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Metallography Lab. 0 Effects of target current on the mechanical properties of Cr-C coatings by using the Unbalanced Magnetron Sputtering Professor Dr. Yu-Sen Yang Speaker Jia-Hau Lin Date 2011.05.20 Slide 2 Metallography Lab. 1 Outline Introduction Experiment Results and discuss Conclusion Slide 3 Metallography Lab. 2 Introduction 1.The chromium carbide (Cr-C) films have excellent properties including chemical stability, oxidation resistance, low coefficient of friction and wear resistance. 2. The excellent anti-wear performance of Cr-C films can be attributed to the large content of carbide. 3. Cr-C coatings have been known to protected tools which may be damaged by high thermal load (high cutting speed). Slide 4 Metallography Lab. 3 Experiment (equipment) Equipment: Unbalance magnetron sputtering Substrate: high speed steel(SKH51) Slide 5 Metallography Lab. 4 Experiment (parameter) 1.Ar cooling time after deposition 20 Min 2.Substrate bias-100 V 3.Chromium target current1A,2A,3A,4A,5A,6A 4.C 2 H 2 flow rate ratio30 % 5.Ion bombardment voltage-300 V 6.Work distance13 cm 7.Frequency of substrate100 KHz 8.Rotation speed of substrate holder 5 rpm : 2010 Cr-C Slide 6 Metallography Lab. 5 Experiment (Properties test ) 1.Component Analysis: EDS 2.Morphology: FE-SEM 3.Microstructure: Raman Analysis 4.Friction coefficient: Ball-on-disc Slide 7 Metallography Lab. 6 Experiment (Properties test ) 5.Wear rate estimation: Calculated after measuring wear track by Alpha-step (1)Alpha-Step (2) V: R: A: Slide 8 Metallography Lab. 7 Results and discuss (Component Analysis) Cr Cr( at.%)C ( at.%) 1 A5.894.2 2 A22.277.8 3 A47.352.7 4 A59.340.7 5 A63.836.2 6 A68.931.1 Slide 9 Metallography Lab. 8 Results and discuss ( Friction coefficient test) Against ballLoadingRotation diameterRotation rateLength Cr ball0.5kg20mm286rpm1000m 1A2A3A4A5A6A 0.290.220.390.610.780.66 Slide 10 Metallography Lab. 9 1A2A3A4A5A6A 6*10 -6 24*10 -6 142*10 -6 270*10 -6 303*10 -6 423*10 -6 :mm 3 N -1 m -1 Results and discuss (Wear rate) Slide 11 Metallography Lab. 10 Results and discuss (friction coefficient) Slide 12 Metallography Lab. 11 Results and discuss (Wear rate) Slide 13 Metallography Lab. 12 Results and discuss 1A 6A Slide 14 Metallography Lab. 13 Results and discuss(Raman) D band 1350 cm-1 G band 1580 cm-1 (cm -1 ) 1332~1334 (C 12 ) 1323 1350 1580~1600 (C 13 ) 1290 1332 (a-C) 1350 1580 Slide 15 Metallography Lab. 14 Conclusions The experimental results show the carbon content in Cr-C films increase with decreasing target current when target current decrease from 6A to 1A,the carbon content increase from31.1 at.% to at 94.2 at.%. The friction coefficient of films decrease from 0.66 to 0.22 and the wear rate is reduced from 423 10 -6 (mm 3 N -1 m -1 ) to 6 10 -6 (mm 3 N -1 m -1 ) when the current reduced from 6A to 1A. The lowest wear rate is 6 10 -6 (mm 3 N -1 m -1 ) at traget current 1A The lowest friction coefficient is 0.22 at traget current 2A The excellent anti-wear performance of Cr-C films can be attributed to the large content of carbide. Slide 16 Metallography Lab. 15 The reasons for a low coefficient of friction is the formation of solid solution carbon in the diamond- like carbon film in the crystal structure, which could effectively reduce wear and promote the wear resistance characteristics. Slide 17 Metallography Lab. 16 The End