| CHENG Xiang-jun,HUANG Guo-long,LIU Jun,WEI Tao,ZHANG Ji-xian.Effect of Different Surface Treatment on Tappet Microstructure and Wear Resistance[J],47(11):119-125 |
| Effect of Different Surface Treatment on Tappet Microstructure and Wear Resistance |
| Received:May 29, 2018 Revised:November 20, 2018 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2018.11.018 |
| KeyWord:compound heat treatment soft nitriding induction hardening wear resistance tappet microstructure |
| Author | Institution |
| CHENG Xiang-jun |
State Key Laboratory of Engine Reliability, Weichai power company limited, Weifang , China |
| HUANG Guo-long |
State Key Laboratory of Engine Reliability, Weichai power company limited, Weifang , China |
| LIU Jun |
State Key Laboratory of Engine Reliability, Weichai power company limited, Weifang , China |
| WEI Tao |
State Key Laboratory of Engine Reliability, Weichai power company limited, Weifang , China |
| ZHANG Ji-xian |
State Key Laboratory of Engine Reliability, Weichai power company limited, Weifang , China |
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| Abstract: |
| The work aims to improve wear resistance. The tappet was treated by three kinds of surface treatment including nitriding, inducting hardening and compound technology. The microstructure and hardness of three tappets were analyzed by microhardness tester and metalloscope. The friction coefficient of tappets under three lubrication conditions, including dry friction, sufficient lubrication and insufficient lubrication was studied by SRV friction wear testing machine. Wear morphology and depth were analyzed by stereoscopic microscope and surface profile measuring instrument. Reliability of different tappets was studied by 1000 hours load cycle endurance test at engine bench. Nitriding tappet surface microstructure consisted of 0.006 mm thick compound layer and 0.2 mm thick diffusion layer. Its hardness layer was thin and the transition was not smooth. There were a lot of porosity defects in white layer. Inducting hardening tappet surface microstructure consisted of 2 mm thick general martensite layer. Its hardness layer was deep and the transition was smooth. Compound technology tappet surface microstructure consisted of 0.04 mm thick nitric martensite layer and 2 mm thick general martensite layer. Its hardness layer was deep and the transition was smooth. The friction coefficient of nitriding and compound technology tappets were constant under dry friction and sufficient lubrication. The friction coefficient was 0.54 and 0.56 under dry friction. The friction coefficient were 0.174 under sufficient lubrication. Both tappets had excellent adhesive and abrasive wear resistance performance. The friction coefficient of inducting hardening tappet sharply increased under dry friction and was up to 0.95. By the time, the test was terminated due to adhesion clamping. Its friction coefficient was constant at 0.164 under sufficient lubricatio. This indicated that inducting hardening tappet had better abrasive wear resistance performance, but it had poor, adhesive wear performance. In addition, the reliability of compound technology tappet was higher than that of nitriding tappet. The surface of compound technology tppet was free from abnormal wear and peeling, while the surface of nitriding tappet had worse peeling. Compound technology can effectively improve the reliability of tappet. |
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