JP4223518B2 - Cubic boron nitride abrasive and method for producing cubic boron nitride abrasive - Google Patents
Cubic boron nitride abrasive and method for producing cubic boron nitride abrasive Download PDFInfo
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Description
本発明は、砥石等に用いられる立方晶窒化ホウ素（以下、ＣＢＮという場合もある。）の砥粒、この砥粒を六方晶窒化ホウ素（以下、ＨＢＮという場合もある。）から製造する方法、さらにこの砥粒を用いた研削砥石に関する。 The present invention relates to abrasive grains of cubic boron nitride (hereinafter sometimes referred to as CBN) used for a grindstone and the like, and a method for producing the abrasive grains from hexagonal boron nitride (hereinafter sometimes referred to as HBN). Furthermore, it is related with the grinding wheel using this abrasive grain.
ＣＢＮは、ダイヤモンドに次ぐ硬さとそれを凌ぐ化学的安定性を持ち、研削・研磨・切削材用の砥粒としての需要が増大している。立方晶窒化ホウ素の製造方法は種々提案されているが、この中で最も良く知られ、工業的にも広く利用されているのは、ＨＢＮをＣＢＮ合成用触媒（溶媒ということもある。）の存在下で、約４〜６ＧＰａ、約１４００〜１６００℃程度の立方晶窒化ホウ素の熱力学的安定領域内に保持し、六方晶窒化ホウ素を立方晶窒化ホウ素に変換する方法である（例えば特許文献１〜７）。この際に使用されるＣＢＮ合成用触媒としては、アルカリ金属やアルカリ土類金属およびこれらの窒化物やホウ窒化物、その他の化合物などが知られており、これらが単独で、または二種類以上組み合わせて用いられる。これらのＣＢＮ合成用触媒は、原料のＨＢＮと混合して用いられる場合が多く、通常、粉体、塊状など、ＨＢＮと混合し易い形態で用いられる。 CBN has hardness next to diamond and chemical stability surpassing that, and demand for abrasive grains for grinding, polishing, and cutting materials is increasing. Various methods for producing cubic boron nitride have been proposed. Among them, the most well known and widely used industrially is HBN as a catalyst for CBN synthesis (sometimes called a solvent). In the presence, it is a method in which hexagonal boron nitride is converted into cubic boron nitride while being held in a thermodynamically stable region of cubic boron nitride of about 4 to 6 GPa and about 1400 to 1600 ° C. (for example, patent document) 1-7). Known catalysts for synthesizing CBN used in this case include alkali metals, alkaline earth metals, nitrides, boronitrides, and other compounds thereof, which are used alone or in combination of two or more. Used. These CBN synthesis catalysts are often used in a mixture with raw material HBN, and are usually used in a form that can be easily mixed with HBN, such as powder and lump.
これらのＣＢＮ合成用触媒は、酸素や水等との反応性が高いため、酸化物や水酸化物、更には炭酸塩等の物質に変質しやすい。その結果、触媒としての機能が低下してしまい、生成するＣＢＮの特性や収率の低下等の悪影響を及ぼすことが知られている。その為、これらＣＢＮ合成用触媒を取り扱う場合には、水分、酸素、二酸化炭素等との接触により、ＣＢＮ合成用触媒が変質、劣化しないように、乾燥窒素ガス等を流したグローブボックス内などで、細心の注意のもとで取り扱われる。 Since these catalysts for CBN synthesis have high reactivity with oxygen, water, etc., they are easily transformed into substances such as oxides, hydroxides, and carbonates. As a result, it is known that the function as a catalyst is lowered, and adverse effects such as a reduction in the characteristics and yield of CBN produced are known. Therefore, when handling these catalysts for CBN synthesis, in a glove box where dry nitrogen gas or the like is flowed so that the catalyst for CBN synthesis does not deteriorate or deteriorate due to contact with moisture, oxygen, carbon dioxide, etc. , Treated with great care.
また、ＣＢＮ合成中に原料中の酸素や水分によって触媒の劣化が進行することも知られており、例えば原料ＨＢＮ中の酸素源（主として酸化ホウ素等の酸化物）を取り除くことによって触媒の劣化を抑制する方法が開示されている（例えば特許文献８〜１３）。これらの文献では、合成中に原料ＨＢＮ中の酸化ホウ素等の酸素源を取り除くため、原料中に炭素源を混合して使用する方法や、合成前の原料ＨＢＮの還元処理、炭素源を添加した原料ＨＢＮの加熱処理等によって、酸素源を取り除く方法も開示されている。
これらの方法によって、原料ＨＢＮ中の酸素源が減少することで触媒の劣化が抑制され、ＣＢＮの特性や収率が向上してきた。
By these methods, the deterioration of the catalyst is suppressed by reducing the oxygen source in the raw material HBN, and the characteristics and yield of CBN have been improved.
これら開示されている方法では、炭素源添加の効果で原料ＨＢＮ中に含まれる酸化ホウ素等のＣＢＮ成長阻害物質が除去されるため、結晶面の発達が阻害されにくくなり、シャープエッジを有する結晶や大型の結晶が得やすい、ＣＢＮ核が発生しやすい、合成条件が低下する、等の効果があると記述されている。即ちここで用いられている炭素源は、原料ＨＢＮ中の不純物を取り除く効果があると考えられ、ＣＢＮの特性と収率を向上させる効果があると考えられる。 In these disclosed methods, CBN growth-inhibiting substances such as boron oxide contained in the raw material HBN are removed by the effect of the carbon source addition, so that the development of the crystal plane is less likely to be inhibited, and crystals having sharp edges or It is described that there are effects such as easy to obtain large crystals, easy generation of CBN nuclei, and reduced synthesis conditions. That is, the carbon source used here is considered to have an effect of removing impurities in the raw material HBN, and is considered to have an effect of improving the characteristics and yield of CBN.
しかしながら、原料ＨＢＮ中の不純物除去だけではＣＢＮの強度の向上が不十分であり、また加熱による強度低下も大きいままである。これはＣＢＮ合成時にＣＢＮ中に取り込まれる触媒成分の影響と考えられる。また、添加した炭素源がＣＢＮ中に取り込まれ（例えば特許文献１４〜１７）ＣＢＮが破砕しやすくなる傾向があることも報告されている。
そのため、これらのＣＢＮを砥石に用いた場合、高負荷研削等の厳しい加工条件の用途では、ＣＢＮが摩滅・磨耗や破砕しやすく、強度や耐熱強度の高いＣＢＮが待ち望まれていた。勿論、従来の炭素源を添加しないＣＢＮ合成用触媒を用いた場合には、炭素源の取り込みによるＣＢＮ結晶の強度低下は認められないものの、原料ＨＢＮ中のＣＢＮ成長阻害物質を除去する効果が無いため、成長阻害やＣＢＮ中への不純物の取り込み等の影響で、ＣＢＮの特性や収率の向上は望めない。
However, the removal of impurities in the raw material HBN alone is not enough to improve the strength of CBN, and the strength reduction due to heating remains large. This is considered to be due to the influence of the catalyst component incorporated into CBN during CBN synthesis. It has also been reported that the added carbon source is taken into CBN (for example, Patent Documents 14 to 17), and CBN tends to be easily crushed.
Therefore, when these CBN are used for a grindstone, CBN is easily worn out, worn, or crushed in applications with severe processing conditions such as high load grinding, and a CBN having high strength and heat resistance has been awaited. Of course, when a conventional catalyst for CBN synthesis without addition of a carbon source is used, there is no effect of removing CBN growth inhibitory substances in the raw material HBN, although a decrease in the strength of CBN crystals due to incorporation of the carbon source is not observed. For this reason, improvement in the characteristics and yield of CBN cannot be expected due to the effects of growth inhibition and incorporation of impurities into CBN.
本発明者らは、ＣＢＮ合成原料中に炭素源を添加した場合、ＣＢＮ特性や収率の向上は認められるものの、高負荷研削等の厳しい加工条件の用途向けにはまだ不十分であるという問題を解決すべく鋭意検討した。その結果、本発明者らは、原料中の不純物のうち、ＣＢＮ合成用触媒中の不純物（触媒劣化成分）を低減または除去することで、ＣＢＮの強度向上と加熱時の強度低下抑制が可能であることを見出し、本発明を完成させた。
本発明によれば、ＣＢＮ合成用触媒の劣化成分を低減または抑制することでＣＢＮの強度が向上することから、使用する有機物は、従来の方法の場合と異なり、ＣＢＮ中に炭素として取り込まれ難くなっているものと考えられる。また、ＣＢＮの加熱後の強度低下が抑制されることから、ＣＢＮ中に取り込まれる触媒成分が減少していると考えられる。
すなわち本発明は、
（１）立方晶窒化ホウ素１ｍｏｌに含まれる立方晶窒化ホウ素合成触媒成分が２．４×１０ −４ 〜７．５×１０ −４ ｍｏｌであり、大気中１１００℃で１時間加熱したときのタフネス値の低下が１０％以下である単結晶からなる立方晶窒化ホウ素砥粒、
（２）立方晶窒化ホウ素に含まれる立方晶窒化ホウ素合成触媒成分が、アルカリ金属、アルカリ土類金属のうち少なくとも１種類以上を含む（１）に記載の単結晶からなる立方晶窒化ホウ素砥粒、
（３）立方晶窒化ホウ素に含まれる立方晶窒化ホウ素合成触媒成分が、リチウム、カルシウム、マグネシウム、バリウムのうち少なくとも１種類以上を含む（１）または（２）の何れか１項に記載の単結晶からなる立方晶窒化ホウ素砥粒、
（４）立方晶窒化ホウ素に含まれる立方晶窒化ホウ素合成触媒成分が、リチウムまたはカルシウムを含む（１）に記載の単結晶からなる立方晶窒化ホウ素砥粒、
（５）立方晶窒化ホウ素１ｍｏｌに含まれる立方晶窒化ホウ素合成触媒成分が２．４×１０ −４ 〜５．０×１０ −４ ｍｏｌである（１）から（４）の何れか１項に記載の単結晶からなる立方晶窒化ホウ素砥粒、
（６）立方晶窒化ホウ素１ｍｏｌに含まれる立方晶窒化ホウ素合成触媒成分が２．４×１０ −４ 〜２．５×１０ −４ ｍｏｌである（５）に記載の単結晶からなる立方晶窒化ホウ素砥粒、
（７）不活性ガス雰囲気下で形成される有機物層を表面に有する立方晶窒化ホウ素合成用触媒を用いて六方晶窒化ホウ素から立方晶窒化ホウ素を合成する立方晶窒化ホウ素砥粒の製造方法、
（８）（１）から（６）の何れか１項に記載の単結晶からなる立方晶窒化ホウ素砥粒を用いた研削砥石、
（９）研削砥石の結合材がガラス質のビトリファイドボンドである（８）に記載の研削砥石、である。
When the carbon source is added to the CBN synthesis raw material, the present inventors can improve the CBN characteristics and yield, but are still insufficient for applications with severe processing conditions such as high load grinding. We studied hard to solve this problem. As a result, the present inventors can improve the strength of CBN and suppress the strength reduction during heating by reducing or removing impurities (catalyst degradation component) in the catalyst for CBN synthesis among the impurities in the raw material. As a result, the present invention was completed.
According to the present invention, since the strength of CBN is improved by reducing or suppressing the degradation component of the catalyst for CBN synthesis, the organic substance to be used is unlikely to be incorporated as carbon in CBN, unlike the conventional method. It is thought that. Moreover, since the strength fall after heating of CBN is suppressed, it is thought that the catalyst component taken in in CBN is reducing.
That is, the present invention
(1) Cubic boron nitride synthesis catalyst component contained in 1 mol of cubic boron nitride is 2.4 × 10 −4 to 7.5 × 10 −4 mol, and toughness when heated at 1100 ° C. in the air for 1 hour. Cubic boron nitride abrasive grains composed of a single crystal whose value is 10% or less ,
(2) The cubic boron nitride abrasive comprising the single crystal according to (1) , wherein the cubic boron nitride synthesis catalyst component contained in the cubic boron nitride includes at least one of alkali metals and alkaline earth metals. ,
(3) The single element according to any one of (1) and (2) , wherein the cubic boron nitride synthesis catalyst component contained in cubic boron nitride contains at least one of lithium, calcium, magnesium, and barium. Cubic boron nitride abrasive grains ,
(4) A cubic boron nitride abrasive comprising a single crystal according to (1) , wherein the cubic boron nitride synthesis catalyst component contained in the cubic boron nitride contains lithium or calcium ,
(5) The cubic boron nitride synthesis catalyst component contained in 1 mol of cubic boron nitride is 2.4 × 10 −4 to 5.0 × 10 −4 mol in any one of (1) to (4) Cubic boron nitride abrasive grains comprising the described single crystal ,
(6) Cubic nitriding composed of a single crystal according to (5) , wherein the cubic boron nitride synthesis catalyst component contained in 1 mol of cubic boron nitride is 2.4 × 10 −4 to 2.5 × 10 −4 mol. Boron abrasive ,
(7) A method for producing cubic boron nitride abrasive grains, in which cubic boron nitride is synthesized from hexagonal boron nitride using a catalyst for synthesizing cubic boron nitride having an organic layer formed on an inert gas atmosphere on the surface ,
(8) A grinding wheel using cubic boron nitride abrasive grains made of the single crystal according to any one of (1) to (6) ,
(9) The grinding wheel according to (8) , wherein the binder of the grinding wheel is a vitreous vitrified bond.
本発明のＣＢＮ砥粒は、触媒成分の取り込みが従来より少ないＣＢＮ砥粒であって、不活性ガス雰囲気下で形成される有機物層を表面に有するＣＢＮ合成用触媒を用いることによって合成することができる。本発明のＣＢＮ砥粒は強度が高く、加熱による強度の低下が小さいＣＢＮ砥粒であり、また（１１１）面が良く発達し、シャープエッジを持つＣＢＮ砥粒であるため、高負荷研削等の厳しい研削条件下で使用する砥石用途に好適である。 CBN abrasive particles of the present invention is a uptake conventional fewer CBN abrasive particles of the catalyst component, be synthesized by using a CBN synthesis catalyst having an organic substance layer formed in an inert gas atmosphere on the surface it can. The CBN abrasive grains of the present invention are high-strength CBN abrasive grains that have a small decrease in strength due to heating, and are well-developed (111) surfaces with sharp edges. Suitable for grindstone applications used under severe grinding conditions.
以下、本発明を詳細に説明する。
本発明のＣＢＮ砥粒は、従来の方法で合成されたＣＢＮ砥粒よりＣＢＮ合成用触媒成分の取り込み量が少ない結晶である。即ち、これらの成分がＣＢＮ結晶中に取り込まれていることに起因すると考えられる結晶欠陥や、加熱時の結晶劣化の低下が少ないため、ＣＢＮ砥粒の強度が大きく、加熱時の強度低下が小さくなるものと考えられる。
ＣＢＮの合成方法には触媒を用いる方法と用いない方法がある。触媒を用いない方法で合成されたＣＢＮは、一般に多結晶や微細結晶組織のＣＢＮとなり、これらは合成時に触媒を使用しないため触媒成分の取り込みは基本的に無い。しかし、結晶組織が微細なために加熱時に酸化し易く、強度は高いが加熱による強度低下が大きい。そのため本発明のＣＢＮ砥粒は、触媒を用いて合成される実質的に単結晶からなるＣＢＮ砥粒であり、触媒を用いないで合成される多結晶や微細結晶組織のＣＢＮ砥粒は含まない。
Hereinafter, the present invention will be described in detail.
The CBN abrasive grain of the present invention is a crystal having a smaller amount of catalyst component for CBN synthesis than the CBN abrasive grain synthesized by the conventional method. That is, since the crystal defects considered to be due to these components being incorporated into the CBN crystal and the decrease in crystal deterioration during heating are small, the strength of the CBN abrasive grains is large, and the decrease in strength during heating is small. It is considered to be.
CBN synthesis methods include a method using a catalyst and a method not using it. CBN synthesized by a method that does not use a catalyst is generally CBN having a polycrystalline or fine crystal structure, and since these do not use a catalyst during synthesis, there is basically no incorporation of catalyst components. However, since the crystal structure is fine, it is easily oxidized during heating, and the strength is high, but the strength is greatly reduced by heating. Therefore, the CBN abrasive grain of the present invention is a CBN abrasive grain composed substantially of a single crystal synthesized using a catalyst, and does not include CBN abrasive grains of a polycrystalline or fine crystal structure synthesized without using a catalyst. .
ＣＢＮ合成用触媒成分のＣＢＮ砥粒結晶中への取り込み量として好ましい量は、触媒成分のうちアルカリ金属、アルカリ土類金属等の金属元素が、ＢＮ分子１ｍｏｌに対して、７．５×１０−４ｍｏｌ以下、好ましくは５．０×１０−４ｍｏｌ以下、より好ましくは２．５×１０−４ｍｏｌ以下である。ＣＢＮ分子１ｍｏｌに対して、７．５×１０−４ｍｏｌ以上取り込まれると、欠陥の生成などによると考えられる強度低下が顕著になる。また、研削加工などでＣＢＮの温度が上昇した場合を考えると、加熱によってＣＢＮ中に取り込まれた触媒成分がＣＢＮと反応して結晶の劣化が起こり、ＣＢＮ強度の低下は大きくなる。 A preferable amount of the catalyst component for CBN synthesis incorporated into the CBN abrasive grain crystal is 7.5 × 10 − with respect to 1 mol of a BN molecule of metal elements such as alkali metal and alkaline earth metal among the catalyst components. 4 mol or less, preferably 5.0 × 10 −4 mol or less, more preferably 2.5 × 10 −4 mol or less. When 7.5 × 10 −4 mol or more is incorporated with respect to 1 mol of the CBN molecule, a decrease in strength considered to be due to generation of defects becomes remarkable. Further, considering the case where the temperature of the CBN is increased by grinding or the like, the catalyst component taken into the CBN by heating reacts with the CBN to cause crystal deterioration, and the decrease in the CBN intensity increases.
本発明のＣＢＮ砥粒を製造するために使用されるＣＢＮ合成用触媒は、酸化物や水酸化物、炭酸塩等の触媒劣化成分の少ない、または、触媒劣化成分を含まない触媒である。更に詳しく述べると、このＣＢＮ合成用触媒は、触媒粒子表面に炭素及び水素を主たる成分とする有機物を反応させ、触媒粒子表面に有機物層を形成させたものである。
ＣＢＮ合成用触媒成分としては、ＨＢＮをＣＢＮに変換可能な触媒を使用でき、具体例を示すと、アルカリ金属（Ｌｉなど）およびこれらの窒化物（Ｌｉ３Ｎなど）やホウ窒化物（Ｌｉ３ＢＮ２など）、アルカリ土類金属（Ｃａ，Ｍｇ，Ｓｒ，Ｂａなど）およびこれらの窒化物（Ｃａ３Ｎ２，Ｍｇ３Ｎ２，Ｓｒ３Ｎ２，Ｂａ３Ｎ２など）やホウ窒化物（Ｃａ３Ｂ２Ｎ４，Ｍｇ３Ｂ２Ｎ４，Ｓｒ３Ｂ２Ｎ４，Ｂａ３Ｂ２Ｎ４など）、アルカリ金属とアルカリ土類金属の複合ホウ窒化物（ＬｉＣａＢＮ２，ＬｉＢａＢＮ２など）などが挙げられ、これらが単独で、または二種類以上組み合わせて用いられる。
The catalyst for synthesizing CBN used for producing the CBN abrasive grains of the present invention is a catalyst with little or no catalyst deterioration component such as oxide, hydroxide and carbonate. More specifically, this CBN synthesis catalyst is obtained by reacting an organic substance containing carbon and hydrogen as main components on the catalyst particle surface to form an organic substance layer on the catalyst particle surface.
As a catalyst component for CBN synthesis, a catalyst capable of converting HBN into CBN can be used. Specific examples include alkali metals (such as Li) and nitrides thereof (such as Li 3 N) and boronitrides (Li 3). BN 2 etc.), alkaline earth metals (Ca, Mg, Sr, Ba etc.) and their nitrides (Ca 3 N 2 , Mg 3 N 2 , Sr 3 N 2 , Ba 3 N 2 etc.) and boronitrides (Ca 3 B 2 N 4 , Mg 3 B 2 N 4 , Sr 3 B 2 N 4 , Ba 3 B 2 N 4, etc.), composite boronitrides of alkali metals and alkaline earth metals (LiCaBN 2 , LiBaBN 2, etc.) These are used alone or in combination of two or more.
ＣＢＮ合成用触媒成分の形状としては特に制限はないが、１５０μｍ以下の粒径（１５０メッシュ以下）の粉末状であることが好ましい。ＣＢＮ合成用触媒成分の粒度が大きすぎると、高温高圧下でＣＢＮ砥粒を合成する際にＨＢＮとの反応性が低下する可能性があるためである。
ＣＢＮ合成用触媒は、触媒表面に劣化成分を生成し難いように、例えば酸素濃度１００ｐｐｍ以下、露点−６０度以下に管理された窒素ガスのような不活性ガスのグローブボックス中などで取り扱うのが好ましい。
Although there is no restriction | limiting in particular as a shape of the catalyst component for CBN synthesis, It is preferable that it is a powder form with a particle size of 150 micrometers or less (150 mesh or less). This is because if the particle size of the catalyst component for CBN synthesis is too large, the reactivity with HBN may be reduced when CBN abrasive grains are synthesized under high temperature and pressure.
The catalyst for CBN synthesis is handled in, for example, a glove box of an inert gas such as nitrogen gas controlled to have an oxygen concentration of 100 ppm or less and a dew point of -60 degrees or less so that it is difficult to generate a deteriorated component on the catalyst surface. preferable.
触媒成分表面の有機物層を形成する有機物は、触媒表面との反応性を考えると液体状態または気体状態で触媒と接触させ、有機物層を形成させることが好ましい。常温で固体状態の有機物で有機物層を形成したい場合は、触媒との混合等によって機械的に接触させても良いが、混合時に有機物の融点以上に加熱することによって有機物層を形成させることがより好ましい。 Considering the reactivity with the catalyst surface, the organic material forming the organic material layer on the surface of the catalyst component is preferably brought into contact with the catalyst in a liquid state or a gas state to form an organic material layer. If you want to form an organic layer with organic material that is solid at room temperature, it may be mechanically contacted by mixing with a catalyst, etc., but it is more preferable to form an organic layer by heating above the melting point of the organic material during mixing. preferable.
ＣＢＮ合成用触媒の劣化成分は、主として触媒粒子の表面に存在すると考えられ、主に触媒の粉砕や原料ＨＢＮとの混合など取り扱い中の劣化と、原料ＨＢＮが触媒成分に溶解しＣＢＮとして析出する際にＨＢＮと共に溶け込む酸化ホウ素などの酸素不純物や、合成原料中の水分等による合成中の劣化で生成すると考えられる。
そのため、触媒劣化成分の低減または除去には、合成前の取り扱い時に触媒劣化成分を低減または除去すると共に、合成中の触媒劣化成分の生成を抑制する必要がある。
触媒成分の劣化が進行すると、合成時にＣＢＮ成長を阻害すると共に、ＣＢＮ結晶中に触媒成分と共に取り込まれることによって、結晶欠陥が生成し、加熱時にはＣＢＮと反応することによって結晶強度が低下する。
The deterioration component of the catalyst for CBN synthesis is considered to be mainly present on the surface of the catalyst particles. The deterioration during handling such as pulverization of the catalyst and mixing with the raw material HBN, and the raw material HBN dissolve in the catalyst component and precipitate as CBN. At this time, it is considered to be generated due to deterioration during synthesis due to oxygen impurities such as boron oxide which dissolve together with HBN or moisture in the synthesis raw material.
Therefore, in order to reduce or remove the catalyst deterioration component, it is necessary to reduce or remove the catalyst deterioration component during handling before the synthesis and to suppress the generation of the catalyst deterioration component during the synthesis.
When the deterioration of the catalyst component progresses, CBN growth is inhibited during synthesis, and is incorporated together with the catalyst component into the CBN crystal, thereby generating crystal defects, and the crystal strength is reduced by reacting with CBN during heating.
取り扱い中のＣＢＮ合成用触媒成分の劣化は、乾燥された窒素ガス雰囲気のグローブボックス中等の酸素量や水分量が厳密に管理された状態で取り扱うことによって抑制することが出来る。但し、そのままでは触媒表面は反応性が高いため、原料ＨＢＮと混合した場合、原料ＨＢＮ中の酸化ホウ素や水分等の不純物と反応し、触媒劣化成分を生成する。更に合成装置に装填する際に大気と接触した場合や、合成中に原料ＨＢＮを溶かし込む場合等、触媒成分の劣化が進行すると考えられる。 Deterioration of the catalyst component for CBN synthesis during handling can be suppressed by handling in a state where the amount of oxygen and moisture in the glove box in a dry nitrogen gas atmosphere are strictly controlled. However, since the catalyst surface is highly reactive as it is, when it is mixed with the raw material HBN, it reacts with impurities such as boron oxide and moisture in the raw material HBN to generate a catalyst deterioration component. Further, it is considered that deterioration of the catalyst component proceeds when it comes into contact with the atmosphere when loaded into the synthesis apparatus or when the raw material HBN is dissolved during synthesis.
また特許文献１４では、ＣＢＮ粒子中に炭素を０．０２〜２．０％含有させるために、ＣＢＮ合成のための高温高圧下において分解して炭素残渣を残す有機物、例えば各種合成樹脂類、油脂類、アルコール類を、原料粉末と混合、原料粉末成形体をそれらの液体または溶液中に浸漬して含浸、或いは原料粉末またはその成形体に蒸着もしくはコーティングする方法が開示されている。特許文献１４の実施例の中にＣＢＮ合成用触媒に有機物を被覆した場合が含まれていないが、本明細書の比較例で後述するように特許文献１４の方法では、本発明の方法に比べてＣＢＮの特性、収率共に劣っている。この原因について詳細は明らかではないが、ＣＢＮ中への炭素や触媒成分の取り込み量などから、原料ＨＢＮとの混合時や合成中に触媒表面に有機物層が維持されず、炭素源を原料中に均一混合した従来の方法と同じ状態になっているためと推測される。これは有機物で被覆する際に既にＣＢＮ合成用触媒表面が劣化した状態であり、触媒表面と有機物の間に結合力が生じないためと推測される。 Moreover, in patent document 14, in order to make CBN particle | grain contain 0.02-2.0% of carbon, the organic substance which decomposes | disassembles under high temperature and high pressure for CBN synthesis, and leaves a carbon residue, for example, various synthetic resins, fats and oils And a method of mixing alcohols with raw material powder, impregnating raw material powder compacts by immersing them in a liquid or solution thereof, or depositing or coating raw material powders or compacts thereof. The example of Patent Document 14 does not include a case where an organic substance is coated on the catalyst for CBN synthesis, but the method of Patent Document 14 is compared with the method of the present invention as will be described later in Comparative Examples of the present specification. Therefore, the characteristics and yield of CBN are inferior. The details of this cause are not clear, but due to the amount of carbon and catalyst components taken into CBN, the organic layer is not maintained on the catalyst surface during mixing with raw material HBN or during synthesis, and the carbon source is contained in the raw material. This is presumed to be in the same state as the conventional method in which uniform mixing is performed. This is presumably because the surface of the catalyst for CBN synthesis has already deteriorated when it is coated with an organic substance, and no bonding force is produced between the catalyst surface and the organic substance.
一方で、本発明で使用されるＣＢＮ合成用触媒は触媒表面が劣化していない状態（反応性の高い状態）で有機物を接触させているため、有機物層中の有機物−ＣＢＮ合成用触媒間の反応によって化学結合が生成すると考えられる。その結合の結合力によって、原料ＨＢＮとの混合から高温高圧のＣＢＮ合成中にかけて、触媒表面に有機物層が保たれ、有機物層は触媒表面近傍で保護膜として機能しているため、触媒成分の劣化が抑制されるものと考えられる。 On the other hand, since the catalyst for CBN synthesis used in the present invention is in contact with an organic substance in a state where the catalyst surface is not deteriorated (highly reactive state), the organic substance in the organic substance layer-the catalyst for CBN synthesis It is thought that chemical bonds are formed by the reaction. The bond strength of the bond keeps the organic layer on the catalyst surface from mixing with the raw material HBN to high temperature and high pressure CBN synthesis, and the organic layer functions as a protective film near the catalyst surface. Is considered to be suppressed.
ＣＢＮ合成用触媒と接触させて有機物層を形成させる有機物の種類としては、炭化水素、芳香族、アルコール、エーテル、アミン、アルデヒド、ケトン、カルボン酸、エステル、アミド等の１種類以上を選択して使用できる。アルデヒド、ケトン、カルボン酸等の酸素を含む有機物を用いる場合は、分子量の大きいものの方が好ましく、一般に炭素数が８以上の化合物が好ましい。炭素数が少ないと有機物中の酸素の比率が高くなり、有機物層中の酸素の悪影響が出るためである。そのため、分子中に酸素を含まない化合物、例えば、炭化水素、アミン、アミド等がより好ましい。 As the kind of organic substance that is brought into contact with the catalyst for CBN synthesis to form an organic substance layer, one or more kinds such as hydrocarbon, aromatic, alcohol, ether, amine, aldehyde, ketone, carboxylic acid, ester, amide, etc. are selected. Can be used. In the case of using an organic substance containing oxygen such as aldehyde, ketone and carboxylic acid, those having a large molecular weight are preferred, and compounds having 8 or more carbon atoms are generally preferred. This is because when the number of carbon atoms is small, the ratio of oxygen in the organic matter increases, and the adverse effect of oxygen in the organic matter layer appears. Therefore, compounds that do not contain oxygen in the molecule, such as hydrocarbons, amines, amides, and the like are more preferable.
有機物層を形成するために必要な有機物量は、触媒の粒度や種類、有機物の種類によって異なるが、触媒に対して好ましくは０．１質量％から５０質量％の範囲、より好ましくは１質量％から３０％の範囲、更に好ましくは２質量％から２０質量％の範囲である。０．１質量％を下回ると触媒表面が充分被覆されずＣＢＮ砥粒の特性や収率の低下が顕著になる。また５０質量％を上回ると、炭素源が多すぎるためＣＢＮ結晶中に炭素源が取り込まれることによる特性の低下が顕著になる。
ＣＢＮ合成用触媒表面の有機物層の量の下限については、触媒表面の保護膜的な働きの他に、例えば原料ＨＢＮを触媒に溶かし込む際に、原料ＨＢＮ中の酸化ホウ素等の不純物と反応して触媒の劣化を抑制する働きもあると考えられるため、１質量％以上がより好ましく、２質量％以上が更に好ましい。また、上限については、例えば酸化ホウ素等の不純物量が少ない原料ＨＢＮを用いた場合などは炭素源が過剰になる場合も考えられ、その際にＣＢＮの成長を阻害したりＣＢＮ結晶中に取り込まれやすくなったりすることが考えられるため、３０質量％以下がより好ましく、２０質量％以下がより好ましい。
The amount of organic matter necessary to form the organic layer varies depending on the particle size and type of the catalyst and the type of organic matter, but is preferably in the range of 0.1% by mass to 50% by mass, more preferably 1% by mass with respect to the catalyst. To 30%, more preferably 2% to 20% by weight. When the amount is less than 0.1% by mass, the catalyst surface is not sufficiently coated, and the characteristics and yield of the CBN abrasive grains are significantly reduced. Moreover, when it exceeds 50 mass%, since there are too many carbon sources, the fall of the characteristic by a carbon source being taken in in a CBN crystal | crystallization will become remarkable.
Regarding the lower limit of the amount of the organic layer on the catalyst surface for CBN synthesis, in addition to the protective film function on the catalyst surface, for example, when the raw material HBN is dissolved in the catalyst, it reacts with impurities such as boron oxide in the raw material HBN. Therefore, 1% by mass or more is more preferable, and 2% by mass or more is more preferable. As for the upper limit, for example, when a raw material HBN having a small amount of impurities such as boron oxide is used, the carbon source may be excessive. In this case, the growth of CBN is inhibited or incorporated into the CBN crystal. Since it may be easier, 30% by mass or less is more preferable, and 20% by mass or less is more preferable.
ＣＢＮ合成用触媒の表面に有機物層を形成させる方法としては、表面が劣化していない状態のＣＢＮ合成用触媒と有機物とを接触させることにより、ＣＢＮ合成用触媒の表面に有機物層を形成させることが出来る。
具体的には、例えばアルカリ金属やアルカリ土類金属の窒化物、ホウ窒化物の場合、合成したＣＢＮ合成用触媒をグローブボックス中など酸素や水分の濃度が厳密に管理された雰囲気下で所定の粒度まで粉砕し、次いで有機物の蒸気に曝す、或いは有機物の液体や固体と混合する等によって有機物層を形成させる方法が例示できる。一旦ＣＢＮ合成用触媒表面に劣化成分が生成した場合も、純化によって劣化成分を除去すればよく、触媒を水素やアンモニアガスなどの還元雰囲気下で加熱処理した後、有機物と接触させることによって有機物層を形成させる方法が例示できる。
As a method of forming an organic substance layer on the surface of the catalyst for CBN synthesis, an organic substance layer is formed on the surface of the catalyst for CBN synthesis by bringing the CBN synthesis catalyst in an undegraded state into contact with the organic substance. I can do it.
Specifically, for example, in the case of a nitride or boronitride of an alkali metal or alkaline earth metal, the synthesized CBN synthesis catalyst is used in a glove box or the like under an atmosphere in which oxygen and moisture concentrations are strictly controlled. Examples thereof include a method of forming an organic layer by pulverizing to a particle size and then exposing to an organic vapor or mixing with an organic liquid or solid. Once a deteriorated component is generated on the surface of the catalyst for CBN synthesis, the deteriorated component may be removed by purification. After the catalyst is heated in a reducing atmosphere such as hydrogen or ammonia gas, the organic layer is brought into contact with the organic material. The method of forming can be illustrated.
この様にして表面に有機物層を形成させたＣＢＮ合成用触媒は、有機物層がＣＢＮ合成用触媒表面の保護膜として作用するため、従来のＣＢＮ合成用触媒では劣化してしまうような雰囲気でも触媒の劣化が抑制される。例えば大気中で取り扱った場合でも、酸素や水分との反応性が低くいため触媒の劣化が抑制される。 The catalyst for CBN synthesis having the organic layer formed on the surface in this manner is a catalyst even in an atmosphere where the organic layer acts as a protective film on the surface of the catalyst for CBN synthesis, so that the conventional catalyst for CBN synthesis deteriorates. Deterioration of is suppressed. For example, even when handled in the air, the catalyst is prevented from deteriorating because of its low reactivity with oxygen and moisture.
次に、以上のようにして有機物層を表面に形成したＣＢＮ合成用触媒を使用して、ＨＢＮをＣＢＮに変換し、ＣＢＮ砥粒を得る一例について説明する。
原料であるＨＢＮ粉末としては、例えば昭和電工（株）製ＵＨＰ−１（ＴＭ）グレードなどが例示できる。ついで、ＨＢＮ粉末１００質量部に対してＣＢＮ合成用触媒を１〜５０質量部程度の範囲で加え、ロッキングミキサー等で混合する。ついでこの混合物を密度１．５〜２．０ｇ／ｃｍ３に成形する。
そして、この成形体を、反応容器（例えば、特開２０００−２９０００５号公報の実施例において記載されているような反応容器）内に収納して、ＣＢＮ合成用触媒が溶融し、かつ、ＣＢＮが熱力学的に安定な温度・圧力条件で成形体を保持することにより、ＨＢＮがＣＢＮに変換される。
Next, an example of obtaining CBN abrasive grains by converting HBN into CBN using the CBN synthesis catalyst having the organic layer formed on the surface as described above will be described.
Examples of the HBN powder as a raw material include UHP-1 (TM) grade manufactured by Showa Denko K.K. Next, the catalyst for CBN synthesis is added in the range of about 1 to 50 parts by mass with respect to 100 parts by mass of the HBN powder, and mixed with a rocking mixer or the like. The mixture is then molded to a density of 1.5 to 2.0 g / cm 3 .
Then, the molded body is housed in a reaction vessel (for example, a reaction vessel as described in the examples of JP-A-2000-290005), the CBN synthesis catalyst is melted, and the CBN is By holding the molded body under thermodynamically stable temperature and pressure conditions, HBN is converted to CBN.
なお、ＣＢＮが熱力学的に安定である温度・圧力条件は、例えば、Ｏ．Ｆｕｋｕｎａｇａ，Ｄｉａｍｏｎｄ Ｒｅｌａｔ．Ｍａｔｅｒ．，９（２０００），７−１２に示されており、一般的には、約４〜６ＧＰａ、約１４００〜１６００℃の範囲内である。また、このような高温高圧下における保持時間は、一般的には約１秒〜６時間程度である。 The temperature and pressure conditions under which CBN is thermodynamically stable are, for example, O.D. Fukunaga, Diamond Relat. Mater. , 9 (2000), 7-12, generally in the range of about 4-6 GPa, about 1400-1600 ° C. In addition, the holding time under such a high temperature and high pressure is generally about 1 second to 6 hours.
その後、反応容器から合成塊（ＣＢＮ、ＨＢＮおよびＣＢＮ合成用触媒成分の混合物）を取り出して解砕し、ＣＢＮ砥粒を単離精製する。
単離精製方法としては、例えば特公昭４９−２７７５７号公報に開示されている方法を用いることが出来る。即ち、合成塊を例えば５ｍｍ以下に解砕した後、これに水酸化ナトリウムと少量の水を加え３００℃程度に加熱し、ＨＢＮを選択的に溶解させる。これを冷却後、酸で洗浄、水洗後、ろ過することによりＣＢＮ砥粒を得ることができる。
Thereafter, a synthetic lump (a mixture of CBN, HBN and CBN synthesis catalyst components) is taken out from the reaction vessel and pulverized to isolate and purify the CBN abrasive grains.
As an isolation and purification method, for example, the method disclosed in Japanese Patent Publication No. 49-27757 can be used. That is, after smashing the synthetic mass to, for example, 5 mm or less, sodium hydroxide and a small amount of water are added thereto and heated to about 300 ° C. to selectively dissolve HBN. CBN abrasive grains can be obtained by cooling, washing with acid, washing with water, and filtering.
このようにして得られたＣＢＮ砥粒は、有機物層を表面に形成したＣＢＮ合成用触媒を用いて合成されたものであるので、ＨＢＮからＣＢＮへの変換収率（ＣＢＮ収率）が高く、また得られたＣＢＮ砥粒は結晶面が良く発達し、シャープなエッジを持っている。更に得られたＣＢＮ砥粒の化学成分を分析すると炭素や触媒成分の取り込み量が従来より少ないため、結晶の強度が高く、加熱時の強度低下が小さくなる。 Since the CBN abrasive grains thus obtained were synthesized using a CBN synthesis catalyst having an organic layer formed on the surface, the conversion yield from HBN to CBN (CBN yield) was high, Further, the obtained CBN abrasive grains have a well-developed crystal surface and have sharp edges. Further, when the chemical components of the obtained CBN abrasive grains are analyzed, the amount of carbon and catalyst components incorporated is less than before, so that the crystal strength is high and the strength reduction during heating is small.
以上説明したように本発明のＣＢＮ砥粒は強度が高く、加熱時の強度低下が小さく、更に結晶面の発達したシャープエッジを有するため、研削用砥粒として、特に高負荷研削のような厳しい加工条件下で使用される砥石用途に好適である。また、ＣＢＮ合成用触媒表面に形成させた有機物層の効果で、有機物層形成後の触媒は大気中などの酸素や水分等との反応性が低く、グローブボックス内などで厳密に取り扱わなければならない従来のＣＢＮ合成用触媒に比べ格段に取り扱い性が向上した。よって、このようなＣＢＮ合成用触媒を使用することにより、工業的にＣＢＮ砥粒を生産するに際して作業や工程の簡略化が可能となり、生産性が向上した。 As described above, the CBN abrasive grains of the present invention are high in strength, small in strength reduction during heating, and have sharp edges with developed crystal planes. Suitable for grindstone applications used under processing conditions. In addition, due to the effect of the organic layer formed on the surface of the catalyst for CBN synthesis, the catalyst after forming the organic layer has low reactivity with oxygen, moisture, etc. in the atmosphere and must be handled strictly in the glove box. Compared with the conventional catalyst for CBN synthesis, the handling property was remarkably improved. Therefore, by using such a CBN synthesis catalyst, operations and processes can be simplified when industrially producing CBN abrasive grains, and productivity is improved.
以下、本発明について実施例を挙げて具体的に説明する。なお、以下に示す実施例により本発明は何ら限定されるものではない。
（実施例１〜２１）
乾燥した窒素ガスフローのグローブボックス中で振動ミルを用いて、表１に記載の各種触媒を５０μｍ以下に粉砕した。表１に記載の組み合わせ及び比率で、粉砕容器から取り出した触媒粉末と、液体状態の有機物とをロッキングミキサーで混合して、触媒表面に有機物層を形成させた。常温で固体状態の有機物を使用する場合は、混合容器を外部から加熱して、混合中に有機物が液体状態を維持できるようにした。
原料ＨＢＮ粉（昭和電工製ＵＨＰ−１（ＴＭ）グレード）１０質量部に対してＣＢＮ合成用触媒を表１の比率で配合・混合し、混合粉体を１．８５ｇ／ｃｍ３の成形密度になるように成形した。
そして、この成形体を、反応容器内に収納して、１４５０℃、５．０ＧＰａの高温高圧条件で１０分間処理した後、合成塊を取り出し、前述の方法によってＣＢＮを分離、回収した。
生成したＣＢＮの原料ＨＢＮに対する比率（ＣＢＮ収率）を表１に示す。このようにして得られたＣＢＮ砥粒は何れも、（１１１）面が発達したシャープエッジを持つ粒子が多く観察された。
Hereinafter, the present invention will be specifically described with reference to examples. In addition, this invention is not limited at all by the Example shown below.
(Examples 1 to 21)
Various catalysts listed in Table 1 were pulverized to 50 μm or less using a vibration mill in a dry glove box with a nitrogen gas flow. The catalyst powder taken out from the pulverization container and the organic substance in the liquid state were mixed with a rocking mixer in the combinations and ratios shown in Table 1 to form an organic substance layer on the catalyst surface. When using an organic substance in a solid state at room temperature, the mixing container was heated from the outside so that the organic substance could maintain a liquid state during mixing.
A catalyst for CBN synthesis is blended and mixed at a ratio shown in Table 1 with 10 parts by mass of raw material HBN powder (UHP-1 (TM) grade made by Showa Denko ) , and the mixed powder has a molding density of 1.85 g / cm 3. It shape | molded so that it might become.
The molded body was placed in a reaction vessel and treated for 10 minutes under high temperature and high pressure conditions of 1450 ° C. and 5.0 GPa. Then, the synthetic mass was taken out, and CBN was separated and collected by the method described above.
Table 1 shows the ratio (CBN yield) of the generated CBN to the raw material HBN. In the CBN abrasive grains thus obtained, many particles having a sharp edge with a developed (111) plane were observed.
（比較例１〜３）
表２に記載の組み合わせ及び比率で、ＣＢＮ合成用触媒、有機物をロッキングミキサーを用いて混合する際、混合容器中の雰囲気を乾燥窒素から大気に入れ替えた以外は、実施例１〜２１と同じ方法で触媒を作製し、その触媒を用いてＣＢＮを合成した。
ＣＢＮ収率を表２に示す。このようにして得られたＣＢＮ砥粒は（１１１）面のほかに（１００）面も発達した粒子が多く観察された。
(Comparative Examples 1-3)
The same method as in Examples 1 to 21 except that the atmosphere in the mixing vessel was changed from dry nitrogen to air when the catalyst for CBN synthesis and the organic substance were mixed using a rocking mixer in the combinations and ratios shown in Table 2. Then, a catalyst was prepared, and CBN was synthesized using the catalyst.
The CBN yield is shown in Table 2. In the CBN abrasive grains obtained in this way, many grains with (100) faces developed in addition to the (111) faces were observed.
（比較例４）
表３に記載の組み合わせ及び比率で、ＣＢＮ合成用触媒、有機物、及び原料ＨＢＮを、グローブボックス中でロッキングミキサーを用いて混合した。混合後は実施例１〜２１と同じ方法でＣＢＮを合成した。
ＣＢＮ収率を表３に示す。このようにして得られたＣＢＮ砥粒は（１１１）面のほかに（１００）面も発達した粒子が多く観察された。
(Comparative Example 4)
In the combinations and ratios shown in Table 3, the catalyst for CBN synthesis, the organic substance, and the raw material HBN were mixed in a glove box using a rocking mixer. CBN was synthesize | combined by the same method as Examples 1-21 after mixing.
The CBN yield is shown in Table 3. In the CBN abrasive grains obtained in this way, many grains with (100) faces developed in addition to the (111) faces were observed.
（比較例５〜１０）
表４に記載の組み合わせ及び比率で、ＣＢＮ合成用触媒と原料ＨＢＮを、グローブボックス中でロッキングミキサーを用いて混合した。混合後は実施例１〜２１と同じ方法でＣＢＮを合成した。
ＣＢＮ収率を表４に示す。このようにして得られたＣＢＮ砥粒は（１１１）面のほかに（１００）面も発達した粒子が多く観察され、形状は丸みを帯びたブロッキー形状であった。
(Comparative Examples 5 to 10)
With the combinations and ratios described in Table 4, the catalyst for CBN synthesis and the raw material HBN were mixed in a glove box using a rocking mixer. CBN was synthesize | combined by the same method as Examples 1-21 after mixing.
The CBN yield is shown in Table 4. In the CBN abrasive grains obtained in this manner, many particles with the (100) plane developed in addition to the (111) plane were observed, and the shape was a rounded blocky shape.
（実施例２２〜２５、比較例１１〜１８）
表５に記載の実施例および比較例のＣＢＮ砥粒を、ＪＩＳ Ｂ ４１３０：１９９８「ダイヤモンド／ＣＢＮ工具−ダイヤモンド又はＣＢＮと（砥）粒の粒度」に記載の粒度１４０／１７０に分級した。ＪＩＳ Ｂ ４１３０：１９９８に記載の粒度の表示１４０／１７０とは、目開きが１６５μｍ、１１６μｍ、９０μｍ、６５μｍの４枚の電成ふるいを用いた場合、１枚目の目開き１６５μｍの篩を９９．９％以上通過し、２枚目の目開き１１６μｍの篩上にとどまる量が１１％未満であり、３枚目の目開き９０μｍの篩上に８５％以上とどまり、同じ９０μｍの篩を通過する量が１１％以下であり、４枚目の目開き６５μｍの篩を通過する量が２％未満であるように、粒度調整されたものである。粒度１４０／１７０に調整されたＣＢＮについて、ＣＢＮの強度の指標の一つとして、砥粒の耐衝撃破砕性の指標であるタフネス値を測定した。
タフネス値は、得られた１４０／１７０のＣＢＮ一定量を、約１ｇの鋼球１個と共に容積２ｍｌの鉄製のカプセルに入れ、このカプセルを振動数３０００±１００回／分の振動機で３０．０±０．３秒間振動させ、カプセル内のＣＢＮを鋼球で粉砕した後、粉砕粉を７５μｍの篩網で篩い分けし、篩網上のＣＢＮ残存質量を粉砕粉全体に対する百分率で表すことで求められる。測定結果を表５に示す。
更に粒度１４０／１７０の粒を大気中１１００℃×１時間保持の条件で加熱処理した後、同様にタフネス値を測定し、加熱前のタフネス値からの低下率を算出した。加熱によるタフネス値の低下率を表５に示す。また、粒度１４０／１７０の粒について化学分析を行い、ＣＢＮ中に含まれる触媒成分（触媒中の金属元素）量を調査した。また一部についてはＣＢＮ中に含まれる炭素量も調査した。結果を表５に示す。
(Examples 22 to 25, Comparative Examples 11 to 18)
The CBN abrasive grains of Examples and Comparative Examples described in Table 5 were classified into JIS B 4130: 1998 “Diamond / CBN Tool—Grain Size of Diamond or CBN and (Abrasive) Grain” to 140/170. The particle size indication 140/170 described in JIS B 4130: 1998 is that when four electroscreens having openings of 165 μm, 116 μm, 90 μm, and 65 μm are used, the first sieve having a mesh opening of 165 μm is 99. Passing 9% or more, the amount remaining on the second sieve having a mesh size of 116 μm is less than 11%, staying on the third mesh having a mesh size of 90 μm, staying 85% or more, and passing through the same 90 μm sieve. The amount is 11% or less, and the particle size is adjusted so that the amount passing through the fourth sieve having a mesh size of 65 μm is less than 2%. For CBN adjusted to a particle size of 140/170, the toughness value, which is an index of the impact crush resistance of abrasive grains, was measured as one of the CBN strength indexes.
The toughness value was obtained by placing a constant amount of CBN of 140/170 obtained in an iron capsule having a volume of 2 ml together with one steel ball of about 1 g, and this capsule with a vibration frequency of 3000 ± 100 times / min. Vibrating for 0 ± 0.3 seconds, pulverizing the CBN in the capsule with a steel ball, sieving the pulverized powder with a 75 μm sieve mesh, and expressing the residual mass of CBN on the sieve mesh as a percentage of the total pulverized powder. Desired. Table 5 shows the measurement results.
Furthermore, after heat-treating the particles having a particle size of 140/170 in the atmosphere at 1100 ° C. × 1 hour, the toughness value was measured in the same manner, and the rate of decrease from the toughness value before heating was calculated. Table 5 shows the rate of decrease in toughness value due to heating. Moreover, the chemical analysis was performed about the particle | grains of the particle size 140/170, and the amount of the catalyst component (metal element in a catalyst) contained in CBN was investigated. In addition, the amount of carbon contained in CBN was also investigated for a part. The results are shown in Table 5.
（実施例２６、比較例１９）
実施例２０及び比較例３のＣＢＮ砥粒をＪＩＳ Ｂ ４１３０：１９９８に記載の粒度１４０／１７０に分級し、それを用いて砥石セグメントを作製した。ＣＢＮ、結合剤としてのホウ珪酸系ガラス質結合材、バインダー（フェノール系樹脂）の混合物を調製し、１５０℃で加圧成形後、１１００℃（大気雰囲気）で焼成した。使用したバインダーは砥石焼成時に燃焼し気孔となった。配合比率は砥粒率５０体積％、ボンド率２０体積％、バインダー１０体積％で、焼成後の気孔率は３０体積％であった。このようにして得られた砥石セグメントをアルミ製の台金に接着して砥石化した後に、以下の研削条件で研削試験を行った。研削結果を表６に示す。
(Example 26, Comparative Example 19)
The CBN abrasive grains of Example 20 and Comparative Example 3 were classified into a grain size of 140/170 described in JIS B 4130: 1998, and a grindstone segment was produced using the classified particles. A mixture of CBN, a borosilicate glassy binder as a binder, and a binder (phenolic resin) was prepared, pressure-molded at 150 ° C., and fired at 1100 ° C. (atmosphere). The binder used burned during the grinding of the grindstone and became pores. The mixing ratio was 50% by volume of abrasive grains, 20% by volume of bond, and 10% by volume of binder, and the porosity after firing was 30% by volume. The grindstone segment thus obtained was bonded to an aluminum base metal to form a grindstone, and then a grinding test was performed under the following grinding conditions. Table 6 shows the grinding results.
砥石 １Ａ１形、１５０Ｄ × ５Ｕ × ３Ｘ × ７６．２Ｈ
研削盤 横軸平面研削盤（砥石軸モーター ３．７ｋＷ）
被削材 ＳＫＨ−５１（ＨＲｃ＝６２〜６４）
被削材面 ２００ｍｍ長 × １００ｍｍ幅
研削方式 湿式平面トラバース研削方式
研削条件 砥石周速度 １８００ｍ／分
テーブル速度 １５ｍ／分
クロス送り ５ｍｍ／パス
切り込み ４０μｍ
研削液 ＣＢＮ専用液（水溶性 ５０倍希釈）
Whetstone 1A1, 150D x 5U x 3X x 76.2H
Grinding machine Horizontal axis surface grinding machine (Wheel axis motor 3.7kW)
Work material SKH-51 (HRc = 62-64)
Work surface 200mm length x 100mm width Grinding method Wet surface traverse grinding method Grinding conditions Wheel peripheral speed 1800m / min
Table speed 15m / min
Cross feed 5mm / pass
Cutting depth 40μm
Grinding fluid CBN exclusive solution (water-soluble 50 times dilution)
尚、砥石形状の記号は、ＪＩＳ Ｂ ４１３１：１９９８「ダイヤモンド／ＣＢＮ工具−ダイヤモンド又はＣＢＮホイール」に基づき標記した。本実施例及び比較例で用いた砥石は、台金が円盤状で、砥粒層断面が長方形で、台金最外周に砥粒層が取り付けてあるものであり、砥石外径が１５０ｍｍφで、砥粒層の幅が５ｍｍで、砥粒層の厚みが３ｍｍで、砥石の取り付け部の穴径が７６．２ｍｍφである。
また、被削材の記号は、ＪＩＳ Ｇ ４４０３「高速度工具鋼鋼材」に基づき表記したものであり、本実施例で用いた被削材は、所定の寸法、硬度に加工した市販の鋼材を用いた。
In addition, the symbol of the grindstone shape was marked based on JIS B 4131: 1998 “Diamond / CBN Tool—Diamond or CBN Wheel”. The grindstone used in this example and the comparative example is a base having a disc shape, a cross section of the abrasive layer is rectangular, an abrasive layer is attached to the outermost periphery of the base, and the outer diameter of the grindstone is 150 mmφ. The width of the abrasive grain layer is 5 mm, the thickness of the abrasive grain layer is 3 mm, and the hole diameter of the mounting portion of the grindstone is 76.2 mmφ.
Moreover, the symbol of a work material is described based on JIS G4403 "High-speed tool steel material", and the work material used in this example is a commercially available steel material processed to a predetermined size and hardness. Using.
以上、各実施例におけるＣＢＮ収率は同じ触媒を用いた比較例のＣＢＮ収率よりも高く、実施例で使用したＣＢＮ合成用触媒の方がＨＢＮからＣＢＮへの変換能力に優れていた。
また、各実施例におけるＣＢＮ砥粒中への触媒成分の取り込み量は、比較例よりも少なく、また実施例の方がタフネス値が高く、加熱によるタフネス値の低下が小さかった。
さらに、実施例で得られたＣＢＮ砥粒は、比較例で得られたＣＢＮ砥粒より、（１１１）面が発達し、シャ−プエッジを持っていた。
As mentioned above, the CBN yield in each Example was higher than the CBN yield of the comparative example using the same catalyst, and the CBN synthesis catalyst used in the Examples was superior in the ability to convert HBN to CBN.
Further, the amount of the catalyst component incorporated into the CBN abrasive grains in each example was smaller than that in the comparative example, the example had a higher toughness value, and the decrease in the toughness value due to heating was small.
Furthermore, the CBN abrasive grains obtained in the examples had a (111) plane and a sharp edge compared to the CBN abrasive grains obtained in the comparative examples.
以上説明したように本発明のＣＢＮ砥粒は、触媒成分の取り込みが従来より少ないＣＢＮ砥粒であって、不活性ガス雰囲気下で形成される有機物層を表面に有するＣＢＮ合成用触媒を用いることによって合成することができる。本発明のＣＢＮ砥粒は強度が高く、加熱による強度の低下が小さいＣＢＮ砥粒であり、また（１１１）面が良く発達し、シャープエッジを持つＣＢＮ砥粒であるため、高負荷研削等の厳しい研削条件下で使用する砥石用途に好適である。
また、使用されるＣＢＮ合成用触媒は、ＣＢＮ合成用触媒の表面に有機物層を形成したものであり、有機物層の効果によってＣＢＮ合成用触媒の取り扱い時からＣＢＮ合成中にかけて触媒の劣化が抑制されるため、ＣＢＮ収率が高くなり、触媒成分のＣＢＮ中への取り込みも減少する。
更にこのＣＢＮ合成用触媒は有機物層を形成した後は、酸素や水分等との反応性が低下するため、従来のＣＢＮ合成用触媒のように、乾燥窒素などの不活性乾燥ガスを流したグローブボックス内などで取り扱わなくても劣化を防ぐことができるため、ＣＢＮ砥粒を簡便な工程および作業で生産性良く製造することができる。
Or CBN abrasive of the present invention as described provides a uptake conventional fewer CBN abrasive particles of the catalyst component, the use of the CBN synthesis catalyst having an organic substance layer formed in an inert gas atmosphere on the surface Can be synthesized. The CBN abrasive grains of the present invention are high-strength CBN abrasive grains that have a small decrease in strength due to heating, and are well-developed (111) surfaces with sharp edges. Suitable for grindstone applications used under severe grinding conditions.
In addition, the CBN synthesis catalyst used is an organic layer formed on the surface of the CBN synthesis catalyst, and the deterioration of the catalyst is suppressed from the handling of the CBN synthesis catalyst to the CBN synthesis due to the effect of the organic layer. Therefore, the CBN yield is increased and the incorporation of the catalyst component into CBN is also reduced.
Furthermore, since this CBN synthesis catalyst has a reduced reactivity with oxygen, moisture, etc. after the organic layer is formed, a glove with an inert dry gas such as dry nitrogen flowing like a conventional CBN synthesis catalyst. Since the deterioration can be prevented without being handled in a box or the like, CBN abrasive grains can be produced with high productivity by simple processes and operations.
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