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Journal of Thin Films, Coating Science Technology & Application Review Article

Characterization of Polyurethane at Multiple Scales for Erosion Mechanisms Under Sand Particle Impact

  1. Nirmal Sigamani Department of Mechanical Engineering, Pennsylvania State University, State College,
  2. Zoubeida Ounaies Department of Mechanical Engineering, Pennsylvania State University, State College,
  3. Ramesh Talreja Department of Aerospace Engineering and Material Science & Engineering, Texas A&M University, College Station, TX, 77843, USA.

Abstract

Thin polyurethane layers have been widely used as erosion-resistant coatings on helicopter rotor blades such as UH-60 Black Hawk and Eurocopter SA 315. Published research has mainly focused on empirical studies that relate the mechanical properties such as rebound resilience and hardness of polyurethane to solid particle erosion resistance. However, polyurethane possesses phase mixing at multiple scales and thus sand particle erosion resistance depends also on the microstructure and the phase mixing. Hence, it is very important to carry out detailed investigations to understand the stepby- step mechanism of erosion and how it relates to the polyurethane micro, meso, and macrostructure. This study carries out systematic investigations on multiple scales using Fourier Transform Infrared Spectroscopy (FTIR) in the micro scale, Differential Scanning Calorimetry (DSC) in the meso scale and Scanning Electron Microscopy (SEM) in the macro scale are performed to understand the step-by-step mechanism of erosion and how it is affected by the polyurethane microstructure. The comparison of FTIR results on pre-eroded and eroded films reveal the removal of macromolecular bonds corresponding to soft segments in the micro scale. The reduction of the crystalline portion of the soft segment observed from DSC results supports the FTIR findings. SEM images of the eroded specimens are used to correlate the sequence of the damage due to erosion. The observations reveal that after initial ductile deformation of the soft segments on the surface, brittle cracks are formed on the hard segments. The increased exposure to sand particles leads to formation of fragments containing mainly soft segments with cracks in the hard segments propagating in a brittle manner. As exposure increases, cracks intersect and material on the surface gets removed. The removed material mainly contains soft segments, as revealed by the FTIR and DSC results.

Keywords

References (15)

  1. Li J, Hutchings IM. Resistance of cast polyurethane elastomers to solid particle erosion. Wear. 1990;135(2):293-303. doi:10.1016/0043-1648(90)90032-6
  2. Arnold JC, Hutchings IM. The mechanisms of erosion of unfilled elastomers by solid particle impact. Wear. 1990;138(1-2):33-46. doi:10.1016/0043-1648(90)90166-8
  3. Born L, Hespe H, Crone J, Wolf KH. The physical crosslinking of polyurethane elastomers studied by X-ray investigation of model urethanes. Colloid & Polymer Science. 1982;260(9):819-828. doi:10.1007/bf01419091
  4. Preece CM, Macmillan NH. Erosion. Annual Review of Materials Science. 1977;7(1):95-121. doi:10.1146/annurev.ms.07.080177.000523
  5. Spathis G, Niaounakis M, Kontou E, Apekis L, Pissis P, Christodoulides C. Morphological changes in segmented polyurethane elastomers by varying the NCO/OH ratio. Journal of Applied Polymer Science. 1994;54(7):831-842. doi:10.1002/app.1994.070540701
  6. Lee, D.K., and Tsai, H.B., Properties of segmented polyurethanes derived from different diisocyanates. J. Appl. Polym. Sci., 75: 167-174 (2000). https://doi.org/10.1002/(SICI)1097-4628(20000103)75:13.0.CO;2-N
  7. Zahavi J, Schmitt GF. Solid particle erosion of reinforced composite materials. Wear. 1981;71(2):179-190. doi:10.1016/0043-1648(81)90337-9
  8. Hutchings IM, Deuchar DWT, Muhr AH. Erosion of unfilled elastomers by solid particle impact. Journal of Materials Science. 1987;22(11):4071-4076. doi:10.1007/bf01133360
  9. Tocha E, Janik H, Debowski M, Vancso GJ. MORPHOLOGY OF POLYURETHANES REVISITED BY COMPLEMENTARY AFM AND TEM. Journal of Macromolecular Science, Part B. 2002;41(4-6):1291-1304. doi:10.1081/mb-120013098
  10. Arjula S, Harsha AP, Ghosh MK. Solid-particle erosion behavior of high-performance thermoplastic polymers. Journal of Materials Science. 2008;43(6):1757-1768. doi:10.1007/s10853-007-2405-0
  11. Vu‐Khanh T, De Charentenay FX. Mechanics and mechanisms of impact fracture in semi‐ductile polymers. Polymer Engineering & Science. 1985;25(13):841-850. doi:10.1002/pen.760251309
  12. Woo EJ, Farber G, Farris RJ, Lillya CP, Chien JCW. Structure‐property relationships in thermoplastic elastomers: I. Segmented polyether‐polyurethanes. Polymer Engineering & Science. 1985;25(13):834-840. doi:10.1002/pen.760251308
  13. Zhang N, Yang F, Li L, Shen C, Castro J, Lee LJ. Thickness effect on particle erosion resistance of thermoplastic polyurethane coating on steel substrate. Wear. 2013;303(1-2):49-55. doi:10.1016/j.wear.2013.02.022
  14. Zhang SW, He R, Wang D, Fan Q. Abrasive erosion of polyurethane. Journal of Materials Science. 2001;36(20):5037-5043. doi:10.1023/a:1011814506377
  15. F1864-05, Standard Test Method for Dust Erosion Resistance of Optical and Infrared Transparent Materials and Coatings, in: ASTM, 2005.
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