JPH0681621B2 - Dental micro drill and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a dental microdrill and a method for manufacturing the same.

(Prior Art) A conventional dental microdrill has been manufactured with a hard metal having an uneven surface and a hard metal having fine particles such as metal or non-metal carbide or oxide adhered as an abrasive. However, as the abrasive particles become finer, it becomes difficult to make irregularities on the surface of the member, and in some cases the corners of the particles are not fully utilized, resulting in poor sharpness as a drill and often lacking in wear resistance. It was The inventors of the present invention previously coated a member with a diamond film and / or a diamond-like carbon film produced by a plasma vapor deposition method in which a microwave is applied in a hydrocarbon and hydrogen atmosphere to perform high-performance medical incision and press-fitting. Although a successful application for an instrument was filed (Japanese Patent Application Laid-Open No. 63-92345), when it was applied to a dental microdrill, the above-mentioned points were not yet sufficiently satisfied.

(Problems to be Solved by the Invention) The present invention is a further improvement of the invention of the above-mentioned application in order to solve the above-mentioned drawbacks. To provide a high performance dental microdrill with

(Means for Solving the Problem) The inventors of the present invention have arrived at the present invention as a result of earnestly examining the material and surface treatment method of the dental microdrill member in order to solve the problem.

BEST MODE FOR CARRYING OUT THE INVENTION 1. A dental microdrill in which the surface of a member that has been plasma-etched is coated with needle-like and / or columnar crystals of diamond-like carbon, and the gaps between the crystals are filled with electroless nickel plating, and 2. After plasma etching the member surface, acicular and / or columnar crystals of diamond-like carbon were deposited by plasma vapor deposition method applying microwave of 1 to 10 GHz in hydrocarbon and hydrogen atmosphere. Then, a method for manufacturing a dental microdrill, in which graphite generated in the crystal gaps is removed by plasma etching and the crystal gaps are filled with electroless nickel plating, is a gist.

The present invention will be described in detail below.

First, the dental microdrill according to the first invention will be described.

Examples of the members of the dental microdrill include metals such as Mo, W and Ti, carbides of these metals (Mo ₂ C, W ₂ C ₃ , Ti ₂ C, etc.) and ceramics (Al ₂ O ₃ , ZrO, etc.). However, a metal carbide is preferably used in terms of strength and rigidity. In order to minimize the incision and press-fit resistance of at least the part of these members that come into contact with the living body, that is, the cutting edge part with respect to the living body, the surface of the member is first roughened by plasma etching. This roughness ranges from 0.001 to 0.1 mm, preferably 0.
005-0.05mm is good. If it is 0.001 mm or less, it is too fine, 0.1 mm
The above results are too rough and unreliable.

Then, it is coated with acicular and / or columnar crystals of diamond-like carbon produced by the plasma vapor deposition method. If the length of this diamond-like carbon crystal is less than 50 μm, the cutting force becomes unreliable, and if it exceeds 500 μm, the frictional resistance between the cutting edge and the living body increases, so the range of 50 μm to 500 μm, preferably 70 μm. ~ 500μ
It is preferable to set it in the range of m.

In the present invention, only this diamond-like carbon crystal coating,
Since the adhesive strength between the member and the crystal is poor, and if there is a gap between the crystals, there are problems such as breakage of columnar crystals and clogging during grinding. Solved. The thickness of the electroless nickel plating may be the same as the thickness of the diamond crystal, and the plated portion may completely fill the gaps between the crystals, and it is not necessary to entirely cover the upper surface of the crystal.

Next, a method for manufacturing the dental microdrill according to the second invention will be described. In order to manufacture a dental microdrill, the surface of the member is first ground by a grinder, plasma etching or the like so as to have a roughness within the above range. Then, a mixture gas of hydrocarbon and hydrogen or, if necessary, an inert gas such as helium or argon is used as a carrier gas, and a known plasma vapor deposition method is used to form a needle-shaped diamond-like carbon layer from hydrocarbon on the member. And / or a method of precipitating columnar crystals.

Examples of the plasma vapor deposition method include high-frequency, direct current, microwave and plasma methods in which a heating coil of a metal wire is inserted, an ion beam deposition method, etc., but microwave power of 1 GHz or more, preferably 1 to 10 GHz. It is better to use. First, a microdrill member is installed in the reactor, and a mixed gas of hydrocarbon and hydrogen or, if necessary, an inert gas is introduced into the reactor. Examples of the hydrocarbon used here include methane, ethane, propane and ethylene, but methane is preferable. The volume ratio of hydrocarbon (A) and hydrogen gas (B) can be used in a wide range of A / B = 500 to 0.001. When an inert gas is used, the volume ratio of hydrocarbon (A) to hydrogen gas (B) and to inert gas (C) is A /
It is preferable that B + C = 500 to 0.001 and the substitution ratio of C to B is 50% by volume or less. The pressure in the vessel was adjusted to be in the range of 75 to 230 Pascal to maintain the plasma stable, and then microwave power was applied to this to generate plasma in the system and the temperature of the member was 500 ~ 1
Adjust to 300 ° C. When the member temperature is 500 ° C or lower, the needle-like and columnar crystal strength of the precipitated diamond-like carbon is insufficient, and when it exceeds 1300 ° C, the precipitated diamond-like carbon causes a reverse transformation to graphite, so 500 ° C to 1200 ° C.
The range is preferably Under this condition, the needle-like and columnar crystals of diamond-like carbon deposited by the thermal decomposition of hydrocarbons in contact with the plasma flame are uniformly deposited on the surface of the member with the desired thickness in the state that graphite is contained in the gaps. To do. Next, the graphite formed in the gaps between the diamond-like carbon crystals is removed. The member coated with this diamond-like carbon crystal is placed in another reactor, and hydrogen is introduced. The pressure inside the vessel was adjusted to be in the range of 5 to 55 pascals for plasma stabilization, and then the microwave power (13.5
6MHz x 50W) is applied to generate plasma in the system, and graphite is removed by etching. When air is introduced instead of hydrogen, incomplete diamond and graphite react with oxygen and are etched, and fine needle-like and / or columnar diamond remains, so that the subsequent plating is poor. In addition, electroless nickel plating is applied to this member for the final finishing. The electroless nickel plating bath composition may be based on a conventionally known technique. For example, one using sodium hypophosphite as a reducing agent can be mentioned. 80 ° C for parts in this plating bath
When immersed for 20 minutes to 90 ° C for 60 minutes, nickel enters into the crystal instead of the graphite, etc. removed in the above step, and needle-shaped,
Supports columnar diamond-like carbon crystals and firmly adheres to members.

Hereinafter, specific embodiments of the present invention will be described with reference to examples, but the present invention is not limited to these. Parts and percentages in the examples are by weight.

(Example) After grinding the surface of a conical molybdenum rod having a diameter of 0.5 mm by plasma etching until the surface roughness became 0.01 mm,
This was installed in the reactor, the pressure in the reactor was exhausted to about 5 Pascal, and then 5% by volume of methane and 95
Introduce a mixed gas consisting of hydrogen gas of volume%, adjust the pressure inside the reactor to 100 Pascal under the gas flow, and under this atmosphere, the microwave emitted from the magnetron (2.45GH
z) is passed through an isolator, a power motor and a slush tub tuner, and is guided to a quartz reaction tube by a waveguide to generate plasma discharge around the member, so that the member is heated to a predetermined temperature (930 ° C). When the wave power (300 w) was adjusted, needle-like columnar crystals of diamond-like carbon having a length of 150 μm were formed on the member. Then, install this member in another reactor, exhaust the pressure in this reactor to about 5 Pascal, and then introduce air into it to adjust the pressure in the reactor to 20 Pascal, and under this atmosphere Microwave power (13.56MHz) was applied to generate plasma discharge around the member, and the graphite in the gaps between the diamond-like carbon crystals was etched and removed, leaving only needle-like and columnar diamond-like carbon. It was covered with. Further, this member was immersed in an electroless nickel plating solution (bath composition: nickel chloride 30 g / l, sodium hypophosphite 10 g / l, sodium citrate 10 g / l, pH = 4 to 6) at 90 ° C. for 20 minutes. A dental microdrill having a shape in which the gaps between acicular and columnar diamond-like carbons were filled with nickel and only the heads of acicular and columnar crystals appeared on the surface was obtained. Next, a cutting test of this drill was conducted. The work material is a 5 mm transparent glass plate, the pressing load is 80 g, and the rotation speed of the drill is 48
At 10,000 revolutions, the grinding distance under water injection was 26 mm in 50 seconds. This shows excellent grindability as compared with the conventional 18 mm diameter diamond particle-bonded drill.

(Effects of the Invention) According to the present invention, as compared with the prior art, it is possible to obtain a dental microdrill having extremely excellent sharpness and cutting of a fine portion, and having wear resistance, which is useful in the medical industry. Is extremely high.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Toshihiro Tsumori, Toshihiro Tsumori, Izumi, Kashima-gun, Kamisu-cho 1 Towada, Shin-Etsu Chemical Co., Ltd., Polymer Functional Materials Research Institute (72) Masatsugu Ueoka, Kamisu, Kashima-gun, Ibaraki No. 1 Towada, Oomachi-machi, Shin-Etsu Chemical Co., Ltd., Functional Polymer Research Center

Claims (2)

[Claims] 1. A dental microdrill in which the surface of a member subjected to plasma etching is covered with needle-like and / or columnar crystals of diamond-like carbon, and the gaps between the crystals are filled with electroless nickel plating. 2. A needle-like and / or columnar crystal of diamond-like carbon is formed by a plasma vapor deposition method in which a microwave of 1 to 10 GHz is applied in a hydrocarbon and hydrogen atmosphere after plasma-treating the surface of a member. A method for manufacturing a dental microdrill, which comprises depositing, then removing the graphite generated in the crystal gaps by plasma etching, and further filling the crystal gaps with electroless nickel plating.