Fretting-corrosion behavior in hip implant modular junctions: The influence of friction energy and pH variation

Fretting-corrosion behavior in hip implant modular junctions: The influence of friction energy and pH variation

Author’s Accepted Manuscript Fretting-Corrosion Behavior in Hip Implant Modular Junctions: The Influence of Friction Energy and pH Variation Dmitry Ro...

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Author’s Accepted Manuscript Fretting-Corrosion Behavior in Hip Implant Modular Junctions: The Influence of Friction Energy and pH Variation Dmitry Royhman, Megha Patel, Maria J. Runa, Markus A. Wimmer, Joshua J. Jacobs, Nadim J. Hallab, Mathew T. Mathew www.elsevier.com/locate/jmbbm

PII: DOI: Reference:

S1751-6161(16)30151-5 http://dx.doi.org/10.1016/j.jmbbm.2016.05.024 JMBBM1937

To appear in: Journal of the Mechanical Behavior of Biomedical Materials Received date: 26 September 2015 Revised date: 24 February 2016 Accepted date: 18 May 2016 Cite this article as: Dmitry Royhman, Megha Patel, Maria J. Runa, Markus A. Wimmer, Joshua J. Jacobs, Nadim J. Hallab and Mathew T. Mathew, FrettingCorrosion Behavior in Hip Implant Modular Junctions: The Influence of Friction Energy and pH Variation, Journal of the Mechanical Behavior of Biomedical Materials, http://dx.doi.org/10.1016/j.jmbbm.2016.05.024 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Figures

A.

B.

Figure 1. (A) Diagram of the fretting corrosion aparatus, which includes a square rod undergoing minute displacement against two, axially-loaded, metallic pins and integrated into an electrochemical cell with the rod and pins as the working electrode, a graphite rod as the counter electrode, and a saturated calomel reference electrode. (B) Diagram of the experimental design. Free potential, potentiostatic, and electrochemical impedance spectroscopy (EIS) experiments were performed to evaluate the electrochemical and dissipated friction energy behavior of a Ti6Al4V rod loaded against two CoCrMo pins, and displaced at 5 different displacement amplitudes (25µm, 50 µm, 100 µm, 150 µm and 200 µm).

A. Energy Ratio =

! "

Evolution of Potential (V vs. SCE)

B Start Fretting

End Fretting

-0.25 VRecovery

-0.30 -0.35

DVFretting

VDrop

-0.40

VFretting

-0.45 -0.50 0

1000 2000 3000 4000 5000 6000

Time (s) Figure 2: (A) Representation of Mindlin energy ratio, for which the transition criteria between partial slip and gross slip is defined at a ratio of 0.2 of the disspipated energy (Ed) to total energy (Et). (B) A representaion of the criteria used to decribe the behavior of potential throughtout the fretting experiment.

B Evolution of Potential (V vs. SCE)

A -0.20

Evolution of Potential pH 3.0

-0.25

Fretting Phase

-0.30 25mm 50mm 100mm 150mm 200mm

-0.35 -0.40 -0.45 -0.50 -0.55 0

1000 2000 3000 4000 5000 6000

Time (s)

C

D Drop in Potential

pH 3.0 pH 7.6

-0.24

0.25

-0.26 -0.28

0.20

VFretting (V vs. SCE)

VDrop (V vs. SCE)

pH 3.0 pH 7.6

Average Fretting Potential

-0.22

0.15

0.10

0.05

-0.30 -0.32 -0.34 -0.36 -0.38 -0.40 -0.42 -0.44 -0.46

0.00

-0.48 -0.50 0

50

100

150

200

250

300

0

Displacement Amplitude (mm)

50

100

150

200

250

300

Displacement Amplitude (mm)

E

F Change in Fretting Potential

Fretting Recovery

pH 3.0 pH 7.6

0.12

VRecovery (V vs. SCE)

DVFretting (V vs. SCE)

0.25

pH 3.0 pH 7.6

0.20

0.15

0.10

0.05

0.00

0.10

0.08

0.06

0.04

0.02

0.00 0

50

100

150

200

250

Displacement Amplitude (mm)

300

0

50

100

150

200

250

300

Displacement Amplitude (mm)

Figure 3: The effects of mechanical stimulation on the electrochemical behavior can be evaluated by monitoring the evolution of potential. The response in potential as a function of displacement amplitude and pH (3.0 and 7.6) is shown in (A) and (B) respectively. Specific regions of the curves such as “Drop in Potential,” “Fretting Potential,” “Change in Fretting Potential’” and “Fretting Recovery,” are shown in (C-F), respectively.

A

B. pH 3.0

pH 7.6

D pH 3.0 0.08 0.07 0.06

25mm 50mm 100mm 150mm 200mm

0.05 0.04 0.03 0.02 0.01 0.00 0

Dissipated Friction Energy (J)

Dissipated Friction Energy (J)

C

pH 7.6 0.08 0.07 0.06

25mm 50mm 100mm 150mm 200mm

0.05 0.04 0.03 0.02 0.01 0.00

500 1000 1500 2000 2500 3000 3500 4000

0

500 1000 1500 2000 2500 3000 3500 4000

Cycle (#)

Time (s)

E pH 3.0 0.08

0.06

200mm 150mm

0.04

100mm 0.02

50mm 0.00 0.00

25mm 0.02

0.04

0.06

0.08

0.10

Total Path (m)

0.12

0.14

Dissipated Friction Energy (J)

Dissipated Friction Energy (J)

F pH 7.6 0.08

0.06

200mm 0.04

150mm 100mm

0.02

50mm 0.00 0.00

25mm 0.02

0.04

0.06

0.08

0.10

0.12

0.14

Total Path (m)

Figure 4. The hysteresis response, under free potential mode, of the tangential load/displacement behavior throughout the applied fretting motion at (A) pH 3.0 and (B) pH 7.6. This dissipated friction energy is shown by representative plots of dissipated friction energy in Joules at each movement cycle as a function of (C) pH 3.0 and (D) pH 7.6. Dissipated friction energy in Joules over the total distance traveled, in meters, is shown by averaged curves of all trials with standard deviations (grey) for (E) pH 3.0 and (F) pH 7.6. Darker regions indicate areas of overlap in standard deviation.

pH 7.6 25um amplitude displacement

-0.28 -0.29

0.008

Free Potential 0.006

-0.30 -0.31

0.004

-0.32

Dissipated Energy

0.002

-0.33 -0.34

0.000

Evolution of Dissipated Energy (J)

Evolution of Potential (V vs. SCE)

0.010 -0.27

-0.35 1000

2000

3000

4000

5000

TIme (s) Figure 5. The relationship between the evolution of potential (Y1 axis) and the dissipated friction energy (Y2 axis). The two curves show a correlation in behavior. As the dissipated friction energy increases or decreases, there is a corresponding response in evolution of potential.

B pH 3.0

1.6

Ti Cr Co Mo Total

1.4 1.2

Total Metal Content (mg/Kg)

Total Metal Content (mg/Kg)

A

1.0 0.8 0.6 0.4 0.2 0.0 25

50

100

150

pH 7.6

1.6

Ti Cr Co Mo Total

1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0

200

25

Displacement Amplitude (mm)

50

100

150

200

Displacement Amplitude (mm)

C

D pH 7.6 pH 3.0

Total Charge

6.0x10-3

Kwc (mg)

Total Charge (C)

8.0x10-3

4.0x10-3 2.0x10-3

0.0 25

50

100

150

200

Displacement Amplitude (mm)

pH 7.6 pH 3.0

Material Loss Due to Wear and Corrosion

110 100 90 80 70 60 50 40 30 20 10 0 25

50

100

150

200

Displacement Amplitude (mm)

Figure 6. Total metal content (ions and particles) of Ti, Co, Cr, Mo and their total sum in solution at the conclusion of the potentiostatic tests at pH (A) 3.0 and (B) pH 7.6, analyzed by ICM-MS. Total charge (C) and total material loss (Kwc) (D) during the fretting corrosion test.

Potential (V vs. SCE)

1.5

Potentiodynamic Scan

1.0 Pitting region

0.5 0.0

Chosen potential for potentiostatic tests (-0.250V)

pH 3.0 pH 7.6

Passivation region

Anodic region

-0.5 Equilibrium potential

Cathodic region

-1.0 1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0.01

Current Density (A/cm2) Figure 7. Potentiodynamic scans, at pH 3.0 and pH 7.6, for the metal alloy coupled system of CoCrMo alloy pins loaded against a Ti6Al4V rod.

A

B pH 3.0

pH 7.6 1.0x10-5

Sliding Duration

Current Density (A/cm2)

Current Density (A/cm2)

1.0x10-5 8.0x10-6 6.0x10-6

200mm 150mm 100mm 50mm 25mm

4.0x10-6 2.0x10-6 0.0 1000

2000

3000

4000

8.0x10-6 6.0x10-6

Sliding Duration 150mm 200mm 100mm 50mm 25mm

4.0x10-6 2.0x10-6 0.0 1000

5000

Time (s)

2000

3000

4000

5000

Time (s)

D

Evolution of Current Dissipated Friction Energy

4.0x10-6

25mm 50mm 100mm 150mm 200mm

0.12

6.0x10-6

0.10

5.0x10-6

0.08

3.0x10-6

0.06

2.0x10-6

0.04

1.0x10-6

0.02 0.00

0.0

pH 7.6 Evolution of Potential Dissipated Friction Energy

Current (A)

Current (A)

5.0x10-6

pH 3.0

Dissipated energy (J)

6.0x10-6

4.0x10-6

0.12 25mm 50mm 100mm 150mm 200mm

0.10 0.08

3.0x10-6

0.06

2.0x10-6

0.04

1.0x10-6

0.02

Dissipated energy (J)

C

0.00

0.0

1500 2000 2500 3000 3500 4000 4500

1500 2000 2500 3000 3500 4000 4500

Time(s)

Time(s)

Figure 8. Changes in current evolution as a function of sliding distance under potentiostatic mode at (A) pH 3.0 and (B) pH 7.6. Comparison of evolution of current (Y1 axis; smoothed curves using 25 point adjacent averaging) under potentiostatic mode compared to the dissipated friction energy (Y2 axis) at the corresponding time point at (C) pH 3.0 and (D) pH 7.6.

A

B pH 3.0

0.10

0.08

200mm 0.06

150mm

0.04

100mm

0.02

50mm 25mm

0.00 0

500

1000

1500

2000

2500

Cycle (#)

pH 7.6

0.12

3000

3500

4000

Dissipated Friction Energy (J)

Dissipated Friction Energy (J)

0.12

0.10

0.08

200mm

0.06

150mm

0.04

100mm

0.02

50mm 25mm

0.00 0

500

1000

1500

2000

2500

3000

3500

4000

Cycle (#)

Figure 9. Dissipated friction energy under potentiostatic mode, in Joules, as a function of cycle number, shown by averaged curves of all trials, with standard deviations (grey), for (A) pH 3.0 and (B) pH 7.6. Darker areas indicate regions of overlap in standard deviation.

A

B

pH 3.0

pH 7.6

Energy Ratio

0.7 0.6

0.8

50mm

0.6

0.5 0.4

Gross Slip

0.3 Transition Criteria

0.2

25mm

0.1 0.0 1000

2000

Cycle (#)

50mm

0.5 0.4

Gross Slip

0.3 Transition Criteria

0.2

25mm

0.1 0.0

Partial Slip

0

200mm 150mm 100mm

0.7

Energy Ratio

0.8

200mm 150mm 100mm

3000

4000

Partial Slip

0

1000

2000

3000

4000

Cycle (#)

Figure 10. Energy ratios of displacement amplitudes under potentiostatic mode shown as function of cycle number, is shown by averaged curves of all trials, with standard deviations (grey), for (A) pH 3.0 and (B) pH 7.6. Darker areas indicate regions of overlap in standard deviation.

A

B

C 10000 Zmod Zmod Fit Zphase Zphase Fit

50

75

40

45

100

Zimag (W)

60

Zphz(o)

Zmod(W)

1000

90

30 10

Nyquist Nyquist Fit

30 20 10

15 1 10-2

10-1

100

101

102

103

104

0

0

0

105

10

20

30

40

50

Zreal (W)

Frequency (Hz)

D

E

F

G

Figure 11. (A) Electrochemical equivalent circuit used for modelling the EIS data. The representative

properties of the two alloys were incorporated into the model with individual components for: Rsol (resistance of the solution), CPETi (Capacitance of the Ti alloy passive film), RTi (Resistance of the Ti alloy passive film), CPECoCr (Capacitance of the CoCrMo alloy passive film), RCoCr (Resistance of the CoCrMo alloy passive film). A single representative EIS result is presented as Bode and Nyquist plots are shown in (B) and (C), respectively. All EIS results, under free potential mode, are shown as numerical values, before and after fretting, at (D) pH 3.0 and (E) 7.6. All EIS results, under potentiostatic mode, are shown as numerical values, before and after fretting, at (F) pH 3.0 and (G) 7.6.

Roughness

700 600

Ra (nm)

500

pH 3.0 pH 7.6

400 300 200 100 0 0

50

100

150

200

Displacement (mm) Figure 12. Changes in surface roughness of the CoCrMo pins as a function of displacement amplitude under free potential mode.

A.

Ti Atomic % (In weight)

B. 70 60

pH 3.0 pH 7.6

50 40 30 20 10 0 0

50

100

150

200

Displacement Amplitude (mm) Figure 13. (A) SEM images of the wear scar regions of the CoCrMo pins after fretting corrosion test for each pH and displacement amplitude group. At 25µm groups, several fretting features can be seen. At high amplitude displacements (150-200µm), sliding wear predominates, and tribolayer formation occurs. Particle deposits from the counterbody (Ti-alloy rod) were observed in the 200µm groups. (B) the correpoding EDS findings of the atomic percent (In weight) of Ti deposited onto the CoCrMo pins.

A.

B

C.

D.

200

4.0x10-3

100

2.0x10-3 0 0.0

8.0x10-3

300

6.0x10-3

200

4.0x10-3

100

2.0x10-3 0

Friction Energy (J)

6.0x10-3

Total Charge (C)

pH 7.6 300

Friction Energy (J)

Total Charge (C)

pH 3.0 8.0x10-3

0.0 25

50

100

150

200

Displacement Amplitude (mm)

25

50

100

150

200

Displacement Amplitude (mm)

Figure 14: Drop in potential during the fretting-corrosion test for the Ti6Al4V-CoCrMo alloy couple at various displacement amplitudes for free potential tests at (A) pH 3.0 and (B) pH 7.6 and potentiostatic tests at (C) pH 3.0 and (D) pH 7.6. The corresponding friction energies for each group at each condition are plotted on the secondary Y (right) axes.

Figure 15: Degradation mechanisms in the experimental setup as a function of displacement amplitude.