• Title/Summary/Keyword: mating ball

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Effect of Hardness of Mating Materials on DLC Tribological Characteristics

  • Na, Byung-Chul;Akihiro Tanaka
    • KSTLE International Journal
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    • v.3 no.1
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    • pp.38-42
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    • 2002
  • Diamond-like Carbon(DLC) films were deposited on Si wafers by an RF-plasma-assisted CVD using CH$_4$gas. Tribological tests were conducted with the use of a rotating type ball on a disk friction tester with dry air. This study made use of four kinds of mating balls that were made with stainless steel but subjected to different annealing conditions in order to achieve different levels of hardness. In all load conditions, testing results demonstrated that the harder the mating materials, the lower the friction coefficient was. The friction coefficients were fecund to be lower with austenite mating balls than with fully annealed martensite balls. Conversely, the high friction coefficient found in soft martensite balls appeared to be caused by the larger contact area between the DLC film and the ball. The wear tracks on DLC films and mating balls could prove that effect. Measuring the wear track of both DLC films and mating balls revealed a similar tendency compared to the results of friction coefficients. The wear rate of austenite balls was also less than that of fully annealed martensite balls. Friction eoefficients decrease when applied leads exceed critical amount. The wear track on mating balls showed that a certain amount of material transfer occurs from the DLC film to the mating ball during a high friction process. Raman Spectra analysis Showed that the transferred materials were a kind of graphite and that the contact surface of the DLC film seemed to undergo a phase transition from carbon to graphite during the high friction process.

A Study on Tribological Characteristics of DLC Films Considering Hardness of Mating Materials (상대 재료의 경도를 고려한 DLC필름의 트라이볼로지 특성)

  • Na, Byeong-Cheol;Tanaka, Akihiro
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.2
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    • pp.260-266
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    • 2002
  • DLC films were deposited on Si wafer by RF plasma assisted CVD using CH4 gas. Tribological tests were conducted using rotating type ball on disk friction tester in dry air. Four kinds of mating balls were used. The mating balls were made with stainless steel but apply different annealing conditions to achieve different hardness conditions. Testing results in all load conditions showed that the harder the mating materials, the lower the friction coefficient among the three kind of martensite mating balls. In case of austenite balls, the friction coefficients were lower than fully annealed martensite ball. The high friction coefficient in soft martensite balls seems to be caused by the larger contact area between DLC film and ball. The wear tracks of DLC films and mating balls could have proven that effect. Measuring the wear track of both DLC films and mating balls have similar tendency comparing to the results of friction coefficients. Wear rate of austenite balls were also smaller than that of fully annealed martensite ball. The results of effect of applying load showed, the friction coefficients were become decrease when the applying loads exceed critical load conditions. The wear track of mating balls showed that some material transfer occurs from DLC film to mating ball during the high friction process. Raman spectra analysis showed that transferred material was a kind of graphite and contact surface of DLC film seems to undergo phase transition from carbon to graphite during the high friction process.

Tribology Characteristics of DLC Film Based on Hardness of Mating Materials (경질탄소 필름과 대면물질 경도변화에 대한 트라이볼로지 특성)

  • Na Byung Chul;Tanaka Akihiro
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2003.11a
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    • pp.50-55
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    • 2003
  • Tribological testing of DLC films was conducted using a rotating type ball on a disk friction tester in a dry chamber. This study made use of four kinds of mating balls that were made with stainless steel but subjected to diverse annealing conditions in order to achieve different levels of hardness. In all load conditions using martensite mating balls, the test results demonstrated that the friction coefficient was lower when the mating materials were harder. The high friction coefficient found in soft martensite balls appeared to be caused by the larger contact areas. The wear track on the mating balls indicated that a certain amount of material transfer occurs from the DLC film to the mating ball during the high friction process. Raman Spectra analysis showed that the transferred materials were a kind of graphite and that the contact surface of the DLC film seemed to undergo a phase transition from carbon to graphite during the high friction process.

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Report on the group mating of Asian keelback snake Hebius vibakari Boie 1826(Squamata; Colubridae) in South Korea (한국산 대륙유혈목이 Hebius vibakari의 집단 번식 사례 보고)

  • Koo, Kyo Soung;Chang, Min-Ho;Song, Jae-Young
    • Korean Journal of Environmental Biology
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    • v.37 no.1
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    • pp.88-92
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    • 2019
  • The objective of this study was to report the group mating of Asian Keelback snake, Hebius vibakari, in South Korea. On May 20, 2009, the group mating of H. vibakari was observed in the Maeng-gol do, Jindo-gun, Jeollanam-do, in the rocky area (107 m above sea level) on the ridge of the island. Six female and five male snakes made a form of mating behavior called "mating ball". Two couples showed "tail-wrestling" which is the copulation behavior in snake species. During the mating, the temperature and humidity were $25.7^{\circ}C$ and 59%, respectively. The result of this study was the first case report of the group mating in H. vibakari, a rare reptile.

EFFECT OF SURFACE ROUGHNESS OF MATING SURFACE AND TRANSFER LAYER ON FRICTION BETWEEN a-CNx AND $Si_3N_4$ IN NITROGEN

  • Umehara, N.;Tokoroyama, T.;Tomita, H.;Takenoshita, Y.
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.155-156
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    • 2002
  • During the sliding between a-CNx and $Si_3N_4$, applying nitrogen as environmental gas provided very low friction as the level of 0.01 in friction coefficient. In order to know the effect of the running-in process on the reduction of the friction, the effect of surface roughness of mating surface on friction was investigated. It was shown that smooth surface in wear scar of ball provided low friction coefficient. Friction coefficient after running-in was proportional to the Ry value of wear scar of ball. Also smooth thin transferred layer was observed on the wear scar of balls with an AFM after sliding test. Those results showed the smoothing of wear scar of ball, the generating of the transferred layer from CNx was necessary for low friction.

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Tribological Characteristics of Diamond-like Carbon Films Based on Hardness of Mating Materials

  • Na, Byung-Chul;Tanaka, Akihiro
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.147-148
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    • 2002
  • This study made use of four kinds of mating balls that were made with stainless steel but subjected to different annealing conditions in order to achieve different levels of hardness. In all load conditions, testing results demonstrated that the harder the mating materials, the lower the friction coefficient was. Conversely, the high friction coefficient found in soft martensite balls appeared to be caused by the larger contact area between the DLC film and the ball. Raman Spectra analysis showed that the transferred materials were a kind of graphite and that the contact surface of the DLC film seemed to undergo a phase transition from carbon to graphite during the high friction process.

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Premature Failure of Deep Grooved Ball Bearing for Automobiles : Part 2 - Critical Dent Size (자동차용 깊은홈 볼베어링의 조기파손 : 2보 - 임계압흔의 크기)

  • Hyun Joons;Park Tae Jo
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2003.11a
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    • pp.395-401
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    • 2003
  • In this paper, the dent printing phenomena and critical dent size which lead to premature failure of deep grooved ball bearing for automobiles are presented. The results of newly assembled test bearings showed that the ball dent size strongly affect the bearing life and inner ring raceways were the major failed parts in spite of using the dented balls. The dent printing phenomena are a root cause of premature failure, which was not reported until now. And there exist the critical ball dent size for given rolling bearings and operating conditions. So, the initial condition of tribologically mating parts should be treated as important as the failed body itself.

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TRIBOLOGICAL PROPERTIES OF DLC FILMS SLIDING AGAINST DIFFERENT STEELS

  • Suzuki, M.;Tanaka, A,
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.173-174
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    • 2002
  • To study the effects of mating materials on the tribological properties of DLC films. we used a ball-on-plate reciprocating friction tester in dry air and mating materials of martensite stainless steel (hardened, annealed SUS440C), austenite stainless steels (SUS304), and bearing steel (hardened, annealed SUJ2). At a light load of 0.6 N, the friction coefficient always exceeded ${\mu}>0.3$. Tribological properties of DLC film were still excellent above 0.6 N, except in sliding against annealed SUJ2. Analysis using micro-laser Raman spectroscopy showed that the difference between annealed SUJ2 and others materials appears mainly due to structural change in film.

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A Study on the Wear Behavior of SPS5 Steel Surface-Treated by Induction Hardening Method (고주파 열처리에 따른 SPS5 강의 마모특성 변화에 대한 연구)

  • Kim, Min-Ho;Rhee, Kyong-Yop;Paik, Young-Nam;Hong, Jai-Sung;Ham, Young-Sam
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.10
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    • pp.74-79
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    • 2006
  • In this study, the tempering effect on the wear characteristics of induction-hardened SPS5 steel was investigated. For this purpose, three tempering conditions were applied to control the hardness of heat-treated SPS5 steel. Ball-on-disk wear tests have been performed using zircornia balls on the tempered specimens to determine the variation of wear characteristics. The results showed that friction coefficient decreased with increasing hardness for induction hardening conditions. This seems to occur because real contact area between specimen and mating ball was affected by the specimen hardness.

A study on the wear behavior of spring steel surface-treated by induction hardening method (고주파로 열처리된 스프링강의 마모특성)

  • Kim M.H.;Rhee K.Y.;Paik Y.N.;Oh T.Y.;Hong J.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.409-410
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    • 2006
  • In this study, the tempering effect on the wear characteristics of induction-hardened SPS5 steel was investigated. For this purpose, three tempering conditions were applied to control the hardness of heat-treated SPS5 steel. Ball-on-disk wear tests have been performed using zircornia balls on the tempered specimens to determine the variation of wear characteristics. The results showed that friction coefficient decreased with increasing hardness for induction hardening conditions. This seems to occur because real contact area between specimen and mating ball was affected by the specimen hardness.

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