JP2000038653A - Die or mold having surface film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die or the like having a surface film simultaneously improving thermal crack resistance and oxidation-resistance and having a long life. SOLUTION: On the surface of a die base metal or a mold base metal composed of cemented carbide, ceramics, steel or cast iron, a film composed of (Ti(1-x-y)CrxAly) N (x) and (y) are value satisfying 0.02<=x<1.0 and 0.02<=y<=0.7), having 0.3 to 50 μm film thickness and compression stress of 0.5 to 8 GPa by the average value of residual stress is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mold or a mold having a surface coating.

[0002]

2. Description of the Related Art When forging iron-based parts, aluminum alloy parts, and magnesium alloy parts such as automobile parts, machine parts, parts for home appliances, etc., in warm or hot, or
Molds and molds used for casting (hereinafter referred to as “molds, etc.”
Abbreviated. ) Is caused by the high temperature applied to the surface of the mold or the like during use (generally, a high temperature of 500 ° C. or more), causing damage to the surface of the mold or the like due to oxidation, generation of fatigue cracks due to repeated thermal stress, and the like. A phenomenon called “heat check” occurs. In particular, in the casting of aluminum, the surface of a mold or the like is eroded by aluminum,
"Dare" occurs. This “bare-spotting” proceeds due to an increase in the number of processes, and the life of the mold and the like is determined when it becomes difficult to maintain the dimensional accuracy. Similarly, a mold used when the molten glass is sealed in the mold to transfer and mold the shape of the mold is similarly damaged by the high temperature applied to the mold surface from the molten glass. Further, since a surface of a mold or the like reacts with molten aluminum, molten (or semi-molten) magnesium, or molten glass, a phenomenon that aluminum or glass is welded and adheres to the mold or the like becomes a problem. Such a welding phenomenon between the workpiece and the mold causes a reduction in work efficiency.

[0003] In order to delay the above-mentioned mold damage as much as possible, current forged or cast dies and the like are subjected to a nitriding treatment such as a tuftrite treatment, a gas nitriding treatment, an ion nitriding treatment and a sulphonitriding treatment. Processing is widely performed. The feature of these nitriding treatments is that the element mainly composed of nitrogen is diffused and infiltrated into the surface of a base material such as a steel mold to increase the surface hardness, introduce surface compressive stress, etc. Has improved durability.

[0004] However, the nitriding treatment cannot improve the oxidation resistance of the surface of a mold or the like. For this reason, the surface of the mold and the like is oxidized, and this oxide scale grows, falls off,
Oxidation occurs again. Due to such a cycle, the surface of the mold and the like is damaged by oxidation.

As a surface treatment method other than the nitriding treatment, there is a method of forming a ceramic film such as titanium carbide, titanium nitride, titanium carbonitride, etc. by a chemical vapor deposition method (CVD method), a physical vapor deposition method (PVD method) or the like. Can be Also, TR
There is also a method of forming a vanadium carbide coating by a thermal reaction / precipitation method called a D method or a TD method.

[0006]

However, titanium carbonitride, vanadium carbide and the like have oxidation resistance of 5%.
It is lost at around 00 to 600 ° C., and no remarkable effect is observed in suppressing the oxidation of the mold surface.

In a glass molding die, heat resistance, oxidation resistance, high-temperature hardness, etc. are improved by overlaying a hard alloy on the surface of a metal material or forming a heat-resistant metal film. However, since the material is based on a metal or an alloy, the material hardness is as low as about 700 kg / mm ^{2 in} Vickers hardness, and it is not possible to prevent damage to the mold due to biting of hard particles. Was enough.

In order to overcome these drawbacks, there is disclosed a method in which a surface hardening treatment such as the above-mentioned nitriding treatment and a film forming treatment such as the above-mentioned vapor deposition method are combined. For example, Japanese Patent Application Laid-Open No. 62-103368 proposes a ceramic coating metal in which a nitride layer is formed on the surface of a metal substrate and the ceramic coating layer is coated. In this case, a CVD method is used as a film forming method. Japanese Patent Application Laid-Open No. 2-158661 discloses that an ion nitriding treatment and an ion plating are continuously performed in the same vacuum chamber to remove metal nitrides, carbides, carbonitrides, carbonitrides, oxides and the like. A method for forming a film in one or more layers is disclosed. Further, JP-A-5-98422 discloses that
Generate plasma using a high frequency power supply in a vacuum vessel,
A continuous processing method is disclosed in which a hardened layer is formed by colliding nitrogen ions with an object to be processed, and ceramic coating is immediately performed as it is. Furthermore, Japanese Patent Application Laid-Open No. 8-35075 discloses that a metal member is ion-nitrided by performing glow discharge in an atmosphere of ammonia gas and hydrogen gas, and then a hard coating is formed on the ion-nitrided layer by a PVD method. A method of forming is disclosed.

All of these prior arts merely disclose a processing method or merely disclose a material system. A material system which satisfies both heat crack resistance and oxidation resistance simultaneously, and a material system which satisfies both conditions are disclosed. It did not show satisfactory mechanical properties.

Accordingly, an object of the present invention is to provide a long-life mold or the like having a surface coating that simultaneously improves heat crack resistance and oxidation resistance.

[0011]

The present invention provides a cemented carbide,
On the surface of a mold base material or a mold base material made of ceramics, steel or cast iron, (Ti _(1-xy) Cr _x Al _y ) N (where
x and y are 0.02 ≦ x <1.0, 0.02 ≦ y ≦
It is a value that satisfies 0.7. ), The film thickness is 0.3 to 50 μm, and the average value of the residual stress is 0.5 to 50 μm.
The above problem was solved by forming a film having a compressive stress of 8 GPa.

The above coating is excellent in heat crack resistance and oxidation resistance. Even if forging or casting is performed warm or hot using a mold or a mold having this coating, the surface of the die or the like can be obtained. Damage and fatigue cracks due to oxidation of the steel can be suppressed.

[0013]

Embodiments of the present invention will be described below. A first embodiment of a mold or a mold having a surface coating according to the present invention is a mold base material or a mold base material (hereinafter, referred to as a base material).
Abbreviated as "base material such as mold". ), A coating composed of a nitride of an alloy of titanium, chromium and aluminum is formed.

Examples of the base material such as a mold include a cemented carbide, ceramics, steel, cast iron and the like. The nitride of the above alloy of titanium, chromium and aluminum can be represented by the following formula [1].

(Ti _(1-xy) Cr _x Al _y ) N [1] At this time, the content ratio of chromium, that is, x in the formula [1], satisfies 0.02 ≦ x <1.0. Is good. Also,
The content ratio of aluminum, that is, y in the formula [1]
Preferably satisfies 0.02 ≦ y ≦ 0.7. further,
The content ratio of titanium, that is, 1-xy in the formula [1]
May be a positive value.

The oxidation resistance of the coating can be improved by adding chromium and aluminum to titanium nitride. This is because chromium and aluminum in the coating are oxidized in a high-temperature atmosphere when the mold is used, and a strong protective film made of chromium oxide and aluminum oxide is formed on the surface of the coating. Such a dense oxide film has an effect of greatly suppressing the progress of oxidation of the titanium nitride film, and greatly suppresses oxidative wear of the mold surface.

If the composition ratio x of chromium is 1 or more, the above-mentioned coating tends to become brittle. When x is less than 0.02, it is difficult to obtain the effect of improving the oxidation resistance. Further, when the aluminum composition ratio y exceeds 0.7, the hardness of the coating may be extremely reduced. On the other hand, when y is less than 0.02, it is difficult to obtain the effect of improving the oxidation resistance.

The thickness of the above coating is preferably 0.3 to 50 μm. If it is less than 0.3 μm, it is difficult to obtain the effect of the coating. On the other hand, if it exceeds 50 μm, the coating may be broken by impact during use.

It is preferable that a compressive stress exists as a residual stress in the coating. The residual stress is measured by an X-ray diffraction method (sin ² ψ method). The residual stress of the film is preferably a compressive stress having an average value of 0.5 to 8 GPa. If this residual stress is a compressive stress smaller than 0.5 GPa or if it is a tensile residual stress, the effect of suppressing the occurrence of thermal cracks cannot be obtained, which is not preferable. On the other hand, when the residual stress is a compressive stress exceeding 8 GPa, it is not preferable because cracks are accelerated.

As a method for forming the coating on the surface of the mold or the like, there are a PVD method such as an ion plating method and an arc ion plating method, and a CV method such as a plasma CVD method.
A method such as the D method can be adopted.

By satisfying these requirements, a mold having a coating having heat crack resistance and oxidation resistance can be obtained.

The second embodiment, such as a mold having a surface coating according to the present invention, differs from the first embodiment only in the structure of the coating, and differs from the first embodiment in the type of base material, the thickness of the coating and the residual stress. The conditions other than those described above, the film formation method, and the like are the same as those in the first embodiment except for the film structure.

The coating in the second embodiment is formed on the surface of a base material such as a mold, and is made of a nitride of an alloy of titanium, chromium, and aluminum. The coating is a coating having a composition in which the composition ratio of Cr or Al is continuously or stepwise increased from the surface of the base material such as the mold toward the coating surface.

The nitride of the alloy of titanium, chromium and aluminum can be represented by the above formula [1], and x,
y has the above range.

In order to make this coating a gradient composition, the alloy composition of the evaporation source is continuously adjusted from the surface of the base material such as the mold toward the coating surface so as to become chromium-rich or aluminum-rich. There are a method of changing, a method of changing in a stepwise manner, a method of laminating a thin film of a specific composition, and the like.

The effect of adding chromium and aluminum to titanium nitride is as described above. However, when the film is made rich in chromium or aluminum toward the surface of the film as in this embodiment, the oxidation resistance of the film surface is reduced. Can be particularly improved.

The third embodiment, such as a mold having a surface coating according to the present invention, differs from the first embodiment only in the structure of the coating, and differs from the first embodiment in the type of base material, the thickness of the coating and the residual stress. The conditions other than those described above, the film formation method, and the like are the same as those in the first embodiment except for the film structure.

The coating in the third embodiment is formed on the surface of a base material such as a mold, and is formed by alternately forming thin layers of titanium nitride, chromium nitride and aluminum nitride by at least 10 layers.
It is a film that has been repeatedly laminated. The order of the titanium nitride thin layer, the chromium nitride thin layer, and the aluminum nitride thin layer may be arbitrary, but three thin layers are alternately stacked in a predetermined order.
With such a laminated structure, even if the outer layer is worn away and disappears, the next layer is exposed and the oxidation resistance is maintained.

This laminated coating can be laminated by adjusting the alloy composition of the evaporation source for each thin layer.

The fourth embodiment, such as a mold having a surface coating according to the present invention, differs from the first embodiment only in the structure of the coating, and differs from the first embodiment in the type of base material, the thickness of the coating and the residual stress. The conditions other than those described above, the film formation method, and the like are the same as those in the first embodiment except for the film structure.

The coating according to the fourth embodiment is formed on the surface of a base material such as a mold, and a thin layer of titanium aluminum nitride and chromium nitride is alternately formed once or at least two times.
It is a film that has been repeatedly laminated. The thin layer of titanium aluminum nitride is formed by using an alloy of titanium and aluminum as an evaporation source to form a thin layer of nitride. With such a laminated structure, even if the outer layer is worn away and disappears, the next layer is exposed and the oxidation resistance is maintained.

This laminated coating can be laminated by adjusting the alloy composition of the evaporation source for each thin layer.

The fifth embodiment, such as a mold having a surface coating according to the present invention, differs from the first embodiment only in the structure of the coating, and differs in the type of the base material, the thickness of the coating and the residual stress. The conditions other than those described above, the film formation method, etc. are the same as those in the first embodiment except for the film structure.

The coating in the fifth embodiment is formed on the surface of a base material such as a mold, and is a coating obtained by alternately repeating thin layers of titanium chromium nitride and aluminum nitride at least 10 times. The titanium-chromium nitride thin layer is formed by using a titanium-chromium alloy as an evaporation source to form a nitride thin layer. With such a laminated structure, even if the outer layer is worn away and disappears, the next layer is exposed and the oxidation resistance is maintained.

This laminated film can be laminated by adjusting the alloy composition of the evaporation source for each thin layer.

The sixth embodiment of the present invention, such as a mold having a surface coating, differs from the first embodiment only in the structure of the coating, and differs from the first embodiment in the type of base material, the thickness of the coating and the residual stress. The conditions other than those described above, the film formation method, etc. are the same as those in the first embodiment except for the film structure.

The coating in the sixth embodiment is formed on the surface of a base material such as a mold, and a thin layer of chromium aluminum nitride and titanium nitride is alternately formed once or at least two times.
It is a film that has been repeatedly laminated. The thin layer of chromium aluminum nitride is formed by using an alloy of chromium and aluminum as an evaporation source to form a thin layer of nitride. With such a laminated structure, even if the outer layer is worn away and disappears, the next layer is exposed and the oxidation resistance is maintained.

The laminated coating can be laminated by adjusting the alloy composition of the evaporation source for each thin layer.

According to a seventh embodiment of a mold having a surface coating according to the present invention, a nitriding layer is formed on the surface of a base material such as a mold made of steel or cast iron. The above-mentioned coating is formed by using the above method, and a mold or the like having the surface coating of any of the first to sixth embodiments is produced.

The nitriding layer is formed by diffusing and infiltrating nitrogen into the surface of the base material such as the mold. As the nitriding method, many nitriding methods such as a tuftride process, a gas nitriding process, and an ion nitriding process can be applied. However, in many of the above methods,
Γ′-Fe ₄ N or γ′- which is a brittle compound called a compound layer or an embrittlement layer on the surface of a base material such as a mold after nitriding.
A layer of Fe _2-3 N occurs. Therefore, it is necessary to remove such a compound layer by polishing. In addition,
By using the ion nitriding method, the nitriding treatment can be performed without forming the compound layer.

The thickness of the nitrided layer, that is, the depth from the surface of the base material such as a mold on which the nitrided layer is formed is preferably 50 to 500 μm. If it is less than 50 μm, the effect of the nitriding layer cannot be sufficiently exerted. Also,
In the case where the thickness exceeds 500 μm, nitridation treatment for an extremely long time is required to form a nitridation treatment layer having this thickness.
Not economic.

By forming this nitrided layer,
An excellent effect of improving heat crack resistance is provided. Further, it is preferable to apply a compressive residual stress to the nitriding layer.
This compressive residual stress can be measured by the same X-ray diffraction method as described above. 10μ depth from the surface of the base material such as the mold
The residual stress over m is 0.2-1.5 G on average
Good compressive stress of Pa. Compressive stress less than 0.2 GPa,
Alternatively, when the residual stress is tensile, it is difficult to obtain the effect of suppressing the occurrence of thermal cracks. On the other hand, when the compressive stress exceeds 1.5 GPa, crack generation is accelerated.

The eighth embodiment of the mold having a surface coating according to the present invention is the base material such as the mold used in the first to sixth embodiments or the mold used in the seventh embodiment. A hard coating intermediate layer is provided between the surface of a base material such as a mold having a nitrided layer applied to the surface to be formed and any of the coatings formed in the first to sixth embodiments. It is.

The hard coating intermediate layer is formed of either titanium nitride or chromium nitride. By providing this hard coating intermediate layer, the adhesion between the base material such as the mold and the coating can be improved. In particular, when the base material such as a mold used in the seventh embodiment is used, the adhesion to the coating can be further improved.

The molds or molds having the surface coatings of the first to seventh embodiments are molds or molds having both heat crack resistance and oxidation resistance. It can be used as a mold base material or a mold for warm or hot forging of a system component, for casting of an aluminum alloy, for casting or thixoforming of a magnesium alloy, or for forming molten glass.

[0046]

Embodiments of the present invention will be described below. The processing used in each example and comparative example is shown below.

[Nitriding Treatment of Base Material Surface] Treatment: Tuftride treatment The base material was held in a salt bath at a temperature of 550 ° C. for a time period of 30 minutes to 20 hours to obtain a hardened layer having a depth of 25 to 450 μm on the surface.
The compound layer having a depth of 5 to 10 μm formed on this surface was polished and removed, and the surface roughness (Rz) was reduced to 0.3 μm or less.

Processing: ion nitriding temperature 500 ° C., time 15 minutes to 2 hours, nitrogen gas 60 flow%, hydrogen gas 40 flow%, standby pressure in processing tank 2 Torr
Under a condition of r, a DC voltage of −100 V applied to the base material (base material), and a high-frequency power (13.56 MHz) of 1000 W, a cured layer of 40 to 150 μm was obtained on the surface. No harmful compound layer was formed on this surface, but the surface roughened by the plasma treatment was lightly wrapped and the surface roughness (R
z) was set to 0.3 μm or less.

[0049] [Formation of coating film] _{process: (Ti (1-xy)} Cr x Al y) with the formation of N coatings arc ion plating method, depends on the composition x and y targeted titanium - chromium - aluminum alloy (Cr composition x or Al composition y is 100 ×
(x atomic%, 100 x y atomic%), an arc current of 100 A and a substrate (base material) temperature of 450
C., a nitrogen atmosphere, a vacuum chamber pressure of 30 mTorr, and a DC voltage of -200 V applied to a base material (base material), changing the processing time and changing the processing time to 0.2 to 55 μm thick (Ti _(1-xy)
A Cr _x Al _y ) N coating was formed. The base material (base material)
One in which the residual stress in the coating was changed by changing the temperature or the DC voltage applied to the base material (base material) was also prepared.

Treatment: Formation of TiN / CrN / AlN laminated film Pure titanium (containing 0.5% by weight or less of inevitable impurities), pure chromium (including 0.5% by weight or less of inevitable impurities), pure aluminum (Including 0.5% by weight or less of unavoidable impurities).
These three evaporation sources were used individually and arranged so as to be adjacent to the inner wall of the vacuum chamber. A rotary table was arranged at the center of the three evaporation sources, and a base material (base material) was attached thereto. Using the arc ion plating method, the arc current of each evaporation source was 100 A, the substrate (base material) temperature was 450 ° C., the pressure in the vacuum chamber was 30 mTorr in a nitrogen atmosphere, the DC voltage applied to the substrate was −200 V, and the TiN / CrN having a thickness of about 5 μm under the conditions of a rotation speed of 1 rpm and a processing time of 20 minutes.
/ AlN laminated film was formed. Number of repetitions of lamination is 2
Five times. In addition, samples were prepared in which the number of times of lamination was changed from 9 to 500 by changing the number of rotations of the table.

Treatment: Formation of Titanium Aluminum Nitride / Chromium Nitride Laminate Film The treatment was carried out according to the above treatment. That is, an evaporation source made of a titanium-aluminum alloy having a desired composition (containing 0.5% by weight or less of unavoidable impurities) and pure chromium (including 0.5% by weight or less of unavoidable impurities) is used. Each one was placed in opposition to the inner wall of the vacuum chamber. The rotation speed of the table was 0.8 rpm. Other conditions are the same as the method described in the above-mentioned treatment,
A titanium-aluminum nitride / chromium nitride laminated film having a thickness of ６6 μm was formed. The number of times of lamination was 25 times.
Also, a table was prepared in which the number of times of lamination was changed to 500 times by changing the number of rotations of the table. Further, for the samples in which the number of repetitions of lamination was one or two, the base material (base material) was allowed to stand still for a predetermined time in front of each evaporation source so that the desired number of repetitions was achieved.

Treatment: Formation of titanium chromium nitride / aluminum nitride laminated film A titanium chromium alloy (containing 0.5% by weight or less of inevitable impurities) having a desired composition and pure aluminum (0.5% by weight or less of inevitable impurities) ), Except that the evaporation source prepared in each of the above steps was used, to form a laminated film by the same method as the above-mentioned treatment.

Treatment: Formation of Chromium Aluminum Nitride / Titanium Nitride Laminated Coating A chromium aluminum alloy (containing 0.5% by weight or less of inevitable impurities) having a desired composition and pure titanium (0.5% by weight or less of inevitable impurities) ), Except that the evaporation source prepared in each of the above steps was used, to form a laminated film by the same method as the above-mentioned treatment.

Processing: (Ti _(1-xy) Cr _x Al _y ) N
Formation of gradient composition film (Ti _(1-x1-y1) Cr _x1 Al _y1 ) N → (Ti _(1-x2-y2)
A Cr _x2 Al _y2 ) N gradient composition coating was formed by the following method. Using an arc ion plating method, a titanium-chromium-aluminum alloy determined by target x1 and y1 (Cr composition x1 or Al composition y1 is 1
An evaporation source made of 00 × x1 atomic% and 100 × y1 atomic% and a titanium-chromium-aluminum alloy (Cr composition x2 or Al composition y2) determined by x2 and y2 are 100 × x2 atomic% and 100 × 2 atomic%, respectively. × y2 at%) with an evaporation source spaced apart by a distance of 300 mm
Arranged in parallel, arc current 100A, base material (base material) temperature 450 ° C, nitrogen atmosphere, vacuum chamber pressure 30mTorr
r, a DC voltage applied to the base material (base material) of -200 V, a processing time of 60 minutes, and slowly moving the base material (base material) between the two evaporation sources to obtain a 2 μm-thick 2 μm stage of _{(Ti (1-x1-y1} ) Cr x1 Al y1) N → (Ti
_{(1-x2-y2) Cr} x2 Al y2) forming the N gradient composition film.

[Formation of Hard Coating Intermediate Layer] Treatment: Performed by a method similar to the treatment for forming a TiN coating or a CrN coating. That is, a 2 μm-thick TiN film or CrN film was formed using the evaporation source made of titanium or chromium under the same conditions as the processing method. Although the hard coating intermediate layer was formed by this method, in the case of providing a coating on this intermediate layer, in forming each coating, the above-mentioned "[Formation of coating]"
Each method was performed.

[Measurement of Residual Stress] The residual stress in the vicinity of the surface of the base material such as a mold and in the coating was measured by the X-ray diffraction method by the sin ² ψ method. The angle ψ in the sin ² ψ method is the tilt angle に お け る in X-ray diffraction. It means the direction based on the normal line of the material (base material) surface.
0 ° indicates the direction of the normal to the surface of the material (base material), and ψ = 90 ° indicates the direction parallel to the surface of the material (base material). A compressive stress in a direction parallel to the material surface (ψ = 90 °) causes the material to shrink the most in the same direction and expand the material the most in the perpendicular direction (垂直 = 0 °). If the degree of expansion and contraction of the material at this time is replaced with a change in the plane spacing of the crystal lattice constituting the material, the change in the plane spacing (strain)
And ψ are related as follows. Change in plane spacing = (constant determined by Young's modulus and Poisson's ratio)
× Stress × sin ² ψ Then, the lattice constant of a specific crystal plane was measured while changing ψ at the time of X-ray diffraction, and a graph was written with sin ²横 as the abscissa and the plane interval as the ordinate. The points are approximately on a straight line. Since the slope of this straight line is the product of the stress and a constant determined by the Young's modulus and Poisson's ratio inherent to the material, the stress value can be calculated from the slope.

[Preparation of Samples and Comparative Samples Used in Examples and Comparative Examples] φ40 × made of JIS steel type SKD61
A block having a cylindrical shape of h30 was formed, and heat treatment was performed by quenching and tempering to prepare a base material having a Rockwell C scale hardness of 52. One surface of φ40 of this base material was polished to a surface roughness (Rz) of 0.3 μm or less. Samples 1 to 30 were prepared by subjecting the polished surface of the base material to the surface treatment and film formation shown in Tables 1 to 3 according to the above-described treatment methods. Similarly, Comparative Samples 1 to 10 were prepared.
In addition, the residual stress of the base material and the residual stress of the coating film shown in Tables 1 to 3 each indicate the value of the compressive stress measured by the above measurement method.

[0058]

[Table 1]

[0059]

[Table 2]

[0060]

[Table 3]

(Example 1, Comparative Example 1) Using each of the above samples and comparative samples, a heat load was applied by repeating the operation of heating at 600 ° C. in the atmosphere for 60 seconds and then rapidly cooling in water for 60 seconds. After the heat load cycle was applied 100 times, damage on the coating surface or the base material surface was observed with an optical microscope, and the number of crack initiation cycles was evaluated. The results are shown in Tables 4 to 6. As is clear from Tables 4 to 6, in the present invention, it was confirmed that generation of thermal cracks was significantly suppressed.

Example 2, Comparative Example 2 Samples 1, 4, 8,
9, 14, 21, 24, 28 and comparative samples 1, 3, 6,
8 were converted to warm forging die punches (JIS
For each of the steel types SKH51 and Rockwell C scale hardness 53), the die life evaluation during warm forging was actually performed. During forging, the mold surface was heated to 700 ° C. The life was determined when the dimensional accuracy of the workpiece was out of the specified range. Tables 4 to 6 show the life evaluation results. As is clear from Tables 4 to 6, in the present invention, it was confirmed that the life of the mold was greatly improved.

Example 3, Comparative Example 3 Samples 1, 4, 8,
9, 14, 21, 24, 28 and comparative samples 1, 3, 6,
Each of the treatments performed in No. 8 was performed on a cast-out pin (JIS steel type SKD61, Rockwell C scale hardness 51) for casting an aluminum alloy, and the life of the cast-out pin when actually casting an aluminum alloy was evaluated. The casting method was gravity casting, and the surface of the cast pin was heated to 670 ° C. The life was determined when the dimensional accuracy of the workpiece was out of the specified range. Tables 4 to 6 show the life evaluation results.
As is clear from Tables 4 to 6, in the present invention, it was confirmed that the life of the cast pin was greatly improved.

Example 4, Comparative Example 4 Samples 1, 4, 8,
9, 14, 21, 24, 28 and comparative samples 1, 3, 6,
Each of the treatments performed in No. 8 was performed on a glass lens molding die made of cemented carbide or a glass lens molding die made of alumina-titanium carbide ceramics, and glass lenses were actually molded. However, since the nitriding treatment could not be applied to the mold base material, each of the above treatments was applied only to the coating portion. The molding method was press molding, and the portion of the mold surface where the glass material first contacted was heated to 800 ° C. In the evaluation of various prototypes, the mold life was defined as the time when the mold release property was reduced and continuous use was impossible.
The results are shown in Tables 4 to 6. As is clear from Tables 4 to 6,
In the present invention, it was confirmed that the life of the mold was greatly extended.

Example 5, Comparative Example 5 Samples 1, 4, 8,
9, 14, 21, 24, 28 and comparative samples 1, 3, 6,
8 were performed on magnesium alloy thixomolding dies (JIS steel type SKD61, Rockwell C scale hardness 51), and the mold life when thixomolding was actually performed was evaluated. The forming method is to heat the magnesium alloy (AZ91D) to 580 ° C to make it a semi-molten state,
The "thixo molding method" in which injection molding was performed inside a mold kept at 250 ° C was adopted. The mold surface was spray-coated with a release agent every shot. The evaluation of various prototypes was defined as the life of the mold when the magnesium alloy was seized on the surface of the mold and molding became difficult continuously. The results are shown in Tables 4 to 6. As is clear from Tables 4 to 6, it was confirmed that in the product of the present invention, the mold life was significantly extended.

[0066]

[Table 4]

[0067]

[Table 5]

[0068]

[Table 6]

[0069]

According to the present invention, a mold or a mold having a coating excellent in heat crack resistance and oxidation resistance can be obtained, and damage and fatigue cracks due to oxidation of the surface of the mold or the mold can be suppressed. it can. Thereby, the life of the mold or the mold can be improved.

Claims (9)

[Claims] 1. The surface of a mold base material or a mold base material made of cemented carbide, ceramics, steel or cast iron, is provided with (Ti _(1-xy)
Cr _x Al _y ) N (where x and y are 0.02 ≦ x <
1.0, 0.02 ≦ y ≦ 0.7. A) a mold or a mold having a surface film formed with a film having a thickness of 0.3 to 50 μm and a compressive stress having an average residual stress of 0.5 to 8 GPa. 2. The method according to claim 1, wherein the coating is formed continuously or stepwise from the surface of the mold base material or the mold base material toward the coating surface.
The mold or the mold having a surface coating according to claim 1, which is a coating having a composition in which the composition ratio of r or Al is increased. 3. A thin layer of titanium nitride, chromium nitride and aluminum nitride is alternately and repeatedly laminated at least 10 times on a surface of a mold base material or a mold base material made of cemented carbide, ceramics, steel or cast iron, Its film thickness is 0.3-50
A mold or a mold having a surface coating formed with a coating having a compressive stress of 0.5 to 8 GPa with an average residual stress of 0.5 to 8 GPa. 4. Thin layers of titanium aluminum nitride and chromium nitride are alternately and repeatedly laminated at least once or twice on the surface of a mold base material or a mold base material made of cemented carbide, ceramics, steel or cast iron. Whose thickness is 0.3 to 50
A mold or a mold having a surface coating formed with a coating having a compressive stress of 0.5 to 8 GPa with an average residual stress of 0.5 to 8 GPa. 5. A thin layer of titanium chromium nitride and aluminum nitride alternately having a thickness of at least 10 on the surface of a mold base material or a mold base material made of cemented carbide, ceramics, steel or cast iron.
Times, and the thickness is 0.3 to 50 μm
A mold or a mold having a surface coating on which a coating having an average residual stress of 0.5 to 8 GPa is formed. 6. A thin layer of chromium aluminum nitride and titanium nitride is alternately and repeatedly laminated once or at least twice on the surface of a mold base material or a mold base material made of cemented carbide, ceramics, steel or cast iron. , The thickness of which is 0.3 to 50
A mold or a mold having a surface coating formed with a coating having a compressive stress of 0.5 to 8 GPa with an average residual stress of 0.5 to 8 GPa. 7. An average value of residual stress over a thickness of 50 to 500 μm and a depth of 10 μm from the surface by diffusing and infiltrating nitrogen into the surface of a mold base material or a mold base material made of steel or cast iron. The mold or the mold having a surface coating according to any one of claims 1 to 6, wherein a nitrided layer having a compressive stress of 0.2 to 1.5 GPa is formed. 8. A hard coating intermediate layer formed of either titanium nitride or chromium nitride is provided between the mold base material or the mold base material and the coating.
A mold or a mold having the surface coating according to any one of the above. 9. For hot or hot forging of an iron-based part, for casting of an aluminum alloy, formed by using a mold or a mold having the surface coating according to any one of claims 1 to 8. For magnesium alloy casting or thixoforming,
Alternatively, a mold or a mold for forming molten glass.