JP2008174448A - Crystalline turbostratically structured boron nitride - Google Patents
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本発明は、結晶性乱層構造窒化硼素に関する。 The present invention relates to crystalline boron layered boron nitride.
窒化硼素（ＢＮ）は硼素と窒素からなる化合物であるが、炭素とほぼ同じ結晶構造を有する多形が存在する。すなわち、窒化硼素には無定形窒化硼素（以下、ａ−ＢＮという）、六角形の網目層が二層周期で積層した構造を持つ六方晶系窒化硼素（以下、ｈ−ＢＮという）、六角形の網目が三層周期で積層した構造を持つ菱面体晶系窒化硼素（以下、ｒ−ＢＮという）、六角形の網目層がランダムに積層した構造を持つ乱層構造窒化硼素（以下、ｔ−ＢＮという）、高圧下の安定相であるジンクブレンド型窒化硼素（以下、ｃ−ＢＮという）及びウルツアイト型窒化硼素（以下、ｗ−ＢＮという）が知られている。 Boron nitride (BN) is a compound composed of boron and nitrogen, but there are polymorphs having substantially the same crystal structure as carbon. That is, the boron nitride includes amorphous boron nitride (hereinafter referred to as a-BN), hexagonal boron nitride (hereinafter referred to as h-BN) having a structure in which hexagonal network layers are laminated in a two-layer cycle, hexagonal Rhombohedral boron nitride (hereinafter referred to as r-BN) having a structure in which a network of three layers is stacked in a three-layer cycle, and a turbostratic boron nitride (hereinafter referred to as t-) having a structure in which hexagonal network layers are randomly stacked. BN), zinc blend type boron nitride (hereinafter referred to as c-BN) and wurtzite type boron nitride (hereinafter referred to as w-BN) which are stable phases under high pressure are known.
上記の窒化硼素の多形の内、背景技術において材料として実用性が認められているのはｈ−ＢＮとｃ−ＢＮのみである。ｈ−ＢＮは黒鉛より耐酸化性に優れている安定相であり、合成された結晶性ｈ−ＢＮ粉末の粒子は通常六角板状の自形を有しており、黒鉛と同様に良好な耐熱性、機械加工性（切削加工性）及び固体潤滑性を有しているが、黒鉛と異なり白色で優れた絶縁性を有する。他方ａ−ＢＮは不安定で吸湿性があるため、ａ−ＢＮの状態では使用できない。典型的なｈ−ＢＮとａ−ＢＮのＣｕＫα線による粉末Ｘ線回折図を図１と図２に示す。 Of the above polymorphs of boron nitride, only h-BN and c-BN are recognized as practical materials in the background art. h-BN is a stable phase that is superior in oxidation resistance to graphite, and the synthesized crystalline h-BN powder particles usually have a hexagonal plate-like self-shape. , Mechanical workability (cutting workability) and solid lubricity, but unlike graphite, it is white and has excellent insulation. On the other hand, since a-BN is unstable and hygroscopic, it cannot be used in the state of a-BN. The powder X-ray diffraction patterns of typical h-BN and a-BN with CuKα rays are shown in FIGS.
図１から分かるように、ｈ−ＢＮの粉末Ｘ線回折図では［００２］［１００］［１０１］［１０２］及び［００４］の回折線が顕著である。これに対して図２のａ−ＢＮの粉末Ｘ線回折図ではｈ−ＢＮの粉末Ｘ線回折図の［１００］回折線と［１０１］回折線の位置にある［１００］と［１０１］回折線が合体したブロードな（半価幅の大きい）回折線と、ｈ−ＢＮの粉末Ｘ線回折図の［００２］回折線の位置にあるブロードな回折線とがあるのみで、他の回折線は見当らないか、存在したとしてもブロードで存在が不明瞭な弱い回折線しか存在しない。ａ−ＢＮの構造では硼素と窒素からなる六角網目層が発達しておらず、発達していない微小な六角網目層の積層構造にも規則性がないものである。 As can be seen from FIG. 1, the diffraction lines [002] [100] [101] [102] and [004] are prominent in the powder X-ray diffraction pattern of h-BN. On the other hand, in the powder X-ray diffraction diagram of a-BN in FIG. 2, [100] and [101] diffraction at the positions of the [100] diffraction line and the [101] diffraction line of the powder X-ray diffraction diagram of h-BN. There is only a broad diffraction line with a combined line and a broad diffraction line at the position of the [002] diffraction line in the powder X-ray diffraction diagram of h-BN. There are only weak diffraction lines that are broad and unclear even if they exist. In the structure of a-BN, the hexagonal network layer composed of boron and nitrogen is not developed, and the laminated structure of the minute hexagonal network layer that is not developed does not have regularity.
ｈ−ＢＮの結晶では硼素と窒素からなる発達した六角網目層が・・ａａ'ａａ'ａａ'ａａ'ａ・・のパターンで積層した結晶構造を有しており、六角網目層が３層周期で積層したものがｒ−ＢＮである。 The crystal of h-BN has a crystal structure in which developed hexagonal network layers composed of boron and nitrogen are laminated in a pattern of aa'aa'aa'aa'a ... The layer laminated with is r-BN.
六角網目層は発達しているが六角網目層の積層構造に規則性のないものをｔ−ＢＮという。広義に解釈するとａ−ＢＮも乱層構造の窒化硼素であると考えられるので、たとえば非特許文献１では粉末Ｘ線回折図がブロードな回折線しか示さない窒化硼素をｔ−ＢＮと記載しているが、このような窒化硼素はｔ−ＢＮと区別してａ−ＢＮであるとするのが妥当である。
A hexagonal network layer is developed, but the layered structure of the hexagonal network layer has no regularity is called t-BN. When interpreted broadly, a-BN is considered to be boron nitride having a disordered layer structure. For example, in
本発明の目的は、新規な窒化硼素である結晶性乱層構造窒化硼素（以下、「結晶性ｔ−ＢＮ」という）を提供することである。 An object of the present invention is to provide a crystalline boron layered boron nitride (hereinafter referred to as “crystalline t-BN”) which is a novel boron nitride.
本発明の第１視点によれば、ＣｕＫα線によるＸ線回折パターンが、２θが２０°〜３０°の範囲に位置する六方晶系窒化硼素の［００２］回折ピークに相当する（００１）回折ピークと、２θが４０°〜５０°の範囲に位置する六方晶系窒化硼素の［１００］及び［１０１］回折ピークに相当する回折ピークが一部重複して結合した（１０）回折ピークと、２θが５０°〜６０°の範囲に位置する六方晶系窒化硼素の［００４］回折ピークに相当する（００２）回折ピークと、を有し、２θが５０°付近に六方晶系窒化硼素の［１０２］回折ピークに相当するシャープな回折ピークを有さない結晶性ｔ−ＢＮを提供する。結晶性ｔ−ＢＮは水に対して不活性である。 According to the first aspect of the present invention, the X-ray diffraction pattern by CuKα rays corresponds to the [002] diffraction peak of hexagonal boron nitride in which 2θ is in the range of 20 ° to 30 ° (001) diffraction peak. And (10) a diffraction peak in which diffraction peaks corresponding to the [100] and [101] diffraction peaks of hexagonal boron nitride whose 2θ is in the range of 40 ° to 50 ° are partially overlapped and 2θ Having a (002) diffraction peak corresponding to the [004] diffraction peak of hexagonal boron nitride in the range of 50 ° to 60 °, and 2θ of [102] of hexagonal boron nitride in the vicinity of 50 °. ] Crystalline t-BN that does not have a sharp diffraction peak corresponding to the diffraction peak is provided. Crystalline t-BN is inert to water.
上記第１視点の好ましい形態によれば、（１０）回折ピークは、六方晶系窒化硼素の［１００］回折ピークに相当する回折ピークの高角度側に、六方晶系窒化硼素の［１０１］回折ピークに相当する裾を引いて広がった形の回折ピークを有する。 According to the preferred form of the first aspect, the (10) diffraction peak is located on the high angle side of the diffraction peak corresponding to the [100] diffraction peak of hexagonal boron nitride, and [101] diffraction of hexagonal boron nitride. It has a diffraction peak with a shape that broadens with a tail corresponding to the peak.
上記第１視点の好ましい形態によれば、結晶性ｔ−ＢＮは一次粒子の大きさがサブミクロンである。 According to a preferred embodiment of the first aspect, the crystalline t-BN has a primary particle size of submicron.
本発明は、以下の効果のうち少なくとも１つを有する。 The present invention has at least one of the following effects.
本発明の結晶性ｔ−ＢＮは、水に対して不活性である。また、本発明の結晶性ｔ−ＢＮは、結晶粒子径（一次粒子径と同じ）が細かく、一次粒子の粒径が揃っていて、焼結性が良好である。 The crystalline t-BN of the present invention is inert to water. Further, the crystalline t-BN of the present invention has a fine crystal particle diameter (same as the primary particle diameter), uniform primary particle diameter, and good sinterability.
本発明者らは、先に出願した特願平９−２１０５２号に生産性に優れた結晶性ｔ−ＢＮ微粉末の製造方法を提案した。本発明は、特願平９−２１０５２号に記載した結晶性ｔ−ＢＮ微粉末の有する特徴である、湿気に対して不活性であり、結晶粒子径（一次粒子径と同じ）が細かく、一次粒子の粒径が揃っていて、焼結性が良好な結晶性ｔ−ＢＮ微粉末を提案するものである。 The present inventors proposed a method for producing crystalline t-BN fine powder having excellent productivity in Japanese Patent Application No. 9-21052 filed earlier. The present invention is characterized by the crystalline t-BN fine powder described in Japanese Patent Application No. 9-21052, which is inert to moisture, and has a fine crystal particle diameter (same as the primary particle diameter). The present invention proposes a crystalline t-BN fine powder having a uniform particle size and good sinterability.
本発明の結晶性ｔ−ＢＮの粉末Ｘ線回折図の一例を図３に示す。図３から分かるように、この粉末Ｘ線回折図ではｈ−ＢＮの粉末Ｘ線回折図の［００２］及び［００４］回折線に対応する回折線がシャープな回折線となっているが、［１００］回折線に対応する回折線が高角度側に裾を引いて広がった形をしていて［１０１］に対応する回折線が弱く目立たず、［１０２］に対応する回折線は存在しないか、存在しても非常に弱い。この［１０２］に対応する回折線は六角網目層が規則的に積層していることによって始めて現れる回折線である。 An example of the powder X-ray diffraction pattern of the crystalline t-BN of the present invention is shown in FIG. As can be seen from FIG. 3, in this powder X-ray diffraction diagram, diffraction lines corresponding to [002] and [004] diffraction lines of the h-BN powder X-ray diffraction diagram are sharp diffraction lines. 100] Diffraction lines corresponding to [102] do not exist because diffraction lines corresponding to [101] are weak and inconspicuous because the diffraction lines corresponding to the diffraction lines are widened with a skirt on the high angle side. Even if it exists, it is very weak. The diffraction line corresponding to [102] is a diffraction line that appears only when the hexagonal mesh layers are regularly stacked.
結晶性ｔ−ＢＮ微粉末を製造する好ましい方法は、前述の特願平９−２１０５２号に記載された結晶性ｔ−ＢＮ微粉末の製造方法、すなわち有効量の溶融硼酸アルカリを共存させて窒素等の非酸化性雰囲気中でａ−ＢＮ粉末を加熱し、ａ−ＢＮをｔ−ＢＮに結晶化させる方法である。複合セラミックス焼結体は多くの場合多孔質の焼結体であるが、結晶性ｔ−ＢＮ微粉末はサブミクロンの微細な一次粒子からなっているのでｈ−ＢＮ粉末より焼結しやすく、成形するとａ−ＢＮを混合した粉末より緻密な成形体になり、焼結すれば緻密な複合焼結体となる。この複合焼結体は気孔率が相当あっても強度が比較的大きい。微細な結晶性ｔ−ＢＮ微粒子が焼結時にｈ−ＢＮに転移しないで焼結体中に残存している場合には微細な結晶性ｔ−ＢＮ微粒子の存在によって微細な気孔が形成され、焼結体中の気孔はサブミクロンサイズの微細な平均気孔径を有するものとなる。 A preferred method for producing the crystalline t-BN fine powder is a method for producing the crystalline t-BN fine powder described in the above-mentioned Japanese Patent Application No. 9-21052, that is, nitrogen in the presence of an effective amount of molten alkali borate. A-BN powder is heated in a non-oxidizing atmosphere such as a to crystallize a-BN into t-BN. In many cases, the composite ceramic sintered body is a porous sintered body, but the crystalline t-BN fine powder is composed of fine sub-micron primary particles, so that it is easier to sinter and form than the h-BN powder. Then, it becomes a denser compact than the powder mixed with a-BN, and if it is sintered, it becomes a dense composite sintered body. This composite sintered body has a relatively high strength even if the porosity is considerable. When fine crystalline t-BN fine particles remain in the sintered body without being transferred to h-BN at the time of sintering, fine pores are formed due to the presence of fine crystalline t-BN fine particles. The pores in the aggregate have a fine average pore size of submicron size.
特願平９−２１０５２号に記載されている結晶性ｔ−ＢＮ微粉末の合成方法は、たとえば次の通りである。出発原料に尿素と硼酸及び少量の硼酸アルカリからなる硼素より窒素成分が過剰な混合物を出発原料に用い、硼酸ナトリウムの共存下で加熱して９５０℃以下で反応させ、ａ−ＢＮを主体とし硼酸やナトリウムイオンを含むカルメ焼き状の中間生成物を得る。次いでこの中間生成物を１ｍｍ以下に粉砕して窒素雰囲気中で約１３００℃に加熱し、結晶化させると結晶性ｔ−ＢＮが生成する。この結晶化した反応物を水、特に温純水で洗浄（必要に応じてアルカリ成分の中和洗浄のために酸を用いる）して精製すると、純度が高く、円板状又は球状の形状を有する微細な一次粒子からなる結晶性ｔ−ＢＮ微粉末が得られる。結晶性ｔ−ＢＮ微粉末の微細な一次粒子は集合してミクロンサイズの二次粒子となっているが、アトリションミルなどで湿式粉砕すれば、微細な一次粒子にまで容易に微粉砕することができる。結晶性ｔ−ＢＮ微粉末の一次粒子は、微細な円板状又は球状であることによって微粉砕された混合粉末を成形するときに六角板状のｈ−ＢＮ粒子のように配向しないので、複合焼結体としても熱膨張率の成形時の方向による差異が殆どない焼結体が得られるという利点がある。また、前述の製造方法によって高純度の結晶性ｔ−ＢＮを製造できる。 The method for synthesizing the crystalline t-BN fine powder described in Japanese Patent Application No. 9-21052 is, for example, as follows. The starting material is a mixture of urea, boric acid, and a small amount of alkali borate, which contains an excess of nitrogen components. The mixture is heated in the presence of sodium borate and reacted at 950 ° C. or lower, and boric acid mainly composed of a-BN. And a calme-baked intermediate product containing sodium ions. Next, this intermediate product is pulverized to 1 mm or less, heated to about 1300 ° C. in a nitrogen atmosphere, and crystallized to produce crystalline t-BN. When this crystallized reaction product is purified by washing with water, particularly warm pure water (if necessary, an acid is used for neutralization washing of the alkali component), it is highly pure and has a fine disk shape or spherical shape. Crystalline t-BN fine powder composed of primary particles can be obtained. Fine primary particles of crystalline t-BN fine powder are aggregated to form micron-sized secondary particles. If wet pulverized with an attrition mill, etc., they can be easily pulverized to fine primary particles. Can do. The primary particles of the crystalline t-BN fine powder are not oriented like the hexagonal plate-like h-BN particles when forming a finely pulverized mixed powder by being a fine disc or spherical. As a sintered body, there is an advantage that a sintered body having almost no difference in the coefficient of thermal expansion depending on the molding direction can be obtained. Moreover, highly purified crystalline t-BN can be manufactured with the above-mentioned manufacturing method.
結晶性ｔ−ＢＮ微粉末を複合セラミックス焼結体の原料に用いる利点は、前述の方法によって従来市販されているｈ−ＢＮ粉末と比べて安価に製造でき、結晶性ｔ−ＢＮ微粉末の一次粒子が微細であることによってセラミックス混合粉末の成形体が焼結しやすく、多孔質な複合焼結体の場合も強度が大きく、窒化硼素が結晶性ｔ−ＢＮの状態で焼結体中に残留している場合には微細で揃った大きさの気孔を有する複合セラミックス焼結体が得られる点である。また、原料にａ−ＢＮ粉末を使用方法と比較すると、結晶性ｔ−ＢＮ微粉末はａ−ＢＮ粉末と比べて湿気などの水分に対して安定であるので焼結体の原料として使いやすく、ａ−ＢＮ粉末を混合したセラミックス混合粉末と比べて密度の大きい成形体が得られ、密度の大きい複合セラミックス焼結体が得られる点である。背景技術に係るｈ−ＢＮ粉末を含む複合セラミックス焼結体の場合と同じく、本発明の製造方法による窒化硼素含有複合セラミックス焼結体は、ｈ−ＢＮ及び／又はｔ−ＢＮを焼結体の内部に含有していることによってヤング率が小さく熱伝導率が大きいので耐熱衝撃性に優れており、固体潤滑性があり、溶融金属に対して優れた耐食性を有し、電気絶縁性に優れている等の好ましい特徴がある。 The advantage of using the crystalline t-BN fine powder as a raw material for the composite ceramic sintered body is that the crystalline t-BN fine powder can be produced at a lower cost than the commercially available h-BN powder by the above-described method. Due to the fineness of the particles, the compact of the ceramic mixed powder is easy to sinter, and in the case of a porous composite sintered body, the strength is high, and boron nitride remains in the sintered body in a crystalline t-BN state. In this case, a composite ceramic sintered body having fine and uniform pores can be obtained. Compared with the method of using a-BN powder as a raw material, the crystalline t-BN fine powder is more stable than moisture such as moisture than the a-BN powder, so it is easy to use as a raw material for a sintered body. Compared with the ceramic mixed powder in which the a-BN powder is mixed, a compact having a higher density is obtained, and a composite ceramic sintered body having a higher density is obtained. As in the case of the composite ceramic sintered body containing the h-BN powder according to the background art, the boron nitride-containing composite ceramic sintered body according to the production method of the present invention comprises h-BN and / or t-BN. Because it has a low Young's modulus and high thermal conductivity, it has excellent thermal shock resistance, solid lubricity, excellent corrosion resistance against molten metal, and excellent electrical insulation. There are preferable characteristics such as being.
結晶性ｔ−ＢＮ微粉末の微粉砕や他のセラミックス粉末との混合、あるいは粉砕を兼ねる混合は分散性のよいアルコールなどを媒体とする湿式のボールミルやアトリションミルによって行なうのが好ましい。複合セラミックス焼結体の原料とするセラミックス混合粉末に混合する窒化硼素粉末は微細である方が成形体の焼結性がよく、前述の製造方法によって得られる結晶性ｔ−ＢＮ微粉末の一次粒子は平均粒径が０．４μｍ以下と微細であるのでこの結晶性ｔ−ＢＮ微粉末を混合したセラミックス混合粉末の成形体は焼結性に優れていて好ましい。複合セラミックス焼結体の製造方法としては、無加圧焼結又は加圧焼結のいずれを採用してもよいが、無加圧焼結を採用すれば、製造できる複合焼結体の形状に自由度があり、各種の形状と寸法の複合セラミックス焼結体を安価に製造できる点で好ましい。 The fine pulverization of crystalline t-BN powder, mixing with other ceramic powders, or mixing that also serves as pulverization is preferably performed by a wet ball mill or attrition mill using alcohol having good dispersibility as a medium. The finer the boron nitride powder mixed with the ceramic mixed powder used as the raw material of the composite ceramic sintered body, the better the sintered body of the molded body, and the primary particles of the crystalline t-BN fine powder obtained by the above-mentioned manufacturing method. Since the average particle size is as fine as 0.4 μm or less, a ceramic mixed powder compact in which this crystalline t-BN fine powder is mixed is preferable because of its excellent sinterability. As a method for producing a composite ceramic sintered body, either pressureless sintering or pressure sintering may be employed. However, if pressureless sintering is employed, the shape of the composite sintered body that can be produced is obtained. It is preferable in that it has a degree of freedom and can produce composite ceramic sintered bodies of various shapes and dimensions at low cost.
以下、本発明を実施例によって具体的に説明するが、以下の実施例は本発明の一実施例であって本発明を限定するものではない。 EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the following examples are only examples of the present invention and do not limit the present invention.
［結晶性ｔ−ＢＮの合成］結晶性ｔ−ＢＮ微粉末を次のようにして合成した。無水硼酸（Ｂ２Ｏ３）３．５ｋｇ、尿素（（ＮＨ２）２ＣＯ）５．３ｋｇ、硼砂（Ｎａ２Ｂ４Ｏ７・１０Ｈ2Ｏ）０．６３ｋｇからなる混合物を出発原料とし、この混合物を直径５３０ｍｍの蓋付きステンレス鋼製容器に入れ、この反応容器を炉内に入れて２５０〜５００℃、５００〜６００℃、６００〜７００℃、７００〜８００℃、８００〜９００℃の各段階にそれぞれ１０分かけて昇温し、最後は９００±１℃に１０分間保持して反応させた（合計１時間）。この間１００℃を超えたところで水蒸気が噴出し始め、２００℃で成分が溶融し始め、ぶくぶくと泡が出てガスの放出を伴って反応が進んだ。３５０〜４００℃まで主に水蒸気を放出し、９００℃に１０分間保持したところガス（水蒸気及び炭酸ガス）の放出が減少した。 [Synthesis of Crystalline t-BN] Crystalline t-BN fine powder was synthesized as follows. A mixture of 3.5 kg of anhydrous boric acid (B 2 O 3 ), 5.3 kg of urea ((NH 2 ) 2 CO) and 0.63 kg of borax (Na 2 B 4 O 7 · 10H 2 O) was used as a starting material. The mixture is put in a stainless steel vessel with a lid having a diameter of 530 mm, and this reaction vessel is put in a furnace and each stage of 250 to 500 ° C., 500 to 600 ° C., 600 to 700 ° C., 700 to 800 ° C., and 800 to 900 ° C. The temperature was raised over 10 minutes, and finally, the reaction was carried out by holding at 900 ± 1 ° C. for 10 minutes (total 1 hour). During this time, water vapor began to spout at a temperature exceeding 100 ° C., components began to melt at 200 ° C., and bubbles burst out and the reaction proceeded with gas release. When water vapor was mainly released from 350 to 400 ° C. and kept at 900 ° C. for 10 minutes, the release of gas (water vapor and carbon dioxide) decreased.
この後放冷して反応容器の蓋を開けたところ、反応容器中の混合物はＢ２Ｏ３が反応を完了してカルメ焼き状の反応物となっていた。このカルメ焼き状の反応物を反応容器中で解砕し、真空吸引して反応容器中から取り出し、粉砕して１ｍｍ目の篩を通した。この粉砕した反応物をアルミナ製の蓋付き匣鉢に入れて蓋を閉じ、窒素雰囲気とした電気炉中で１３００℃まで１０時間かけて昇温し、この温度に２時間保持し、その後放冷した。匣鉢から取り出した粉末を８０〜８５℃に温めたイオン交換水で洗浄してアルカリ成分と硼酸成分を除き、次いで希塩酸で中和し、さらに温めたイオン交換水で洗浄して乾燥し、純度の高い結晶性ｔ−ＢＮ微粉末を得た。この一連の工程による結晶性ｔ−ＢＮ微粉末の収量は出発原料１０ｋｇに対して約２．８ｋｇであり、出発原料中の仕込み硼素量に基く製造歩留は７０％以上であった。ｔ−ＢＮの純度は水洗の程度により９０−９７％以上に亘る。 Thereafter, the reaction vessel was allowed to cool and the lid of the reaction vessel was opened. As a result, B 2 O 3 completed the reaction in the mixture in the reaction vessel and became a carme-baked reaction product. The carme-baked reaction product was crushed in a reaction vessel, vacuumed and taken out from the reaction vessel, crushed and passed through a 1 mm sieve. The pulverized reaction product is put in an alumina lidded pot and closed, and the temperature is raised to 1300 ° C. over 10 hours in an electric furnace with a nitrogen atmosphere. This temperature is maintained for 2 hours and then allowed to cool. did. The powder taken out from the mortar is washed with ion exchange water warmed to 80 to 85 ° C. to remove the alkali and boric acid components, then neutralized with dilute hydrochloric acid, further washed with warm ion exchange water and dried. High crystalline t-BN fine powder was obtained. The yield of crystalline t-BN fine powder by this series of steps was about 2.8 kg with respect to 10 kg of the starting material, and the production yield based on the amount of boron charged in the starting material was 70% or more. The purity of t-BN ranges from 90 to 97% or more depending on the degree of water washing.
得られた結晶性ｔ−ＢＮ微粉末をエタノールを媒体として直径１．２ｍｍのジルコニアビーズを用いるアトリションミル（芦沢鉄工所社製パールミル）によって２時間微粉砕した。微粉砕後の結晶性ｔ−ＢＮ微粉末について粒度分布を調べた（堀場製粒度分布アナライザＬＡ−７００使用）結果、約９５％が１μｍ以下の微粒子となっており、平均粒径は約０．３０μｍであった。また、窒素吸着法で測定した粉末の比表面積は１２ｍ２／ｇであった。 この結晶性ｔ−ＢＮ微粉末のＣｕＫα線による粉末Ｘ線回折図を図３に、１３３００倍に拡大した結晶性ｔ−ＢＮ微粉末の顕微鏡写真を図４に、同結晶性ｔ−ＢＮ微粉末をアトリションミルで微粉砕後の粒度分布グラフを図５にそれぞれ示す。また、図４の拡大電子 顕微鏡写真から分かるように、この結晶性ｔ−ＢＮ微粉末の一次粒子の平均結晶粒径は約０．２７μｍであり、結晶性ｔ−ＢＮ微粉末の一次粒子は円板状又は球状の粒子からなっている。 The obtained crystalline t-BN fine powder was finely pulverized for 2 hours by an attrition mill (Pearl Mill manufactured by Serizawa Iron Works Co., Ltd.) using ethanol as a medium and zirconia beads having a diameter of 1.2 mm. As a result of examining the particle size distribution of the finely pulverized crystalline t-BN powder (using a Horiba particle size distribution analyzer LA-700), about 95% are fine particles of 1 μm or less, and the average particle size is about 0.00. It was 30 μm. Moreover, the specific surface area of the powder measured by the nitrogen adsorption method was 12 m 2 / g. FIG. 3 shows a powder X-ray diffraction pattern of the crystalline t-BN fine powder by CuKα ray, FIG. 4 shows a micrograph of the crystalline t-BN fine powder magnified 13300 times, and FIG. 4 shows the crystalline t-BN fine powder. FIG. 5 shows the particle size distribution graphs after pulverizing with an attrition mill. Further, as can be seen from the enlarged electron micrograph of FIG. 4, the average crystal grain size of the primary particles of the crystalline t-BN fine powder is about 0.27 μm, and the primary particles of the crystalline t-BN fine powder are circular. It consists of plate-like or spherical particles.
結晶性ｔ−ＢＮ微粉の純度は、洗浄の程度により自由にコントロールでき、９０％以上〜９７％以上さらに９８％、９９％以上の高純度のものまで得られる。残留分としては、上記の方法で得られる結晶性ｔ−ＢＮ微粉はＢ２Ｏ３を主体とする。従って、所定量の残留Ｂ２Ｏ３を含有する結晶性ｔ−ＢＮ微粉を用いれば、残留Ｂ２Ｏ３が焼結助剤の役割も果たすので、焼結性の一層の増進に資する。 The purity of the crystalline t-BN fine powder can be freely controlled depending on the degree of washing, and it can be obtained in high purity of 90% to 97% or more, 98% or 99% or more. As a residue, the crystalline t-BN fine powder obtained by the above method is mainly composed of B 2 O 3 . Therefore, if crystalline t-BN fine powder containing a predetermined amount of residual B 2 O 3 is used, residual B 2 O 3 also serves as a sintering aid, contributing to further enhancement of sinterability.
本発明の結晶性乱層構造窒化硼素は、上記実施形態に基づいて説明されているが、上記実施形態に限定されることなく、本発明の範囲内において、かつ本発明の基本的技術思想に基づいて、上記実施形態に対し種々の変形、変更及び改良を含むことができることはいうまでもない。また、本発明の請求の範囲の枠内において、種々の開示要素の多様な組み合わせ・置換ないし選択が可能である。 The crystalline disordered layer boron nitride of the present invention has been described based on the above embodiment, but is not limited to the above embodiment, and is within the scope of the present invention and within the basic technical idea of the present invention. It goes without saying that various modifications, changes and improvements can be included in the above embodiment. Further, various combinations, substitutions, or selections of various disclosed elements are possible within the scope of the claims of the present invention.
本発明のさらなる課題、目的及び展開形態は、請求の範囲を含む本発明の全開示事項からも明らかにされる。 Further problems, objects, and developments of the present invention will become apparent from the entire disclosure of the present invention including the claims.
Claims (3)
２θが２０°〜３０°の範囲に位置する六方晶系窒化硼素の［００２］回折ピークに相当する（００１）回折ピークと、
２θが４０°〜５０°の範囲に位置する六方晶系窒化硼素の［１００］及び［１０１］回折ピークに相当する回折ピークが一部重複して結合した（１０）回折ピークと、
２θが５０°〜６０°の範囲に位置する六方晶系窒化硼素の［００４］回折ピークに相当する（００２）回折ピークと、を有し、
２θが５０°付近に六方晶系窒化硼素の［１０２］回折ピークに相当するシャープな回折ピークを有さない結晶性乱層構造窒化硼素であって、
水に対して不活性であることを特徴とする結晶性乱層構造窒化硼素。 X-ray diffraction pattern by CuKα ray
A (001) diffraction peak corresponding to the [002] diffraction peak of hexagonal boron nitride in which 2θ is in the range of 20 ° to 30 °;
(10) a diffraction peak in which diffraction peaks corresponding to [100] and [101] diffraction peaks of hexagonal boron nitride located in the range of 2θ in the range of 40 ° to 50 ° are partially overlapped;
A (002) diffraction peak corresponding to the [004] diffraction peak of hexagonal boron nitride in which 2θ is located in the range of 50 ° to 60 °, and
A crystalline turbostratic boron nitride that does not have a sharp diffraction peak corresponding to the [102] diffraction peak of hexagonal boron nitride in the vicinity of 2θ of 50 °,
Crystalline disordered boron nitride characterized by being inert to water.
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| JPH01305861A (en) * | 1988-06-01 | 1989-12-11 | Koransha Co Ltd | Compound body of boron nitride type ceramic |
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