposed between the metal mold and the B layer, and a surface of the B layer has an arithmetic mean roughness Ra≤0.2 μm, a maximum height Rz≤2.0 μm, and a skewness Rsk<0, and wherein, in the B layer, a content percentage (atomic %) of hydrogen is in a range of from 5% to 30% and a content percentage (atomic %) of nitrogen is in a range of from 5% to 20%, wherein the metal mold material being coated with the hard coating is hot die steel, or high-speed steel.
2. The coated metal mold according to claim 1 , wherein the film thickness of the A layer in a range of from 8 μm to 70 μm.
3. A method for manufacturing a coated metal mold having a hard coating on a surface thereof, wherein the method comprises:
applying an A layer formed from a nitride and having a film thickness of 5 μm or more using an arc ion plating method,
polishing a surface of the A layer so that the A layer has a surface roughness Ra≤0.2 μm, a maximum height Rz≤2.0 μm, and a skewness Rsk<0,
after polishing the surface of the A layer, applying a coating film having a composition different from that of the A layer wherein the coating film contains titanium carbide, and
after applying the coating film, applying a B layer formed from a diamond-like carbon coating,
wherein a surface of the B layer has an arithmetic mean roughness Ra≤0.2 μm, a maximum height Rz≤2.0 μm, and a skewness Rsk<0, and wherein, in the B layer, a content percentage (atomic %) of hydrogen is in a range of from 5% to 30% and a content percentage (atomic %) of nitrogen is in a range of from 5% to 20%.
4. The method for manufacturing the coated metal mold according to claim 3 , wherein the film thickness of the A layer in a range of from 8 μm to 70 μm.