JPH101332A - Chemical resistant member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of local corrosion of the conventional diamond film by contact with an acid or alkali. SOLUTION: The surface of a member brought into contact with an acid, alkali, etc., is made of a dense void-free diamond-base hard carbon film excellent in surface smoothness. This hard carbon film has peaks in 1,340±40cm-1 and 1,160±40cm<-1> in its Raman spectrum and the peak intensity ratio (H1 /H2 ) of the peak intensity H1 of the highest peak in 1,160±40cm<-1> to the peak intensity H2 of the highest peak in 1,340±40cm<-1> is >=0.05.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical resistant member used for a chemical laboratory device, a chemical plant member, a medical device, etc., which comes into contact with a chemical such as an acid or an alkali.

[0002]

2. Description of the Related Art Conventionally, as a member for chemical experiments, a member for a chemical plant, and a member for contact with an acid or an alkali,
It is required to have excellent chemical resistance, and until now, metal materials such as stainless steel and copper, glass materials such as quartz glass and borosilicate glass, and fluorine-based resins such as polytetrafluoroethylene and polychlorotrifluoroethylene And ceramics such as Al ₂ O ₃ (alumina) have been used.

However, in particular, hydrofluoric acid (hydrofluoric acid)
Metallic materials, glass materials, and ceramics corrode chemicals such as strong acids and strong alkalis, and their uses have been limited. In addition, members made of resin, etc.
Although its corrosion resistance is excellent to some extent, its use has been limited due to its dissolution in solvents and poor heat resistance.

[0004] Therefore, as these chemical resistant members, it is known to form diamond-like carbon or a diamond thin film on the surface thereof, as disclosed in JP-A-64-27638 and JP-A-4-194.
No. 86 has been proposed. Since these thin films contain chemically very stable diamond bonded by SP ³ with carbon, high chemical resistance to hydrofluoric acid or the like is expected.

[0005]

However, the surface of the above-mentioned diamond thin film has an average particle diameter of 1-10.
It is composed of diamond crystal grains of about μm, and a grain boundary phase exists between the crystal grains. In some cases, voids are formed between the crystal grains. When such a diamond thin film is brought into contact with, for example, hydrofluoric acid, the grain boundary phase and voids are locally eroded, and the chemical erodes into the inside of the thin film, and finally reaches the member on which the thin film is formed. There was a problem of doing.

Further, in the case of diamond-like carbon, when the film thickness is increased, the adhesion to the substrate becomes insufficient and the film is liable to be peeled off. Therefore, it is necessary to reduce the film thickness. There was a problem of exposure.

[0007] Further, the conventional diamond film surface has
Irregularities due to coarse diamond crystals exist, and when they come into contact with various chemicals, the chemicals sometimes remain in the recesses and voids.

[0008]

The inventors of the present invention have repeatedly studied methods for solving the above-mentioned problems. As a result, the surface of the member which comes into contact with chemicals such as acids and alkalis has a Raman spectrum of 1160 ± 40 cm. ^-1 and 1340 ± 4
By forming a hard carbon film having a peak at 0 cm ⁻¹ , it is possible to form a highly reliable surface having excellent chemical resistance without causing local corrosion to chemicals, The present invention has been reached.

That is, in the chemical resistant member of the present invention, the surface in contact with a chemical such as an acid or an alkali has peaks at 1340 ± 40 cm ^-1 and 1160 ± 40 cm ^-1 in Raman spectroscopy, and 1160 ± 40 cm ¹ a strong peak intensity of most intense among the peaks present in ^-1 H _1, 134
0 when a strong peak intensity of most intense among the peaks present in ± 40 cm ^-1 was H _2, characterized in that the peak intensity ratio represented by H ₁ / H ₂ is 0.05 or more hard carbon film It is assumed that.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The chemical resistant member according to the present invention comprises:
Materials that need to be in direct contact with chemicals such as acids or alkalis, for example, beakers, instruments for chemical experiments such as flasks,
It is used for chemical plant members such as pipe members through which an acid or alkali liquid flows, and medical instruments such as tweezers.

A generally known diamond film is made of high-purity diamond, and has a structure in which carbon atoms are combined by SP ³ hybridization.
It has a peak only at 1340 ± 40 cm ⁻¹ , and in some cases contains carbon having a graphite structure bonded by SP ² hybridization, it is 1500 to 1600 cm ^−1.
There may be a broad peak in the vicinity. In addition, since the diamond film has large diamond crystal grains, the surface of the diamond film has large irregularities due to its own shape, crystal grain boundaries exist, and a large amount of voids exist inside the thin film.

On the other hand, the hard carbon film formed on the surface of the chemical resistant member of the present invention is mainly composed of diamond, and its Raman spectrum is 134%.
In addition to 0 ± 40 cm ^-1, and has a peak at 1160 ± 40 cm ^-1. This peak at 1160 ± 40 cm ⁻¹ is considered to mean that the period of the crystal is short because it is composed of diamond particles of extremely fine crystals, although it has a diamond structure. Therefore, the hard carbon film according to the present invention is composed of very fine diamond crystals. As described above, since the hard carbon film itself is formed of a film that is very dense and has almost no crystal grain boundary components, when it comes into contact with a chemical, local hardening due to voids or the like in the film or crystal grain boundaries occurs. There is no erosion and excellent chemical resistance can be exhibited. Moreover,
It is excellent in flatness without unevenness due to a diamond crystal as in the prior art. Further, even if it contains a trace amount of graphite structure, it has high hardness and wear resistance.

Therefore, when the hard carbon film is formed on a predetermined base material surface, a smooth and dense film surface conforming to the base material surface shape can be formed even if the hard carbon film is formed on a base material surface of any shape. Even when high smoothness is required on the surface of a member requiring chemical resistance, a hard carbon film excellent in smoothness can be formed by finishing the base material surface to a desired surface roughness. . Even if it is necessary to polish the film surface, it can be easily polished compared to the conventional diamond film,
A film surface without voids can be formed.

The peak intensity of 1160 ± 40 cm ⁻¹ in the Raman spectrum of the hard carbon film according to the present invention will be specifically described. In the Raman spectrum curve obtained as shown in FIG. 1, 1100 cm ⁻¹ and 17
Pull the hatched between positions 00cm ^-1, this as a baseline, H ₁ the highest intensity peak intensities of the peaks present in 1160 ± 40cm ^-1, 1340 ± 40cm
High peak intensity of most intense among the peaks present to ^-1 and H _2. At this time, it is important that the peak intensity ratio represented by H ₁ / H ₂ is 0.05 or more.

If the peak intensity ratio is too small, diamond crystal grains grow too large, voids are formed in the film, the surface roughness of the film becomes large, and local corrosion by chemicals easily proceeds. On the other hand, if the peak intensity ratio is too large, the presence of the amorphous diamond increases, and the erosion of the amorphous diamond proceeds to cause roughness and discoloration on the film surface. This peak intensity ratio is desirably 0.2 to 1.0.

According to the chemical resistant member of the present invention, it is preferable that the hard carbon film is coated on a predetermined base material surface. In that case, the hard carbon film is required to have high adhesion to the base material. As the base material of the chemical resistant member, for example, ceramics such as silicon nitride, silicon carbide, alumina, zirconia, titanium alloy, cemented carbide, cermet, metal materials such as stainless steel, quartz glass, borosilicate glass, etc. Glass material. Among these, glass, silicon nitride, and Ti alloy are desirable. These base materials may be used as they are, or may be formed by forming these base material types as thin films on the surface of another member by a thin film forming technique such as a vapor phase growth method. The thickness of the hard carbon film is 1 to 10 μm on average,
Particularly, a thickness of 2 to 8 μm is preferable.

In order to enhance the adhesion between the hard carbon film and the base material, an intermediate layer comprising at least a composite of diamond and metal carbide is interposed between the base material surface and the hard carbon film. Thus, a hard carbon film having extremely good adhesion can be formed.

The reason why the adhesion strength between the hard carbon film and the base material is improved by the interposition of the intermediate layer is considered as follows. Atoms are bonded by intervening electrons, but in general, electrons are shared by both atoms rather than ionic bonds, in which electrons between atoms are present on one side and bonded by electrical connection. An existing covalent bond has a stronger binding force. Diamond has a strong bonding force because it is constituted by a covalent bond of carbon. Therefore, in order to improve the adhesion strength between diamond and a different compound, it is considered that a covalent compound having a similar bonding mode is desirable. Also, it seems that a compound containing carbon which is a component of diamond has better consistency. There are many metal carbides, most of which are mainly ionic bonds. The covalent carbide includes silicon carbide and boron carbide, but silicon carbide is most desirable in the chemical resistant member of the present invention.

By forming such an intermediate layer containing a mixture of metal carbide and diamond between the hard carbon film and the base material, the adhesion strength between the hard carbon film and the base material is improved. In addition, the diamond and the metal carbide do not exist in a layer-separated state, but have a structure in which the metal carbide surrounds the diamond. This improves the adhesion.

As a method of manufacturing a hard carbon film in the present invention, a so-called plasma CVD method has been used in which a carbon film is formed on a predetermined substrate surface by using a carbon film as a means for generating plasma by microwaves or high frequencies. Alternatively, the hot filament method is the mainstream. However, in the plasma CVD method, since the plasma generation area is small,
The area in which a film can be formed is small, and the area in which a film can be formed is generally about 20 mm in diameter, and its application as a processing member is limited. In addition, when the pressure is too high or the plasma density is too low, if the substrate has a complicated structure or has a curved surface structure, uniform plasma along the structure cannot be obtained, and the film thickness distribution becomes uneven. Prone.

On the other hand, in the hot filament CVD method, the filament is liable to be cut, and it is necessary to set the filament according to the shape of the base material in order to suppress the variation in the film thickness. have.

On the other hand, according to the so-called electron cyclotron resonance plasma CVD method in which a magnetic field is applied to the plasma generation region in the plasma CVD method, low pressure (1 t)
or less), high-density plasma can be obtained, so that plasma can be uniformly generated in a wide area, and a film can be uniformly formed in an area about 10 times as large as that of a normal plasma CVD method. It can be performed.

Therefore, here, the electron cyclotron resonance plasma CVD method (ECR plasma CVD method) will be described as an example. In this method, a reaction gas is introduced into a reaction furnace in which a predetermined base material is installed, and at the same time, 2.4 is introduced.
A microwave of 5 GHz is introduced. At the same time, a magnetic field of a level of 875 Gauss or more is applied to this region. This allows the electrons to have a cyclotron frequency f = eB /
2πm (m: mass of electron, e: charge of electron, B:
Cyclotron motion is generated based on the magnetic flux density). When this frequency coincides with the microwave frequency (2.45 GHz), it resonates and electrons are remarkably absorbed by the energy of the microwave, accelerated, collide with neutral molecules and cause ionization to generate high-density plasma. Become like At this time, the temperature of the base material was 150 to 1000 ° C., and the furnace pressure was 1 × 10 ^−2.
１1 torr.

According to this method, the base material temperature during film formation,
By changing the furnace pressure and the reaction gas concentration, the components and the like of the formed hard carbon film change. In particular,
As the pressure in the furnace increases, the area of the plasma decreases, and the growth rate of the film decreases, but the crystallinity tends to improve. Also, when the concentration of the reaction gas increases, the size of the particles constituting the film tends to decrease, and the crystallinity tends to deteriorate. Specifically these conditions by controlled appropriately as described in the examples below, it is possible to control the H ₁ / H ₂ ratio described above.

In the above-described film forming method, when producing the chemical resistant member of the present invention, hydrogen and a carbon-containing gas are used as raw material gases in forming the hard carbon film. Examples of the carbon-containing gas used include, for example, alkanes such as methane, ethane, and propane; alkenes such as ethylene and propylene; alkynes such as acetylene; aromatic hydrocarbons such as benzene; cycloparaffins such as cyclopropane; And cycloolefins such as cyclopentene. In addition, oxygen-containing carbon compounds such as carbon monoxide, carbon dioxide, methyl alcohol, ethyl alcohol, acetone, mono (di, tri) methylamine, mono (di,
Nitrogen-containing carbon compounds such as tri) ethylamine can also be used as the carbon source gas. These can be used alone or in combination of two or more.

In order to form an intermediate layer comprising a mixture of diamond and silicon carbide as described above, after performing a diamond nucleation treatment as desired, hydrogen, a carbon-containing gas and a silicon-containing gas are used as reaction gases. Is introduced. As the silicon-containing gas, silicon tetrafluoride,
In addition to halides such as silicon tetrachloride and silicon tetrabromide, oxides such as silicon dioxide, silane compounds such as mono (di, tri, tetra, penta) silane and mono (di, tri, tetra) methylsilane, and trimethyl And silanol compounds such as silanol. These can be used alone or in combination of two or more.

As described above, the hard carbon film of the present invention is mainly composed of diamond having a fine grain structure.
Moreover, the film is dense, has no defects such as voids on the surface and inside of the film, and has excellent smoothness on the film surface. Therefore, when this hard carbon film is formed on the surface of a member that comes into contact with an acid or an alkali, high corrosion resistance to these chemicals can be imparted. It is also possible to prevent the film from remaining in voids and concave portions.

Further, by interposing an intermediate layer containing at least diamond and metal carbide between the member surface and the hard carbon film, the adhesion of the hard carbon film to the base material can be increased. The peeling of the hard carbon film from the base material can be prevented.

[0029]

【Example】

(Example) in an oven at electron cyclotron resonance plasma CVD apparatus, silicon nitride sintered bodies as the base material (Y ₂ O ₃ 3% by weight, Al ₂ O ₃ 4% by weight containing), titanium alloy (Ti-6Al
-4V), 100 of any of borosilicate glass
ml container was set up.

There, 297 sccm of H ₂ , 3 s of CH ₄
ccm gas, gas concentration 1%, base material temperature 650
° C., 3 hours to at reactor pressure 0.1 torr, after generating the diamond nuclei, H ₂ gas as the source gas, C
Using H ₄ gas and Si (CH ₃ ) ₄ gas, the gas concentration is 1% at a rate of H ₂ 297 sccm CH _{4 3} sccm Si (CH ₃ ) ₄ 0.3 sccm, the base material temperature is 650 ° C., and the furnace pressure is 0.05 torr. Electron cyclotron resonance (E
CR) A magnetic field having a maximum intensity of 2 kGauss was applied by a plasma CVD method, and a microwave power of 3.0 KW was applied.
Film formation was performed for 0 hour to form an intermediate layer having a thickness of 1 μm in which diamond and silicon carbide were mixed on the inner surface of the container.

In Table 1, sample No. 4 was made of silicon carbide in exactly the same manner as described above except that the intermediate layer was formed at a gas ratio of H ₂ 300 sccm Si (CH ₃ ) ₄ 0.3 sccm. The intermediate layer was formed with a thickness of 1 μm, and was evaluated similarly.

Next, on the intermediate layer, gas ratios, gas concentrations, base material temperatures, and furnace interiors shown in Table 1 were used by using H ₂ gas, CH ₄ gas, and CO ₂ gas having a purity of 99.9% or more. Film formation was performed under pressure, and a 4 μm hard carbon film was further formed on the inner surface of the container.

[0033] For the formed hard carbon film, subjected to Raman spectrum analysis of the film surface, draw a line between positions 1100 cm ^-1 and 1700 cm ^-1 from the Raman spectrum chart, which was the baseline, 1160 ± 40
The peak intensity of the maximum peak existing at cm ^-1 is H ₁ , 13
The peak intensity of the maximum peak present in 40 ± 40 cm ^-1 as H _2, was calculated intensity ratio expressed by H ₁ / H _2.
In Table 1, charts of Sample No. 3 and Sample No. 9 are shown in FIGS. The laser used as an oscillation source in the Raman spectroscopic analysis was an Ar laser (oscillation line 48).
8.0 nm).

Next, 80 ml of a 45% hydrofluoric acid solution was poured into the obtained container and left for 48 hours. The surface after standing was observed with a binocular microscope and the state of corrosion is shown in Table 1.

Comparative Example 1 Using borosilicate glass,
The same corrosion test as in Examples 1 and 2 was performed, and the results are shown in Table 1 Sample No. 17.

(Comparative Example 2) Using the borosilicate glass used in the examples as a base material, the intermediate layer was formed by microwave CVD at a gas concentration of 1 at the same gas ratio as in the examples.
%, A base material temperature of 950 ° C. and a furnace pressure of 30 torr for 10 hours, and then a film was formed under the conditions shown in Sample No. 9 in Table 1 to form a 4 μm hard carbon film.

For this, a corrosion test was performed in the same manner as in Examples 1 and 2, and the results are shown in Sample No. 9 in Table 1.

[0038]

[Table 1]

According to the results shown in Table 1, H ₁ / H ₂ is 0.0
All of the samples of the present invention on which a hard carbon film of 5 or more was formed showed no corrosion even in a strong acid or strong alkali solution, and showed excellent chemical resistance.

As a comparative example, the surface of a conventional borosilicate glass turned white in one hour against a strong acid. In addition, a hard carbon film manufactured by a microwave CVD method or the like,
In Samples Nos. 1, 2, 9, and 10 in which the ratio of H ₁ / H ₂ was smaller than 0.05 depending on the film forming conditions, there were many spots of 10 to 1000 μm on the film surface after the test, which were considered to be due to corrosion. It was observed that the corrosion had progressed locally.

In the same manner as above, 40% N
80 ml of an alkaline solution of an aOH solution was poured, and the state of corrosion after being left for 48 hours was observed. As a result, corrosion was observed on the entire surface of the container made of borosilicate glass of Sample No. 17, but the other Sample No. For 1-16, little change was observed.

[0042]

As described in detail above, the chemical resistant member of the present invention exhibits excellent corrosion resistance on the contact surface with an acid or alkali, and particularly suppresses the progress of local corrosion and the like, Excellent chemical resistance over a long period of time. As a result, the reliability of the member that comes into contact with the acid or the alkali with respect to the chemical resistance can be improved.

[Brief description of the drawings]

FIG. 1 shows a hard carbon film (Sample No. in Table 1) of the present invention.
It is a Raman spectroscopy spectrum figure of 3).

FIG. 2 is a Raman spectrum diagram of a conventional hard carbon film (sample No. 9 in Table 1).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C23C 16/50 C23C 16/50

Claims (1)

[Claims] The surface in contact with a chemical such as an acid or an alkali has a Raman spectrum of 1340 ± 40 cm ^-1 and 1
There is a peak at 160 ± 40 cm ⁻¹ and 1160 ±
When the highest peak intensity among peaks existing at 40 cm ^-1 is H ₁ , and the highest intensity peak among 1340 ± 40 cm ^-1 peaks is H ₂ , H ₁
A chemical resistant member comprising a hard carbon film having a peak intensity ratio represented by / H ₂ of 0.05 or more.