Component for die-casting mold, die-casting mold, and die-casting method using same

Abstract

This component for a die-casting mold comprises: a base material (11); a first carbide layer (13) formed from carbide and covering a portion of the base material (11); a first tetrahedral amorphous carbon layer (14) formed from tetrahedral amorphous carbon and covering the first carbide layer (13); and a laminated structure part (15) that includes at least one set comprising a second carbide layer (151) and a second tetrahedral amorphous carbon layer (152) covering the second carbide layer (151), and that has a structure in which the second carbide layer (151) and the second tetrahedral amorphous carbon layer (152) are alternately laminated.

Description

Parts for die-casting molds, die-casting molds, and die-casting methods using the same

[0006] ,

[0001] The present invention relates to parts for die-casting molds, die-casting molds, and die-casting methods using the same.

[0002] A first layer composed of a diamond-like carbon film containing silicon (Si) and hydrogen (H) is formed on at least a part of the exposed surface of the base material. A second layer composed of a metal oxide film containing magnesium (Mg), silicon (Si), and aluminum (Al) is formed on at least a part of the DLC outer surface, which is the surface opposite to the exposed surface of the base material of the first layer. An aluminum die-casting mold part is proposed in which the atomic ratio (Al / O) of aluminum (Al) to oxygen (O) in the metal oxide film is 0.04 or more and less than 0.68 (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2019-162653

[0004] By reducing so-called seizure in which the molten metal injected inside the aluminum die-casting mold reacts with or fuses to the surfaces of the aluminum die-casting mold, punching pins, etc., improvement in dimensional accuracy and productivity of die-cast products are required for the aluminum die-casting mold parts as described in Patent Document 1.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a die-casting mold part, a die-casting mold, and a die-casting method capable of suppressing seizure of molten metal.

[0006] To achieve the above objective, the die-casting mold part according to the present invention includes a base material, a first carbide layer formed from carbide and covering at least a portion of the base material, a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer, and a laminated structure comprising at least one set of a second carbide layer formed from carbide and a second tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the second carbide layer, wherein the second carbide layer and the second tetrahedral amorphous carbon layer are alternately laminated, with one end in the lamination direction being the second carbide layer and the other end in the lamination direction being the second tetrahedral amorphous carbon layer, and the laminated structure covering the first tetrahedral amorphous carbon layer at one end in the lamination direction.

[0007] A die-casting mold according to the present invention, viewed from another perspective, comprises a mold body and a protective film formed to cover an opposing portion of the mold body that faces a cavity from which molten metal is injected, wherein the protective film includes at least one set of a set consisting of a first carbide layer covering the surface of the opposing portion, a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer, and a second tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the second carbide layer, and has a structure in which the second carbide layer and the second tetrahedral amorphous carbon layer are alternately stacked, with one end in the stacking direction being the second carbide layer and the other end in the stacking direction being the second tetrahedral amorphous carbon layer, and having a stacked structure portion that covers the first tetrahedral amorphous carbon layer at one end in the stacking direction.

[0008] A die-casting method according to the present invention, viewed from another perspective, includes a die-casting mold comprising a mold body and a protective film formed to cover an opposing portion of the mold body from which molten metal is injected, a casting step in which molten metal is injected into the cavity, oxygen is discharged from the cavity, and the cavity is made to be an oxygen-free environment due to the oxidation reaction between the oxygen in the cavity and the molten metal, and a preparation step in which the cavity of the die-casting mold is opened to make the cavity an oxygen-rich environment, the die-cast product cast in the casting step is removed, and preparation is made for the next casting step, wherein the protective film comprises a first carbide layer covering the surface of the opposing portion, and a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer, The present invention includes at least one set comprising a second carbide layer formed from carbide and a second tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon that covers the second carbide layer, wherein the second carbide layer and the second tetrahedral amorphous carbon layer are alternately stacked, with one end in the stacking direction being the second carbide layer and the other end being the second tetrahedral amorphous carbon layer, and the stacked structure portion covering the first tetrahedral amorphous carbon layer at one end in the stacking direction.

[0009] The die-casting mold components and die-casting molds according to the present invention have excellent mold release properties, leading to a reduction in the amount of mold release agent used and improved maintainability. Therefore, for example, the time required to stop the die-casting process for maintenance can be reduced, thereby improving the productivity of die-cast products. Furthermore, the die-casting mold components and die-casting molds according to the present invention have higher wear resistance and seizure resistance compared to conventional die-casting molds equipped with protective films such as TiAlN, thereby improving the lifespan of the die-casting mold components and die-casting molds.

[0010] This is a cross-sectional view of a part of a die-casting mold component according to an embodiment of the present invention. This figure shows the time change of the surface temperature of the die-casting mold in the die-casting method according to the embodiment. This figure shows the relationship between the heat resistance temperature and hardness of a material that is relatively frequently used as a protective film for die-casting mold components. This figure shows the results of evaluating the temperature dependence of hardness in an oxygenated and oxygen-free environment for a laminated structure film of tetrahedral amorphous carbon (ta-C) and tungsten carbide (WC). This figure shows the results of evaluating the temperature dependence of film thickness in an oxygenated and oxygen-free environment for a laminated structure film of tetrahedral amorphous carbon (ta-C) and tungsten carbide (WC). This is a cross-sectional view of a part of a die-casting mold component according to a comparative example. This figure shows the change in the maximum height roughness of the surface of a casting when using the die-casting mold according to the example. This figure shows the change in the arithmetic mean roughness of the surface of a casting when using the die-casting mold according to the example. This is a cross-sectional view of a part of a die-casting mold component according to a modified example of the present invention. This is a cross-sectional view of a part of a die-casting mold component according to a modified example of the present invention.

[0011] Hereinafter, a die-casting mold component according to an embodiment of the present invention will be described with reference to the drawings. The die-casting mold component according to this embodiment comprises a base material, a first carbide layer formed from carbide and covering at least a portion of the base material, and a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer.

[0012] As shown in Figure 1, the die-casting mold component according to this embodiment comprises a base material 11, a base layer 12 covering the surface of the base material 11 in the +Z direction, a first carbide layer 13 formed from carbides and covering the base layer 12 in the +Z direction, a first tetrahedral amorphous carbon layer 14 formed from tetrahedral amorphous carbon (ta-C) and covering the first carbide layer 13 in the +Z direction, and a laminated structure 15. Here, the base material 11 can be, for example, the mold body or casting pin that constitutes the cavity of the die-casting mold. The material used to form the base material 11 is, for example, alloy tool steel (SKD61, SKD8, SKT4, etc.) specified in JIS G 4404. When the base material 11 is the mold body, the aforementioned underlayer 12, first carbide layer 13, first tetrahedral amorphous carbon layer 14, and laminated structure 15 form a protective film 16 that covers the opposing portion of the base material 11, which is the mold body, that faces the cavity from which the molten metal is injected.

[0013] The base layer 12 is formed from a material mainly composed of one or more metals selected from chromium (Cr), titanium (Ti), tungsten (W), and niobium (Nb), or alloys thereof. The first carbide layer 13 is formed from a metal or semiconductor carbide containing at least one element selected from group 4 elements, group 5 elements, group 6 elements, and group 14 elements other than carbon. As metal carbides, tungsten carbide (WC), silicon carbide (SiC), vanadium carbide (VC), tantalum carbide (TaC), etc. The base layer 12 is formed on the surface of the base material that has been nitrided, and the presence of this base layer 12 ensures the adhesion of the first carbide layer 13 to the base material 11. Furthermore, the adhesion of the first carbide layer 13 to the base layer 12 is ensured by forming the first carbide layer 13 to cover the +Z direction side of the base layer 12. Furthermore, the first tetrahedral amorphous carbon layer 14 is formed to cover the first carbide layer 13 on the +Z direction side.

[0014] The laminated structure 15 includes at least one set of a second carbide layer 151 formed from carbide and a second tetrahedral amorphous carbon layer 152 formed from tetrahedral amorphous carbon (ta-C) that covers the +Z side of the second carbide layer 151. In the example shown in Figure 1, there are three sets of the second carbide layer 151 and the second tetrahedral amorphous carbon layer 152. The laminated structure 15 has a structure in which the second carbide layer 151 and the second tetrahedral amorphous carbon layer 152 are alternately stacked. Here, one end of the laminated structure 15 in the stacking direction, i.e., the -Z direction side, is the second carbide layer 151, and the other end in the stacking direction, i.e., the +Z direction side, is the second tetrahedral amorphous carbon layer 152. Furthermore, the laminated structure 15 covers the +Z side of the first tetrahedral amorphous carbon layer 14 at one end in the lamination direction, i.e., the -Z side.

[0015] The second carbide layer 151, like the first carbide layer 13, is formed from a metallic or semiconductor carbide containing at least one element selected from Group 4, Group 5, Group 6, and Group 14 elements other than carbon. The metallic carbide is selected from tungsten carbide (WC), silicon carbide (SiC), vanadium carbide (VC), tantalum carbide (TaC), etc.

[0016] In the laminated structure 15, the second carbide layer 151 and the second tetrahedral amorphous carbon layer 152 are alternately laminated, thereby mitigating residual stress in these layers, ensuring their adhesion to each other, and suppressing crack propagation.

[0017] Next, a die-casting method according to this embodiment will be described. In the die-casting method according to this embodiment, a die-casting mold is used that comprises the mold body described above and a protective film formed to cover the opposing portion of the mold body that faces the cavity from which the molten metal is injected. This die-casting method includes a casting step of injecting molten metal into the cavity of the mold body, and a preparation step of opening the cavity of the mold body, removing the die-cast product cast in the casting step, and preparing for the next casting step. In the casting step, by injecting molten metal into the cavity of the clamped mold, oxygen in the cavity is discharged, and the molten metal injected into the cavity reacts preferentially with the oxygen present in the cavity, so it can be considered a pseudo-oxygen-free environment. In the preparation step, the cavity is open, so it can be considered an oxygen-rich environment. The casting step and the preparation step are then repeated alternately. Furthermore, in the casting process, a vacuum pump may be provided, and an exhaust means for exhausting gas present in the cavity of the mold body may be connected to the mold body, so that the gas present in the cavity of the mold body is exhausted by the exhaust means. Alternatively, in the casting process, after exhausting the gas present in the cavity, an inert gas may be introduced into the cavity so that an inert gas is present in the cavity. Examples of inert gases include nitrogen gas.

[0018] In this die-casting method for producing aluminum die-cast products, as shown in the example in Figure 2, the maximum temperature of the mold surface is kept below the molten aluminum temperature range by appropriately cooling the mold during the casting process, which is treated as a pseudo-oxygen-free environment. Then, before moving to the preparation process, which is an oxygen-rich environment, the mold surface temperature is kept below 500°C. In this pseudo-oxygen-free casting process, the maximum temperature of the mold surface is kept below 800°C, and in the preparation process, which is an oxygen-rich environment, the maximum temperature of the mold surface is kept below 500°C. A casting cycle consisting of a preparation process and a casting process is set up, and aluminum die-cast products are continuously produced by repeating this casting cycle. In other words, the surface temperature of the mold body during die-casting is repeatedly and continuously controlled to be below the heat resistance temperature of the protective film in both the preparation process and the casting process.

[0019] Figure 3 shows the relationship between heat resistance temperature and hardness for materials that are relatively frequently used as protective films for die-casting mold parts. As shown in Figure 3, TiAlN is commonly used as a protective film material because its heat resistance temperature in an oxygenated environment is higher than the molten aluminum die-casting temperature. Tetrahedral amorphous carbon (ta-C) has a heat resistance temperature of around 500°C in an oxygenated atmosphere. Furthermore, tetrahedral amorphous carbon (ta-C) has higher hardness and a lower coefficient of friction compared to TiAlN.

[0020] Here, the inventors evaluated the temperature dependence of hardness and film thickness of a laminated structure film of tetrahedral amorphous carbon (ta-C) and tungsten carbide (WC) under oxygen-rich and oxygen-free environments, and the results are shown in Figures 4A and 4B. As shown in Figures 4A and 4B, it was found that under oxygen-rich environments, the laminated structure film deteriorated and broke down when the ambient temperature exceeded 600°C. On the other hand, under oxygen-free environments, it was found that there was no deterioration of the laminated structure film in the ambient temperature range of 600°C to 800°C. From this, it is presumed that if this laminated structure film is used as a protective film for the mold body, deterioration of the protective film will not occur even in the casting process in the die-casting method described above, where the cavity is in an oxygen-free environment.

[0021] Therefore, in the die-casting method for aluminum die-casting according to this embodiment, the casting cycle consisting of a preparation step and a casting step is set such that in the casting step, which is a pseudo-oxygen-free environment, the maximum temperature of the mold surface is below the molten metal temperature range, and in the preparation step, which is an oxygen-rich environment, the temperature is below the temperature at which deterioration of the protective film on the mold surface does not occur. Here, just before moving to the preparation step, where the inside of the cavity becomes an oxygen-rich environment, the temperature inside the cavity is lowered to a temperature at which deterioration of the protective film does not occur before moving to the preparation step, which opens the inside of the cavity. This makes it possible to use a mold body in which the second tetrahedral amorphous carbon layer, formed from the aforementioned tetrahedral amorphous carbon (ta-C), is exposed in the cavity.

[0022] Here, as mentioned above, tetrahedral amorphous carbon (ta-C) has higher hardness and a lower coefficient of friction compared to TiAlN. Therefore, the die-casting mold having a mold body in which the second tetrahedral amorphous carbon layer is exposed in the cavity according to this embodiment has the advantage of higher wear resistance and better release properties of die-cast products compared to a die-casting mold in which a layer formed from TiAlN is exposed in the cavity. This leads to a reduction in the amount of release agent used and also has the advantage of being easy to maintain. For this reason, for example, the time that the die-casting process has to be stopped for maintenance can be reduced, and thus the productivity of die-cast products can be improved.

[0023] Incidentally, for die-casting molds, those coated with titanium aluminum nitride (TiAlN), which has excellent heat resistance, using PVD (Physical Vapor Deposition) technology are commonly used to improve seizure resistance. However, such die-casting molds do not have sufficient seizure resistance against molten metal injected into them, and further improvement in seizure resistance is required. In addition, for die-casting molds, those coated with amorphous carbon (a-C:H), which has poor reactivity due to its chemical compatibility with non-ferrous soft metals such as aluminum, have also been proposed. However, amorphous carbon deteriorates due to oxidation reactions when the temperature exceeds 400°C in an aerobic environment, and its wear resistance decreases significantly. Therefore, die-casting molds coated with amorphous carbon have reduced adhesion between the amorphous carbon film and the mold body, especially in aerobic environments exceeding 450°C, and their use in such environments is restricted. For this reason, it has traditionally been considered unsuitable for use in die casting processes that require molten metal temperatures of around 700°C, such as die casting of magnesium, aluminum, and other materials.

[0024] In contrast, this embodiment focuses on the fact that the heat resistance temperature of tetrahedral amorphous carbon (ta-C) differs between oxygen-free and oxygen-containing environments. By adjusting the temperature in both the casting process, which is performed in an oxygen-free environment, and the preparation process, which is performed in an oxygen-containing environment, so that the maximum temperature is below the heat resistance temperature, wear and seizure caused by thermal deterioration of the protective film of the die-casting mold can be suppressed.

[0025] Here, the changes in surface roughness of the cast product when die casting is performed multiple times using the die casting mold according to this embodiment will be explained in comparison with the die casting mold according to the comparative example. As the die casting mold according to the embodiment, a protective film 16 having the structure shown in Figure 1 is formed on the surface of the punching pin facing the cavity in the mold body from which the molten metal is injected. Here, SKD61 was used as the material for forming the base material 11 which is the punching pin. In addition, the thickness of the part consisting of the first carbide layer 13, the first tetrahedral amorphous carbon layer 14, and the laminated structure part 15 according to the embodiment was set to 4 μm.

[0026] Furthermore, as a comparative example, a die-casting mold was used in which a protective film 9016 having the structure shown in Figure 5 was formed on the surface of the punching pin facing the cavity in the mold body from which the molten metal is injected. Note that in Figure 5, components similar to those in the embodiment are denoted by the same reference numerals as in Figure 1. The surface of the base material 11 on the +Z direction side is subjected to nitriding treatment. The protective film 9016 comprises a first carbide layer 13 formed from carbide that covers the nitrided surface of the base material 11, which is the punching pin, on the +Z direction side; a first TiAlN layer 9014 formed from TiAlN that covers the +Z direction side of the first carbide layer 13; and a laminated structure portion 9015. The laminated structure portion 9015 has a structure that includes multiple sets of sets consisting of a second carbide layer 151 formed from carbide and a second TiAlN layer 9152 formed from TiAlN that covers the +Z direction side of the second carbide layer 151. The laminated structure 9015 has a structure in which the second carbide layer 151 and the second TiAlN layer 9152 are alternately laminated. Here, the -Z direction side of the laminated structure 9015 is the second carbide layer 151 and the +Z direction side is the second TiAlN layer 9152. The laminated structure 9015 covers the +Z direction side of the first TiAlN layer 9014 on its -Z direction side. Here, as with the example, SKD61 was used as the material for forming the base material 11 which is the cast-out pin. In addition, the thickness of the portion composed of the first carbide layer 13, the first TiAlN layer 9014 and the laminated structure 9015 in the comparative example was set to 8 μm.

[0027] Figures 6A and 6B show the changes in surface roughness of the portion of the casting pins when die casting is performed multiple times using the die casting molds according to the example and comparative example, respectively. Here, aluminum was used for die casting. Figure 6A shows the maximum height roughness in accordance with JIS B 0601, and Figure 6B shows the arithmetic mean roughness. As shown in Figures 6A and 6B, in the case of the comparative example, the surface roughness tended to increase as the number of die castings (number of shots) increased, whereas in the case of the example, it remained almost constant regardless of the number of shots within the range of 20,000 shots or less. This suggests that the die casting mold according to the example has relatively less adhesion of aluminum to the protective film 16 on the surface of the casting pins compared to the die casting mold according to the comparative example, and that the increase in surface roughness of the castings produced using this die casting mold is suppressed.

[0028] Thus, the die-casting mold according to this embodiment can reduce the adhesion of molten material to the protective film 16 compared to the die-casting mold provided with a protective film using TiAlN according to the comparative example. As a result, it is possible to suppress the increase in surface roughness of the castings produced using this die-casting mold and improve the quality of the castings.

[0029] Although embodiments of the present invention have been described above, the present invention is not limited to the configuration of the embodiments described above. For example, as shown in Figure 7, the protective film 2016 may not include an underlayer 12 and a laminated structure 15 that cover the base material 11. That is, the protective film 2016 that covers the base material 11 of the die-casting mold part may have a first carbide layer 13 formed from carbide that covers at least a part of the base material 11, and a first tetrahedral amorphous carbon layer 14 formed from tetrahedral amorphous carbon that covers the first carbide layer.

[0030] In the embodiment, for example as shown in Figure 8, the protective film 3016 may be formed from a material different from tetrahedral amorphous carbon and further comprises a sacrificial layer 3017 that covers the second tetrahedral amorphous carbon layer on the other end side in the lamination direction of the laminated structure 15. The sacrificial layer 3017 should be formed from a material that has a relatively low heat resistance temperature and reacts with oxygen present around the protective film 3016, decomposes and disappears as soon as the temperature of the base material 11 on which the protective film 3016 is formed exceeds a preset temperature. Specifically, the sacrificial layer 3017 can be formed from, for example, amorphous carbon (a-C) or Si-containing amorphous carbon (a-C:Si). Although the protective film 3016 shown in Figure 8 is described as having only one sacrificial layer 3017 covering the +Z direction side of the laminated structure 15, the embodiment is not limited to this, and for example, the protective film may have a structure in which multiple sacrificial layers formed from different materials are laminated on the +Z direction side of the laminated structure 15.

[0031] In this embodiment, at least one of the first carbide layer 13 and the second carbide layer 151 may be formed from a carbide containing at least one of nitrogen (N) and boron (B), and at least one element selected from group 4 elements, group 5 elements, group 6 elements, group 13 elements, and group 14 elements other than carbon. Specifically, at least one of the first carbide layer 13 and the second carbide layer 151 may be formed from TiCN and CrCN.

[0032] In the embodiment, the base layer 12 may be formed from a compound containing at least one of nitrogen (N) and boron (B), and at least one element selected from group 4, group 5, and group 6 elements. Specifically, the base layer 12 may be formed from TiCN and CrCN. In the embodiment, a plurality of base layers formed from different compounds containing at least one of nitrogen (N) and boron (B), and at least one element selected from group 4, group 5, and group 6 elements may be interposed between the base material 11 and the first carbide layer 13 in a laminated state.

[0033] In the embodiment, an example was described in which the material forming the base material 11 is alloy tool steel. However, the material forming the base material 11 is not limited to this, and may be, for example, general structural rolled steel (SS330, SS400, SS490, SS540) as specified in JIS G3101.

[0034] Although the embodiment described an aluminum die-casting method, the die-casting method according to the present invention is not limited thereto and is applicable to die-cast products containing at least one selected from aluminum, zinc, and magnesium. In this case, in the die-casting method, the molten metal injected into the cavity of the mold body may contain at least one selected from aluminum, zinc, and magnesium.

[0035] This invention allows for various embodiments and modifications without departing from the broad spirit and scope of the invention. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of the invention. In other words, the scope of the invention is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and the equivalent meaning of the invention are considered to be within the scope of the invention.

[0036] This application is based on Japanese Patent Application No. 2024-226921, filed on 24 December 2024, and Japanese Patent Application No. 2025-099164, filed on 13 June 2025. The entire specification, claims and drawings of Japanese Patent Application No. 2024-226921 and the entire specification, claims and drawings of Japanese Patent Application No. 2025-099164 are incorporated herein by reference.

[0037] The present invention is widely applicable as a protective film for die-casting mold components.

[0038] 11: Base material, 12: Substrate layer, 13: First carbide layer, 14: First tetrahedral amorphous carbon layer, 15: Laminated structure, 16, 2016, 3016: Protective film, 151: Second carbide layer, 152: Second tetrahedral amorphous carbon layer, 3017: Sacrificial layer

Claims

1. A die-casting mold component comprising: a base material; a first carbide layer formed from carbide and covering at least a portion of the base material; a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer; and at least one set comprising a second carbide layer formed from carbide and a second tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the second carbide layer, wherein the second carbide layer and the second tetrahedral amorphous carbon layer are alternately stacked, with one end in the stacking direction being the second carbide layer and the other end being the second tetrahedral amorphous carbon layer, and the stacked structure covering the first tetrahedral amorphous carbon layer at one end in the stacking direction.

2. The die-casting mold component according to claim 1, further comprising a sacrificial layer formed from a material different from tetrahedral amorphous carbon, which covers the second tetrahedral amorphous carbon layer on the other end side in the lamination direction of the laminated structure.

3. The die-casting mold component according to claim 1 or 2, wherein the first carbide layer is formed from a metal or semiconductor carbide containing at least one element selected from Group 4 elements, Group 5 elements, Group 6 elements, and Group 14 elements other than carbon.

4. The die-casting mold component according to claim 1 or 2, wherein the first carbide layer is formed from a carbide containing at least one of nitrogen (N) and boron (B), and at least one element selected from Group 4 elements, Group 5 elements, Group 6 elements, Group 13 elements, and Group 14 elements other than carbon.

5. The die-casting mold component according to claim 1 or 2, further comprising an underlayer interposed between the base material and the first carbide layer, formed from a material mainly composed of one or more metals selected from chromium (Cr), titanium (Ti), tungsten (W), and niobium (Nb), or alloys thereof.

6. The die-casting mold component according to claim 1 or 2, further comprising at least one underlayer interposed between the base material and the first carbide layer, the underlayer comprising at least one of nitrogen (N) and boron (B), and at least one element selected from group 4, group 5, and group 6 elements.

7. The die-casting mold component according to claim 1 or 2, wherein at least the portion of the base material covered by the first carbide layer is subjected to nitriding treatment.

8. The die-casting mold component according to claim 1 or 2, wherein the base material is formed from rolled steel for general structural use as specified in JIS G3101.

9. A die-casting mold comprising: a mold body; and a protective film formed to cover an opposing portion of the mold body opposite to a cavity from which molten metal is injected, wherein the protective film includes at least one set of a set consisting of a first carbide layer covering the surface of the opposing portion; a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer; and a second tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the second carbide layer, wherein the second carbide layer and the second tetrahedral amorphous carbon layer are alternately stacked, with one end in the stacking direction being the second carbide layer and the other end in the stacking direction being the second tetrahedral amorphous carbon layer, and the stacked structure portion covering the first tetrahedral amorphous carbon layer at one end in the stacking direction.

10. The die-casting mold according to claim 9, wherein the molten metal comprises at least one selected from aluminum, zinc, and magnesium.

11. A casting process comprising: using a die-casting mold comprising a mold body and a protective film formed to cover an opposing portion of the mold body facing a cavity from which molten metal is injected, injecting molten metal into the cavity, discharging oxygen from the cavity, and creating a pseudo-oxygen-free environment in the cavity due to the oxidation reaction between the oxygen in the cavity and the molten metal; and a preparation process to create an oxygen-rich environment in the cavity by opening the cavity of the die-casting mold, removing the die-cast product cast in the casting process, and preparing for the next casting process, wherein the protective film comprises: a first carbide layer covering the surface of the opposing portion; and a first tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the first carbide layer, A die-casting method comprising at least one set of a second carbide layer formed from carbide and a second tetrahedral amorphous carbon layer formed from tetrahedral amorphous carbon and covering the second carbide layer, wherein the second carbide layer and the second tetrahedral amorphous carbon layer are alternately stacked, with one end in the stacking direction being the second carbide layer and the other end being the second tetrahedral amorphous carbon layer, and the stacked structure covering the first tetrahedral amorphous carbon layer at one end in the stacking direction.

12. The die-casting method according to claim 11, wherein in the casting step, the surface temperature of the protective film is 800°C or less, and in the preparation step, the surface temperature of the protective film is 500°C or less.

13. The die-casting method according to claim 11 or 12, wherein the gas present in the cavity is exhausted during the casting process.

14. The die-casting method according to claim 11 or 12, wherein in the casting process, after exhausting the gas present in the cavity, an inert gas is introduced into the cavity to create a state in which an inert gas is present in the cavity, and then molten metal is injected into the cavity.

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