JPS63201094A - Diamondlike material - Google Patents

Abstract

PURPOSE:To develop a diamondlike material having improved coefft. of surface friction by forming an F-contg. layer on the surface of thin film of synthetic diamond by allowing the surface to contact with gaseous F or gaseous F compd. under specified conditions. CONSTITUTION:A thin layer of artificial diamond is formed on the surface of several kinds of substrate comprising diamond, Mo, W, Ta, Cu, Au, Si, graphite, carbon, glass, sapphire, BN, AlN, cermet, etc. by the hot CVD process, etc. An F.C contg. layer consisting of 0.5-1.1 ratio of number of F atom to C atom and having 200Angstrom -1nm thickness is formed on the surface of the thin layer by heating the thin layer at 350-550 deg.C in F gas under 10-300Torr, or by activating with plasma generated from gaseous F compd. such as mono-, di-, tri-, tetra fluoromethane, or several kinds of fluoroethane and diluted with N2, Ar. Thus, a diamondlike material having small coefft. of surface friction is prepd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to spinning and drawing of synthetic fibers, as well as high thermal conductivity and wear resistance of mechanical sliding parts such as bearings.
Used in fields where low frictional resistance is required.

[Prior Art] Materials used for sliding surfaces that require heat supply or heat removal must have high thermal conductivity, wear resistance, and a low coefficient of friction. Until now, there has been no material that satisfies all three properties; for example, various metals have high thermal conductivity but poor wear resistance, and various ceramics have relatively high wear resistance but low thermal conductivity. Also, diamond, which is said to be an extreme material, has excellent thermal conductivity and wear resistance, but has the drawback of a high coefficient of friction.

[Problems to be Solved by the Invention] An object of the present invention is to provide a diamond-like material with an improved coefficient of friction.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration.

That is, the present invention relates to a diamond-like material characterized by having a layer containing fluorine and carbon on its surface.

The diamond-like material in the present invention consists of a layer containing fluorine and carbon and diamond. The term diamond here refers to a composition containing 50% by weight or more of diamond, and the pond portion may have sp3 bonds in which 70% or more of the carbon-carbon bonds are necessarily crystalline. There's no need. Further, components other than carbon and hydrogen may be included in a proportion of 20% or less of the total weight.

In the present invention, diamond thin films synthesized by CVD and PVD methods such as sputtering, natural diamond,
High-pressure synthetic diamond or the like is used. The method of synthesizing diamond by CVD and PVD is disclosed in Japanese Patent Application Laid-open No. 59-2.
This can be seen in JP-A No. 32991, JP-A-60-54995, JP-A-59-63732, and the like. Diamond films are typically grown on a substrate. Various substrates are used, including diamond, molybdenum, tungsten, tantalum, copper, gold, silicon, graphite,
A wide variety of materials including carbon, glass, sapphire, boron nitride, aluminum nitride, and cermet. The form of the substrate can also be appropriately selected as required, such as film, fiber, and bulk.

The layer containing fluorine and carbon in the present invention only needs to have a surface friction coefficient lower than that of diamond, and there is no particular limit to its thickness, but it is usually 1.
μ or less and up to about 200 people is suitable.

The atomic ratio of fluorine to carbon in this layer is 1 if fluorination has progressed sufficiently.

There are cases where some of the carbon is not fluorinated, and cases where fluorination has progressed completely and extra fluorine has entered between the carbon layers.Although it can be selected within a wide range, usually the fluorine atoms relative to carbon The numerical ratio is preferably in the range of 0.5 to 1.1.

Next, a method for forming a fluorine-containing layer on the surface of diamond will be described. This can be achieved by bringing the diamond into contact with fluorine in a suitable manner after the diamond has been synthesized.

The rate of contact with fluorine varies depending on temperature, pressure of fluorine, crystallinity of diamond, etc. The pressure of fluorine is usually selected preferably from 1 atm or less, in the range of 10 Torr to 300 Torr. Although 100% fluorine may be used, it is more suitable to dilute it with an inert gas such as nitrogen.

A suitable reaction temperature is 350 to 550°C. At lower temperatures, the rate is lower, and at higher temperatures, fluorocarbon begins to decompose, resulting in a lower F/C (atomic ratio) ratio. Since fluorine gas is extremely corrosive, a reactor made of a dust-resistant material such as nickel or Monel is required, and contamination with water is undesirable. Fluorination using fluorine can be activated by plasma in addition to the above-mentioned thermal activation method. Next, a method of forming a fluorine-containing layer on the surface of diamond using fluoride will be described. In this method, fluoride is activated with a plasma. The fluoride that can be utilized in this method is preferably a compound containing carbon and fluorine. Examples include mono-, di-, tri- and tetrafluoromethane, fluoroethane with various degrees of substitution, fluorinated hydrocarbons such as propane, and fluorides in which some of these fluorines are replaced by other halogens, various Various compounds such as fluorobenzene, tetrafluoroethylene, and unsaturated fluorohydrocarbons partially substituted with other halogens can be used. These raw materials may be used alone, or may be used in combination of two or more, and may be further diluted with hydrogen or an inert gas such as nitrogen or argon. The fluoride concentration in these inert gases is not particularly limited and is selected within a wide range of 2% to 100%.

The plasma used to activate these fluorides is excited by direct current discharge, electromagnetic waves such as radio waves, microwaves, etc. In the case of generating plasma by excitation with microwaves, the microwave power and frequency can be selected from a wide range, for example, from several watts to several kilowatts, and from 10 to 1011 Hz.

It is possible to place the diamond in the microwave or after the microwave. Although diamond is heated by plasma generated by microwaves, it is also possible to adjust the temperature by heating or cooling it by other suitable methods.

When activating raw materials with radio waves, the coupling of the power source may be inductive or capacitive. In this case as well, two choices of frequency and power can be made within a wide range. For example, the frequency is 102~
It is selectable over 107Hz. It is also possible to apply a bias voltage to the diamond if necessary. In this case, the bias voltage is usually less than a few kilovolts.

The reaction pressure depends on the activation method of the raw materials, but is usually 0.1
-100 Torr, especially around 1-40 Torr is suitable.

[Examples] The present invention will be described in more detail in the following examples, but the present invention is not limited thereto.

Example 1 A 5 x 5 mm silicon carbide sample with a 3 μ diamond layer synthesized by thermal CVD method was heated to 500 °C in a Monel reactor and heated with nitrogen at a pressure of 20 Torr.
Fluorine diluted to 0% was passed through at a flow rate of 30 ml/min and treated for 1.5 hours. After the reaction, fluorine and carbon on the sample surface were quantified by ESCA, and the F/C (atomic ratio) was 0.92.
obtained the value of The coefficient of friction of a diamond-like material having a layer containing fluorine and carbon on its surface is 0.15 at room temperature, which is remarkable compared to the coefficient of friction of diamond before fluorination, which is 0.6. has declined to

Example 2 Microwave oscillator (2,5GIZ, 1,2KW)
The electromagnetic waves generated were guided into a quartz reaction tube with a diameter of 40 mm using a waveguide. A sample of 5×10 mm boron nitride with 2μ diamonds attached by microwave CVD was set inside a reaction tube. The pressure of the system was set to 15 Torr, and hydrogen containing 10% dichlorodifluoromethane was introduced from the top of the reaction tube at a flow rate of 40 ml/mi. The microwave energy consumed by the system was 0.6 KW.

After reacting for 1 hour, the sample was taken out, and the fluorine and carbon on the sample surface were determined by ESCA, and the F/C (atomic ratio) was 0.8.
A value of 5 was obtained. The coefficient of friction of a diamond-like material having a fluorine-containing layer and a carbon-containing layer on its surface is 0.10 at room temperature, which is compared to 0.6 for diamond before fluoridation. It has decreased significantly.

Example 3 Ten copper coils with an inner diameter of 4 om are placed in a quartz tube with an outer diameter of 30 mm.
The winding was capacitively coupled to a 13.58H2,2 dark radio wave power source. A sample of 5×1 mm silicon wafer with 2 μm diamonds attached by microwave CVD was set inside a reaction tube.

The pressure of the system was set to 5 Torr, and hydrogen containing 5% chlorotrifluoromethane was introduced from the top of the reaction tube at a flow rate of 20 m.
The mixture was introduced at a rate of 1/min and an lhr reaction was performed. After the reaction, the sample was taken out, and fluorine and carbon on the sample surface were determined by ESCA, and a value of 0.99 was obtained as F/C (atomic ratio). The coefficient of friction of a diamond-like material having a layer containing fluorine and carbon on its surface is 0513 at room temperature.
This is significantly lower than the coefficient of friction of diamond before fluorination, which is 0.6.

[Effects of the Invention] According to the present invention, a diamond-like material having a low coefficient of friction can be provided.

Claims (2)

[Claims] (1) A diamond-like material characterized by comprising a surface layer containing fluorine and carbon and diamond. (2) A diamond-like material according to claim (1), characterized in that fluorine and carbon are contained in an atomic ratio of fluorine to carbon of 0.5 or more and 1.1 or less. .