灰口鐵的磨耗與固有值的分析

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题名:	灰口鐵的磨耗與固有值的分析
作者:	邱裔舜;Chiu,Yi-Shun
贡献者:	機械工程學系
关键词:	灰口鐵;微結構;摩擦;磨耗;自然頻率;gray iron;microstructure;friction;wear;natural frequency
日期:	2016-08-22
上传时间:	2016-10-13 14:56:30 (UTC+8)
出版者:	國立中央大學
摘要:	本研究探討三種高低澆鑄溫度(1423°C、1398°C與1368°C)與澆鑄方案(中央進湯與環狀進湯)對灰口鐵Y-block與碟盤的影響。首先，先對碟盤進行自然頻率的測試。而後將鑄件研磨拋光進行金相觀察，並以Ball-on-disc對拋光的表面進行摩擦磨耗實驗，觀察不同石墨與基地組織對灰口鐵自然頻率、摩擦係數與磨耗行為的影響。從自然頻率與金相中可知當基地上團狀形(Type C)石墨的比例上升時，碟盤的自然頻率會下降。溫度越高的澆鑄溫度與越接近入模口，具有較慢的冷卻速率，易形成粗大的片狀石墨，甚至團狀石墨。除此之外基地因為冷卻速率慢，傾向於石墨周圍形成肥粒鐵與粗波來鐵。當摩擦開始時，粗大的石墨可迅速地析出形成石墨層保護及潤滑摩擦面。然而因石墨離開，或者是石墨周圍較軟的基地，如粗波來鐵與肥粒鐵，易受摩擦變形剝落成碎片，會在基地表面形成坑洞，同時碎片會對表面產生刮傷。在持續的摩擦後碟盤表面容易形成大型坑洞與裂痕，對剎車系統的性能、震動與噪音產生不良影響。 ;In this study, we focus on the influence of three pouring temperature(1423°C、1398°C and 1368°C) and two casting projects. First, we have the measurement of natural frequency on the brake disc. Second, we have the suitable samples be polished and pictured by the optical microscopes. After that, let samples have friction and wear test on a Ball-on-disc test machine. At the last, we have to observe the different wear surface of different casting samples. From the test of natural frequency and picture of microstructure, we get the relation between them. When the content of Type C graphite increase in the matrix of gray iron, the value of natural frequency will decrease. The higher the pouring temperature and the closer to the in-gate of the molten iron, having the slower solidification rate and will form larger flake graphite or lump graphite. Besides, because of the lower solidification, matrix of gray iron tends to form ferrite and coarse pearlite near the larger or lump graphite. At the beginning of friction, graphite will be smeared onto the wear surface and form graphite layer protect surface form directly friction and serve as lubrication. Unfortunately, with the leave of graphite or soften matrix near graphite, such as ferrite and coarse pearlite, ease to transform or peel off and cause cavities on the wear surface. Meanwhile, the fragment will have abrasive wear on the surface. With the constant friction, the surface of brake disc will form bigger cavities and crack. For the performance、vibration and noise of brake system, it will cause harmful influence.
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