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| Abstract No.: |
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Scheduled at:
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Tuesday, May 04, 2010, Sophia Room 2:05 PM
Young Scientists
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| Title: |
Effect of annealing on microstructure of cold sprayed cBNp/NiCrAl composite coating
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| Authors: |
Chang-Jiu Li / Xi'an Jiaotong University, P.R. China
Xiao-Tao Luo* / School of Materials Science and Engineering, Xi'an Jiaotong University, P.R.China
Guan-Jun Yang/ School of Materials Science and Engineering, Xi'an Jiaotong University, P.R.China
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| Abstract: |
Cermet material coatings have been used for various applications, especially for antiwear, for their excellent mechanical properties such as high hardness, strength and elastic modulus and so on. Dense cermet coatings without the oxidation of metallic binder phase can be deposited by cold spraying owing to its low process temperature. cBN is the hardest nature material except of diamond and it is expected to deposit high performance cBN/NiCrAl cermet coating using cBN/NiCrAl composite by cold spray.
In the present work, cBNp/NiCrAl composite powders were prepared by mechanical alloying process and the coating was deposited by cold spray using the composite powder. To modify its microstructure, especially the bonding between cBN particles and NiCrAl alloy matrix, annealing treatment at different temperatures in Ar atmosphere was carried out. The microstructure was characterized by SEM and TEM?iHRTEM?j. The results show that a zigzag interface reaction layer is formed at the interface between cBN particle and NiCrAl matirx after the deposit was annealed at 825oC for 300 min. This temperature is much lower than that estimated thermodynamically. HRTEM analysis revealed that the morphology of the reaction layer at the cBN/NiCrAl interface changes with the interface position. Moreover, the bonding at the interfaces between deposited spray particles and the plastic deformation ability of the cermet coating can be improved through annealing treatment. Vickers microhardness test shows that the hardness decreases with the increase of annealing temperature owing to the minimizing of work hardening effect and grain growth of NiCrAl alloy matrix which is attributed to recovery and recrystallization during annealing.
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