Improvement of Durability of Hybrid Ceramic Ball Bearings in Liquid Hydrogen at 3 Million DN (120,000 rpm)
The durability of a hybrid ceramic 25-mm-bore ball bearing having a single outer land-guided retainer was evaluated and improved in liquid hydrogen at speeds up to 120,000 rpm (120,000 min-1) (3 million DN) by comparing the propagation of superficial thermal microcracks on Si3N4 balls at various spe...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Japanese Society of Tribologists
2010-02-01
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| Series: | Tribology Online |
| Subjects: | |
| Online Access: | https://www.jstage.jst.go.jp/article/trol/5/1/5_1_60/_pdf/-char/en |
| _version_ | 1818742138114932736 |
|---|---|
| author | Masataka Nosaka Satoshi Takada Makoto Yoshida Masataka Kikuchi Takayuki Sudo Shohei Nakamura |
| author_facet | Masataka Nosaka Satoshi Takada Makoto Yoshida Masataka Kikuchi Takayuki Sudo Shohei Nakamura |
| author_sort | Masataka Nosaka |
| collection | DOAJ |
| description | The durability of a hybrid ceramic 25-mm-bore ball bearing having a single outer land-guided retainer was evaluated and improved in liquid hydrogen at speeds up to 120,000 rpm (120,000 min-1) (3 million DN) by comparing the propagation of superficial thermal microcracks on Si3N4 balls at various speeds. To select a tough Si3N4 ball capable of restraining crack propagation, bearing tests were conducted for three kinds of the Si3N4 balls with different jet-cooling systems. The test results showed that the Si3N4 ball having high fracture toughness as well as high thermal shock resistance could restrain the propagation of wide-ditch microcracks. With regard to the jet-cooling system, four nozzles were better than two nozzles with increasing jet speed. Furthermore, the jet flow aimed at the retainer was superior to that aimed at the inner race, and its result indicated that microcracks might be generated at the trace in contact with the outer raceway under insufficient cooling conditions with a large centrifugal force. Thus, decreasing the maximum contact stress of the outer race to 2.0 GPa by a limited race curvature of 0.51 could restrain the propagation of superficial microcracks. |
| first_indexed | 2024-12-18T02:07:45Z |
| format | Article |
| id | doaj.art-1c5118125fa74da89a8231a6d5a0ff69 |
| institution | Directory Open Access Journal |
| issn | 1881-2198 |
| language | English |
| last_indexed | 2024-12-18T02:07:45Z |
| publishDate | 2010-02-01 |
| publisher | Japanese Society of Tribologists |
| record_format | Article |
| series | Tribology Online |
| spelling | doaj.art-1c5118125fa74da89a8231a6d5a0ff692022-12-21T21:24:33ZengJapanese Society of TribologistsTribology Online1881-21982010-02-0151607010.2474/trol.5.60trolImprovement of Durability of Hybrid Ceramic Ball Bearings in Liquid Hydrogen at 3 Million DN (120,000 rpm)Masataka Nosaka0Satoshi Takada1Makoto Yoshida2Masataka Kikuchi3Takayuki Sudo4Shohei Nakamura5Department of Mechanical Engineering, The University of TokyoKakuda Space Center, Japan Aerospace Exploration AgencyKakuda Space Center, Japan Aerospace Exploration AgencyKakuda Space Center, Japan Aerospace Exploration AgencyKakuda Space Center, Japan Aerospace Exploration AgencyAerospace Project Team, Industrial Sales Headquarters, NTN corporationThe durability of a hybrid ceramic 25-mm-bore ball bearing having a single outer land-guided retainer was evaluated and improved in liquid hydrogen at speeds up to 120,000 rpm (120,000 min-1) (3 million DN) by comparing the propagation of superficial thermal microcracks on Si3N4 balls at various speeds. To select a tough Si3N4 ball capable of restraining crack propagation, bearing tests were conducted for three kinds of the Si3N4 balls with different jet-cooling systems. The test results showed that the Si3N4 ball having high fracture toughness as well as high thermal shock resistance could restrain the propagation of wide-ditch microcracks. With regard to the jet-cooling system, four nozzles were better than two nozzles with increasing jet speed. Furthermore, the jet flow aimed at the retainer was superior to that aimed at the inner race, and its result indicated that microcracks might be generated at the trace in contact with the outer raceway under insufficient cooling conditions with a large centrifugal force. Thus, decreasing the maximum contact stress of the outer race to 2.0 GPa by a limited race curvature of 0.51 could restrain the propagation of superficial microcracks.https://www.jstage.jst.go.jp/article/trol/5/1/5_1_60/_pdf/-char/encryogenic tribologysolid-lubricationball bearinghybrid ceramic bearingsi3n4 ballthermal shockcrush loadthermal cracksjet coolingbearing acceleration |
| spellingShingle | Masataka Nosaka Satoshi Takada Makoto Yoshida Masataka Kikuchi Takayuki Sudo Shohei Nakamura Improvement of Durability of Hybrid Ceramic Ball Bearings in Liquid Hydrogen at 3 Million DN (120,000 rpm) Tribology Online cryogenic tribology solid-lubrication ball bearing hybrid ceramic bearing si3n4 ball thermal shock crush load thermal cracks jet cooling bearing acceleration |
| title | Improvement of Durability of Hybrid Ceramic Ball Bearings in Liquid Hydrogen at 3 Million DN (120,000 rpm) |
| title_full | Improvement of Durability of Hybrid Ceramic Ball Bearings in Liquid Hydrogen at 3 Million DN (120,000 rpm) |
| title_fullStr | Improvement of Durability of Hybrid Ceramic Ball Bearings in Liquid Hydrogen at 3 Million DN (120,000 rpm) |
| title_full_unstemmed | Improvement of Durability of Hybrid Ceramic Ball Bearings in Liquid Hydrogen at 3 Million DN (120,000 rpm) |
| title_short | Improvement of Durability of Hybrid Ceramic Ball Bearings in Liquid Hydrogen at 3 Million DN (120,000 rpm) |
| title_sort | improvement of durability of hybrid ceramic ball bearings in liquid hydrogen at 3 million dn 120 000 rpm |
| topic | cryogenic tribology solid-lubrication ball bearing hybrid ceramic bearing si3n4 ball thermal shock crush load thermal cracks jet cooling bearing acceleration |
| url | https://www.jstage.jst.go.jp/article/trol/5/1/5_1_60/_pdf/-char/en |
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