DEVELOPMENT OF CRACK-RESISTING CEMENTED CARBIDE SLIDING MATERIALS
Grant-in-Aid for Scientific Research (A)
|Research Institution||KYUSHU INSTITUTE OF TECHNOLOGY|
KANETA Motohiro KYUSHU INSTITUTE OF TECHNOLOGY FACULTY OF ENGINEERING,PROFESSOR, 工学部, 教授 (90039123)
今里 州一 日本タングステン(株), 基山工場, 副主幹
徳本 啓 日本タングステン(株), 基山工場, 主幹
坂口 茂也 日本タングステン(株), 基山工場, 主席
MATSUDA Kenji KYUSHU INSTITUTE OF TECHNOLOGY FACULTY OF ENGINEERING,ASSOCIATE PROFESSOR, 工学部, 助教授 (40229480)
TOKUMOTO Kei NIPPON TUNGSTEN CO.LTD.KIYAMA FACULTY,MANAGER
IMASATO Shuichi NIPPON TUNGSTEN CO.LTD.KIYAMA FACULTY,DEPUTY MANAGER
SAKAGUCHI Shigeya NIPPON TUNGSTEN CO.LTD.KIYAMA FACULTY,DEPUTY GENERAL MANAGER
|Project Fiscal Year
1996 – 1997
Completed(Fiscal Year 1997)
|Budget Amount *help
¥9,100,000 (Direct Cost : ¥9,100,000)
Fiscal Year 1997 : ¥3,700,000 (Direct Cost : ¥3,700,000)
Fiscal Year 1996 : ¥5,400,000 (Direct Cost : ¥5,400,000)
|Keywords||Cemented Carbides / Ceramics / Surface Cracking / Thermal Stress / Residual Stress / Corrosion / Machine Elements / Tribology / 超硬合金 / セラミックス / 表面き裂 / 熱応力 / 残留応力 / 腐食 / 機械要素 / トライボロジー / き裂 / 滑り軸受 / メカニカルシール / 熱弾塑性解析|
Cemented carbides have been widely used as rubbinng materials. They have, however, a critical defect that numerous shallow cracks, that run perpendicular to the direction of sliding, occasionally occur on the rubbing surface. The purpose of this study is to establish the design instruction for the development of crack-resisting cemented carbide materials. The effects of factors affecting the occurrence of these cracks were stdied by thermal and elastic-plastic analyzes taking into account the thermal stresses were conduced. The experiments were carried out by pairing 7 kinds of cemented carbide rings with and without Co or Ni binder, a stellite and Ti alloy rings with some ceramic rings. The effects of carbon and Cr on the corrosion resistance in WC-Ni and WC-Ni-Cr cemented carbides were also omvestigated, together with corrosion behavior of Ti-Mo alloys. The main results obtained are summarized as follows :
1.A high contact stress together with a high tangential force is an essential c
ondition for the occurrence of cracks and the direction of their propagation.
2.Cracking is mainly produced bythe residual tensile stress due to thermal stresses induced by frictional heat under conditions of a low contact pressure and high sliding speed. On the other hand, cracking is induced by the tensile stress due to a high friction fource under conditions of a high contact pressure and low sliding speed.
3.The selection of shape and material for reducing the contact pressure and friction coefficient are necessary to prevent cracking.
4.Comparing among cemented carbide materials with the same composition, the critical load against cracking increases as the thermal shock fracture resistance of the material increases.
5.The residual compressive stress existing in the direction of sliding suppresses the occurrence of cracks. 6.It is difficult for cracks to occur on the surface of cemented carbide surface paired with materials with a high thermal diffusivity.
7.The corrosion resistance of WC-Ni-Cr cemented carbides is improved with decreasing of carbon content and with increasing of Cr content.
8.The corrosion resistance of Ti-Mo alloy increases with an increase of Mo content.
The occurrence of cracking on the frictional surface of cemented carbides can be prevented by producing cemented carbide with a high thermal shock fracture resistance, by adding a high residual compressive stress in the direction of the rubbing, and by mating with materials having a high thermal diffusivity and giving a low friction coefficient.
Research Output (6results)