Comparison of plasma sprayed NbB2-NbC coatings obtained by ex-situ and in-situ approaches

• Published in: Journal of the European Ceramic Society Vol. 41; no. 10; pp. 5088 - 5099
• Main Authors: Wang, Xiao-long, Shao, Yu-xuan, Guo, Ming-yan, Yang, Yong, Ma, Yu-duo, Cui, Yu-hang, Sun, Wen-wei, Dong, Yan-chun, Yan, Dian-ran
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2021
• Subjects: Coating; NbB2; NbC; Reactive plasma spraying; Wear resistance; NbB2; Reactive plasma spraying; Wear resistance; Coating; NbC
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2021.04.021

•NbB2-NbC coating was developed by plasma spraying NbB2-NbC and Nb-B4C powders.•The microstructure and properties of the coating were investigated.•The coating of Nb-B4C system displayed dense microhardness and good quality.•The formation mechanism of Nb-B4C system coating was studied and drawn. NbB2-NbC composite coatings were fabricated on the surface of TC4 by plasma spraying NbB2-NbC and Nb-B4C composite powders. The microstructure and properties of the as-prepared coatings were investigated, and the reaction mechanism of the Nb-B4C composite powder in the plasma jet and the formation mechanism of the NbB2-NbC coatings were revealed. During the plasma spraying process, NbB2-NbC composite powder underwent melting-depositing and no phase transformation occurred. The formation mechanism of the coating by plasma spraying Nb-B4C composite powder was solid phase diffusion-reaction-melting-deposition, and NbB2 and NbC were formed in situ by the solid phase diffusion reaction between Nb and B4C in the plasma jet. The coating obtained by reactive plasma spraying Nb-B4C composite powder has obvious lamellar structure, low porosity, high density, higher microhardness, good toughness, and better wear resistance compared with the coating prepared by NbB2-NbC composite powder, which is attributed to the exothermic reaction between Nb and B4C.