Using scratch test to evaluate cohesive bond strength of Mo composite coating

Koiprasert, Hathaipat;Thaiwatthana, Sirinee;Sheppard, Panadda

  • Received : 2015.06.07
  • Accepted : 2015.11.07
  • Published : 2015.12.31


Bonding strength of a thermal sprayed coating is difficult to measure using a conventional pull-off test method. Scratch test is a potential alternative testing method. An adhesive and a cohesive bond strength of the coating can be measured by the pull-off test while the scratch test performed on the cross-section of the thermal sprayed coating can only demonstrate the cohesive bond strength of the coating. Nevertheless, it is still beneficial to perform the scratch testing on the cross-section of the coating for the sake of comparison thus providing an alternative to the pull-off test. The scratch test method can reduce testing time and cost in the long run due to a significant cost reduction in consumables and energy and time saving from the curing step of the glue used in the pull-off test. This research investigates the possibility of using the scratch test to measure the cohesive bond strength of Mo/NiCrBSi composite coating. The results from the pull-off test and the scratch test indicate that the cohesive bond strengths of the Mo composite coating show similar trend and that the cohesive bond strength are increased when increasing NiCrBSi content.


scratch test;thermal spray;MoNiCrBSi;bond strength


  1. Grigorescu, C, Di Rauso, C, Drira-Halouani, R, Lavelle, B, Di Giampaolo, R, Lira, J. 1995. Phase characterization in Ni alloy-hard carbide composites for fused coatings. Surface and Coatings Technology. 76-77. pp494-498.
  2. Tobar, M.J., Alvarez, C, Amado, J.M., Rodriguez, G., Yanez, A. 2006. Morphology and characterization of laser clad composite NiCrBSi-WC coatings on stainless steel. Surface and Coatings Technology. 200. 22-23. pp6313-6317.
  3. Nicoll, A.R. 1982. Self-fluxing coatings for stationary gas turbines. Thin Solid Film. 95. pp285-295
  4. Rodriguez, J, Martin, A, Fernandez, R, Fernandez, J.E. 2003. An experimental study of the wear performance of NiCrBSi thermal spray coatings. Wear. 255. pp950-955.
  5. Niranatlumpong, P, Koiprasert, H. 2010. The effect of Mo content in plasma-sprayed Mo-NiCrBSi coating on the tribological behaviour. Surface and Coatings Technology. 205. pp 483-489.
  6. Nohava, J, Bonferroni, B, Bolelli, G, Lusvarghi, L. 2010. Interesting aspects of indentation and scratch methods for characterization of thermally-sprayed coatings. Surface and Coatings Technology. 205. pp1127-1131.
  7. Vencl, A, Arostegui, S, Favaro, G, Zivic, F, Mrdak, M, Mitrovic, Popovic, V. 2011. Evaluation of adhesion/cohesion bond strength of the thick plasma spray coatings by scratch testing on coatings crosssections. Tribology International. 44. pp1281-1288.
  8. Koiprasert, H, Thaiwatthana, S, Sheppard, P. 2013. Feasibility study on the use of scratch test to evaluate bond strength of thermal sprayed coating and optimization of test parameters. International Symposium on the Fusion Technologies between Korea and Thailand 2013(ISFT2013). 1st-3rd August. Thailand.