JPH046200A - Burner body for synthesis of diamond by combustion method - Google Patents

Abstract

PURPOSE:To enlarge the synthesis area of diamond and to prevent the generation of back-fire by providing plural jet opening in the nozzle part of a nozzle body, specifying the diameter of the jet openings and the distance, and constituting the nozzle part of a water cooling structure. CONSTITUTION:This burner body 1 having a fuel supply pipe 3 and an oxygen supply pipe 4 for the synthesis of diamond by combustion method is provided at its top end with the nozzle part 5 having plural jet openings 10 and is constituted of the cooling structure having a water supply pipe 6 and a water discharge pipe 7, the jet openings 10 are made in such a way that the diameter (d) is <= 5mm and the distance (p) is <= 20mm.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a burner body for synthesizing diamonds using a combustion method, and more particularly to a burner body for synthesizing diamonds by burning fuel and an oxidizing agent. It is.

[Conventional technology and issues]

There are two methods for artificially synthesizing diamonds: high-pressure synthesis and low-pressure vapor phase synthesis. Recently, a so-called diamond synthesis combustion method using a combustion flame has been proposed as one of the low-pressure gas phase synthesis methods. This method uses hydrocarbon fuels (eg acetylene, ethylene, methane propane, etc.) as carbon sources for diamond precipitation, as shown in FIG.

(methanol, ethanol, etc.) is burned in the burner 32 using pure oxygen as an oxidizing agent with an amount of oxygen much lower than the stoichiometric mixing ratio, and the flame 34 near the crater 34 in the specific flame 33 obtained under such combustion conditions A substrate 36 is placed in a flame 35 called a feather generated in
By forcibly cooling 6 by the cooling means of the substrate holder 37 and maintaining the temperature at 600 to 1200 °C,
Diamond is synthesized on the surface of the substrate 36.

By the way, most of the proposed diamond synthetic combustion methods are based on basic experiments, and most commercially available fusing torches or welding torches are used as the burner 32. The injection hole of the crater is
Since it is formed as a single hole and has a relatively small diameter, the substrate 36
Even if the diamond is placed in the optimum position, the area where diamonds are synthesized is very small and is limited to a range of 3 to 5 times the size of the injection hole used for boat fishing. That is, since the diameter of the injection hole of commercially available burners is about 31II11 at the maximum, the diameter of the largest area where diamond can be synthesized is only about 15+m. This has the problem that the area where diamond can be synthesized is narrower than in chemical vapor deposition (referred to as CVD), which is generally used as a method for synthesizing diamond.

Additionally, in general, fusing torches and welding torches have a structure in which the fuel and oxidizer are mixed in advance far upstream from the outlet of the injection port, and in addition, the synthetic combustion time for diamond is several hours, and it is necessary to maintain the substrate temperature at a high temperature. The area around the crater is exposed to a high-temperature atmosphere and becomes red-hot, making it easy for flashbacks to occur, leading to the risk of explosions and torch burnouts.

The present invention has been made in view of the above circumstances, and includes:
The object is to provide a burner body for diamond synthesis that allows a large synthesis area of diamond to be obtained in diamond synthesis by the combustion method and that is less likely to cause backfire.

[Means to solve the problem]

In order to achieve the above object, a burner body for diamond synthesis using a combustion method according to the present invention is provided, the burner body for diamond synthesis using a combustion method having a nozzle portion having a plurality of ejection holes and having a water-cooled structure at its tip. The diameter of the ejection holes is 5 mm or less, and the spacing between the ejection holes is 20 m5 or less.

[For production]

In the present invention, a plurality of ejection holes are provided in the nozzle part of the burner body, and the nozzle surface is formed to have a wide surface, so that the feathers generated by the individual ejection holes can spread diamond uniformly over a wide range of the surface of the substrate. Can be synthesized. Moreover, the nozzle part has a water-cooled structure, so
Even if the nozzle part is exposed to a high-temperature atmosphere, it will not be heated to a high temperature, preventing backfire and eliminating the risk of explosion or torch burnout.

The diameter of the ejection hole drilled in the nozzle part is 5III.
III or less, preferably 2 to 5 III. This is because if the pore diameter exceeds 5II11, flashback is likely to occur, and if combustion is performed to prevent flashback, flame conditions suitable for synthesizing diamond cannot be obtained. On the other hand, the smaller pore size is
As mentioned above, the range of diamonds that can be synthesized from a single hole is limited to 3 to 5 times the pore size, so if the pore size is less than 21, it is difficult to obtain diamonds uniformly from the ejection hole. The spacing must be extremely narrow, and this, combined with the water cooling structure, complicates the structure of the nozzle and makes it impractical.

In addition, the spacing between the jet holes drilled in the nozzle part is 20I1m.
The following is good, preferably 10 to 20 II1M. The reason is that when the spacing exceeds 20+m+m, the pore diameter is reduced to 5InI
If the distance is less than 11 mm, diamonds will not be obtained uniformly, and problems will occur when the hole diameter is over 5 m.On the other hand, if the distance is narrower than 10 mm,
It is good if the hole diameter is small, but if the hole diameter is relatively large, it becomes difficult to provide a water cooling structure in the nozzle portion, and the nozzle portion cannot be cooled sufficiently. As a result, the problem of backfire occurs.

Incidentally, the present inventors used a commercially available welding torch, used a crater with a hole diameter of up to 6 mm, and adjusted the volume ratio of acetylene and pure oxygen (C211□10□).
to premix and burn by varying the range up to 1.2.
The backfire condition and diamond synthesis condition were observed.

The results are shown in FIG.

In this figure, the striped axis shows the volume ratio of acetylene and pure oxygen (Czllz10□), the horizontal axis shows the pore diameter of the crater, and the curve A in the figure is the boundary line where flashback occurs (the shaded area is the range where flashback occurs). ) is shown. As a result of this experiment, the volume ratio of acetylene and pure oxygen that can be synthesized into diamond is limited to a range of 0.8 to 1.2, and diamond can be reliably synthesized if the pore diameter is within 1.5 to 5 mm. Moreover, it was confirmed that there was little problem of backfire.

〔Example〕

Examples of the present invention will be described below based on the M plane.

1-1-1 No. 121 is an explanatory diagram of a burner body for diamond synthesis using the combustion method according to the present invention, FIG. 2 is an enlarged cross-sectional explanatory diagram of the nozzle part shown in FIG. 1, and FIG. , is an explanatory view seen from arrow B in FIG. 2.

In the figure, l is a burner body made of a long tube,
A premixing chamber 2 is formed in a tube on the rear end side of the burner body 1, and a fuel supply pipe 3 and an oxygen supply pipe 4 are connected thereto, respectively. In addition, there is a nozzle 5 at the tip of the burner body 1.
A cooling water supply pipe 6 and a drain pipe 7 are provided therein.
are connected to each other.

The nozzle 5 is composed of a disk-shaped nozzle surface 8 and a tube body 9 for attaching to the burner body 1, and the nozzle surface 8 is provided with nine ejection ports 10, and around these ejection ports 10 are A cooling water passage 11 is formed. The water supply pipe 6 and the drain pipe 7 are connected to the cooling water supply port 12 and the water discharge port 13, respectively.

In the burner body for diamond synthesis using the combustion method having the above configuration, the hole diameter (d) of the jet ports 10 on the nozzle surface 8 is formed to be 4 mm, and the interval (p) between the jet ports 10 is formed to be 151 mm, and this burner body is used. , acetylene and pure oxygen were supplied and burned at a volume ratio of 1.0, and diamond was synthesized on the substrate. As a result, approximately 40 mm in diameter is placed on the substrate.
Diamond was uniformly synthesized over a wide area of 11II11, and no backfire occurred during the synthesis.

FIG. 4 is an enlarged cross-sectional explanatory view of a separate layer-like nozzle portion according to the present invention. In the figure, the nozzle 5'' is the spout 10.
' shape is formed by the parallel part 14 and the tapered part 15, and the hole diameter (d) and interval -) of the parallel part 14 are formed to the desired hole diameter and interval of the present invention, and the other configuration is as follows.
It is basically the same as the nozzle 5 shown in FIG. 2 above.

By using such a nozzle 5'', the parallel portion 14
In combination with cooling, backfire is prevented, and the taper part 1
In No. 5, the flow velocity of the ejected gas is reduced toward the outlet, so a flat surface is formed, and diamond can be synthesized uniformly over a wider area.

Fig. 5 is a cross-sectional illustration of the different layers of a burner body for diamond synthesis using the combustion method according to the present invention, and Fig. 6 is an illustration as seen from arrow B in Fig. 5. It is between.

In the figure, reference numeral 16 denotes a disk-shaped nozzle portion, and this nozzle portion 16 is provided with nine jet ports 17, and a cooling water passage 18 is formed around these jet ports 17. , the cooling water is supplied from the cooling water supply port 19 and drained from the drain port 20.

21 is a cylindrical burner body, and this burner body 21
is composed of a lower chamber 22 and an upper chamber 23. The nozzle portion 16 is fixedly provided at the lower end of the lower chamber 22. Further, between the lower chamber 22 and the upper chamber 23, a partition wall 24 having a diameter larger than the body diameter of the burner body 21 is fixedly provided on the lower end side of the upper chamber 23, and the outer peripheral flange portion 25 of this partition wall 24 and the lower By bolting a flange 26 formed on the outer periphery of the upper end of the chamber 22 via a packing 27, the lower chamber 22
and Royal Family 23 are combined.

Further, nine pipes 28 are penetrated and fixed in the partition wall 24 so as to face the spout 17 of the nozzle part 16, and the tip wall of each of these pipes 28 has a large number of small holes arranged in upper and lower stages. 29
is drilled.

Furthermore, in the royal house 22, there is a connecting pipe 3 for introducing an oxidizer (pure oxygen).
0, and the upper chamber 23 is provided with a connecting pipe 31 for introducing fuel (acetylene).

Even in the burner body for diamond synthesis configured in this way, by forming the hole diameter and spacing of the ejection ports 17 of the nozzle portion 16 to the desired hole diameter and spacing of the present invention,
Similar to the burner body shown in Example 1 above, diamond can be synthesized uniformly over a wide area without causing backfire.

〔Effect of the invention〕

As described above, according to the burner body for diamond synthesis using the combustion method according to the present invention, diamond can be synthesized over a wide range without worrying about accidents due to backfire. Moreover, this makes it easier than the CVD method.
Diamond can be synthesized economically on the surface of a substrate.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a burner body for diamond synthesis using the combustion method according to the present invention, Fig. 2 is an enlarged sectional explanatory diagram of the nozzle part shown in the first part, and Fig. 3 is an arrow B in Fig. 2. FIG. 4 is an explanatory diagram showing an enlarged cross-section of the nozzle part in a separate layer according to the present invention, and FIG. Explanatory diagram, Figure 6 is an explanatory diagram viewed from arrow B in Figure 5, and Figure 7 shows the effect of the volume ratio of acetylene to pure oxygen (CJzlox) on flashback and diamond synthesis in relation to pore diameter. A diagram showing the influence, FIG. 8, is an explanatory diagram of the prior art. 1 Burner body 2 3 Fuel supply pipe 4 5.5゛ Nozzle 6 7 Drain pipe 8 9 Pipe body 10 11 Cooling water passage 12 13 Drain port 14 15 Tapered part 16 Premixing chamber oxygen supply pipe Water supply pipe Disc-shaped nozzle surface 10' Spout port Water supply port Parallel part Nozzle part Fig. 1 Fig. 2 Spout port 18 Lower chamber of cylindrical burner main body 23 Partition wall 28 Small hole 30 Connection pipe for oxidizing agent introduction Cooling water passage Upper chamber pipe Connection pipe for fuel introduction Patent application People Kobe Steel, Ltd.

Claims (1)

[Claims] (1) A burner body for diamond synthesis using a combustion method, which has a plurality of ejection holes and is equipped with a nozzle part configured in a water-cooled structure at the tip, the hole diameter of the ejection holes being 5 mm or less,
A burner body for diamond synthesis using a combustion method, characterized in that the spacing between nozzle holes is 20 mm or less.