JPH0550443B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an Al salt compound of carbon nitride, which has a novel chemical composition and is a precursor of AlN, and the oxidation resistance of AlN, which is useful as a ceramic for highly thermally conductive IC substrates, etc. Concerning raw material powder and its manufacturing method. [Conventional technology and problems to be solved] Conventionally, as a polymer having a triazine ring,
Polymers of vinyl-s-triazines [Polymer 38,
196 (1989)] and melamine resin, but the former is a one-dimensional (linear) polymer, and the latter is amorphous because it bonds in a three-dimensional disorder. The s-triazine ring is a 6π electron system, and 6 base papers (3 carbon atoms, 3 nitrogen atoms) form the same plane, so if the π electron system can be extended two-dimensionally, it will be very useful optically and electrically. Although it is expected that it can be used as a material, no triazine cyclic polymer that forms a two-dimensional plane has been synthesized until now. Therefore, as a result of repeated studies under various conditions, the present inventors have developed carbon nitride, which is synthesized by using a compound containing a triazine ring of carbon and nitrogen, such as cyanuric chloride or melamine, as a reaction raw material, and a method for producing the same. An application has already been filed under the heading "Carbon nitride and its manufacturing method" (Japanese Patent Application No. 173186-1986). Subsequently, an application was also filed for the above-mentioned compound of carbon nitride and an alkali metal (Japanese Patent Application No. 1-27240), and the following chemical structure was proposed as the structure of carbon nitride. In this plane, there are three >NH surrounded by
A 0.394 nm vacancy exists, into which the alkali metal is introduced. On the other hand, AlN ceramics have high thermal conductivity and are used for various purposes such as IC substrates, but if the raw material powder contains oxygen, it is undesirable because it causes a decrease in thermal conductivity. There is a problem that not only oxygen remains in the powder during the manufacturing process, but also that a portion of the ceramic sintered body is oxidized when stored in air before manufacturing. Therefore, methods such as surface treatment with surfactants have been proposed to prevent powder oxidation (Japanese Patent Laid-Open No. 64-61304), but these methods are economically disadvantageous as they require the use of solvents, increase the number of processing steps, etc. become. [Means for solving the problem] Based on the above, the present inventors investigated a reaction with an Al salt compound to utilize nitrogen in carbon nitride, and found that the reactant at low temperature vacates the Al salt. It has a new chemical structure incorporated into the pores, and it is possible to generate AlN powder coated with an oxidation-resistant organic film by further high-temperature treatment or by directly reacting the above raw materials at high temperatures. This is the heading that led to the present invention. That is, in the present invention, the general formula is C ₆ N〓H〓Al〓X〓 (8≦α≦10, 0≦β≦10, 0.6≦γ≦1.5,
0≦δ≦1, X represents an acid group. ), and the general formula [(C ₃ N ₃ ) ₂ N _x H _y ] (where 2≦x≦4,
Carbon nitride represented by 0≦y≦8) is mixed with Al salt at 200
The above-mentioned method for producing an Al salt compound of carbon nitride is characterized in that the reaction is carried out in a temperature range of ~500°C, and the general formula is C ₆ N〓H〓Al〓X〓 (where 8≦α≦10,
0≦β≦10, 0.6≦γ≦1.5, 0≦δ≦1, X represents an acid group. ) is obtained by further heat-treating the Al salt _compound of carbon nitride at 800 _{to 950 ° C} . A composition consisting of amorphous carbon, nitrogen, and hydrogen obtained by reacting carbon nitride represented by ≦y≦8) with an Al salt at 800 to 950°C [provided that the molar ratio is C:N:H
=(0-1.5):(0-1.5):(0-1.0) Provides an AlN powder coated with a film of (0-1.0). Carbon nitride, which is a raw material, is obtained from a patent application previously filed in 1983.
As detailed in No. 173186, it is obtained by reacting cyanuric chloride with ammonia or cyanuric chloride with melamine, and then thermally decomposing it at 400 to 600°C. The compound is a layered polymer represented by the general formula [(C ₃ N ₃ ) ₂ N _x H _y ] (where 2≦x≦4, 0≦y≦8), and contains only cyanuric chloride-ammonia, melamine, Those synthesized from a melamine-cyanuric chloride system are preferred as raw materials for the present invention. Regarding carbon nitride, although the method of expressing the general formula is different from that in the previous application, the ratio of the constituent atoms in the compound is exactly the same, indicating exactly the same compound. The compound of the present invention is obtained by reacting the above carbon nitride with an Al salt, and as an Al salt consisting of various acid groups represented by X, AlCl ₃ , AlBr ₃ , AlI ₃ ,
Al ₂ (SO ₄ ) ₃ etc. can be used, but these can also be used in the form of hydrates. The reaction is achieved by mixing the raw materials carbon nitride and Al salt powder and then heating the mixture in an inert gas such as nitrogen, but the products differ depending on the reaction temperature. First, when the reaction temperature is set in the range of 200 to 500°C, an Al salt compound of carbon nitride (hereinafter referred to as AlN precursor) having a layered structure represented by the general formula C ₆ N〓H〓Al〓X〓 is formed. generate, while 800-950
Coated by a composition of amorphous carbon, nitrogen and hydrogen by setting in the range of °C.
AlN powder can be obtained. In addition, once the AlN precursor is generated, 800~
When treated at a temperature of 950° C., AlN powder coated with the above organic coating can be obtained as well. The reaction does not proceed at temperatures lower than 200℃, and at temperatures below 500℃
At higher temperatures, the original carbon nitride structure is destroyed until it reaches around 800℃, but crystalline AlN
However, at temperatures higher than 950°C, the coating composition of amorphous carbon, nitrogen, and hydrogen decomposes and scatters, forming ordinary powdered AlN.
Changes to The Al compound is used and reacted at a ratio of 0.8 to 2.0 mol, preferably 0.9 to 1.5 mol, per 210 g of carbon nitride as a raw material. If it is less than 0.8mol,
This is undesirable because unreacted carbon nitride remains.
On the other hand, if the amount exceeds 2.0 mol, there will be a large amount of unreacted Al salt, making it difficult to remove it. This is 200~500℃
The same is true for both the reaction at 800 and 950°C. In the present invention, the product obtained when the reaction is carried out at a temperature of 200 to 500°C is a yellow powder, and the X-ray diffraction spectrum and IR spectrum show that the structure of carbon nitride, which is the raw material, is mostly preserved and is surrounded by >NH. lost
Al metal is incorporated into 0.394 nm pores, and when incorporated, >NH hydrogen and Al salt react and some of it is lost as an acid, but some of the acid groups of the remaining Al salt is taken into the pores as is. Therefore, this compound can be represented in the form C ₆ N〓H〓Al〓X〓. The above compound is stable and hardly absorbs moisture or decomposes even when exposed to air. On the other hand, the compound produced when the reaction temperature was 800 to 950°C was a white to grayish powder, which was found to be AlN powder as a result of X-ray diffraction. However, the presence of other organic substances was confirmed from the IR spectra and elemental analysis of these compounds, and since these organic substances do not appear at all in the X-ray diffraction diagram, they are considered amorphous, and subtracting the confirmed composition of AlN, it is assumed that the organic substances are amorphous. The composition has a molar ratio of C:N:H=(0
-1.5):(0-1.5):(0-1.0).
AlN powder is coated with these films, so it is not easily oxidized, and these organic films sublime and decompose when heated above 1000℃, but these films are all composed of reducing substances. Therefore, no oxygen is left on the surface during sublimation and decomposition. Therefore, by heat-treating the powder at 1000° C. or higher immediately before molding, after molding, and before sintering, it is possible to obtain AlN ceramics with high thermal conductivity and no oxygen in the sintered body. It was found that the AlN powder obtained in the present invention cannot be obtained by a reaction between melamine, etc., which is a raw material for carbon nitride, and an Al salt, but is only produced once it passes through a precursor. Therefore, the AlN powder of the present invention is advantageous for producing oxygen-free ceramics coated with organic matter.
Only with the method of the invention is this possible. [Example] Hereinafter, the present invention will be explained in detail with reference to Examples. Example 1 In a quartz reaction tube, 1.0 g of carbon nitride and 0.66 g of AlCl ₃
The mixture was placed in a reaction dish and placed in a nitrogen stream.
The temperature was raised to 500°C and the mixture was reacted for 3 hours. As the temperature was gradually raised from room temperature, the reaction started at about 120°C and HCl was released, as revealed by the IR spectrum of the produced gas. The temperature is about 300
When the temperature reached 500°C, the reaction proceeded vigorously, and the release of HCl almost stopped 3 hours after reaching 500°C. Although 1.22 g of the product was more yellow in color than the original carbon nitride, it existed stably in the air with almost no moisture absorption or decomposition. The elemental analysis values of this product and its composition are shown in Table 1. Next, the X-ray diffraction diagram of the product is shown in Figure 1. Although the crystallinity is lower than that of the raw material carbon nitride, the position of the diffraction line of the 002 plane does not change much.
The interlayer distance did not change much. FIG. 3 shows the IR spectrum of the product of this example. This figure is almost the same as that of the raw material carbon nitride, and it can be seen that the product retains the skeleton of the raw material as it is. However, absorption at 2186 cm ^-1 indicating CN stretching and absorption at 2980 cm ^-1 indicating CH stretching were observed, suggesting that some decomposition occurred during the exothermic reaction and the structure was disordered. Based on the above data, the mechanism and structure of the reaction are thought to be as follows. As mentioned above, carbon nitride has one 0.394 nm hole surrounded by >NH in the unit cell,
This >NH is highly reactive and is thought to cause a dehydrochlorination reaction with AlCl ₃ to take Al and unreacted Cl into the pores. Therefore, most of the original structure is retained and the layer spacing is almost unchanged, but the structure is slightly disordered. In this way, it is thought that _three molecules of AlCl react with one unit cell of carbon nitride in this reaction, but in reality, when the reaction is carried out at that molar ratio, the yield of the product is good, and in this example The ideal chemical formula for carbon nitride is [(C ₃ N ₃ ) ₂ (NH) ₃ ]
On the other hand, Al is 0.9, which is almost 1. Example 2 Example 1 except that the reaction temperature was set at 900°C.
The reaction was carried out under the same conditions. The reaction proceeded in the same manner as in Example 1 up to 500°C,
White powder is generated in the low temperature part of the electric furnace at around 600℃,
Furthermore, black powder was generated at around 800℃. After the reaction is complete, a slightly grayish white powder is produced at 0.30%.
g remained. The product was stable in air. Table 1 shows the results of elemental analysis of the product and the molar composition of the compound calculated from this. This result shows that almost no Al used in the reaction was lost.
It was discovered that the products produced during the process were organic substances consisting of nitrogen, carbon, and hydrogen. The X-ray diffraction pattern of the final product is shown in Figure 2, and this diffraction pattern matched that of AlN, indicating that it was AlN powder. However, the results of elemental analysis are
The products are considered to be a mixture of these, as they still contain significant amounts of carbon, excess nitrogen, and a small amount of hydrogen, but the absence of this peak in the X-ray diffraction pattern suggests that they are amorphous. Next, the IR spectrum of the product is shown in Figure 4, and this spectrum is also completely different from that of the original carbon nitride. AlN shows almost no absorption peak even in IR,
When these spectra were examined, C, N, H
It was found that the peak was related to From this, it is considered that the surface of the product at 900° C. is coated with an amorphous organic substance composed of C, N, and H. The elemental analysis values of this product after treatment at 1000°C are also shown in Table 1, and as a result of such treatment, the organic matter on the surface sublimated and decomposed, leaving only AlN.

[Table] Comparative Example 1 1 g of melamine containing a triazine ring and used as a nitrogen source for nitride ceramics and AlCl ₃ 0.66
g was reacted under the same conditions as in Example 1, but 300
At around ℃, both melt, bubbles are generated, and a brown product is obtained. When the temperature is further increased, the color changes to black.
No AlN powder was obtained. [Effect of the invention] The Al salt compound of carbon nitride, which is the precursor of the AlN powder according to the present invention, incorporates a part of Al and the acid groups combined with Al into the pores surrounded by >NH of carbon nitride. It is a novel structure, these metals can be substituted, and by processing this compound at higher temperatures, organic-coated AlN powder can be produced, and this powder can be used. By doing so, various useful applications can be considered, such as the production of oxygen-free AlN ceramics with high thermal conductivity.

[Brief explanation of the drawing]

Figure 1 shows the raw materials carbon nitride and AlCl ₃
FIG. 2 is an X-ray diffraction diagram of the compound when the reaction was carried out at a temperature of 900°C. FIG. In addition, Figure 3 shows the IR spectrum of the compound obtained by reacting raw material carbon nitride and AlCl ₃ at a temperature of 500°C, and Figure 4 shows the
This is an IR spectrum obtained when a similar reaction was carried out at 900°C.

Claims (1)

[Claims] 1 General formula C ₆ N〓H〓Al〓X〓 (however, 8≦α≦10,
0≦β≦10, 0.6≦γ≦1.5, 0≦δ≦1, X represents an acid group. ) Al salt compound of carbon nitride with a layered structure. 2 General formula [(C ₃ N ₃ ) ₂ N _x H _y ] (However, 2≦x≦
The general formula C ₆ N〓H〓Al〓X〓 (where 8≦α ≦
10, 0≦β≦10, 0.6≦γ≦1.5, 0≦δ≦1, X
indicates an acid group. ) A method for producing a carbon nitride Al salt compound having a layered structure. 3 General formula C ₆ N〓H〓Al〓X〓 (However, 8≦α≦10,
0≦β≦10, 0.6≦γ≦1.5, 0≦δ≦1, X represents an acid group. ) can be obtained by further heat-treating a carbon nitride Al salt compound represented by the formula [(C ₃ N ₃ ) ₂ N _x H _y ] (however,
A composition consisting of amorphous carbon, nitrogen, and hydrogen obtained by reacting carbon nitride represented by 2≦x≦4, 0≦y≦8) with an Al salt at 800 to 950°C [however, the molar ratio is C:N:H=
AlN powder coated with a film of (0-1.5):(0-1.5):(0-1.0)].