JP3205363B2 - Mold with diamond-like protective film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold protected by a diamond-like thin film, and more particularly to a high-performance mold using inexpensive steel and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, molds for molding or processing such as injection molding, extrusion molding, compression molding and the like of glass and plastic have been manufactured from ultra-hard materials. However, such materials are expensive and require time and expense to arrange and manufacture. In addition, there is a disadvantage that it is easily broken due to lack of toughness. To compensate for the brittleness and wear resistance of super-hard materials, it is known to form a protective film by coating a frictional surface or a sliding surface of a mold surface with a diamond-like thin film. However, the diamond-like thin film has a problem in that the diamond-like thin film has a weak bonding force to the surface of the mold base and is a collection of microcrystals, and is easily peeled off from the mold surface by the action of an external force. Therefore, the effect cannot be sufficiently exerted in applications requiring corrosion resistance, wear resistance, etc. as a protective coating.

[0003] On the other hand, hardened steel is available at low cost and requires little labor and cost for processing, but has the disadvantage that the mold surface is easily worn and the life is short. In order to remedy this drawback, JP-A-2-15169, JP-A-2-22012, and JP-A-2-151
It is preferable to coat the diamond-like thin film by a gas phase method as shown in No. 70, etc., but the bonding force is insufficient for the same reason. There are various types of diamond-like thin film production methods by other methods (for example, “Surface Chemistry” Vol. 5, No. 1).
No. 08 (1984) pp. 108-115) generally requires a high substrate temperature of 600 ° C. or more, which causes the problem that the quenched steel is annealed and the hardness of the mold is impaired. is there.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to manufacture a mold having high wear resistance by using inexpensive hardened steel. However, this quenched steel has low heat resistance and poor adhesion to a diamond-like thin film, so that it was not possible to industrially form a wear-resistant diamond-like thin film-coated mold. Japanese Patent Application No. 1-214913 describes a technique of using a substrate bombard by Ar ions or the like and a subsequent diamond film formation by an ionization vapor deposition method to protect metals and ceramics. It does not disclose any application to the manufacture of.

[0005]

SUMMARY OF THE INVENTION The present invention can effectively form a protective film on affinity poor die table surface of a diamond-like carbon film. That is, the present invention
The surface that is subject to mold wear from the
Obtained by vapor deposition under the first negative bias condition for
Hardness greater than the surface and diamond-like thin film described later
Hardness Hv = 1000-5000 kg
/ Mm ² carbon film intermediate layer and hydrocarbon plasma on it
From the larger second negative
Hardness obtained by evaporation under ias conditions is greater than that of the intermediate layer.
Mold with protective film consisting of diamond-like thin film
I will provide a. Here, the intermediate layer is a bias-applied plasma C
It can be formed by VD method or ion or vapor deposition method.
You. Preferably, the hardness of the intermediate layer of the present invention increases stepwise or continuously from the mold toward the diamond-like thin film. The present invention also provides a method for converting hydrocarbon gas into plasma,
The surface subjected to mold wear has a higher hardness than the surface
And hardness H which is lower than that of the diamond-like thin film described later
v = 1000-5000 kg / mm ² carbon film intermediate layer
Deposited under a first negative bias condition to obtain
Then, the negative bias condition is increased on the intermediate layer.
In place of the second negative bias condition, a harder diamond
Mold protective film characterized by forming Monde-like thin film
A method of forming is provided. In the present invention, a negative bias is applied during film formation.
Hydrogen and carbon in plasma by controlling deposition conditions
Elemental positive ions are deposited on the mold surface,
Hardness is higher than that of diamond-like thin film
To form a carbon intermediate layer with small
Without any modification and using the same ionized deposition method.
Changing diamond deposition conditions to form diamond-like thin films
You. In particular, the intermediate layer has a diamond-like hardness from the mold surface.
During the deposition of the intermediate layer itself,
It is preferable to change the deposition conditions stepwise or continuously.
Good.

According to the present invention, a carbon intermediate layer having a hardness higher than that of the mold and a hardness lower than that of a diamond-like thin film described later is formed on the surface of the mold by controlling the deposition conditions of the ionization vapor deposition method. Then, a metal mold with a protective film is provided by changing the film forming conditions without changing the raw material hydrocarbon and using the same ionization vapor deposition method to form a diamond-like thin film. In particular, it is preferable to change the film forming conditions stepwise or continuously even when forming the intermediate layer itself so that the hardness of the intermediate layer increases from the mold surface toward the diamond-like thin film.

A method for forming an intermediate layer is disclosed in
The ionization deposition method described in JP-A-8-174507 and JP-A-1-234396 is used. According to this method, after the formation of the intermediate layer, the next diamond-like thin film can be formed by changing the conditions to the diamond-like thin film formation conditions without exposing the layer to air or without interrupting the operation itself. Can be shifted to the forming process.
For this reason, the method of the present invention has extremely good workability. Preferably, prior to this step, the mold is arranged in a vacuum chamber of a film forming apparatus, a bombarding gas such as Ar is introduced into the vacuum chamber, and a hot cathode filament and a cathode provided around the hot cathode filament are provided. The ionization means consisting of ionizing means to form a flow of ions, accelerated by a grid at a lower potential than the counter cathode, accelerated by bombarding the surface of the mold, and activated. Good.

The intermediate layer may be a film having a constant composition larger than the hardness of the mold and smaller than the hardness of the diamond-like thin film. Preferably, the intermediate layer has a low hardness on the mold surface side and a high hardness on the diamond side. This can improve the connectivity. For forming the intermediate layer and the diamond-like thin film, the same ionized vapor deposition apparatus is used, the same raw material is used, and the vapor deposition conditions may be simply changed continuously or stepwise.
The thickness of the intermediate layer is preferably 0.02 to 3 μm, more preferably 0.05 to 0.5 μm. If it is too thin, there is no effect, and if it is too thick, the effect is saturated.

[0009] The hardness of the diamond-like thin film is about 6000 kg / mm ² or more as measured by ionization vapor deposition. On the other hand, the hardness of the mold as the substrate varies depending on the material, but is usually 200 to 3000 kg / mm ² . Therefore, the hardness of the intermediate layer may be selected in the range of 1000 to 5000 kg / mm ² which is the intermediate hardness between the substrate material and the diamond-like thin film.

In the formation of the intermediate layer and the diamond-like thin film by the ionization vapor deposition method, a hydrocarbon raw material gas or a raw material gas capable of generating hydrocarbon by decomposition or reaction (here, hydrocarbon means methane, ethane, propane, etc.) There are unsaturated hydrocarbons such as saturated hydrocarbons, ethylene, propylene, and acetylene, etc., and raw material gases that can be decomposed to produce hydrocarbons include alcohols such as methyl alcohol and ethyl alcohol, and ketones such as acetone and methyl ethyl ketone. The raw material gas which reacts to generate a hydrocarbon gas includes carbon monoxide, a mixed gas of carbon dioxide and hydrogen, etc. The raw material includes a rare gas such as helium, neon, argon or hydrogen, At least one of oxygen, nitrogen, water, carbon monoxide, carbon dioxide, etc.). (I) ionization by means such as arc discharge between the cathode and the cathode, ionization by thermionic emission between the cathode hot filament and the cathode, and the like, and the ion stream is accelerated by an electric field and directed to the mold to form an intermediate layer. And a method of forming a diamond-like thin film, the details of which are described in JP-A-58-174507 and JP-A-1-234396. The intermediate layer can be formed by lowering the film formation energy of the diamond-like thin film.

FIG. 1 shows a preferred example of a film forming apparatus according to JP-A-58-174507. Of course, other known ionized vapor deposition devices may be used.
In the figure, reference numeral 30 denotes a vacuum container, and 31 denotes a chamber, which is connected to an exhaust system 38 and is evacuated to a high vacuum of about 10 ^-6 Torr. Reference numeral 32 denotes a substrate electrode provided on the back surface of the mold S and maintained at a negative potential Va. A mask 42 having a window which regulates the shape of the diamond-like thin film in proximity to or in contact with the surface of the mold S is provided. This mask may be in contact with the mold, but should be separated as much as possible in order to reduce the thickness of the peripheral part of the film and reduce cracks. Reference numeral 33 denotes a grid to which the same potential Va as that of the mold is applied, which is used for accelerating hydrocarbon ions in a film forming process. This grid 33 uses a grid with an appropriately determined void ratio (area of holes per unit area) and hole density (number of holes per unit length) to increase the continuity of the film and smooth the surface. Alternatively, a means for vibrating in the in-plane direction may be provided. Numeral 34 denotes a hot cathode filament maintained at a negative potential Vd, which is heated by a current If from an AC power supply to generate thermoelectrons. 35 is a raw material gas supply port,
37 is a gas supply passage, and 37 'is a plasma excitation chamber.
An anode 36 is arranged around the filament 34. This anode is grounded in this case, but has a positive voltage Vd for the filament and a positive potential Va for the electrode 32 and the grid 33. An electromagnetic coil 39 energized by a current Ic from a power supply Vc is provided to surround the filament 34, the anode 36, and the supply port 35 to generate a magnetic field for confining the ionized gas. Therefore, the film quality can be changed by adjusting If, Va, Vd, and the current Ic of the coil. In particular, control of Va (substrate voltage) and Vd (potential difference between hot cathode and anode) is preferable. Such control of the film forming conditions can be easily performed by program control by a computer.

In forming a film, the inside of the chamber 31 is 10 ^−6.
A high vacuum was applied to Torr, and a valve for the gas supply passage 37 was operated to operate a predetermined flow rate of a gas for forming an intermediate layer, a gas for forming a diamond, a mixed gas of hydrogen and gas, or Ar, He, The exhaust system 38 is adjusted while introducing a carrier gas such as Ne from each supply port 35 to a predetermined gas pressure, for example, 10 ^-1 Torr. On the other hand, the plurality of hot cathode filaments 34 are heated by passing an alternating current If, and a potential difference Vd is applied between the filaments 34 and the anode 36.
Is applied to form a discharge. The raw material gas supplied from the supply port 35 is thermally decomposed and collides with thermoelectrons from the filament to generate positive ions and electrons. This electron collides with another pyrolysis particle. By repeating such a phenomenon under the confinement effect of the magnetic field of the electromagnetic coil, methane gas becomes a positive ion of a pyrolysis substance.
The positive ions are attracted by the negative potential Va applied to the electrode 32 and the grid 36, accelerated toward the mold S, collide with the mold and perform a film forming reaction, thereby forming a diamond-like thin film. For the conditions such as the potential, current, and temperature of each part, refer to the above-mentioned patent publications in addition to the above-mentioned conditions.

Hereinafter, the present invention will be exemplified.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An intermediate layer was formed on a hardened steel mold made of SKD11 and SKS2 under the conditions shown in Table 1, and then a diamond-like thin film was formed under the conditions shown in Table 1 by ionization deposition. The filament 34 was coil-shaped and had a width of 3 mm and a gap of 8 mm with the electrode 36 surrounding the filament. The grid 33 was vibrated at a speed of 5 mm / min.
Filament current If = 25A, filament voltage Vd
Variable, variable substrate voltage Va, magnetic flux density of electromagnetic coil 300
Under the conditions of G, CH ₄ was introduced to obtain intermediate layers having various thicknesses, and then a diamond-like thin film having a thickness of 3.0 μm.

[0014]

[Table 1]

The characteristics of the protective film of the obtained mold with a protective film are as shown in Table 2. However, the evaluation of adhesion and scratching power was as follows. Adhesion is 1cm square, length 1
A square material of 0 cm was adhered to the diamond-like thin film with an epoxy resin, and pulled and peeled off by a tensile tester (Tensilon-trade name) to measure. The scratch force is Rhesca
It was measured with a CSR-02 tester manufactured by the company. Each value is a relative value based on the value in the first row of Table 2.

[0016]

[Table 2]

Further, the number of durable shots at the time of molding a ferrite core having a diameter of 20 mm in a mold using hardened steel of SKD11 was measured, and the results shown in Table 3 were obtained.

[0018]

[Table 3]

[0019]

According to the present invention, it is possible to apply a diamond-like thin film to a mold which is usually difficult to bond by interposing an intermediate layer, and to greatly improve the wear resistance and durability of the mold. Can be improved.

[Brief description of the drawings]

FIG. 1 shows an outline of an ionization vapor deposition apparatus used in the present invention.

[Explanation of symbols]

 Reference Signs List 30 vacuum vessel 31 chamber 32 negative electrode 42 mask 33 grid 34 hot cathode filament 35 source gas supply port 36 anode 37 gas supply passage 37 ′ plasma excitation chamber

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-201095 (JP, A) JP-A-2-15169 (JP, A) JP-A-2-22012 (JP, A) JP-A-2-2 15170 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C30B 1/00-35/00

Claims (5)

(57) [Claims] From 1. A hydrocarbon plasma to a surface subject to wear of the mold, a first negative bias with respect to hydrocarbon plasma
Hardness H, which is higher than the surface and lower than the diamond-like thin film described later , obtained by vapor deposition under
v = 1000 kg / mm ² of carbon film intermediate layer, and a hydrocarbon plasma
Deposited under a second larger negative bias condition
Large diamond-like carbon film obtained hardness than the intermediate layer
Mold having become more protective film when. 2. The mold having a protective film according to claim 1, wherein the intermediate layer is formed by a bias-applied plasma CVD method or an ion or vapor deposition method. 3. The mold having a protective film according to claim 1, wherein the hardness of the intermediate layer increases stepwise or continuously from the mold toward the diamond-like thin film. 4. The gold having a protective film according to claim 1, wherein the thickness of the intermediate layer is 0.2 to 3.0 μm.
Type . 5. The method according to claim 5, wherein the hydrocarbon gas is converted into plasma and the mold is polished.
The surface subjected to wear has a higher hardness and
Hardness Hv = 1, which is smaller than the diamond-like thin film
000-5000 kg / mm ² carbon film intermediate layer is obtained
Deposited under a first negative bias condition such that
On said intermediate layer, said negative bias condition is
Harder diamonds with negative bias
Of forming a protective film on a mold characterized by forming a uniform thin film
Law.