WO2006103930A1

WO2006103930A1 - Method for producing material containing aluminum nitride

Info

Publication number: WO2006103930A1
Application number: PCT/JP2006/305138
Authority: WO
Inventors: Yoshihiro Seimiya
Original assignee: Tama-Tlo Ltd.
Priority date: 2005-03-29
Filing date: 2006-03-15
Publication date: 2006-10-05
Also published as: JPWO2006103930A1; JP5181329B2

Abstract

Provided is a method for producing a composition containing aluminum nitride or aluminum nitride in the form of an aggregated solid (bulk) or a powder without the use of a high temperature up to 1600˚C. In the method, aluminum (21) and a boron compound (20) are charged into a reaction vessel [a crucible (12)], and the reaction vessel is heated in a nitrogen atmosphere, to thereby melt the aluminum and form a composition containing aluminum nitride by a solid-liquid two phase reaction between molten aluminum and a solid boron compound.

Description

Specification

Method for producing aluminum nitride-containing material

Technical field

TECHNICAL FIELD [0001] The present invention relates to a method for producing an aluminum nitride-containing material, and particularly relates to a method for producing a massive aluminum nitride-containing material or powdered aluminum nitride.

Background art

[0002] Aluminum nitride is a material having excellent properties such as high thermal conductivity, low thermal expansion coefficient and low chemical stability. Therefore, in recent years, it is expected to be applied to various fields such as semiconductor devices and engine members.

Conventionally, as a method for producing aluminum nitride, there is a method in which aluminum is heated at a high temperature (for example, 1600 °) in a nitrogen atmosphere at a very high atmospheric pressure (for example, 100 atmospheric pressure). According to this method, an aluminum nitride powder can be obtained. Non-Patent Document 1 discloses a study on the production of aluminum nitride.

Non-Patent Document 1: Jun Kobashi, Kenzo Saiki et al., The 104th Annual Meeting of the Japan Institute of Light Metals (2003) 2.

Disclosure of the invention

Problems to be solved by the invention

[0004] In the method described above, in order to obtain aluminum nitride, it is necessary to make the pressure extremely high, atmospheric pressure, and high temperature. Therefore, the manufacturing cost of aluminum nitride has been increasing.

[0005] Also, only aluminum nitride powder can be obtained. For this reason, in order to obtain an aluminum nitride-containing material having a desired shape, it is necessary to add a binder to the aluminum nitride powder to obtain a desired shape and then to fire. For this reason, massive aluminum nitride

-The production cost of um-containing materials was even higher.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing an aluminum nitride-containing material at a low production cost.

Means for solving the problem

[0007] The method for producing an aluminum nitride-containing material according to the present invention comprises aluminum and nitrogen in a nitrogen atmosphere. A first heat treatment step for producing an aluminum nitride-containing material containing aluminum nitride by heating the nitride in the same container to melt the aluminum is provided. The aluminum nitride-containing material can be agglomerated and can be powdered

[0008] In the container, it is preferable to perform heating while the aluminum is positioned on the nitride. The nitride is preferably in the form of powder. The nitride is at least one selected from the group force of, for example, boron nitride, magnesium nitride, or calcium nitride force.

[0009] The heat treatment temperature in the first heat treatment step is preferably 900 ° C or higher and 1400 ° C or lower. In the first heat treatment step, the nitrogen gas atmosphere is preferably a pressurized atmosphere. In this case, the nitrogen gas atmosphere may be 50 atm or less.

[0010] Preferably, the method further includes a second heat treatment step after the first heat treatment step, in which the aluminum nitride-containing material is cooled and then heat-treated again in a nitrogen gas atmosphere. After the first heat treatment step, the aluminum nitride-containing material contains aluminum nitride and aluminum. By the second heat treatment, the aluminum nitride content of the aluminum nitride-containing material is increased and the aluminum content is reduced. descend.

[0011] In the second heat treatment step, the nitrogen gas atmosphere is preferably a pressurized atmosphere. In this case, the nitrogen gas atmosphere may be 50 atm or less.

[0012] It is preferable that the second heat treatment step is performed under conditions that facilitate the nitriding reaction of A1 than the first heat treatment step. The heat treatment temperature in the second heat treatment step is preferably equal to or higher than the heat treatment temperature in the first heat treatment step. The heat treatment temperature in the first heat treatment step is preferably 900 ° C. or more and 1200 ° C. or less, and the heat treatment temperature in the second heat treatment step is preferably 1100 ° C. or more and 1200 ° C. or less. In this way, the characteristics of the aluminum nitride-containing material can be improved.

[0013] If the second heat treatment step is repeated a plurality of times, the aluminum nitride content can be increased even under low temperature and low pressure conditions.

[0014] Another method for producing an aluminum nitride-containing material according to the present invention is to heat aluminum and nitride in the same container under an inert gas atmosphere to melt the aluminum. Thus, a massive aluminum nitride-containing material containing aluminum nitride and aluminum is produced.

The invention's effect

[0015] According to the method for producing an aluminum nitride-containing composition of the present invention, it is possible to produce an aluminum nitride-containing material without increasing the pressure to a very high pressure and at a temperature as high as 1600 ° C. In particular, by adjusting the production conditions, a massive aluminum nitride-containing material can be produced directly. For this reason, a manufacturing cost becomes remarkably low.

Brief Description of Drawings

FIG. 1 is a configuration diagram of a carbon resistance furnace which is a manufacturing apparatus used in an aluminum nitride manufacturing method according to an embodiment of the present invention.

FIG. 2 is an X-ray diffraction chart obtained in Example 1.

FIG. 3 is an energy dispersive X-ray analysis chart obtained in Example 1.

FIG. 4 is a differential thermal analysis chart obtained in Example 2.

FIG. 5 is a view showing the state of the aluminum nitride-containing composition when the atmospheric nitrogen gas pressure and the heat treatment temperature are variously changed in Example 4.

FIG. 6 is a diagram showing the state of the aluminum nitride-containing composition when the atmospheric nitrogen gas pressure and the heat treatment temperature are variously changed in Example 5.

FIG. 7 is an X-ray diffraction chart obtained in Example 6.

FIG. 8 is an X-ray diffraction chart obtained in Example 6.

FIG. 9 is an X-ray diffraction chart obtained in Example 6.

FIG. 10 is an X-ray diffraction chart obtained in Example 6.

FIG. 11 is a graph showing the relationship between the atmospheric nitrogen pressure in the second heat treatment and the A1N volume fraction in the aluminum nitride-containing material.

FIG. 12 is an X-ray diffraction chart obtained in Example 7.

FIG. 13 is a graph showing the results of average thermal expansion examined in Example 8.

FIG. 14 is a graph showing the coefficient of thermal expansion obtained in Example 9.

FIG. 15 is a graph showing the electrical conductivity obtained in Example 10.

FIG. 16 is a graph showing the micro Vickers hardness obtained in Example 11. FIG. 17 is a graph showing the thermal conductivity obtained in Example 12.

FIG. 18 is a graph showing the relationship between the number of second heat treatments and the aluminum nitride content.

FIG. 19 is an SEM photograph of the aluminum nitride-containing material after aluminum is melted.

Explanation of symbols

[0017] 10 ... Reaction chamber

11… Gas inlet

12 ··· Crucible (Reaction vessel)

13 ... Graph Eye Heater

14 ... Thermocouple monitor wire

20 ··· Boron nitride

21… Anoleum

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] Hereinafter, a method for producing an aluminum nitride-containing composition according to an embodiment of the present invention will be described with reference to the drawings.

[0019] (First embodiment)

FIG. 1 is a configuration diagram of a single-bonn resistance furnace used in the method for producing an aluminum nitride-containing material according to the first embodiment. This carbon resistance furnace has a reaction chamber 10. The reaction chamber 10 is provided with an exhaust port (not shown) and a gas inlet port 11. In the reaction chamber 110, a graph eye heater 13 for heating the crucible 12 is provided. Since the crucible 12 is provided with a thermocouple, the temperature of the crucible 12 can be monitored outside the reaction chamber 10 through the monitor wire 14.

[0020] Next, a method for producing an aluminum nitride-containing material using the carbon resistance furnace will be described.

First, aluminum 21 and powdered nitride 20 crushed into small pieces are put into the crucible 12. The nitride 20 may be a force other nitride such as hexagonal boron nitride (eg, magnesium nitride (Mg N) or calcium nitride (Ca N;)). Boron nitride, nitrogen

3 2 3 2

Magnesium halide and calcium nitride strength group strength may be a mixture of two or more selected. At this time, the nitride 20 is positioned below the aluminum. Nitride 20 Or you can stack multiple layers of aluminum and aluminum 21 alternately. The weight ratio of nitride 20 to aluminum is preferably 0.1 or more and 1 or less.

Next, the inside of the reaction chamber 10 is evacuated from the exhaust port, and then nitrogen gas is also introduced into the gas inlet 11. As a result, the inside of the reaction chamber 10 becomes a nitrogen atmosphere. The pressure of nitrogen gas inside the reaction chamber 10 is, for example, 5 to 50 atmospheres in a pressurized atmosphere.

Next, the crucible 12 is heated by the graph eye heater 13, and the inside of the crucible 12 is heated to a melting point (660 ° C.) or higher of aluminum, preferably 900 ° C. to 1400 ° C. As a result, the aluminum 21 in the crucible 12 is melted, and a solid-liquid two-phase reaction occurs between the molten aluminum 21 and the solid phase nitride 20. At this time, nitrogen in the atmosphere also reacts. As a result, the nitriding reaction of aluminum proceeds, and an aluminum nitride-containing material and slag are formed (hereinafter referred to as first heat treatment). In the nitriding reaction of aluminum in the first heat treatment, the nitride 20 other than nitrogen (for example, boron, magnesium, or calcium) is considered to function as a catalyst. The rate at which this nitriding reaction proceeds can be controlled by the processing temperature and the pressure of the atmospheric nitrogen.

[0023] According to X-ray diffraction, the nitride 20 other than nitrogen (for example, boron, magnesium, or calcium) hardly exists in the aluminum nitride-containing material. Nitride 20 other than nitrogen (for example, boron, magnesium, or calcium) is considered to be included in the slag.

Further, when the nitride 20 is positioned below the aluminum 21 inside the crucible 12, the molten aluminum 21 penetrates between the powdered nitrides 20. For this reason, the formation reaction of aluminum nitride proceeds efficiently. In addition, since aluminum nitride has a higher specific gravity than aluminum, the produced aluminum nitride is precipitated, and the nitriding reaction of aluminum proceeds above the aluminum nitride.

[0025] In the method for producing an aluminum nitride-containing material according to the present embodiment, the aluminum nitride content varies depending on the processing conditions of the first heat treatment, such as the processing temperature, the pressure of atmospheric nitrogen, the reaction time, and the ratio of boron nitride to aluminum. Can make different states of inclusions [0026] For example, under predetermined processing conditions, an aluminum nitride-containing material in which a plurality of aluminum nitride particles are bonded by aluminum is obtained in the form of aggregated coalescence (balta), that is, a lump. The obtained aluminum nitride-containing material has a force in which a plurality of aluminum nitride particles are filled with aluminum, or a network-like or network-grown aluminum nitride is filled with aluminum. Therefore, the porosity is 1. / _{0 or} less. As described above, the porosity is significantly reduced as compared with the aluminum nitride-containing material obtained by the sintering method, and a balta-like aluminum nitride-containing material can be obtained in a state close to a metal. Note that aluminum located between the network-like or network-like grown aluminum nitrides may contain aluminum nitride particles without forming a network.

[0027] Under the condition that the formation reaction of aluminum nitride is promoted (for example, 40 atm at 1300 ° C), the proportion of aluminum nitride contained in the product aluminum nitride-containing material is increased and the proportion of aluminum is increased. Can be lowered.

[0028] When the aluminum content is 40% or more and 70 or less, the workability of the obtained aluminum nitride-containing material is improved. In addition, when the aluminum content is 20% or less, the mechanical properties (hardness, etc.) of aluminum nitride are high. In addition, when the aluminum content is 5% or less, the characteristics (including thermal conductivity and resistance) of the obtained aluminum nitride-containing material are close to those of pure A1N.

[0029] When the aluminum contained in the aluminum nitride-containing material is below a certain value, the aluminum nitride-containing material becomes a mixture of agglomerated coal (balta) and a powdered material. As the proportion decreases, the product becomes powdery. The powdered product is high-purity aluminum nitride as shown in the following examples. The powder form is considered to be because there is almost no unreacted A1.

[0030] Further, as shown in the examples described later, the crystal structure of aluminum nitride contained in the aluminum nitride-containing material can be controlled by the pressure of atmospheric nitrogen.

[0031] As described above, according to the method for producing an aluminum nitride-containing material according to the present invention, a massive aluminum nitride-containing material can be easily obtained. The properties of the obtained aluminum nitride-containing material vary depending on the proportion of aluminum. For example, the proportion of aluminum is high When the processability of aluminum nitride-containing materials is improved and the proportion of aluminum is low

The characteristics of aluminum nitride inclusions are close to those of A1N. In addition, since the surfaces of the aluminum nitride particles are covered with aluminum, good moisture resistance can be obtained.

[0032] Further, the manufacturing conditions are low temperature and low pressure as compared with the conventional method. Therefore, the manufacturing cost is significantly lower than the conventional one. Also, the ability to produce powdered aluminum nitride by adjusting the production conditions. In this case as well, the production conditions are lower and lower pressure than in the past, so the production cost is lower than in the past. Greatly reduced.

[0033] (Second Embodiment)

In the method for producing an aluminum nitride-containing material according to the second embodiment, the bulk aluminum nitride-containing material is produced by the first heat treatment shown in the first embodiment, and the obtained aluminum nitride-containing material is used. After cooling, the aluminum nitride-containing material is further reheated (hereinafter referred to as second heat treatment) in a nitrogen gas atmosphere. The aluminum nitride is cooled by furnace cooling, for example. The second heat treatment is performed using, for example, the carbon resistance furnace used in the first heat treatment. By performing the second heat treatment, the nitridation reaction of aluminum contained in the aluminum nitride-containing material proceeds, the aluminum content is decreased, and the aluminum nitride content is increased.

[0034] In the present embodiment, the second heat treatment is preferably performed under conditions that facilitate the nitriding reaction of aluminum than the first heat treatment. This is because the nitridation reaction of aluminum is an exothermic reaction, so if the first heat treatment is performed under conditions that facilitate the nitridation reaction of aluminum, the nucleation of aluminum nitride proceeds rapidly during the first heat treatment, This is because aluminum nitride is difficult to form a network. For example, the heat treatment temperature in the second heat treatment is preferably equal to or higher than the heat treatment temperature in the first heat treatment. Specifically, the heat treatment temperature in the first heat treatment is preferably 900 ° C. or higher and 1200 ° C. or lower, and the heat treatment temperature in the second heat treatment is preferably 1100 ° C. or higher and 1200 ° C. or lower.

In addition, the pressure of the nitrogen gas atmosphere in the second heat treatment is preferably a pressurized atmosphere, for example, 5 atm or more and 50 atm or less.

[0035] Also in the second heat treatment, by changing the processing conditions (specifically, temperature and pressure). By promoting the formation reaction of aluminum nitride, the proportion of aluminum nitride contained in the aluminum nitride-containing product can be increased and the proportion of aluminum can be decreased. If the nitridation reaction of aluminum proceeds excessively, the aluminum nitride-containing material becomes a mixture of agglomerated (balta) -like material and a powder-like material, and further powdery. The powdered product is high purity aluminum nitride.

[0036] The second heat treatment, that is, the cooling and heating cycle of the aluminum nitride-containing material may be performed a plurality of times. As a result, the aluminum content is further reduced and the aluminum nitride content is further increased even at low temperatures (eg, 1100 ° C.) and low pressure conditions (eg, 15 atmospheres). In addition, the aluminum nitride content can be increased as compared with the case where the heat treatment time is simply increased.

[0037] Even in this embodiment, a massive aluminum nitride-containing material can be easily obtained. The characteristics of the obtained aluminum nitride-containing material vary depending on the proportion of aluminum. For example, when the proportion of aluminum is high, the workability of the aluminum nitride-containing material is improved, and when the proportion of aluminum is low, the characteristics of the aluminum nitride-containing material are close to those of A1N. In addition, since the surfaces of the aluminum nitride particles are covered with aluminum, good moisture resistance can be obtained.

[0038] Further, the manufacturing conditions are low temperature and low pressure as compared with the conventional method. Therefore, the manufacturing cost is significantly reduced compared to the conventional one. In addition, powdered aluminum nitride can be produced by adjusting the production conditions. Even in this case, the manufacturing conditions are low temperature and low pressure as compared with the conventional case, and the manufacturing cost is significantly reduced as compared with the conventional case.

[0039] Alternatively, the second heat treatment may be performed after the shape of the massive aluminum nitride-containing material after the first heat treatment is processed into a desired shape (for example, a heat dissipation substrate, a piston, or a cylinder). In particular, when the A1 content in the aluminum nitride-containing material after the first heat treatment is set to 40 to 70%, for example, the workability of the aluminum nitride-containing material is improved. Even in this case, the aluminum nitride content of the aluminum nitride-containing material after shape processing can be increased (for example, 98% or more) by the second heat treatment.

[0040] (Third embodiment)

In the method for producing an aluminum nitride-containing material according to the third embodiment, the atmosphere is a nitrogen atmosphere. The first heat treatment shown in the first embodiment is substantially the same as the first heat treatment except that it is an atmosphere of an inert gas such as argon. In the present embodiment, only the nitride 20 serves as a nitrogen supply source in the aluminum nitride production reaction.

First, aluminum crushed into small pieces and powdered nitride 20 are put into the crucible 12. At this time, the nitride 20 is positioned below the aluminum. The weight ratio of nitride 20 to aluminum is preferably 0.8 or more and 2 or less.

Next, the inside of the reaction chamber 10 is evacuated from the exhaust port, and then the inert gas is also introduced into the gas inlet 11. Next, the crucible 12 is heated with the graph eye heater 13, and the inside of the crucible 12 is heated to a temperature equal to or higher than the melting point of aluminum (660 ° C.). As a result, the aluminum in the crucible 12 is melted, and a solid-liquid two-phase reaction occurs between the molten aluminum and the solid phase nitride 20. As a result, the nitriding reaction of aluminum proceeds, and an aluminum nitride-containing material and slag are formed.

[0043] In this embodiment, the same effect as in the first embodiment can be obtained.

[0044] Thus, according to the method for producing an aluminum nitride-containing material according to each of the above-described embodiments, the aluminum nitride-containing material can be obtained in the form of an agglomerated solid (balta), that is, a lump by the first heat treatment. This aluminum nitride-containing material is obtained by joining a plurality of aluminum nitride particles to aluminum. Further, by performing the second heat treatment, the remaining aluminum can be nitrided and the content of aluminum nitride can be increased.

[0045] Further, according to the present embodiment, the production conditions of the aluminum nitride-containing material are lower pressure and lower temperature than the conventional method. Therefore, the manufacturing cost can be greatly reduced.

[0046] Further, in the conventional method, in order to obtain massive aluminum nitride, it was necessary to sinter aluminum nitride produced in powder form. In addition, aluminum nitride obtained by sintering has a drawback of poor workability because of its high porosity and easy cracking. However, according to the present embodiment, a massive aluminum nitride-containing material can be directly produced. Therefore, the produced aluminum nitride-containing material has a low porosity and excellent workability.

It should be noted that the present invention is not limited to the above-described embodiments, and can be implemented with various modifications without departing from the spirit of the present invention. For example, the manufacturing apparatus described above It is not limited to a carbon resistance furnace. Further, the first heat treatment condition and the second heat treatment condition can be variously changed depending on the intended aluminum nitride content and A1 content.

Example 1

[0048] (Example 1)

As a raw material, bulk aluminum crushed into small pieces (purity 99.99% or higher) and powdered hexagonal boron nitride (purity 99.9% or higher) are weighed to a weight ratio of 1: 1, The carbon resistance furnace shown in Fig. 1 was placed in an alumina crucible (inner diameter: 40 mmφ) and heated to react under the conditions shown below. At this time, the heating rate of the furnace was set to 10 ° CZ.

• Nitrogen atmosphere, pressure: 20 atmospheres ± 10%

• Heating temperature and time: 1250 ° C ± 10%, 1 hour to 6 hours

By the above reaction, a lump-like, agglomerated solid (balta) -like product (diameter 40 mmφ, thickness 20 mm) was obtained.

[0049] With respect to this aggregated solid product, the crystal structure was identified using a Rint 2500 rotary cathode X-ray diffractometer manufactured by Rigaku Corporation. For X-ray diffraction, Cu ka line was used, and the cathode conditions were 50 kV and 300 mA.

FIG. 2 is a chart showing the results of X-ray diffraction. As shown in this chart, diffraction peaks peculiar to aluminum nitride based on the hexagonal system were observed, and the other diffraction peaks were almost unrecognized. As a result, it was found that the obtained agglomerated solid (balta) product had a high aluminum nitride content.

[0051] Further, elemental analysis contained in the obtained product was performed using an energy dispersive X-ray analyzer by a scanning electron microscope that measures characteristic X-rays by irradiation with an electron beam. It is a chart which shows an elemental analysis result. As shown in this chart, for N

There was a slight increase in A1.

[0052] From these experimental results, the manufacturing method of the present embodiment can produce strong aluminum nitride, which cannot be obtained with a powder in the past, in the form of a high-purity agglomerated solid (balta). I was divided. In addition, this aluminum nitride-containing material was also a composite of aluminum nitride and aluminum. [0053] (Example 2)

In order to investigate the reaction temperature for producing aluminum nitride, a DTA 50 type differential thermal analyzer manufactured by Shimadzu Corporation was used. The heating rate during thermal analysis was 10 ° CZ and the atmosphere was Ar and N respectively.

2

Fig. 4 is a differential thermal analysis chart when aluminum pieces and BN powder are weighed at a ratio of 6: 1 and subjected to differential thermal analysis in an Ar atmosphere.

From Fig. 4, there was an endothermic peak near 600 ° C and a sharp exothermic peak around 1200 ° C. The first peak confirmed in the chart has a reaction start temperature of 660 ° C, which is consistent with the melting point of aluminum. On the other hand, the exothermic peak near 1200 ° C is considered to be due to the solid-liquid reaction between molten A1 and BN powder, and the reaction starting temperature shown in the following reaction formula (1) is considered to be 1200 ° C. .

[0054]

13A1 + 12BN → 12A1N + A1B…

12

[Example 3]

In Example 1, the pressure of the nitrogen (N) gas in the atmosphere was 10 atmospheres, 20 atmospheres, and 30 atmospheres.

2

The yield and crystal structure of the aluminum nitride obtained when changed were investigated.

Similarly, the yield and crystal structure of aluminum nitride obtained when the atmospheric gas was changed to argon (Ar) and the pressure was changed to 10, 20, and 30 atmospheres were examined.

[0056] It was clarified that A1N having two types of crystal structures, cubic and hexagonal, coexists in the product when reacted in an Ar gas atmosphere regardless of the gas pressure.

On the other hand, in the N gas atmosphere, the crystal structure of A1N is cubic and above 10 atm.

2

It was revealed that it was transformed into a hexagonal system.

On the other hand, the diffraction peak of A1B, which is conventionally considered to be a reaction product, was observed.

12

It wasn't.

[0057] The hardness of A1N having a cubic and hexagonal crystal structure was measured with a micro Vickers tester. As a result, cubic A1N had a Hv of about 19, whereas hexagonal A1N = Found to show a hardness of around 900.

[Example 4] In Example 1, it was obtained by changing the pressure of the nitrogen atmosphere to 10 atm, 15 atm, 20 atm, 25 atm, and changing the heat treatment temperature to 900 ° C, 1000 ° C, 1100 ° C, 1200 ° C. The state of the aluminum nitride-containing composition was examined.

[0059] The results are shown in FIG. In FIG. 5, as states corresponding to the respective atmospheric pressures and temperatures described above, state 1 indicates that a powdery composition was obtained, and state 2 indicates that a mixture of the agglomerated solid (balta) composition and the powdered composition is present. State 3 indicates that an agglomerated solid (balta) composition was obtained.

[0060] According to the above X-ray diffraction, the above powdery composition is aluminum nitride, and the agglomerated solid (baltha) composition is a composite of aluminum nitride and aluminum, as shown in FIG.

This shows that A1N can be generated at lower temperature and lower pressure than previously reported A1N generation conditions. This is because BN decomposes and B binds A1 and N as the temperature rises.

2

It is thought to be the purpose of working.

[Example 5]

In Example 1, the aluminum nitride obtained by changing the pressure of the nitrogen atmosphere to 10 atm, 20 atm, 30 atm, 40 atm, and changing the heat treatment temperature to 1100 ° C, 1200 ° C, 1300 ° C For each of the humic substances, the A1N content (measured at two points in each sample), the presence or absence of an A1 peak by X-ray diffraction, and Vickers hardness were examined.

[0062] The results are shown in FIG. In Fig. 6, the black circles indicate that the A1 peak was not observed. The numerical value above each point is the A1N content (%), and the numerical value below each point is Vickers hardness (Hv). From this figure, it is clear that the nitriding reaction of aluminum is most advanced when the heat treatment temperature is around 1200 ° C, and that the A1N-containing material can be hardened.

[0063] (Example 6)

As a raw material, agglomerated aluminum (purity 99.99% or more) crushed into small pieces and powdered boron nitride (purity 99.9% or more) were weighed to a weight ratio of 6: 1, and the carbon shown in Fig. 1 The first heat treatment was performed by putting it in an alumina crucible (inner diameter: 40 mmφ) in a resistance furnace. The conditions for the first heat treatment are a nitrogen atmosphere pressure of 10 atm ± 10%, a furnace heating rate of 10 ° CZ min, a heating temperature of 1100 ° C ± 10%, and a heating time of 1 hour. By this treatment, agglomerated solid ( Balta-like aluminum nitride-containing material (diameter 40 mmφ, thickness 20 mm) was obtained.

FIG. 7 is an X-ray diffraction chart of the aluminum nitride-containing material obtained by the first heat treatment, and shows a defract pattern. Based on the JCPDS card, “A1N” was added to the diffraction peak of A1N. The other peak is the A1 diffraction peak based on the face-centered cubic lattice. Under the above conditions, it can be seen that A1N and A1 coexist. The weight ratio between A1N and A1 is considered to be that the intensity ratio of the diffraction peak is A1 60% or more and 70% or less.

[0065] Then, the second heat treatment is performed on the aluminum nitride-containing material obtained by the first heat treatment.

(Re-heat treatment) was performed under a plurality of pressure conditions. The conditions for the second heat treatment are a heating temperature and time of 1300 ° C. for one hour, but the nitrogen atmosphere has four patterns of 10 atm, 30 atm, 35 atm and 40 atm.

FIG. 8 shows an X-ray diffraction chart of the aggregated solid (balta) nitride-containing material subjected to the second heat treatment in a nitrogen atmosphere of 10 atm. It can be seen that the diffraction intensity of A1N is significantly increased and the diffraction intensity of A1 is decreased compared to before the second heat treatment. This is thought to be because unreacted A1 was nitrided to A1N by reheat treatment. It was also confirmed that fine aluminum was present on the sample surface. This is thought to be due to the fact that A1, which was not nitrided, spouted to the surface due to reheating.

[0067] FIG. 9 shows an X-ray diffraction chart of the aggregated solid (balta) nitride-containing material subjected to the second heat treatment in a nitrogen atmosphere of 30 atm. Compared to FIG. 7, it can be seen that the diffraction intensity force S of A1N is further increased and the diffraction intensity of A1 is further decreased.

FIG. 10 shows an X-ray diffraction chart of the agglomerated solid (balta) -like aluminum nitride-containing material subjected to the second heat treatment in a nitrogen atmosphere of 35 atm. Compared to Fig. 8, the diffraction intensity of A1N was further increased. Almost no diffraction peak of A1 is seen. In this state, the A1 content in the aluminum nitride-containing material is 2% or less.

[0069] When the aggregated solid (balta) -like aluminum nitride-containing material is subjected to a second heat treatment in a nitrogen atmosphere of 40 atm, powdered aluminum nitride is obtained. This is probably because most of A1 that joined the aluminum nitride particles changed to A1N.

[0070] From the above results, it is understood that in the aggregated solid (balta) -like aluminum nitride-containing material, it is aluminum that joins the plurality of A1N particles. Also, the second heat treatment condition By adjusting the conditions (for example, pressure, temperature, and time), it was found that the A1 content of the aluminum nitride-containing material can be adjusted to achieve characteristics suitable for the intended use.

FIG. 11 is a graph showing the relationship between the atmospheric pressure of the nitrogen atmosphere in the second heat treatment and the volume percentage of A1N contained in the generated A1N-containing material. The volume percentage of A1N was calculated based on the X-ray diffraction chart. As shown in this graph, the volume% of A1N increases as the pressure of the nitrogen atmosphere in the second heat treatment increases, and is about 98% by volume when the pressure of the nitrogen atmosphere is 35 atmospheres. This shows that the A1N content contained in the A1N-containing material can be controlled by controlling the pressure of the nitrogen atmosphere in the second heat treatment.

[Example 7]

As a raw material, bulk aluminum crushed into small pieces (purity 99.99% or more) and powdered boron nitride (purity 99.9% or more) were weighed at a weight ratio of 1: 1, and the carbon shown in Fig. 1 was measured. The first heat treatment was performed by putting it in an alumina crucible (inner diameter: 40 mmφ) in a resistance furnace. The conditions for the first heat treatment are a nitrogen atmosphere pressure of 25 atm ± 10%, a furnace heating rate of 10 ° CZ min, a heating temperature of 1250 ° C ± 10%, and a heating time of 1 hour. By this treatment, a powdered aluminum nitride-containing material was obtained.

FIG. 12 is an X-ray diffraction chart of the powdered aluminum nitride-containing material obtained by the above treatment. From this chart, it is considered that the powdered aluminum nitride-containing material has a purity of nearly 100%.

The conventional A1N powder manufacturing method required high-temperature and high-pressure conditions where the atmospheric pressure of the nitrogen atmosphere was 100 atm and the processing temperature was 1600 ° C. According to this example, the low-temperature and low-pressure conditions of 1250 ° C and 25 atm were used. However, it was confirmed that A1N powder could be produced. This is thought to be because BN, which has excellent wettability with A1, functions as a catalyst.

[Example 8]

The thermal expansion characteristics of the aluminum nitride-containing material obtained in Example 6 were examined. In addition, the thermal expansion characteristics of aluminum alone and silicon alone were examined. A Shimadzu thermal analyzer TMA-50 was used for the measurement. The rate of temperature increase was 10 ° CZ, and the average amount of thermal expansion from room temperature to 500 ° C was measured.

FIG. 13 is a graph showing the measurement results of the thermal expansion amount. The vertical axis is the thermal expansion m) The horizontal axis is temperature (° C). Symbol a is the measurement result of the sample with a nitrogen atmosphere pressure of 10 atm in the second heat treatment (reheat treatment), and symbol b is the measurement result of the sample with a nitrogen atmosphere pressure of 30 atm in the second heat treatment (reheat treatment). Yes, symbol c is the measurement result of a sample with a nitrogen atmosphere pressure of 35 atm in the second heat treatment (reheat treatment). Symbol d is the measurement result for aluminum alone, and symbol e is the measurement result for silicon alone.

[0076] From this figure, by performing the second heat treatment (re-heat treatment), the remaining A1 is changed to A1N, and the remaining A1 is squeezed onto the surface of the sample, so that the thermal expansion is achieved. It was possible to reduce the rate. By adjusting the conditions for the second heat treatment, the thermal expansion coefficient of the aluminum nitride-containing material can be made close to the thermal expansion coefficient of A1N alone. Specifically, the higher the pressure of the nitrogen atmosphere in the second heat treatment, the closer the thermal expansion rate of the aluminum nitride-containing material is to the value of A1N alone. Note that the conditions of the second heat treatment of 1300 ° C, 35 atm, and 1 hour are considered to be close to the critical point at which the agglomerated solid (balta) -like force also changes to powder,

[0077] (Example 9)

FIG. 14 is a graph showing the relationship between the thermal expansion coefficient of the aluminum nitride-containing material and the nitrogen atmosphere pressure in the second heat treatment. The same sample as in Example 7 was used. In the figure, X indicates the coefficient of thermal expansion of silicon alone, and y in the figure indicates the coefficient of thermal expansion of aluminum nitride by the conventional sintering method!

[0078] According to this figure, when the pressure of the nitrogen atmosphere in the second heat treatment exceeds 20 atm, the coefficient of thermal expansion decreases rapidly. This is thought to be because the nitriding reaction of A1 and the squeezing effect of A1 become prominent at 20 atm or higher. Therefore, in order to obtain an agglomerated solid (Balta) -like aluminum nitride-containing material that is stable at high temperatures, the pressure of the nitrogen atmosphere in the second heat treatment is preferably 25 to 35 atm. .

[Example 10]

FIG. 15 is a graph showing the relationship between the electrical conductivity of the aluminum nitride-containing material and the nitrogen atmosphere pressure in the second heat treatment. The same sample as in Example 7 was used. The conductivity was measured by the four-terminal method, using electrical resistance and a saddle shape.

[0080] According to this figure, when the pressure of the nitrogen atmosphere in the second heat treatment is 20 atm or less, the nitride Lumium-containing materials show the same electrical conductivity as ordinary metal materials, but when the second heat treatment is performed at a pressure exceeding 20 atm, the conductivity of aluminum nitride-containing materials decreases rapidly. In particular, at 35 atmospheres or more, the conductivity was almost zero, and it could be said to be an insulator.

[0081] (Example 11)

The micro Vickers hardness of the aluminum nitride-containing material obtained in Example 6 was measured. FIG. 16 is a graph showing the relationship between the atmospheric pressure of the nitrogen atmosphere in the second heat treatment and the Micro Vickers hardness of the generated A1N-containing material. In all samples, the processing temperature is 1300 ° C. and the processing time is one hour. As the atmospheric pressure in the nitrogen atmosphere increases, the micro Vickers hardness of the A1N-containing material increases. Such a tendency can be obtained because, as shown in FIG. 10, the volume percentage of A1N contained in the A1N-containing material increases as the pressure of the nitrogen atmosphere increases.

[0082] Specifically, when the nitrogen atmosphere is 20 atm, the hardness is slightly higher than that of Duralumin (trademark). In addition, when the nitrogen atmosphere is 30 atm, the hardness is higher than that of special steel for tools (for example molybdenum steel). Thus, it can be seen that the aluminum nitride-containing material according to the present example has high hardness, high wear resistance, and excellent mechanical properties.

[0083] (Example 12)

The thermal conductivity of the aluminum nitride-containing material obtained in Example 6 was measured.

FIG. 17 is a graph showing the relationship between the atmospheric pressure of the nitrogen atmosphere in the second heat treatment and the thermal conductivity of the generated A1N-containing material. For all samples, the processing temperature is 1300 ° C and the processing time is one hour. As shown in this figure, when the nitrogen atmosphere is 30 atm, it has higher thermal conductivity than the A1N sintered body formed by the sintering method. Thus, it can be seen that the A1N-containing material according to this example has excellent heat conduction properties!

[0084] (Example 13)

As a raw material, agglomerated aluminum (purity 99.99% or more) crushed into small pieces and powdered boron nitride (purity 99.9% or more) were weighed to a weight ratio of 6: 1, and the carbon shown in Figure 1 The first heat treatment was performed by putting it in an alumina crucible (inner diameter: 40 mmφ) in a resistance furnace. The conditions for the first heat treatment are a nitrogen atmosphere pressure of 10 atm ± 10%, a furnace heating rate of 10 ° CZ min, a heating temperature of 1100 ° C ± 10%, and a heating time of 1 hour. By this treatment, agglomerated solid ( Balta-like aluminum nitride-containing material (diameter 40 mmφ, thickness 20 mm) was obtained.

[0085] After that, the second heat treatment was performed a plurality of times, and the relationship between the aluminum nitride content (measured by X-ray diffraction) of the aluminum nitride-containing material and the number of times of the second heat treatment was determined as follows.

It investigated in the case of ° C and the case of 1200 ° C, respectively. In all second heat treatments, the nitrogen atmosphere pressure is 15 atmospheres.

[0086] The results are shown in FIG. From this figure, as the number of second heat treatment increases, aluminum nitride

-It can be seen that the content of hum increases. Also, the aluminum nitride content is

(2) The number of times of performing the second heat treatment in a short time is increased more than when the heat treatment is performed once.

[0087] In addition, when the temperature of the second heat treatment is 1200 ° C, the aluminum nitride content increases with a relatively small number of treatments compared to the case where the temperature of the second heat treatment is 1150 ° C. In this case, the nitriding reaction of aluminum proceeds rapidly.

[0088] (Example 14)

The aluminum nitride-containing material obtained in Example 13 (the treatment temperature in the second heat treatment is 1150 ° C. and the number of treatments is 3 times) is immersed in an aqueous solution of sodium hydroxide and the aluminum contained in the aluminum nitride-containing material is removed. Melted. Figure 19 shows the SEM photograph of this sample. From this photograph, it can be seen that aluminum nitride is formed in a network. In the case of aluminum nitride that is isolated without forming a network, the network force is cut off by the dissolution of aluminum and flows into the aqueous sodium hydroxide solution.

[0089] In the above-described embodiments, the force using boron nitride as the nitride. Magnesium nitride and calcium nitride also have the free energy of formation close to that of boron nitride, and it is considered that similar results can be obtained. .

Industrial applicability

Since the aluminum nitride-containing material according to the present invention is hard and has high thermal conductivity, it is used as a semiconductor material, a base for mounting a semiconductor light emitting device such as a light emitting diode and a semiconductor laser, and a material for an internal combustion engine. be able to.

Claims

The scope of the claims

[I] A nitridation comprising a first heat treatment step for producing an aluminum nitride-containing material containing aluminum nitride by heating aluminum and nitride in the same container under a nitrogen atmosphere to melt the aluminum. A method for producing an aluminum-containing material.

[2] The method for producing an aluminum nitride-containing material according to [1], wherein heating is performed in a state where the aluminum is positioned on the nitride in the container.

[3] The method for producing an aluminum nitride-containing material according to [1] or [2], wherein the nitride is in a powder form.

[4] The method for producing an aluminum nitride-containing material according to any one of [1] to [3], wherein the nitride is at least one selected from the group consisting of boron nitride, magnesium nitride, and calcium nitride force.

[5] The method for producing an aluminum nitride-containing material according to any one of [1] to [4], wherein a heat treatment temperature in the first heat treatment step is set to 900 ° C or higher and 1400 ° C or lower.

6. The method for producing an aluminum nitride-containing material according to any one of claims 1 to 5, wherein in the first heat treatment step, the nitrogen gas atmosphere is a pressurized atmosphere.

7. The method for producing an aluminum nitride-containing material according to claim 6, wherein the nitrogen gas atmosphere is 50 atm or less.

8. The method for producing an aluminum nitride-containing material according to any one of claims 1 to 7, wherein the aluminum nitride-containing material is in a lump shape.

[9] The nitriding according to any one of [1] to [8], further comprising a second heat treatment step of cooling the aluminum nitride-containing material after the first heat treatment step and then heat-treating again in a nitrogen gas atmosphere. A method for producing an aluminum-containing material.

[10] After the first heat treatment step, the aluminum nitride-containing material contains aluminum nitride and aluminum,

10. The method for producing an aluminum nitride-containing material according to claim 9, wherein the second heat treatment increases the aluminum nitride content of the aluminum nitride-containing material and decreases the aluminum content.

[II] In the second heat treatment step, the nitrogen gas atmosphere is a pressurized atmosphere. Or the manufacturing method of the aluminum nitride containing material of 10.

12. The method for producing an aluminum nitride-containing material according to claim 11, wherein the nitrogen gas atmosphere in the second heat treatment step is 50 atm or less.

[13] The method for producing an aluminum nitride-containing material according to any one of [10] to [12], wherein the second heat treatment step is performed under a condition in which the nitriding reaction of A1 proceeds more easily than the first heat treatment step. .

14. The method for producing an aluminum nitride-containing material according to any one of claims 10 to 12, wherein a heat treatment temperature in the second heat treatment step is equal to or higher than a heat treatment temperature in the first heat treatment step.

15. The heat treatment temperature in the first heat treatment step is 900 ° C. or more and 1200 ° C. or less, and the heat treatment temperature in the second heat treatment step is 1100 ° C. or more and 1200 ° C. or less. A method for producing an aluminum nitride-containing material according to claim 1.

[16] The method for producing an aluminum nitride-containing material according to any one of [9] to [15], wherein the second heat treatment step is repeated a plurality of times.

[17] Aluminum nitride containing aluminum nitride and aluminum nitride are produced by heating aluminum and nitride in the same container in an inert gas atmosphere to melt the aluminum, thereby forming a massive aluminum nitride containing material containing aluminum nitride and aluminum Manufacturing method.