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1 Journal of the Korean Ceramic Society Vol. 44, No. 7, pp. 375~380, Tribological Properties of Carbon Layers Produced by High Temperature Chlorination in Comparison with DLC Coating Hyun-Ju Choi, Heung-Taek Bae, Byung Chul Na,* Jeon-Kook Lee** and Dae-Soon Lim Division of Materials Science and Engineering, Korea University, Seoul , Korea *Energy Technology Research Center, KATECH, Chon An , Korea **Thin Film Materials Research Center, KIST, Seoul , Korea (Received July 5, 2007; Accepted July 20, 2007) DLC gq š w k Tribological p x Á káù *Á **Á š w œw * t t l **w w» l ( ; ) ABSTRACT Tribological properties of carbon layers produced by high temperature chlorination of SiC ceramic and DLC (diamond-like carbon) coatings produced by ion plating method were investigated and compared. Carbon coatings were produced by exposure of ball and disc type SiC in chlorine and hydrogen gas mixtures at 1200 o C. After treatment for 10 h, dense carbon films up to 180 µm in thickness were formed. Tribological behavior of newly developed carbon films were compared with that of DLC films. Wear resistance and frictional coefficient of the surface modified ball and disc type SiC were significantly improved compared to an untreated SiC specimen, and also the modified carbon layer had better performance than DLC coatings. Therefore, in this study, the newly developed carbon films have several advantages over existing carbon coatings such as DLC coatings and showed superior tribological performances. Key words : Silicon carbide, DLC, Chlorination, Wear volume, Friction coefficient 1. SiC, TiC, Si 3 N 4 w yw, š, šü p š, š œ, š w y w ü t z š. 1) w w», yw, p wš y k ü» w e w w y w w. 2) w w» w TiC, TiN, MoS 2 p ƒw ù, DLC(diamond-like carbon)ù TiC t gqw ƒ w. 3,4) DLC w w y p w ü t z Corresponding author : Dae-Soon Lim dslim@korea.ac.kr Tel : Fax : t š ù š š. ù DLC 500 y(thermal degradation)» w š. w 10 GPa w Ì ƒƒ š. DLC gqw ü t w» w w» ƒ w w. ¾ 5,6) w w š w w ƒ. SiC š w k t d ü p w ƒ š š. 7,8)», CDC(carbide-derived carbon) substrate gqw ƒ w SiC etching k Ì y ky³ t ù k g k û w. k ky³ ƒ yw w k d w x» gq» (adhesion) 375

2 376 x Á káù Á Á ƒ. ü t k d w û ü p p w w tribology p». 9) CDC g q d tribology p w ƒ w š š ù, Si 3 N 4 SiC w DLC gq d CDC gq d tribology p w š š. 10) ky³ gq DLC ky³ l x CDC SiC Si 3 N 4 w ñ g tribology p wš wš w. 2. x 2.1. k x w w ky³ disc( 20 mm, Ì 3 mm) xk ƒœw., w œ furnace k z,, š ƒ w š w r w. p x ky³ t w g k j» w Ar-5 ~ 10% Cl 2 Ar-5 ~ 10% Cl ~5% H 2 yw ƒ w, š g. x w t Si w w CCl 4 xk w SiCl 4 x k š, t k û w CDC xk k x j. r 1200 o C w, 10 k z þƒ e, z ùƒš û k w y k w. r DLC gq (C 6 H 6 ) v p y jš, e bias ky³ disc DLC x y w. 200 C o ww ƒ w r t k w» w, Raman spectroscopy(labram HR model, Jobin -Yvon, France) w nm q Ar-ion laser g»(excitation) rp - w. w, X-ray diffractometry (XRD) w gq w. r Ì ü w» w Scanning Electron Microscopy(Hitachi S-4300, field emission SEM) Energy Dispersive Spectroscopy(Horiba EX -200, EDS) w d 20 mm Ì 3mm ƒœ disc r gq DLC CDC 6.35 mm Si 3 N 4 SiC w ball-on-plate x ww m/s w w. x - x 5z w, d 30 l pƒ óù z Ÿw x w ball j» w. k x x k j» w» w ¼ d w s³ w. š r w y w N ƒ w ƒ j w r 6 12z d w. 3. š 3.1. t rt q wš XRD w Fig. 1 ùkþ. Moissanite-6H bulk SiC w rhombohedral graphite. w DLC graphite vjƒ w xk y w. Fig. 2 t r t k w» w Raman w ùkþ. t (a) bulk SiC x Si-C w 789 cm cm 1 e vjƒ š, r (b) DLC vjƒ y w 1550 cm cm 1 e. 11) w, (c) t r XRD Fig. 1. XRD patterns of SiC, DLC coating, and modified carbon layer (CDC). w wz

3 DLC gq š w k Tribological p 377 Fig. 2. Micro-Raman spectra of (a) untreated SiC, (b) DLC, and (c) modified carbon coatings. Fig. 3. Cross-sectional images of the fracture surface of DLC and modified carbon coatings. t k C-C w wš disordered graphite D vj G vjƒ š š e ƒƒ cm cm 1. gq d Ì w» w SEM w Fig. 3 ùkþ. r DLC Ì 1µm, ƒ w r 180 µm. CDC d SEM-EDX SiCƒ w š k y y w Tribology p Fig. 4 ƒ k w SiC SiC gq DLC CDC v y ùküš. Fig. 4(a) Si 3 N 4 ñ x w, SiC r w ƒ ù ù 2N w w ƒ ùš. w CDC r 6N¾ w ƒ ù. DLC r 2N¾ w CDC w û ù, z w Fig. 4. Variation of wear volume as a function of applied load for SiC, DLC, and CDC coatings with a (a) Si 3 N 4 and (b) SiC ball. Wear tests were conducted using a steploading procedure by the ball-on-disk type wear tester. ƒw SiC w xk ƒ w ƒ. 4.5 N DLC ü w w w. Fig. 4(b) SiC xw, Si 3 N 4 w w w ù v SiC DLC r ƒ { w w. Si 3 N 4 SiC» w. Si e g k y³ œ ü š. 12) w» w ky³ w û. Fig. 4 ƒ (abrasive wear) k š. Fig. 5 Si 3 N 4 w ƒw w y ùkþ. gq w ky³ w ƒ k «7y(2007)

4 378 x Á káù Á Á Fig. 5. Variation of frictional coefficient as a function of sliding time and applied load for SiC, DLC, and CDC discs with a Si 3 N 4 ball. Fig. 6. Variation of frictional coefficient as a function of sliding time and applied load for SiC, DLC, and CDC discs with a SiC ball. w wz

5 DLC gq š w k Tribological p ¾ y. ù j gq DLC CDC 0.2 w û y. yw w Ì gqw w w, w DLC œ ü p û w Ì ƒ w 1µm Ì gqw» y w. DLC p x DLC CDC w w. DLC ú ƒw w (fluctuating) w. DLC Ì w w gq d x y j w». w, w t k CDC Si 3 N 4 w xw ƒ w û 0.16 w. Fig. 6 SiC w ƒw w y š. ky³ xw , Fig. 5 w ƒ y³ w Fig. 7. SEM micrographs of the worn disc surfaces of (a) SiC, (b) DLC, and (c) CDC wear tracks with a Si 3 N 4 ball, and corresponding magnified images (d) ~ (f). Fig. 8. SEM micrographs of the worn disc surfaces of (a) SiC, (b) DLC, and (c) CDC wear tracks with a SiC ball, and corresponding magnified images (d) ~ (f). û. wr, DLC y gqw r w û û ƒ. w, ü Ì w x w š y». ù k CDC Si 3 N 4 w xw Fig. 5 w DLC w x w 0.1 w. Fig. 7 Fig. 4(a) y³ w xw x w. (a) ~ (c) SiC DLC š CDC disc p (d) ~ (f) ƒƒ p y w. Fig. 4(a) SiC DLC š w ƒw w, p 6N¾ w ƒw w ƒ û. w DLC y (e) gq ü w gq d ƒ û. w CDC ñ. Fig. 8 Fig. 4(b) ky³ w xw x 44«7y(2007)

6 380 x Á káù Á Á w. w t y³ w w. ù p. SEM w mw ky³ ƒ j y³ k y³ abrasive wearƒ w û y w. 13) 4. ü p k w» w 1200 o C š w graphite 180 µm Ì CDC w. SiC Si 3 N 4 w SiC gq DLC CDC - p y k ww š w w. ky³ disc w Si 3 N 4 tribology sƒ abrasive wear p. w DLC gq d ü p ù, Ì w ü w w gq d. t k w r w 1/5 ƒ w û, v 50% w. ƒ, SiC gq DLC r š w k w w û ü w. Acknowledgments t t l»». REFERENCES (1996). 2. B. Bhushan and B. K. Gupta, Handbook of Tribology: Materials, Coating and Surface Treatments; McGraw-Hill Inc., New York, Y. C. LUO and D. Y. LI, New Wear-Resistant Material: Nano-TiN/TiC/TiNi Composite, J. Mater. Sci., (2001). 4. H. Hyuga, M. I. Jones, K. Hirao, and Y. Yamauchi, Tribological Behavior of a Si 3 N 4 /Carbon Short Fiber Composite under Water Lubrication, J. Am. Ceram. Soc., 87 [4] (2004). 5. A. Grill, Tribology of Diamond-like Carbon and Related Materials: An Updated Review, Surface and Coatings Technology, (1997). 6. K. Jia, Y. Q. Li, T. E. Fischer, and B. Gallois, Tribology of Diamond-like Carbon Sliding Against Itself, Silicon Nitride, and Steel, J. Mater. Res., 10 [6] (1995). 7. Y. Gogotsi, S. Welz, D. A. Ersoy, and M. J. McNallan, Conversion of Silicon Carbide to Crystalline Diamondstructured Carbon at Ambient Pressure, Nature, (2001). 8. Y. Gogotsi, I. D. Jeon, and M. J. McNallan, Carbon Coatings on Silicon Carbide by Reaction with Chlorine-containing Gases, J. Mater. Chem., 7 [9] (1997). 9. A. Erdemir, A. Kovalchenko, M. J. McNallan, S. Welz, A. Lee, Y. Gogotsi, and B. Carroll, Effects of High-temperature Hydrogenation Treatment on Sliding Friction and Wear Behavior of Carbide-derived Carbon Flms, Surface & Coatings Technology, (2004). 10. A. Erdemir, The Role of Hydrogen in Tribological Properties of Diamond-like Carbon Films, Surface and Coatings Technology, (2001). 11. G. Irmer and A. Dorner-Reisel, Micro-Raman Studies on DLC Coatings, Advanced Engineering Materials, 7 [8] (2005). 12. S. S. Hwang, S. W. Park, J. H. Han, K. S. Han, and C. M. Kim, Mechanical Properties of Porous Reaction Bonded Silicon Carbide(in Korean), J. Kor. Ceram. Soc., 39 [10] (2002). 13. G. W. Stachowiak and A. W. Batchelor, Engineering Tribology; second edition, pp , Butterworth-Heinemann, USA, S. M. Hsu and M. C. Shen, Ceramic Wear Maps, Wear w wz