FRICTION AND WEAR PROPERTIES OF CN X COATINGS IN THE FLOW OF N 2 GAS

Transcription

1 24 th IRG-OECD Meeting, October , Portoroz, Slovenia FRICTION AND WEAR PROPERTIES OF CN X COATINGS IN THE FLOW OF N 2 GAS Koji Kato, Shin Toyokawa, Koshi Adachi, Boyko Stoimenov Tribology Laboratory, Tohoku University, Sendai, Japan N 2

2

3 β-c 3 C N [A. I. Liu, M. L. Cohen, 1989]

4 Past works on CNx coating and N 2 lubrication Sliding speed: 4 mm/s CNx coating on Si wafer Evacuation Load Strain gauge mN ball N 2 Ar Air Vacuum chamber

5 Friction coefficient μ Friction coefficient, µ Pin : Si 3 N 4 ball (r=4.0mm, R max = 15 nm) Disk : 100 nm CNx / Si (R max = 1~3 nm) Normal load : 100 mn Maximum contact pressure : 200 MPa Sliding velocity : 4 mm/s 240 friction cycles Air Vacuum N CO O (10 5 Pa) (2x10-4 Pa) [N. Umehara, Sato, K. Kato 1997] Si Wafer (7.4x10 4 Pa)

6 Friction Friction coefficient coefficient μ μ Si Wafer [N. Umehara,M.Tatsuno, K. Kato, 1999] Disk : a-cnx on Si (t=100nm) Ball : (r=4.0mm) Normal load : mN Slidnig speed : 44.2x10 mm/s -3 m/s Pressure of N 2, P, x x10 44 Pa 0.007

7 X-Z stage Strain gages Air Spring N 2 gas Inner diameter 4.5 mm Si-wafer Si3N4 ball CNx Disk Ball-on disk tester

8 Friction coefficient, μ Disk: CNx(100nm)/ Pin: ball (r=4 mm) Normal load: 200 mn Rotary speed: 250 rpm(0.4 m/s) Air [K. Adachi, K. Kato, Ueno, 2000] N N l/min 1.2 l/min 4.8 l/min Number Number of friction of cycles cycles 10 3 N, cycles x10 3

9 Air Spring N 2 gas N 2 N 2 gas Inner φ 4.5mm ball Test piece 10 mm N 2 gas φ

10 [K. Adachi, K. Kato, Ueno, 2000] Friction coefficient, Coating: 100n m CNx Substrate: Ball: (r = 4 mm) Normal load: 200 mn Rotatrypeed: 250 rpm Flow rate: 3.6 l/min Air 10 mm Blow angle of N 2 gas φ, degree φ N 2 gas

11 μ Friction coefficient, μ [K. Adachi, K. Kato, Ueno, 2000] Disk: CNx(100nm)/,SiC Pin: ball (r=4mm) Normal load: 200mN Rotary speed: 250rpm Air Flow rate of N 2 gas Q, l/min

12 What is the best combination among /, / and C/C? N 2 C-coating N 2 C-coating N 2 Ar O 2 CO 2 Air Is N 2 gas blow better than Ar, O 2, CO 2 or open air for lubricating / contact?

13 substrate Carbon (Evaporated) N ion (mixing) Electron beam Carbon target

14 Deposition conditions Evaporation Target Coating speed Carbon : % 5, 10, 20, 30, 50 Å/s N ion beam Mixing Gas flow Background Pressure Operating Substrate Coating thickness Rotation speed Acc. voltage Current density 1.5 kv 90 μa/cm 2 N 2 : 3.0 SCCM * < Pa Pa about 400nm 4 rpm Sputter cleaning N ion beam Gas flow Duration Acc. Voltage 1.5 kv Current density 100 μa/cm 2 N 2 : 3.0 SCCM * 5 minutes *SCCM: Standard Cubic Centimeter per Minute

15 The surface of coating on substrate disk

16 The surface of coating on substrate ball ball 5 μm 100 μm coated ball thickness : 400nm 5 μm 100 μm

17 Indentation hardness H, GPa Hardness of and C coatings CNx and C on (t=400nm) Maximum indentation load : 980μN Maximum indentation depth : 50-64nm 5A /s Å/s 10A /s Å/s 20A /s Å/s 30A /s Å/s 50A /s Å/s C 20A /s Å/s Evaporation speed of CNx and C coating V e, A /s

18 / vs. / N N 2 2

19 Friction in N 2 gas blow / sliding / sliding Friction coefficient μ Disk : CNx(Ra=0.025μm) on (t=400nm) Ball : (r=4.0mm) Load : 400mN Maximum contact pressure : 517MPa Sliding speed : 0.2 m/s Gas blow rate : 2.10 cc/mm 2 s Gas blow distance : 10mm Gas blow start cycle : 100 cycles Hv(CNx) : 28.8GPa No blow (in air) N2 gas blow Friction coefficient μ Disk : CNx(Ra=0.025μm) on (t=400nm) Ball : CNx coated (r=4.0mm) Load : 400mN Maximum contact pressure : 517MPa Sliding speed : 0.2 m/s Gas blow rate : 2.10 cc/mm 2 s Gas blow distance : 10mm Gas blow start cycle : 100 cycles Hv(CNx) : 28.8GPa No blow (in air) N2 gas blow Number of cycles N, cycles Number of cycles N, cycles CNx / CNx sliding : low and stable friction faster than CNx / sliding μ=0.03 (blow) μ=0.15 (in air)

20 Wear of ball in N 2 gas blow Friction coefficient μ / Friction coefficient μ Wear volume of ball sliding Disk : CNx(Ra=0.025μm) on (t=400nm) Ball : (r=4.0mm) Load : 400mN Maximum contact pressure : 517MPa Sliding speed : 0.2 m/s Gas blow rate : 2.10 cc/mm 2 s Gas blow distance : 10mm Gas blow start cycle : 100 cycles Hv(CNx) : 28.8GPa Wear volume of ball V, x10-5 mm 3 Friction coefficient μ / sliding Disk : CNx(Ra=0.025μm) on (t=400nm) Ball : CNx coated (r=4.0mm) Load : 400mN Maximum contact pressure : 517MPa Sliding speed : 0.2 m/s Gas blow rate : 2.10 cc/mm 2 s Gas blow distance : 10mm Gas blow start cycle : 100 cycles Hv(CNx) : 28.8GPa Friction coefficient μ Wear volume of ball Wear volume of ball V, x10-5 mm Number of cycles N, cycles 0 μ=0.03 (blow) μ=0.15 (in air) Number of cycles N, cycles 0 at 500~20000cycles W s,s = 5.89x10-8 mm 3 /Nm at 500~20000cycles W s,s = 1.13x10-8 mm 3 /Nm

21 C/C vs. / C-coating N 2 N 2 C-coating

22 Friction coefficient μ C/C with N2 gas blow N 2 CNx/CNx with N2 gas blow Disk : CNx(Ra=0.025μm) on (t=400nm) C(Ra=0.035mm) on (t=400nm) Ball : CNx, C coated (r=4.0mm) Load : 400mN Maximum contact pressure : 517MPa Sliding speed : 0.2 m/s Gas blow rate : 2.10 cc/mm 2 s Gas blow distance : 10mm Gas blow start cycle : 100 cycles Hv(CNx) : 28.8GPa Number of cycles N, cycles

23 C-coated ball Sliding direction of counterface 100 μm C-coated disk Sliding direction of disk 100 μm After sliding of cycles with N 2 gas blow in air

24 coated ball Sliding direction of counterface 100 μm coated disk Sliding direction of disk 100 μm After sliding of cycles with N 2 gas blow in air

25 C-coated ball -coated ball Hv = 33 GPa Hv = 28 GPa Sliding direction of counterface 100 μm C / C 6.42x10-7 mm 3 /Nm After cycles / 9.31x10-9 mm 3 /Nm

26 Effect of Gases of N 2, Ar, CO 2 and Air on friction and wear of CNx / CNx N 2 Ar O 2 CO 2 Air

27 Friction coefficient μ Disk : CNx(R max =0.025mm) on (t=400nm) Ball : CNx coated (r=4.0mm) Load : 400mN Maximum contact pressure : 517MPa Sliding speed : 0.2 m/s Gas blow rate : 2.10 cc/mm 2 s Gas blow distance : 10mm Hv(CNx) : 28.8GPa N2 gas blow O2 gas blow Ar gas blow CO2 blow Air Number of cycles N, cycles

28 (a) N2 blow (b) Argon blow (d) O2 blow (c) CO2 blow (e) Air (No blow) Sliding direction of counterface After cycles Sliding direction of disk 100μm

29 6 0.4 Specific wear rate of ball Ws. x10-7 mm 3 /Nm Disk : CNx(Ra=0.025mm) on (t=400nm) Ball : CNx coated (r=4.0mm) Hv(CNx) : 28.8GPa, Load : 400mN Maximum contact pressure : 517MPa Sliding speed : 0.2 m/s Gas blow rate : 2.10 cc/mm 2 s Gas blow distance : 10mm Gas blow start cycle : 100 cycles Air : 20,RH=30% Specific wear rate Ws Stable friction coefficient μ Friction coefficient 0 N 2 blow N2 blow Ar blow CO2 blow O2 blow Air (No blow) 0 Blow gas

30 Intensity, counts CNx Evaporation speed 20A /s O 2 gas blow Initial Wear track D-band G-band Surface analysis Raman shift, cm -1

31 CNx on disk after sliding cycles in blows of Nitrogen, Oxygen, and in air. W = 400 mn, V = 0.2 m/s Initial surface In Nitrogen blow In Oxygen blow In Air

32 Raman spectra of initial surface and wear track of CNx Evaporation speed 20A /s N2 gas blow CNx Evaporation speed 20A /s O2 gas blow CNx Evaporation speed 20A /s No blow Disk Intensity, counts Initial Wear track D-band G-band Intensity, counts Initial Wear track D-band G-band Intensity, counts Initial Wear track D-band G-band Raman shift, cm Raman shift, cm Raman shift, cm -1 CNx coated Si3N4 ball Evaporation speed 20A /s N2 gas blow CNx coated Si3N4 ball Evaporation speed 20A /s O2 gas blow CNx coated Si3N4 ball Evaporation speed 20A /s No blow Ball Intensity, counts Initial Wear track D-band G-band Intensity, counts Initial Wear track D-band G-band Intensity, counts Initial Wear track D-band G-band Raman shift, cm Raman shift, cm Raman shift, cm -1 N 2 gas blow O 2 gas blow In Air

33 N 2 gas blow O 2 gas blow 100μm Sliding direction of counterface CNx coated ball Evaporation speed 20A /s N 2 gas blow CNx coated ball Evaporation speed 20A /s O 2 gas blow Intensity, counts Initial Wear track D-band G-band Intensity, counts Initial Wear track D-band G-band Raman shift, cm Initial surface Wear track Raman shift, cm -1

34 XPS analysis of the initial surface and wear track after cycles Concentration of of bonds of C C-atoms on in C and CNx coating, % C, % 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Initial surface Wear track Wear track Wear track N 2 blow O 2 blow In air C-N or C-O C=N C=C or C-C

35 XPS analysis of the initial surface and wear track after cycles Concentration of bonds of N N-atoms on in C and CNx coating, % C, % 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% N-O N=C N-N or N=N N-C Initial surface Wear track Wear track Wear track N 2 blow O 2 blow In air

36 Conclusions In N 2 blow μ W s, mm 3 /N.m 1. The combination of / gives lower value of the friction coefficient and wear rate, than the combination of / and C/C in the blow of N 2 gas in open air. / / C/C ~3 x x x10-7 ~0.15 CNx/CNx 2. For the contact of CNx coating against CNx coating N 2 gas blow in open air, gives lowest friction coefficient and wear rate among the gases N 2, Ar, CO 2, O 2 and lower than in open air. Blown gas N 2 Ar CO 2 μ W s, mm 3 /N.m 3.0 x x x10-8 O x10-7 Air x10-7