1. A Metallurgical Comparison of Mack T-12 Rod Bearings. Lots U, V & W
Characterization by: W.R. Wetsel
R&D Application Science Dept.
February 23, 2010

2. Introduction:
This is a comparison in the construction and metallurgy of
Mack T-12 Rod bearings. Lots “U” , “V” and “W” were submitted for evaluation.
Method of Characterization:
Non-standardized Energy Dispersive Spectroscopy and Scanning Electron Microscopy were used to characterize the submitted bearings. The outer surface and cross-sections were characterized. The various metallic layers were identified for composition and thickness. Upper and lower bearing halves were evaluated from each lot.
Findings:
All three bearing lots are similar in the various layers of composition and thickness of each layer. The bearings have an outer tin flash coat, an electroplated lead layer containing copper and tin, a nickel diffusion barrier and a copper matrix liner containing lead particles.

3. A word about EDS and sample preparation:
The cross-sections were given a metallographic polish consisting of grinding with sandpaper then polishing with 3 um. diamond and 0.05 um. aluminum oxide. Embedded debris from polishing can be detected by EDS. Iron and nickel may be reported at low levels in the electroplated lead and the liner.
The various metal layer cross-sections were analyzed using Energy Dispersive Spectroscopy (EDS). Beam spread causes detection of nearby elements that were not intended to be in the analysis. Example: If the electroplated Pb/Sn is being analyzed Ni from the diffuion barrier and Cu from the liner will be picked up.

4. Mack T-12 Rod Bearing Half Shells
Elemental Analysis of the External Surfaces
Method: Energy Dispersive Non-quantitized Spectrometry (EDS)
Element
Lot “U” Lower
Lot “U” Upper
Lot “V” Lower
Lot “V” Upper
Lot
“W” Lower
Lot “W” Upper Pb 18
12.2 20 17 38
9.0 Sn 81 85 77 60 90 Cu
1.1
3.1
2.2 2
0.9 Si -
0.4
Data in wt. %
The electron beam penetrates through the thin tin
electroplate. The EDS results are the flash tin and lead electroplate
combined. The high tin levels indicate a tin flash coating.

5. EDS Results on Cross-sections of the Pb-Sn Electroplate Layer
Element
Lot U” Lower
Lot “U” Upper
Lot “V” Lower
Lot “V”
Upper
Lot “W”
Lower
Lot “W” Upper Pb 67 64 66 60 65 Sn 10 14 11
8.4
8.7 Cu 17 18 21 22 Ni
2.2
1.5
1.4
1.3
1.6 Fe
2.4
2.1
4.1
2.3 Si - Al
0.9
7.8
Data in wt. %

6. EDS Results on Cross-sections of the Cu-Pb Liner
Element
Lot “U” Lower
Lot “U” Upper
Lot “V” Lower
Lot “V” Upper
Lot “W” Lower
Lot “W”
Upper Pb 20 19 17 18 Sn
2.6
2.7
2.4
2.9 Cu 72 74 73 75 Fe
4.4
3.4
4.5 4
5.6
4.2 Si -
1.1 Al
0.6
0.5
1.8 3
Data in wt. %

7. Thickness Measurements on the Four Metal Layers
Lot “U” Lower
Lot “U” Upper
Lot “V” Lower
Lot “V” Upper
Lot “W” Lower
Lot “W” Upper
Flash Sn
0.5
0.06?
0.6
0.2
0.3
0.4
Pb-Sn Electroplate
12.1 9 14
9.5
11.8
11.1
Ni Diffusion
1.7
1.3
1.6
1.9
0.9
Cu-Pb Liner
315
455
361
390
342
440
Units microns
* The outer Sn flash plating is very difficult to measure accurately.
The edge may be slightly damaged from mechanical polishing.
EDS of the outer surface shows similar high levels of Sn.

8. Lot “U” Lower Rod Bearing External Surface
EDS Data
Element
Wt. % Pb 18 Sn 81 Cu
1.1
100X

9. Lot “U” Lower Bearing Shell Cross-section
Element B D Pb 67 20 Sn 10
2.6 Cu 17 72 Fe
2.4
4.4 Al
0.9
0.6 Ni
2.2 - D
steel
100X
EDS Data in wt. %
Flash Sn 0.5 um. thick
Pb-Sn electroplate 12.1 um. thick
Ni diffusion layer 1.7 um. thick
Cu-Pb liner 315 um. thick B D
The black particles are embedded
3 um. diamond polishing compound.
2000X

10. Lot “U” Upper Rod Bearing External Surface
EDS Data
Element
Wt. % Pb 12 Sn 85 Cu
3.1
100X

11. Lot “U” Upper Rod Bearing Shell Cross-section
Element B D Pb 64 19 Sn 14
2.7 Cu 18 74 Ni
1.5 - Fe
1.6
3.4 Al
0.9
0.5 D
steel
100X
EDS Data in wt. % B
Flash Sn 0.06 um. thick
Pb-Sn electroplate 9 um. thick
Ni diffusion layer 1.3 um. thick
Cu-Pb liner 455 um. thick D
2000X

12. Lot “V” Lower Rod Bearing External Surface
EDS Data
Element
Wt. % Pb 20 Sn 77 Cu
2.2 Si
0.4
100X

13. Lot “V” Lower Rod Bearing Cross-section
Element B D Pb 66 17 Sn 10
2.4 Ni
1.4 - Si
1.3
1.1 Fe
2.1
4.5 Al
1.8 Cu 73 D
steel
100X
EDS Data in wt. % B
Flash Sn 0.6 um. thick
Pb-Sn electroplate 14 um. thick
Ni diffusion layer 1.6 um. thick
Cu-Pb liner 361 um. thick D
2000X

14. Lot “V” Upper Rod Bearing External Surface
EDS Data
Element
wt. % Pb 17 Sn 81 Cu
2.0
100X

15. Lot “V” Upper Rod Bearing Cross-section
EDS Data in Wt. % D
Element B D Pb 60 19 Sn 11
2.4 Cu 18 72 Ni
1.3 - Si Fe
2.1 4 Al
7.8 3
steel
100X B
Flash Sn 0.2 um. thick
Pb-Sn electroplate 9.5 um. thick
Ni diffusion layer 1.9 um. thick
Cu-Pb liner 390 um. thick D
2000X

16. BATCH V
TOP TAB SIDE
OPPOSITE TAB SIDE
BOTTOM TAB SIDE
0.0896
0.0884
0.0886
0.0885
0.0902
0.0898
0.0887
0.0901
0.0888
0.0905
0.09
0.0891
0.0883
0.0882
AVERAGE

17. BATCH U
TOP TAB SIDE
OPPOSITE TAB SIDE
BOTTOM TAB SIDE
0.0897
0.0895
0.0881
0.0883
0.0902
0.0892
0.0885
0.0888
0.0903
0.0889
0.0891
0.089
0.0887
0.0901
0.09
0.0886
0.0879
0.0882
AVERAGE

18. Lot “W” External Surface Lower Rod Shell
SEM Images
Element
Wt. % Pb 38 Sn 60 Cu
2.2

19. Cross-sections – SEM Images
Lot “W” Lower Rod Shell
Cross-sections – SEM Images
Element B D Pb 65 17 Sn
8.4
2.9 Cu 21 75 Ni
1.6 - Fe
4.1
5.6 D
100X steel
Flash Sn 0.3 um. thick
Pb-Sn electroplate 11.8 um. thick
Ni diffusion layer 1.7 um. thick
Cu-Pb liner 342 um. thick B D
2000X

20. Lot “W” Upper Rod Shell
Element
Wt. % Pb
9.0 Sn 90 Cu
0.9 Fe
0.1
100X

21. Lot “W” Upper Rod Shell D 100X steel Flash Sn 0.4 um. thick B
Element B D Pb 66
17.5 Sn
8.7
2.9 Cu 22 75 Ni
1.6 - Fe
2.3
4.4 D
100X steel
Flash Sn 0.4 um. thick
Pb-Sn electroplate 11.8 um. thick
Ni diffusion layer 0.9 um. thick
Cu-Pb liner 440 um. thick B D
2000X