JP5830439B2 - Rolling element and manufacturing method thereof - Google Patents
Rolling element and manufacturing method thereof Download PDFInfo
- Publication number
- JP5830439B2 JP5830439B2 JP2012132005A JP2012132005A JP5830439B2 JP 5830439 B2 JP5830439 B2 JP 5830439B2 JP 2012132005 A JP2012132005 A JP 2012132005A JP 2012132005 A JP2012132005 A JP 2012132005A JP 5830439 B2 JP5830439 B2 JP 5830439B2
- Authority
- JP
- Japan
- Prior art keywords
- less
- rolling element
- average particle
- weight
- silicon nitride
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Landscapes
- Rolling Contact Bearings (AREA)
- Ceramic Products (AREA)
Description
本発明は、例えばベアリング等に用いられる転動体及びその製造方法に関する。 The present invention relates to a rolling element used for, for example, a bearing and a manufacturing method thereof.
窒化珪素質焼結体を転動体としたベアリングは軸受鋼製ベアリングに比べ軽量であり、強度、耐熱性、耐摩耗性、及び絶縁性が高く、熱膨張しにくいという特性を有し、高速回転での転動体と金属との耐焼付け性に優れることから、工作機用スピンドルモーター、ファンモーター、風力発電用モーター等のベアリングに広く採用されている（特許文献１参照）。また、特許文献２には、窒化珪素質焼結体が記載されている。 Bearings using silicon nitride sintered bodies as rolling elements are lighter than bearing steel bearings, have high strength, heat resistance, wear resistance, and insulation, and are resistant to thermal expansion. Since it has excellent seizure resistance between rolling elements and metal, it is widely used for bearings such as spindle motors for machine tools, fan motors, and motors for wind power generation (see Patent Document 1). Patent Document 2 describes a silicon nitride sintered body.
窒化珪素質焼結体は、鋼等の金属と比較してヤング率が高い。このことにより、転動体に窒化珪素質焼結体を用い、内輪と外輪に軸受鋼を用いたハイブリッド軸受においては、転動体と軌道部材（ベアリングの内輪又は外輪）との面圧が高くなり、軸受としての寿命が短くなってしまうという問題があった。 The silicon nitride sintered body has a higher Young's modulus than a metal such as steel. As a result, in the hybrid bearing using the silicon nitride sintered body for the rolling element and the bearing steel for the inner ring and the outer ring, the surface pressure between the rolling element and the race member (inner ring or outer ring of the bearing) is increased. There was a problem that the life as a bearing would be shortened.
従来の窒化珪素質焼結体からなる転動体は、高強度と低ヤング率とを両立させることができなかった。例えば、特許文献１記載の窒化珪素質焼結体はヤング率が高く、また、特許文献２記載の窒化珪素質焼結体は強度が低い。 A rolling element made of a conventional silicon nitride-based sintered body cannot achieve both high strength and low Young's modulus. For example, the silicon nitride sintered body described in Patent Document 1 has a high Young's modulus, and the silicon nitride sintered body described in Patent Document 2 has a low strength.
本発明は以上の点に鑑みなされたものであり、高強度且つ低ヤング率である転動体及びその製造方法を提供することを目的とする。 This invention is made | formed in view of the above point, and it aims at providing the rolling element which is high intensity | strength and low Young's modulus, and its manufacturing method.
本発明の転動体は、（ａ）β-窒化珪素の結晶と、（ｂ）希土類、珪素、アルミニウム
、酸素、及び窒素を含む粒界相と、（ｃ）Ti、Zr、Hf、W、Mo、Ta、Nb、V及びCrからなる群から選択される１種以上の元素を含む粒子とを有し、断面において前記（ｂ）が占める面積の比率が１０％以上であり、前記（ａ）の長径における平均粒径が１μｍ以下であるとともに、前記（ｃ）の平均粒径が１μｍ以下であり、マイクロポアの集合体の直径が１００μｍ以下であり、全重量に対する前記（ｃ）の重量比が５重量％以下であることを特徴とする。
The rolling element of the present invention includes (a) β-silicon nitride crystal, (b) a grain boundary phase containing rare earth, silicon, aluminum, oxygen, and nitrogen, and (c) Ti, Zr, Hf, W, Mo , Particles containing one or more elements selected from the group consisting of Ta, Nb, V and Cr, and the ratio of the area occupied by (b) in the cross section is 10% or more, (a) with an average particle diameter of 1μm or less in major axis, the weight of the average particle diameter of (c) is at 1μm or less state, and are diameter 100μm following collection of micropores, wherein relative to the total weight (c) ratio wherein the der Rukoto 5 wt% or less.
本発明の転動体は、ヤング率が低く、強度が高い。また、本発明の転動体は、研削性及び転がり寿命において優れている。
本発明の転動体の製造方法は、（Ａ）α率が７０％以上の窒化珪素と、（Ｂ）希土類酸化物又は希土類水酸化物と、（Ｃ）酸化アルミニウムと、（Ｄ）平均粒径１μｍ以下の粉末であって、Ti、Zr、Hf、W、Mo、Ta、Nb、V及びCrからなる群から選択される１種以上の元素の窒化物、炭化物、珪化物、及び酸化物のうちの１種以上とを、全原料に対し、前記（Ａ）及び（Ｄ）を除いた残りの重量が１０〜３０重量％の範囲内となり、全原料に対し、前記（Ｄ）の重量が５重量％以下となるように混合して成形体を作製し、前記成形体を、窒素を含む非酸化雰囲気中で、揮発率を２重量％以下に抑制しながら、１５００〜１７００℃の温度で焼成することを特徴とする。
The rolling element of the present invention has a low Young's modulus and a high strength. The rolling element of the present invention is excellent in grindability and rolling life.
The rolling element manufacturing method of the present invention includes (A) silicon nitride having an α ratio of 70% or more, (B) rare earth oxide or rare earth hydroxide, (C) aluminum oxide, and (D) average particle diameter. 1 μm or less of powder of nitride, carbide, silicide, and oxide of one or more elements selected from the group consisting of Ti, Zr, Hf, W, Mo, Ta, Nb, V and Cr and one or more out, relative to the total feed, wherein (a) and Ri Do in the range remaining weight is 10 to 30 wt%, excluding the (D), relative to the total feed, wherein the (D) weight to prepare a mixed into so that Do and 5 wt% or less molded body, the molded body in a non-oxidizing atmosphere containing nitrogen, while suppressing the volatilization rate 2% by weight or less, 1500 to 1700 ° C. It is characterized by firing at a temperature of
本発明の製造方法で製造した転動体は、ヤング率が低く、強度が高く、研削性及び転がり寿命において優れている。 The rolling element produced by the production method of the present invention has a low Young's modulus, a high strength, and is excellent in grindability and rolling life.
本発明の実施形態を説明する。
本発明の転動体は、例えば、ベアリングの内輪と外輪との間に位置する球状又は円筒状の転動体である。
An embodiment of the present invention will be described.
The rolling element of the present invention is, for example, a spherical or cylindrical rolling element positioned between an inner ring and an outer ring of a bearing.
本発明の転動体において、β-窒化珪素粒子の結晶の長径における平均粒径は１μｍ以下である。β-窒化珪素粒子は、例えば、長径が０．６μｍ程度、短径が０．３μｍ程度、アスペクト比が２程度とすることができる。 In the rolling element of the present invention, the average particle diameter in the major axis of the β-silicon nitride particles is 1 μm or less. The β-silicon nitride particles can have, for example, a major axis of about 0.6 μm, a minor axis of about 0.3 μm, and an aspect ratio of about 2.
本発明の転動体において、（ｂ）希土類、珪素、アルミニウム、酸素、及び窒素を含む粒界相は、例えば、ガラス相（結晶化していない相）である。粒界相のヤング率は、例えば、６０〜１５０ＧＰａである。本発明の転動体の断面において粒界相が占める面積の比率は１０％以上である。このことにより、転動体のヤング率を低くすることができる。また、転動体の断面において粒界相が占める面積の比率は３０％以下であることが好ましい。３０%を超えると、強度ならびに破壊靭性が低下し、転動体としての寿命が短くなることから好ましくない。１０％未満であると、ヤング率を低くすることができず、また、研削性が悪化するので好ましくない。 In the rolling element of the present invention, (b) the grain boundary phase containing rare earth, silicon, aluminum, oxygen, and nitrogen is, for example, a glass phase (non-crystallized phase). The Young's modulus of the grain boundary phase is, for example, 60 to 150 GPa. The ratio of the area occupied by the grain boundary phase in the cross section of the rolling element of the present invention is 10% or more. As a result, the Young's modulus of the rolling element can be lowered. Moreover, it is preferable that the ratio of the area which a grain boundary phase occupies in the cross section of a rolling element is 30% or less. If it exceeds 30%, the strength and fracture toughness are lowered and the life as a rolling element is shortened, which is not preferable. If it is less than 10%, the Young's modulus cannot be lowered, and the grindability deteriorates, which is not preferable.
本発明の転動体では、（ｃ）Ti、Zr、Hf、W、Mo、Ta、Nb、V及びCrからなる群から選択される１種以上の元素を含む粒子（以下、分散粒子とも言う）の平均粒径が１μｍ以下であり、より好ましくは０．５μｍ以下である。このことにより、転動体における低ヤング率と高強度とを両立することができる。転動体の高強度化には、加工後表面の粗大欠陥を小さくすることが必要である。分散粒子を添加することにより、焼成する際に、ピン止め効果によりβ窒化珪素粒子の粒成長が抑制できる。さらには、平均粒径が１μｍ以下の分散粒子を含むことにより、転動体に加工する際に研削スピードを増加させても粗大な傷がつきにくく、剥離がしにくくなる。分散粒子の平均粒径が１μｍより大きいと、ピン止め効果が小さくなるとともに、加工時の傷の大きさが大きくなるため好ましくない。 In the rolling element of the present invention, (c) particles containing one or more elements selected from the group consisting of Ti, Zr, Hf, W, Mo, Ta, Nb, V and Cr (hereinafter also referred to as dispersed particles) The average particle size is 1 μm or less, more preferably 0.5 μm or less. This makes it possible to achieve both a low Young's modulus and a high strength in the rolling element. In order to increase the strength of the rolling element, it is necessary to reduce coarse defects on the surface after processing. By adding the dispersed particles, the growth of β silicon nitride particles can be suppressed due to the pinning effect when firing. Furthermore, by including dispersed particles having an average particle size of 1 μm or less, even when the grinding speed is increased when processing into rolling elements, coarse scratches are difficult to occur and peeling is difficult. If the average particle size of the dispersed particles is larger than 1 μm, the pinning effect is reduced and the size of the scratches during processing is increased, which is not preferable.
転動体を低ヤング率とするには粒界相を増加させることが有効であるが、ただ単に粒界相を増加させるだけでは、転動体の強度が低くなり、転動体としての寿命が短くなる。さらには、加工コストを低減させるために研削スピードを増しても、転動体に粗大な傷がつきやすく、剥離がしやすくなってしまう。平均粒径１μm以下の分散粒子を含むことは、β窒化珪素粒子の粒成長を抑えることと、さらには加工時の傷、剥離を抑え、転動体の寿命を向上させることとに大きく寄与しているのである。 Increasing the grain boundary phase is effective for making the rolling element have a low Young's modulus, but simply increasing the grain boundary phase decreases the strength of the rolling element and shortens its life as a rolling element. . Furthermore, even if the grinding speed is increased in order to reduce the processing cost, the rolling elements are likely to be coarsely scratched and peeled off easily. Inclusion of dispersed particles having an average particle size of 1 μm or less greatly contributes to suppressing the growth of β silicon nitride particles, and further to suppressing scratches and peeling during processing and improving the life of the rolling elements. It is.
本発明の転動体において、ヤング率が２４０〜２９０ＧＰａの範囲内であることが好ましい。ヤング率が２９０ＧＰａより大きいと、研削性が悪化することと、転動体と軌道部材との面圧が高くなることとにより、好ましくない。また、ヤング率が２４０ＧＰａより小さいと、転動体の強度を高く保てなくなるため好ましくない。 In the rolling element of the present invention, the Young's modulus is preferably in the range of 240 to 290 GPa. If the Young's modulus is greater than 290 GPa, it is not preferable due to deterioration of grindability and an increase in the surface pressure between the rolling elements and the raceway member. On the other hand, if the Young's modulus is less than 240 GPa, the strength of the rolling element cannot be kept high, which is not preferable.
ヤング率は、転動体を製造する際に用いる焼結助剤（例えば、希土類酸化物、希土類水酸化物、酸化アルミニウム、二酸化珪素等）の量を多くすることにより、低くすることができる。焼結助剤量は、転動体の全原料に対し、１０〜３０重量％の範囲が好ましい。また、ヤング率は、転動体を製造する際の混合粉砕条件や焼結条件にも依存する。 The Young's modulus can be lowered by increasing the amount of sintering aid (for example, rare earth oxide, rare earth hydroxide, aluminum oxide, silicon dioxide, etc.) used in producing the rolling element. The amount of sintering aid is preferably in the range of 10 to 30% by weight with respect to the total raw materials of the rolling elements. The Young's modulus also depends on the mixing and grinding conditions and the sintering conditions when manufacturing the rolling elements.
本発明の転動体は、密度が３ｇ／ｃｍ3以上かつ相対密度が９５％以上であることが好ましい。α率が７０%以上でかつ平均粒径が１μm以下の窒化珪素粉末を用い、適切な焼成条件で焼成を行うことで、密度及び相対密度を上記の範囲とすることができる。焼成温度が低すぎると転動体が緻密化しないため、焼成温度を一定温度以上にする必要がある。 The rolling element of the present invention preferably has a density of 3 g / cm 3 or more and a relative density of 95% or more. By using a silicon nitride powder having an α ratio of 70% or more and an average particle diameter of 1 μm or less and performing firing under appropriate firing conditions, the density and relative density can be within the above ranges. If the firing temperature is too low, the rolling elements are not densified, so the firing temperature needs to be a certain temperature or higher.
本発明の転動体は、３点曲げ強度が７００ＭＰａ以上であることが好ましい。焼成条件を、焼結助剤の組成及び量に合わせた適切な焼成条件とすることにより、曲げ強度を上記の範囲内にすることができる。焼成温度が高すぎると、含有する結晶粒子が粒成長するため、強度が低くなってしまう。そのため、焼成温度を一定温度以下にする必要がある。 The rolling element of the present invention preferably has a three-point bending strength of 700 MPa or more. The bending strength can be within the above-mentioned range by setting the firing conditions to suitable firing conditions that match the composition and amount of the sintering aid. If the firing temperature is too high, the contained crystal grains grow and the strength is lowered. Therefore, it is necessary to set the firing temperature below a certain temperature.
本発明の転動体では、含有する各結晶粒子の平均粒径が、それぞれ３μｍ以下であることが好ましい。特に、（ａ）β-窒化珪素粒子と（ｃ）Ti、Zr、Hf、W、Mo、Ta、Nb、V及びCrからなる群から選択される１種以上の元素を含む粒子の平均粒径は、１μｍ以下であることが好ましい。焼成条件を、焼結助剤の組成及び量に合わせた適切な焼成条件とすることにより、各結晶粒子の平均粒径を上記の範囲内にすることができる。焼成温度が高すぎると、含有する結晶粒子が粒成長するため、焼成温度を一定温度以下にする必要がある。 In the rolling element of the present invention, it is preferable that the average particle diameter of each crystal particle contained is 3 μm or less. In particular, the average particle diameter of (a) β-silicon nitride particles and (c) one or more elements selected from the group consisting of Ti, Zr, Hf, W, Mo, Ta, Nb, V and Cr Is preferably 1 μm or less. By setting the firing conditions to suitable firing conditions that match the composition and amount of the sintering aid, the average particle size of each crystal particle can be within the above range. If the firing temperature is too high, the contained crystal grains grow, so the firing temperature must be kept below a certain temperature.
このことにより、転動体の強度が高くなる。また、焼成冷却時に粒界相と結晶粒子の熱膨張差に起因する粒界相の隙間（マイクロポア）を抑制することができる。このマイクロポアは以下のようにして生成する。すなわち、焼成途中の高温時には隙間はないが、焼成冷却時に収縮する際、窒化珪素よりも粒界相の熱膨張の方が大きいために、粒界相がより収縮しようとするが、窒化珪素粒子の粒径が大きいと、粒界相の収縮の障害となって、粒界相が引けてしまい、結果として隙間（マイクロポア）が生じてしまう。窒化珪素粒子形状は針状形状であるため、粒径が大きいほど、粒子が３次元的にからみあい、粒界相が引けやすくなり、隙間（マイクロポア）が多くなってしまう。マイクロポアが多くなると、偏析のように、マイクロポア集合体として存在する。マイクロポア集合体の大きさ（径）が大きくなると、加工時に傷、剥離が出来やすく、軸受として使用した際に表面において剥離が生じやすくなる。 This increases the strength of the rolling elements. In addition, it is possible to suppress a gap (micropore) between the grain boundary phases due to the difference in thermal expansion between the grain boundary phase and the crystal grains during firing cooling. This micropore is generated as follows. That is, there are no gaps at high temperatures during firing, but when shrinking during firing cooling, the thermal expansion of the grain boundary phase is larger than that of silicon nitride, so the grain boundary phase tends to shrink more. If the particle size of the particles is large, it becomes an obstacle to the shrinkage of the grain boundary phase, and the grain boundary phase is drawn, resulting in a gap (micropore). Since the silicon nitride particle shape is a needle shape, the larger the particle size, the more the particles are entangled three-dimensionally, the grain boundary phase is more easily drawn, and the gaps (micropores) are increased. When the number of micropores increases, it exists as a micropore aggregate like segregation. When the size (diameter) of the micropore assembly is increased, scratches and peeling are likely to occur during processing, and peeling is likely to occur on the surface when used as a bearing.
本発明の転動体は、例えば、窒化珪素の結晶に加えて、酸窒化珪素（Si2N2O）の結晶を有するものとすることができる。この場合、酸窒化珪素の結晶の長径における平均粒径が３μｍ以下であることが好ましい。こうすることにより、マイクロポアが生じにくくなり、摺動表面において剥離が生じにくくなる。酸窒化珪素の結晶は、例えば、長径が２．３μｍ程度、短径が０．８μｍ程度、アスペクト比が３程度のものとすることができる。 The rolling element of the present invention may have, for example, a silicon oxynitride (Si 2 N 2 O) crystal in addition to a silicon nitride crystal. In this case, it is preferable that the average particle diameter in the major axis of the silicon oxynitride crystal is 3 μm or less. By doing so, micropores are less likely to occur, and peeling is less likely to occur on the sliding surface. The crystal of silicon oxynitride can have, for example, a major axis of about 2.3 μm, a minor axis of about 0.8 μm, and an aspect ratio of about 3.
本発明の転動体において、マイクロポアの集合体の直径が１００μｍ以下である。マイクロポアの集合体の直径が１００μｍを超えると、加工時に傷、剥離が出来やすく、軸受として使用した際に表面において剥離が生じやすくなることから、好ましくない。マイクロポアの集合体の直径が１００μｍ以下である場合、転動体の強度が一層向上する。 In the rolling element of the present invention, the diameter of the aggregate of micropores is 100 μm or less. If the diameter of the aggregate of micropores exceeds 100 μm, it is not preferable because scratches and peeling can easily occur during processing, and peeling can easily occur on the surface when used as a bearing. When the diameter of the aggregate of micropores is 100 μm or less, the strength of the rolling element is further improved.
本発明の転動体の製造に用いる（Ａ）窒化珪素としては、α率が７０％以上であり、平均粒径が１μｍ以下の粉末が好ましい。転動体の全原料に対し、（Ａ）窒化珪素の重量比は、７０〜９０重量％の範囲が好ましい。この範囲内であることにより、転動体が奏する上記効果が一層顕著になる。なお、α-窒化珪素は焼成の際、大部分がβ-窒化珪素に変化する。このとき、完全にβ-窒化珪素に変化してもよいし、α-窒化珪素が一部残ってもよい。また、粒界相中のAl成分の一部がβ-窒化珪素へ固溶してもよい。 As (A) silicon nitride used for manufacturing the rolling element of the present invention, a powder having an α ratio of 70% or more and an average particle diameter of 1 μm or less is preferable. The weight ratio of (A) silicon nitride is preferably in the range of 70 to 90% by weight with respect to all the raw materials of the rolling elements. By being in this range, the above-mentioned effect produced by the rolling element becomes more remarkable. Note that α-silicon nitride largely changes to β-silicon nitride upon firing. At this time, it may be completely changed to β-silicon nitride, or a part of α-silicon nitride may remain. Further, a part of the Al component in the grain boundary phase may be dissolved in β-silicon nitride.
本発明の転動体の製造に用いる（Ａ）窒化珪素としては、α率が７０％以上が好ましく、さらには９０％以上がさらに好ましい。α率が７０％未満であると、緻密化しにくくなることから、低強度となる。（Ａ）窒化珪素としては、平均粒径が１μｍ以下の粉末が好ましい。１μｍを超える粒径の窒化珪素を用いると、緻密化しにくくなることから、低強度となる。さらには、マイクロポア集合体も大きくなる。 As (A) silicon nitride used for manufacture of the rolling element of the present invention, the α ratio is preferably 70% or more, and more preferably 90% or more. If the α ratio is less than 70%, it becomes difficult to densify, so the strength becomes low. (A) As silicon nitride, a powder having an average particle diameter of 1 μm or less is preferable. When silicon nitride having a particle diameter exceeding 1 μm is used, it becomes difficult to densify, and thus low strength is obtained. Furthermore, the micropore assembly also becomes large.
本発明の転動体の製造に用いる（Ｂ）希土類酸化物又は希土類水酸化物における希土類としては、例えば、La、Y、Ce、Nd、Sm、Gd、Dy、Ho、Er、Yb、Luが挙げられる。いずれの希土類でも同様の効果を得られるが、特にLa又はYは原料が比較的安価であり大量に入手もしやすく、十分緻密化になることから、転動体の製造コストを低減できる。特に、Laを用いると、製造コストを低減できること、さらにはマイクロポア集合体が生成しくいことから好ましい。転動体の原料全体に対し、上記（Ｂ）の重量比は、３〜１５重量％の範囲が好ましい。この範囲内であることにより、転動体が奏する上記効果が一層顕著になる。３重量％未満の場合は、転動体の緻密化あるいは高強度化が不十分となるおそれがある。１５重量％を超えると、粒界相が過量となり、強度が低下するおそれがある。
（Ｂ）希土類酸化物又は希土類水酸化物、及び（Ｃ）酸化アルミニウムは、焼結助剤として機能する。焼結助剤は、上記（Ｂ）と（Ｃ）のみであってもよいし、さらに、酸化ケイ素、窒化アルミニウムを添加してもよい。全原料に対する（Ａ）および（Ｄ）を除いた残りの合計重量比は１０〜３０重量％の範囲内である。（Ｂ）および（Ｃ）にさらに酸化ケイ素、窒化アルミニウムを添加した場合、（Ｂ）および（Ｃ）さらに酸化ケイ素、窒化アルミニウムの合計重量比が１０〜３０重量％の範囲内である。
Examples of the rare earth in (B) rare earth oxide or rare earth hydroxide used in the production of the rolling element of the present invention include La, Y, Ce, Nd, Sm, Gd, Dy, Ho, Er, Yb, and Lu. It is done. Although the same effect can be obtained with any rare earth, in particular, La or Y is relatively inexpensive, easily available in large quantities, and becomes sufficiently dense, so that the manufacturing cost of the rolling elements can be reduced. In particular, the use of La is preferable because the manufacturing cost can be reduced and the micropore aggregate is not easily generated. The weight ratio of the above (B) is preferably in the range of 3 to 15% by weight with respect to the whole raw material of the rolling element. By being in this range, the above-mentioned effect produced by the rolling element becomes more remarkable. When the amount is less than 3% by weight, the rolling elements may not be sufficiently densified or strengthened. If it exceeds 15% by weight, the grain boundary phase becomes excessive, and the strength may decrease.
(B) Rare earth oxide or rare earth hydroxide and (C) aluminum oxide function as a sintering aid. The sintering aid may be only the above (B) and (C), or silicon oxide or aluminum nitride may be added. The remaining total weight ratio excluding (A) and (D) with respect to all raw materials is in the range of 10 to 30% by weight. When silicon oxide and aluminum nitride are further added to (B) and (C), the total weight ratio of (B) and (C), silicon oxide and aluminum nitride is in the range of 10 to 30% by weight.
また、全原料に対する上記（Ｃ）の重量比は、３〜２０重量％の範囲が好ましい。この範囲内であることにより、転動体が奏する上記効果が一層顕著になる。３重量％未満の場合は、転動体の緻密化あるいは高強度が不十分となるおそれがある。１５重量％を超えると、粒界相が過量となり、強度が低下するおそれがある。 Moreover, the weight ratio of the above (C) with respect to all raw materials is preferably in the range of 3 to 20% by weight. By being in this range, the above-mentioned effect produced by the rolling element becomes more remarkable. If it is less than 3% by weight, the rolling elements may become dense or insufficient in strength. If it exceeds 15% by weight, the grain boundary phase becomes excessive, and the strength may decrease.
（Ｄ）平均粒径１μｍ以下の粉末であって、Ti、Zr、Hf、W、Mo、Ta、Nb、V及びCrからなる群から選択される１種以上の元素の窒化物、炭化物、珪化物、及び酸化物のうちの１種以上は、焼結性向上、高強度化、色むら防止の効果を奏する。全原料に対する上記（Ｄ）の重量比は、５重量％以下の範囲が好ましい。この範囲内であることにより、転動体が奏する上記効果が一層顕著になる。 (D) Nitride, carbide, or silicidation of one or more elements selected from the group consisting of Ti, Zr, Hf, W, Mo, Ta, Nb, V, and Cr, and having an average particle size of 1 μm or less One or more of the materials and oxides have the effect of improving sinterability, increasing strength, and preventing color unevenness. The weight ratio of the above (D) with respect to all raw materials is preferably in the range of 5% by weight or less. By being in this range, the above-mentioned effect produced by the rolling element becomes more remarkable.
本発明の転動体の製造方法において、成形体は、例えば、金型成形、鋳込み成形、ラバー成形、射出成形、押出し成形、シート成形等の方法で作製できる。
本発明の転動体の製造方法において、焼成は、例えば、常圧焼成、ガス圧焼成、熱間静水圧プレス（HIP）焼成、ホットプレス焼成等により行うことができる。安価な焼成方法として常圧焼成が好ましいが、常圧焼成で焼成した後に１０MPa以下の圧力でガス圧焼成してもよい。特に１０MPa以下の圧力でのガス圧焼成であれば、１０MPa以上のHIP焼成よりも処理量が増加するため、HIP焼成より安価になることから有用である。焼成温度は、１５００〜１７００℃とすることができる。
（実施例）
１．転動体の製造
以下の（Ａ）〜（Ｅ）を、表１に示す配合比に従って配合し、ボールミル等で粉砕混合して、混合粉末を作製した。ここでは、Ｓ１〜Ｓ１８の１８種類の混合粉末を作製した。
（Ａ）α率が９２%、平均粒径が０．７μmである窒化珪素の粉末
（Ｂ）希土類酸化物又は希土類水酸化物
（Ｃ）酸化アルミニウム
（Ｄ）WO3、WSi2、TiC、TiO2のうちのいずれか
（Ｅ）酸化珪素
In the method for producing a rolling element of the present invention, the molded body can be produced by methods such as mold molding, cast molding, rubber molding, injection molding, extrusion molding, and sheet molding.
In the method for producing a rolling element of the present invention, the firing can be performed by, for example, normal pressure firing, gas pressure firing, hot isostatic pressing (HIP) firing, hot press firing, or the like. Although normal pressure baking is preferable as an inexpensive baking method, gas pressure baking may be performed at a pressure of 10 MPa or less after baking by normal pressure baking. In particular, gas pressure firing at a pressure of 10 MPa or less is useful because the amount of treatment increases as compared with HIP firing at 10 MPa or more, and is cheaper than HIP firing. The firing temperature can be 1500-1700 ° C.
(Example)
1. Manufacture of rolling elements The following (A) to (E) were blended according to the blending ratio shown in Table 1, and pulverized and mixed with a ball mill or the like to produce a mixed powder. Here, 18 kinds of mixed powders S1 to S18 were produced.
(A) Silicon nitride powder having an α ratio of 92% and an average particle size of 0.7 μm (B) Rare earth oxide or rare earth hydroxide (C) Aluminum oxide (D) WO 3 , WSi 2 , TiC, TiO 2 (E) silicon oxide
次に、Ｓ１〜Ｓ１８のそれぞれについて、30MPaの成形圧力でプレス成形し、その後150MPaの静水圧力（CIP）で成形し、球状の成形体を作製した。その後、表１に示す焼成条件（温度、時間、気圧）で焼成し、Φ10mmの転動体および平板を完成した。焼成は、窒素を含む非酸化性雰囲気中で行った。焼成は、１次焼成と２次焼成とを順次行った。 Next, each of S1 to S18 was press-molded at a molding pressure of 30 MPa, and then molded at a hydrostatic pressure (CIP) of 150 MPa to produce a spherical molded body. Thereafter, firing was performed under the firing conditions (temperature, time, atmospheric pressure) shown in Table 1 to complete a rolling element and a flat plate having a diameter of 10 mm. Firing was performed in a non-oxidizing atmosphere containing nitrogen. Firing was performed sequentially with primary firing and secondary firing.
焼成における揮発率は次式で算出した。
揮発率（％）＝（Ｗ1-Ｗ2）/Ｗ1×１００ （１次焼成前の重量Ｗ1、２次焼成後の重量Ｗ2）
２．転動体の評価
各粒子の結晶相はＸ線回折法により同定を行なった。粒界相については、Ｘ線回折法にて同定を行い、さらにはＴＥＭ（透過型電子顕微鏡）にてガラス相か結晶相かを確認した。
The volatilization rate in firing was calculated by the following formula.
Volatility (%) = (W1-W2) / W1 × 100 (weight W1 before primary firing, weight W2 after secondary firing)
2. Evaluation of rolling elements The crystal phase of each particle was identified by an X-ray diffraction method. The grain boundary phase was identified by an X-ray diffraction method, and further confirmed by a TEM (transmission electron microscope) whether it was a glass phase or a crystal phase.
製造したＳ１〜Ｓ１８の転動体を分析した結果、Ｓ２〜Ｓ７、Ｓ９〜Ｓ１６については、（ａ）β-窒化珪素の結晶と、（ｂ）希土類、珪素、アルミニウム、酸素、及び窒素を含む粒界相（ガラス相）と、（ｃ）WO3（Ｓ２〜Ｓ７の場合）、WSi2（Ｓ２〜Ｓ７、Ｓ９、Ｓ１３〜Ｓ１４、Ｓ１６の場合）、TiC（Ｓ１０の場合）、TiＮ（Ｓ１１の場合）、又はＴａＣ（Ｓ１２の場合）の粒子が認められた。 As a result of analyzing the produced rolling elements of S1 to S18, for S2 to S7 and S9 to S16, (a) β-silicon nitride crystals and (b) grains containing rare earth, silicon, aluminum, oxygen, and nitrogen And (c) WO 3 (in the case of S2 to S7), WSi 2 (in the case of S2 to S7, S9, S13 to S14, S16), TiC (in the case of S10), TiN (in the case of S11) ) Or TaC (in the case of S12) particles were observed.
また、Ｓ３、Ｓ７〜Ｓ８の転動体については、酸窒化珪素の結晶が認められた。
Ｓ１〜Ｓ１８のそれぞれの転動体について、密度、相対密度、ヤング率、３点曲げ強度（表２では「強度」と表示）、破壊靱性、β-窒化珪素の長径における平均粒径（表２では「（ａ）の平均粒径」と表示）、（ｃ）の平均粒径、酸窒化珪素の長径における平均粒径（表２では「Si2N2Oの平均粒径」と表示）、マイクロポア集合体の直径、断面において粒界相が占める面積の比率（表２では「粒界相の比率」と表示）、研削性、及び転がり寿命を評価した。その結果を表２及び表３に示す。
Moreover, about the rolling element of S3 and S7-S8, the crystal | crystallization of silicon oxynitride was recognized.
For each of the rolling elements of S1 to S18, density, relative density, Young's modulus, three-point bending strength (indicated as “strength” in Table 2), fracture toughness, and average particle diameter at the major axis of β-silicon nitride (in Table 2) (Displayed as “average particle size of (a)”), average particle size of (c), average particle size of major axis of silicon oxynitride (shown as “average particle size of Si 2 N 2 O” in Table 2), micro The diameter of the pore aggregate, the ratio of the area occupied by the grain boundary phase in the cross section (indicated as “ratio of grain boundary phase” in Table 2), grindability, and rolling life were evaluated. The results are shown in Tables 2 and 3.
研削性は、以下の方法で試験し、以下の評価基準で評価した。
（評価方法）焼結体を＃１８０のダイヤモンド砥石で研削し、研削抵抗を電流値で評価。
Grindability was tested by the following method and evaluated according to the following evaluation criteria.
(Evaluation method) The sintered body was ground with a # 180 diamond grindstone, and the grinding resistance was evaluated by the current value.
（評価基準）
○：３Ａ以下
×：４Ａを超える
なお、研削の際に、１００μm以上の大きい剥離があったものも×とする。
転がり寿命は、以下の方法で試験し、以下の評価基準で評価した。
(Evaluation criteria)
○: 3 A or less ×: More than 4 A In addition, the case where there was a large peeling of 100 μm or more during grinding is defined as x.
The rolling life was tested by the following method and evaluated according to the following evaluation criteria.
ボールとしての転がり疲労寿命は、スラスト型試験で評価した。窒化珪素焼結体をスラスト試験用平板に鏡面研磨加工し、その上に保持器と軸受用の玉３個（軸受鋼ＳＵＪ２製、直径９．５２５ｍｍ）を組み合わせ、油中で、１０００ｒｐｍ、５００ｋｇｆで評価を行った。
評価基準：
◎：１０００h以上でも窒化珪素平板に剥離なし
○：３００h以上でも窒化珪素平板に剥離なし
△：５０〜３００hにて窒化珪素平板に剥離
×：５０h以下にて窒化珪素平板に剥離
表２及び表３に示す評価結果から明らかなように、Ｓ３〜Ｓ５、Ｓ７、Ｓ９〜Ｓ１４の転動体は、ヤング率が低く、強度が高く、研削性及び転がり寿命において優れていた。それに対し、Ｓ１、Ｓ２、Ｓ６の転動体は、研削性又は転がり寿命において顕著に劣っていた。
The rolling fatigue life as a ball was evaluated by a thrust type test. A silicon nitride sintered body is mirror-polished into a flat plate for thrust test, and a cage and three bearing balls (made of bearing steel SUJ2, diameter 9.525 mm) are combined on it, and in oil, at 1000 rpm and 500 kgf. Evaluation was performed.
Evaluation criteria:
A: No peeling on the silicon nitride flat plate even at 1000 hours or longer. ○: No peeling on the silicon nitride flat plate even at 300 hours or longer. Δ: Peeling on the silicon nitride flat plate at 50 to 300 hours x: Peeling on the silicon nitride flat plate at 50 hours or less Tables 2 and 3 As is clear from the evaluation results shown in Fig. 5, the rolling elements of S3 to S5, S7, and S9 to S14 have a low Young's modulus, a high strength, and an excellent grindability and rolling life. On the other hand, the rolling elements of S1, S2, and S6 were significantly inferior in grindability or rolling life.
尚、本発明は前記実施形態になんら限定されるものではなく、本発明の要旨を逸脱しない範囲において種々の態様で実施しうることはいうまでもない。 Needless to say, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist of the present invention.
Claims (5)
（ｂ）希土類、珪素、アルミニウム、酸素、及び窒素を含む粒界相と、
（ｃ）Ti、Zr、Hf、W、Mo、Ta、Nb、V及びCrからなる群から選択される１種以上の元素を含む粒子と、
を有し、
断面において前記（ｂ）が占める面積の比率が１０％以上であり、
前記（ａ）の長径における平均粒径が１μｍ以下であるとともに、前記（ｃ）の平均粒径が１μｍ以下であり、
マイクロポアの集合体の直径が１００μｍ以下であり、
全重量に対する前記（ｃ）の重量比が５重量％以下であることを特徴とする転動体。 (A) a β-silicon nitride crystal;
(B) a grain boundary phase containing rare earth, silicon, aluminum, oxygen, and nitrogen;
(C) particles containing one or more elements selected from the group consisting of Ti, Zr, Hf, W, Mo, Ta, Nb, V and Cr;
Have
The ratio of the area occupied by (b) in the cross section is 10% or more,
The average particle size of the major axis of (a) is 1 μm or less, and the average particle size of (c) is 1 μm or less,
The diameter of the collection of micropores Ri der less 100 [mu] m,
Rolling elements, characterized in der Rukoto weight ratio of 5 wt% or less of the (c) to the total weight.
（Ｂ）希土類酸化物又は希土類水酸化物と、
（Ｃ）酸化アルミニウムと、
（Ｄ）平均粒径１μｍ以下の粉末であって、Ti、Zr、Hf、W、Mo、Ta、Nb、V及びCrからなる群から選択される１種以上の元素の窒化物、炭化物、珪化物、及び酸化物のうちの１種以上とを、
全原料に対し、前記（Ａ）及び（Ｄ）を除いた残りの重量が１０〜３０重量％の範囲内となり、全原料に対し、前記（Ｄ）の重量が５重量％以下となるように混合して成形体を作製し、
前記成形体を、窒素を含む非酸化雰囲気中で、揮発率を２重量％以下に抑制しながら、１５００〜１７００℃の温度で焼成することを特徴とする転動体の製造方法。 (A) silicon nitride having an α ratio of 70% or more;
(B) a rare earth oxide or a rare earth hydroxide;
(C) aluminum oxide;
(D) Nitride, carbide, or silicidation of one or more elements selected from the group consisting of Ti, Zr, Hf, W, Mo, Ta, Nb, V, and Cr, and having an average particle size of 1 μm or less One or more of the product and the oxide,
With respect to the total raw material, the (A) and Ri Do in the range remaining weight is 10 to 30 wt%, excluding the (D), relative to the total feed weight of the (D) is I and 5 wt% or less To produce a molded body,
A method for producing a rolling element, comprising firing the molded body at a temperature of 1500 to 1700 ° C. while suppressing a volatilization rate to 2% by weight or less in a non-oxidizing atmosphere containing nitrogen.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2012132005A JP5830439B2 (en) | 2012-06-11 | 2012-06-11 | Rolling element and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2012132005A JP5830439B2 (en) | 2012-06-11 | 2012-06-11 | Rolling element and manufacturing method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2013256397A JP2013256397A (en) | 2013-12-26 |
| JP5830439B2 true JP5830439B2 (en) | 2015-12-09 |
Family
ID=49953172
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2012132005A Active JP5830439B2 (en) | 2012-06-11 | 2012-06-11 | Rolling element and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP5830439B2 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9869190B2 (en) | 2014-05-30 | 2018-01-16 | General Electric Company | Variable-pitch rotor with remote counterweights |
| US10072510B2 (en) | 2014-11-21 | 2018-09-11 | General Electric Company | Variable pitch fan for gas turbine engine and method of assembling the same |
| JP6321608B2 (en) * | 2014-11-21 | 2018-05-09 | 日本特殊陶業株式会社 | Silicon nitride sintered body, method for producing the same, and rolling element for bearing |
| US20160290228A1 (en) * | 2015-04-06 | 2016-10-06 | General Electric Company | Fan bearings for a turbine engine |
| US10100653B2 (en) | 2015-10-08 | 2018-10-16 | General Electric Company | Variable pitch fan blade retention system |
| US11674435B2 (en) | 2021-06-29 | 2023-06-13 | General Electric Company | Levered counterweight feathering system |
| US11795964B2 (en) | 2021-07-16 | 2023-10-24 | General Electric Company | Levered counterweight feathering system |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06329472A (en) * | 1993-05-21 | 1994-11-29 | Ube Ind Ltd | Sintered silicon nitride |
| JP2000072553A (en) * | 1998-08-31 | 2000-03-07 | Kyocera Corp | Silicon nitride wear resistance member and its production |
| JP2000256066A (en) * | 1999-03-05 | 2000-09-19 | Kyocera Corp | Silicon nitride-base sintered compact, its production and wear resistant member using same |
-
2012
- 2012-06-11 JP JP2012132005A patent/JP5830439B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| JP2013256397A (en) | 2013-12-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5830439B2 (en) | Rolling element and manufacturing method thereof | |
| JP4795588B2 (en) | Wear resistant parts made of silicon nitride | |
| US9440887B2 (en) | Silicon nitride sintered body and wear resistant member using the same | |
| US7056850B2 (en) | Wear-resistant silicon nitride member and method of manufacture thereof | |
| JP5732037B2 (en) | Wear-resistant member and method for manufacturing the same | |
| JP5886337B2 (en) | Wear-resistant member and wear-resistant device using the same | |
| JP5002155B2 (en) | Wear-resistant member made of silicon nitride and method of manufacturing the same | |
| JP5289053B2 (en) | Sliding member and bearing using the same | |
| JP5268750B2 (en) | Impact resistant member and manufacturing method thereof | |
| JP2024019273A (en) | Manufacturing method for slide member made from silicon nitride sintered body | |
| JP6037217B2 (en) | Method for producing silicon nitride sintered body | |
| JP6037218B2 (en) | Silicon nitride sintered body and sliding member using the same | |
| JP5989602B2 (en) | Silicon nitride sintered body, manufacturing method thereof, and rolling element for bearing | |
| US20230093291A1 (en) | Silicon nitride sintered body, wear-resistant member using the same, and method for producing silicon nitride sintered body | |
| JP6321608B2 (en) | Silicon nitride sintered body, method for producing the same, and rolling element for bearing | |
| KR100613956B1 (en) | Silicon nitride anti-wear member and process for producing the same | |
| JP2008273829A (en) | Method of manufacturing wear-resistant member made of silicon nitride | |
| JP5150064B2 (en) | Method for manufacturing wear-resistant member | |
| JP5349525B2 (en) | Rolling element | |
| JP4869171B2 (en) | Method for producing wear-resistant member made of silicon nitride | |
| JP5295983B2 (en) | Method for producing wear-resistant member made of silicon nitride |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20140421 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20150319 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20150407 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20150604 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20150929 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20151026 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 5830439 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313531 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |