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This study explores, through a full factorial experimental design, the effects of graphite concentration and spray flow rate on the morphology, thickness, and tribological performance of graphite coatings for potential tribological applications. Coatings were applied to rough substrates using varying concentrations and flow rates, followed by analysis of their morphological characteristics, roughness, thickness, coefficient of friction (COF), and wear behavior. The results revealed distinct differences in the coating morphology based on flow rate, with low-flow-rate coatings exhibiting a porous structure and higher roughness, while high-flow-rate coatings displayed denser structures with lower roughness. A COF as low as 0.09 was achieved, which represented an 86% reduction compared to uncoated steel. COF and wear track measurements showed that thickness was influential in determining friction and the extent of wear. Flow rate dictated the coating structure, quantity of transfer film on the ball, and the extent of graphite compaction in the wear track to provide a protective layer. SEM and elemental analysis further revealed that graphite coatings provided effective protection against wear, with graphite remaining embedded in the innermost crevices of the wear track. Low flow rates may be preferable for applications requiring higher roughness and porosity, while high flow rates offer advantages in achieving denser coatings and better wear resistance. Overall, this study highlights the importance of optimizing graphite concentration and spray flow rate to tailor coating morphology, thickness, and tribological performance for practical applications.
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Tribological interactions of 3D printed polyurethane and polyamide with water-responsive skin model
Abstract 3D printing in the textile and fashion industry is a new emerging technology. Applications of 3D printing for designing clothes and other wearable accessories require tribological and biological understanding of 3D printing plastics against the complex human skin to mitigate skin-friction related ailments such as calluses and blisters. This study provides tribological insight in search of an optimal 3D printable material that has minimal friction against the skin. Two low friction 3D printable materials, thermoplastic polyurethane (TPU) and polyamide (TPA) were chosen and tribological testing was carried out against a water responsive skin model. The skin model was synthesized using a gelatine based model made with cotton and crosslinked with glutaraldehyde. Tribological testing of TPU/TPA against the skin model in dry and wet conditions were made. The higher coefficient of friction (COF) was observed in the wet condition compared to the dry condition. To overcome the higher friction, TPA/TPU-sodium polyacrylate composites were prepared by heat pressing that significantly reduced COF of TPU and TPA by ∼ 40% and 75%, respectively, in wet conditions.
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- Award ID(s):
- 1852578
- PAR ID:
- 10219637
- Date Published:
- Journal Name:
- Friction
- ISSN:
- 2223-7690
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/s40544-020-0472-2
