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| Abstract No.: |
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Scheduled at:
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Wednesday, May 11, 2016, Room 3G 4:40 PM
Pre- & Post-Treatment
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| Title: |
Effect of pre- and post-processes on cold spray coating properties
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| Authors: |
Pak Keng Koh* / SIM University, Singapore
Heong Wah Ng/ Nanyang Technological University, Singapore
Philip Cheang/ SIM University, Singapore
Kelvin Loke/ ST Kinetics, Singapore
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| Abstract: |
Preliminary study demonstrates the technical viability of cold spray process as an alternate repair method to address corrosion issues for gas turbine engine fan case. However, being a relatively new coating process, the effect of pre and post coating processes on the properties of the coatings needs to be better understood. The effect of pre coating grit blasting of the substrate on the mechanical properties and microstructures of the cold spray coatings was first investigated. The results showed that grit blasting may not enhance the microhardness or tensile adhesion strength of the cold spray coating and may be eliminated as a pre-coat process. The effect of post coating heat treatment was also evaluated. The results indicated that both stress relief and annealing processes reduces as well as homogenizes the microhardness of the coatings while the tensile adhesion strength was unaffected by stress relief but improved significantly when subjected to annealing. In addition, components which are cold sprayed usually come in complex shapes and sizes. It is extremely difficult, if not impossible to ensure that the spray angle is consistently normal to the surface of the component. As such, the effect of the spray angle on the microhardness, tensile adhesion strength, and microstructure was carried out. Results indicated that the effect of off-normal spraying has minimal impact on tensile adhesion strength and positive effect on the microhardness of the coating. Furthermore, the relative coating efficiency of the cold spray process at various spray angles was also evaluated. Significant detrimental impact on the relative coating deposition efficiency was observed for spray angle smaller than 60°.
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