JP3130094B2 - 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, glass and plastic injection molding,
Molding or processing dies such as extrusion molding and compression molding are 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. In order to compensate for the brittleness and wear resistance of a super-hard material, it is known to form a protective film by coating a friction surface or a sliding surface of a mold surface with a diamond-like thin film. -15
170, etc., the diamond-like thin film has a problem in that it 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]

According to the present invention, an intermediate layer made of an amorphous mixture of silicon and carbon and a diamond-like thin film are sequentially formed on the surface of a mold having a poor affinity for the diamond-like thin film. Provided is a mold having a protective film.

The material of the intermediate layer used in the present invention is as follows:
An amorphous mixture derived from a gas of a species.
Here, the gas is a gas of the following low molecular weight compound containing both carbon and silicon, and a mixed gas of low molecular weight substances of 2 and 3, 1 and 2, 1 and 3, or 1 and 2 and 3 It is. The intermediate layer also needs to have sufficient hardness to support the diamond-like film. (1) Organic silicon compound - methylsilane CH ₃ SiH
_3, dimethylsilane (CH _{3) 2} SiH _2, trimethylsilane (CH _{3) 3} SiH, tetramethylsilane Si
(CH _{3) 4.} (2) Silicon compound—silane SiH ₄ , disilane Si ₂
H ₆ , silicon tetrafluoride SiF ₄ . (3) carbon compounds - methane CH _4, ethane C ₂ H _6, propylene C ₃ H _8, ethylene C ₂ H _4, acetylene C ₂
H _2.

A method for forming an intermediate layer is disclosed in Japanese Patent Application No. Hei.
Bias-applied plasma CVD described in JP-A-14480 or ionized deposition described in JP-A-58-174507 and JP-A-1-234396 can be used. After the formation of the intermediate layer, it is desirable to proceed to the next step of forming a diamond-like film without exposing the film to air. For this reason, it is necessary to use the same vacuum chamber. Preferably, prior to this step, the substrate is placed in a vacuum chamber of a film forming apparatus, a bombarding gas such as Ar is introduced into the vacuum chamber, and the hot cathode filament and an anode provided therearound are formed. A pre-process may be employed in which ionization is performed by the ionization means to form a stream of ions, which is accelerated by a grid having a lower potential than the anode, and bombards and activates the surface of the substrate.

The resulting intermediate layer is not crystalline but amorphous. As will be compared later, a larger bonding force is generated as compared with the crystalline intermediate layer. In addition, it is desirable that the intermediate layer initially contains a large amount of a silicon component, decreases the silicon component as the film is formed, and increases the carbon component. Thereby, the coupling force can be further improved. The thickness of the intermediate layer is 0.02-
3 μm is preferable, and 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.

In the formation of the intermediate layer by the ionized vapor deposition method and the bias-applied plasma CVD, the above-described single or mixed gas is used. In the formation of a diamond-like film, a hydrocarbon raw material gas or a raw material gas capable of generating hydrocarbon by decomposition or reaction (here, hydrocarbon is methane,
There are saturated hydrocarbons such as ethane and propane, and unsaturated hydrocarbons such as ethylene, propylene and acetylene.The raw material gas which can be decomposed to produce hydrocarbons is methyl alcohol,
There are alcohols such as ethyl alcohol, ketones such as acetone and methyl ethyl ketone, and the like. The raw material gas which reacts to produce a hydrocarbon gas includes carbon monoxide and a mixed gas of carbon dioxide and hydrogen. The raw material may include a rare gas such as helium, neon, or argon, or at least one of hydrogen, oxygen, nitrogen, water, carbon monoxide, and carbon dioxide. It is a method of forming a diamond-like thin film by ionizing by means such as discharge, ionization by thermionic emission between the cathode hot filament and the anode, and directing this flow to a substrate by accelerating the flow with an electric field,
For details, see JP-A-58-174507 and JP-A-1-23.
No. 4396.

FIG. 1 shows a preferred example of a film forming apparatus. In the figure, 30 is a vacuum vessel, 31 is a chamber, and an exhaust system 38
And a high vacuum of about 10 ^-6 Torr is applied. Reference numeral 32 denotes a negative potential V provided on the back surface of the base (mold) S.
The electrode maintained at a. A mask 42 having a window that regulates the shape of the diamond-like thin film in proximity to or in contact with the surface of the substrate S is provided. This mask may be in contact with the substrate, but should be separated as much as possible in order to reduce the thickness of the peripheral portion of the film and reduce cracks. Reference numeral 33 denotes a grid to which the same potential Va as that of the base 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 forming the film, the inside of the chamber 31 is ^kept at 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, the raw material gas becomes a positive ion of the thermal decomposition substance. The positive ions are attracted by the negative potential Va applied to the electrode 32 and the grid 36, accelerated toward the substrate S, collide with the substrate, and perform a film forming reaction, thereby forming an intermediate layer or 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.

As a method for forming the intermediate layer, a bias-applied plasma CVD method shown in FIG. 2 can be used in addition to the above-mentioned ionization vapor deposition method. A film forming apparatus for the intermediate layer will be exemplified. 51 is a chamber, 52 is an RF power source, 53 is a substrate electrode, 54 is an RF electrode, 55 is a substrate to be protected, 56 is an electrode 53, 5
A variable DC bias power supply for applying a bias voltage between
57 is a source gas inlet, and 58 is an exhaust port. The distance between the electrodes is, for example, about 4 cm. As the bias voltage, for example, -50 V to -5 KV can be used. The RF power can be, for example, 50 W to 2 KW, and the reaction time can be 10 to 60 minutes. The Vickers hardness of the amorphous mixture of silicon and carbon in the intermediate layer can be 300 to 2500 Kg / mm ² . Hereinafter, the present invention will be exemplified.

[0013]

[Explanation of the embodiment]

Example 1 Using molds (SKS2 and SKS) shown in Table 1 using Si ₂ H ₆ and CH ₄ as raw materials and using the ionization vapor deposition apparatus of FIG.
KD11 quenched steel molding die) to form an intermediate layer,
Next, a diamond-like thin film was formed. That is, 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. Grid 33
Was vibrated at a speed of 5 mm / min. If = 25A, Va
= -500 V, Vd = -30 V, and the magnetic flux density of the electromagnetic coil was 400 G to obtain an intermediate layer. No peak was detected anywhere when measured by X-ray, and the intermediate layer was amorphous. Next, the raw material was switched to CH ₄ and If = 25 A, Va =
−900 V, Vd = −30 V, magnetic flux density of the electromagnetic coil 4
Under a condition of 00G, a diamond-like thin film having a thickness of 3.0 μm was obtained.

Example 2 Using Si ₂ H ₆ and CH ₄ as raw materials, and using a bias-applied plasma CVD apparatus shown in FIG.
50 V, flow rate 60 (cm ³ min ^-1 ), total pressure 0.025
The intermediate layer was formed under the conditions of Torr, RF power of 500 W, reaction time of 10 minutes, substrate temperature of 200 ° C., and distance between the electrodes of 4.0 cm. No peak was detected anywhere when measured by X-ray, and the intermediate layer was amorphous. Next, a diamond film was formed by the ionization deposition method according to the first embodiment.

Example 3 Using (CH ₃ ) SiH as a raw material, an intermediate layer and a diamond-like thin film were sequentially formed in the same manner as in Example 1. The intermediate layer was amorphous. Example 4

Using (CH ₃ ) SiH as a raw material, an intermediate layer and a diamond-like thin film were sequentially formed in the same manner as in Example 2. The intermediate layer was amorphous.

Comparative Example 1 SiCl ₄ , CH ₄ , H ₂ , and Ar were used as raw materials.
An SiC intermediate layer was formed by a plasma CVD method. The intermediate layer was crystalline as measured by X-ray. Next, a diamond-like thin film was formed according to Example 1.

Comparative Example 2 An intermediate layer was formed by RF sputtering using a target of Si ₃ N ₄ in Ar gas, and then a diamond-like thin film was formed according to Example 1. As measured by X-ray, the intermediate layer was amorphous.

The characteristics of the protective film of the obtained mold with a protective film are as shown in Table 1. However, the evaluation of adhesion and scratching power was as follows. Adhesion is 1cm square, length 1
A prism of 0 cm was adhered to the diamond-like thin film with an epoxy resin, pulled and peeled off by a tensile tester (Tensilon-trade name), and measured. The scratch force is Rhesca
It was measured with a CSR-02 tester manufactured by the company. However, all values are relative values with the value of the first row (ionization vapor deposition method) in Table 1 being 1.0.

[0020]

[Table 1]

Table 2 shows the number of usable shots in forming a 20 mm diameter ferrite core in a quench molding die made of SKD11.

[0022]

[Table 2]

[0023]

As can be seen from Tables 1 and 2, according to the present invention, a diamond-like thin film is applied to a mold which is usually difficult to bond by interposing an intermediate layer comprising an amorphous mixture of silicon and carbon. And the abrasion resistance and durability of the mold can be greatly improved.

[Brief description of the drawings]

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

FIG. 2 shows a biased ionized CV used in the present invention.
The outline of the D vapor deposition apparatus is shown.

[Explanation of symbols]

32 Base 33 Grid 34 Hot filament 35 Gas inlet 36 Anode 39 Electromagnetic coil 51 Chamber 52 RF power supply 53 Substrate electrode 54 RF electrode 55 Substrate to be protected 56 DC bias power supply for applying a bias voltage between electrodes 53 and 54 57 Gas source Inlet 58 Exhaust port

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-199036 (JP, A) JP-A-61-174128 (JP, A) JP-A-61-281030 (JP, A) JP-A-2-1990 120245 (JP, A) JP-A-2-243523 (JP, A) JP-A-3-2577031 (JP, A) JP-A-4-92826 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) C03B 11/00 C03B 40/00-40/02

Claims (4)

(57) [Claims] 1. A mold having a protective film in which an intermediate layer made of an amorphous mixture of silicon and carbon and a diamond-like thin film are formed in this order on a surface of the mold which is subject to wear. 2. The mold according to claim 1, wherein the intermediate layer is formed by a bias-applied plasma CVD method or an ionization vapor deposition method. 3. The mold according to claim 1, wherein the intermediate layer has a thickness of 0.02 to 3.0 μm. 4. The method according to claim 1, wherein the silicon concentration of the intermediate layer decreases from the mold side to the diamond-like film side, and the carbon concentration has a reverse gradient. The mold described.