JPS644586B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention provides a tungsten carbide (hereinafter referred to as WC)-based cemented carbide member having a microstructure on its surface,
The present invention also relates to a method for depositing and forming an artificial diamond film with excellent adhesion. [Prior Art] Generally, it is well known that an artificial diamond film is deposited and formed on the surface of a WC-based cemented carbide member containing WC as a main component and metal components such as Co and Ni as binder phase forming components. be. Many methods have been proposed for the precipitation formation of these artificial diamond films, among which methods for heating and activating the reaction mixture gas include (a) thermionic emitters, and (b) plasma using high frequency waves. (c) Plasma discharge using microwaves A method employing any of the above (a) to (c) is attracting attention as a typical method. That is, as shown in the schematic illustration in FIG. A reaction mixture gas consisting of hydrogen is caused to flow downward through a WC-based cemented carbide member 5 supported on a metal tungsten filament 3 as a thermionic emitting material and a base plate 4, and during this time the atmospheric pressure in the reaction vessel 1 is maintained. While maintaining the temperature at 0.1 to 300 torr, heat the filament 3 at 1500 to 2500℃.
The reactant mixture gas is activated by heating, and the surface temperature of the member 5 placed below the filament position at a predetermined interval is heated to a temperature within the range of 300 to 1300°C. An artificial diamond film is deposited and formed on the surface of the member 5 by carrying out a reaction for a predetermined period of time. For example, the method described in Japanese Patent Application Laid-Open No. 1983-91100 is a method corresponding to this method. In addition, in the method (b) above, as shown in the schematic explanatory diagram in FIG. A reaction mixture gas consisting mainly of hydrocarbons and hydrogen is introduced from the gas introduction pipe 2 and exhausted from the other side of the reaction vessel 1. During this time, the reaction vessel 1 is
While maintaining the internal atmospheric pressure at several torr to several tens of torr, a high-frequency coil 6 provided at the center outer circumference of the reaction vessel 1 is connected to a high-frequency coil 6 with a frequency of 13.56 MHz and an output of, for example,
Plasma discharge is induced around the member 5 in the reaction vessel 1 by applying a 500W condition, and this plasma discharge is used to heat and activate the reaction mixture gas and increase the member surface temperature, and is maintained in this state for a specified period of time. An artificial diamond film is precipitated and formed on the surface of a member by carrying out the following reaction. For example, the method described in JP-A-58-135117 is a method corresponding to this method. Furthermore, in the above method (c), as similarly shown in the schematic diagram in FIG. A reaction mixture gas consisting mainly of hydrocarbons and hydrogen is introduced from the gas introduction pipe 2, and exhausted from the bottom of the reaction vessel 1. During this time, the atmospheric pressure inside the reaction vessel 1 is maintained at 0.1 to 300 torr, and For example, a 2450 MHz microwave supplied through a waveguide 7 provided at the central outer circumference of
Plasma discharge is generated around the member 5 in the reaction vessel 1, and this plasma discharge heats and activates the reaction mixture gas and increases the member surface temperature, and the reaction is carried out for a predetermined period of time in this state. This method involves depositing and forming an artificial diamond film on the surface of a member, and for example, the method described in Japanese Patent Application Laid-open No. 110494/1983 is a method corresponding to this method. [Problems to be solved by the invention] However, all of these artificial diamond film precipitation formation methods have a common problem in the early stage of the reaction.
The number of diamond crystal nuclei precipitated on the surface of the WC-based cemented carbide member is small, while artificial diamond grows around these crystal nuclei and takes on a film-like appearance. had a rough structure and poor adhesion to the surface of the member. [Means for solving the problem] Therefore, from the above-mentioned viewpoint, the present inventors created an artificial material having a fine crystal structure and excellent adhesion on the surface of a WC-based cemented carbide member. As a result of research to form a diamond film by precipitation,
Prior to depositing and forming an artificial diamond film on the surface of a WC-based cemented carbide member, machining strain is applied to the surface of the member as a pretreatment, and the rate of machining strain caused by the grinding wheel is measured before and after applying the machining strain. The diffraction line of the (100) crystal plane of WC in the above member is
Observe by line diffraction to find the half-width, and assume that the half-width of the diffraction line after applying the processing strain/the half-width of the diffraction line before applying the processing strain = 1.1 to 2. They discovered that the crystal nuclei of artificial diamonds increase significantly in the initial stage, and that the resulting artificial diamond film has a fine structure and excellent adhesion. Therefore, the present invention has been made based on the above knowledge, and consists of hydrocarbons and hydrogen as main components, and is activated by a thermionic emitting material, plasma discharge by high frequency, plasma discharge by microwave, etc. By placing a heated WC-based cemented carbide member in a flow of a heated reaction mixture gas, the member is pre-treated prior to forming an artificial diamond film on the surface of the member. A machining strain is applied to the surface in advance by a grinding wheel, and the ratio of this machining strain is determined by observing the diffraction lines of the (100) crystal plane of WC in the member before and after applying the machining strain by X-ray diffraction. This method is characterized in that the width at half maximum of the diffraction line after applying processing strain/the width at half maximum of the diffraction line before applying processing strain = 1.1 to 2. In addition, in the method of this invention, it is practical to use a silicon carbide grindstone, which is normally used for grinding comparatively soft materials such as steel, or a diamond grindstone to apply processing strain to the surface of the member using a grinding wheel. It is. In addition, in the method of the present invention, the ratio of processing strain to the half width of the diffraction line before applying processing strain is set to 1.1 to 2. If the ratio is less than 1.1,
This is because the desired effect cannot be obtained from the above action, and on the other hand, if the ratio exceeds 2, the amount of strain becomes too large and cracks will occur in the member. [Example] Next, the method of the present invention will be specifically explained with reference to Examples. As a member, it has a composition consisting of Co: 6% by weight and WC: the remainder, and plane: 12.7mm x thickness: 3.5
A WC-based cemented carbide chip with dimensions of In order to measure the percentage of processing strain, this is subjected to X-ray diffraction, the diffraction line of the (100) crystal plane of WC in the chip is observed, its half width is determined, and based on this result, processing strain is applied. Calculate the ratio of the half width of the previous diffraction line (ratio of processing strain), further measure the 10-point average surface roughness R _Z of the chip surface, and then:
These chips, together with chips without processing distortion,
In the apparatus shown in Fig. 1, reaction vessel 1: quartz tube with an outer diameter of 30 mmφ, reaction mixture gas composition: CH ₄ /H ₂ = 0.01, Reaction mixed gas flow rate: 300ml/min, metal tungsten filament 3 and chip 5
Under the following conditions: distance between surfaces of 30 mm, heating temperature of filament 3: 2000℃, degree of vacuum in reaction vessel 1: 20 torr, and in the apparatus shown in Figure 2, reaction vessel 1: quartz with an outer diameter of 50 mmφ tube, reaction mixture gas composition: CH ₄ /H ₂ = 0.01, application conditions to high frequency coil 6 (frequency:
13.56MHz, output: 2KW), degree of vacuum in reaction vessel 1: 20 torr, and in the apparatus shown in Figure 3, reaction vessel 1: quartz tube with outer diameter of 30 mmφ, reaction mixture gas composition: CH ₄ /H ₂ = 0.03, microwave: 2450MHz (output: 500W), degree of vacuum in reaction vessel 1: 30torr, The artificial diamond film was formed under the following conditions.
In either case, the area ratio of the artificial diamond on the chip surface was measured 1 hour after the start of the reaction, and the reaction was stopped when the entire chip surface was covered with the artificial diamond, that is, the area ratio of the artificial diamond was 100%. Methods 1 to 7 of the present invention and Comparative Methods 1 and 2 were carried out by measuring the reaction time. Next, the average grain size of the artificial diamond film formed as a result was measured, and the resulting chip was used as a cutting chip. Work material: Al alloy (Si: 2% content), cutting speed: 500 m/min. , Feed: 0.1mm/rev., Depth of cut: 1.5mm,

【table】

[Table] Cutting time: 20 minutes, interrupted cutting test of Al alloy square material was conducted under the following conditions.
Number of test cutting edges: The number of cutting edges from which the film was peeled out of 10 was measured. These results are shown in Table 1. In addition, FIG. 4 shows the diffraction line of the WC crystal plane (100) on the chip surface without processing distortion of Comparative Method 1.
FIG. 5 shows the same diffraction lines of the chip surface subjected to processing strain according to method 2 of the present invention, and the half widths thereof are expressed in angles. [Effects of the Invention] From the results shown in Table 1, it can be seen that for the chip surface with no machining distortion in Comparative Method 1 and the chip surface with too small amount of machining distortion in Comparative Method 2, In contrast, only artificial diamond films that have a crystalline structure and are easy to peel off can be formed, and the film formation is also slow.
In Methods 1 to 7 of the present invention, the artificial diamond film is formed quickly, which means that the number of crystal nuclei generated at the initial stage is significantly increased, and the artificial diamond film has a fine crystal structure and excellent adhesion. is clearly formed. As mentioned above, according to the method of this invention, WC
By applying processing strain using a grinding wheel as a pretreatment to the surface of the base cemented carbide member, an artificial diamond film with a microcrystalline structure and excellent adhesion is formed at a high precipitation rate. It is possible.

[Brief explanation of drawings]

Figures 1, 2, and 3 are all schematic explanatory diagrams showing an apparatus for depositing artificial diamond films, and Figure 4 shows the WC crystal plane (100) on the chip surface without processing distortion in Comparative Method 1. FIG. 5 is a diagram showing the X-ray diffraction lines of the chip surface with processing distortion according to method 2 of the present invention. 1... Reaction container, 2... Reaction mixed gas introduction pipe, 3...
Filament as thermionic emitting material, 4...base plate,
5... Member, 6... High frequency coil, 7... Waveguide.

Claims (1)

[Claims] 1. In the flow of a heated reaction mixture whose main components are hydrocarbon and hydrogen and which have been activated by a thermionic radiation material, plasma discharge by high frequency, plasma discharge by microwave, etc. By placing a heated tungsten carbide-based cemented carbide member, prior to depositing and forming an artificial diamond film on the surface of the member, applying processing strain to the surface of the member in advance with a grinding wheel as a pretreatment, The rate of the processing strain can be determined by observing the diffraction lines of the (100) crystal plane of tungsten carbide in the member before and after applying the processing strain using X-ray diffraction, and determining the half-width of the diffraction line after applying the processing strain. A method for depositing and forming an artificial diamond film, which satisfies the following: width at half maximum/width at half maximum of a diffraction line before applying processing strain = 1.1 to 2.