Madhav Sonkusare

Minor Specialization Project

Compared specific wear and surface damage in recycled PET and a 10 wt.% graphene grade through 18 pin-on-disc tests at MIT Manipal, with Sohan Kumar Y.

RoleMaterials Engineering · Mini project

  • 18 pin-on-disc tests · ASTM G99
  • rPET vs 10 wt.% graphene
  • Materials Engineering minor, MIT Manipal
Optical micrograph of the worn rPET and graphene pin, showing layers from brittle failure

Testing

We tested 6 mm specimens against a steel disc at three loads and three speeds. Each run covered 250 m; specific wear rate was calculated from mass loss.

  • ASTM G99, dry sliding
  • 10 · 20 · 30 N
  • 160 · 320 · 480 rpm
  • 250 m per run · 60 mm track
FIG. 01PIN-ON-DISC APPARATUS
Schematic of the test apparatus.

Specimens

Pins were cast in an aluminium mould heated in a salt bath, then mounted in a two-part 3D-printed PLA holder. Each was cleaned and weighed before and after testing.

  1. Cross-section of the aluminium pin mould in its salt bath01MouldAn aluminium mould, heated evenly in a salt bath.
  2. Two cast specimen pins, one plain rPET and one graphene grade02Cast pins6 mm pins of plain rPET and the 10 wt.% graphene grade.
  3. The two printed parts of the specimen holder03HolderA two-part 3D-printed PLA holder carries each pin.
  4. An analytical balance04WeighingEach pin cleaned and weighed before and after its run.

Results

Graphene wore more at every load at 320 and 480 rpm, but less at 160 rpm with 10 or 20 N. At 30 N and 480 rpm the graphene grade wore about 29 times faster.

FIG. 02 · SPECIFIC WEAR RATEPlain rPETrPET + graphene
10 N10⁻⁴10⁻³10⁻²16032048020 N10⁻⁴10⁻³10⁻²16032048030 N10⁻⁴10⁻³10⁻²1603204807.7 × 10⁻³
Speed (rpm) · log scale, shared by all three panels · one run per condition30 N · 480 rpm2.7 × 10⁻⁴vs7.7 × 10⁻³mm³/N·m · about 29×

Microscopy

Six worn specimens were examined by optical microscopy. Shown here: both materials at 30 N and 480 rpm.

Optical micrograph of plain rPET with burnt patches, smearing and embedded debris.
Plain rPET · Softening and smearingThe plain rPET specimens showed softening, smearing and embedded debris.
Optical micrograph of the graphene grade with peeled layers and cracks.
rPET + graphene · Cracking and peelingThe graphene-grade specimens showed grooves, cracks and peeled layers, with less visible distortion.

Conclusions

Wear response varied with load and speed. Mass loss and microscopy showed different damage mechanisms in the two materials.

  • Load and speed affected wear
  • Different surface damage mechanisms

Limits: one run per condition; friction and temperature were not measured. Further testing is needed before selecting either material for a working part.

Credits

Madhav Sonkusare and Sohan Kumar Y · Materials Engineering minor · MIT Manipal · November 2025.

Guide: Dr. B. Shivamurthy. Testing: Advanced Material Testing Laboratory, MIT Manipal.

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