热喷涂TiB2-Ni复合涂层组织结构和力学性能

采用团聚烧结方法制备TiB₂-Ni复合粉末喂料,并采用大气等离子喷涂和高速火焰喷涂两种喷涂方法制备了TiB₂-Ni涂层,比较分析了两种涂层的显微组织、物相组成、孔隙率、硬度和断裂韧性.结果表明,与等离子喷涂相比,高速火焰喷涂制备的TiB₂-Ni涂层具有更高的致密度,TiB₂含量,硬度和断裂韧性.两种涂层中TiB₂都没有发生明显的脱硼,氧化,但等离子喷涂过程中TiB₂向金属相中发生了溶解生成了大量脆性Ni₂₀Ti₃B₆相,并降低了涂层中TiB₂的含量,这是涂层硬度和断裂韧性相对较低的主要原因.

Microstructure and mechanical properties of TiB2-Ni composite coating

The TiB₂-Ni composite powder feedstock was fabricated by agglomeration and sintering method. This powder was used to deposit TiB₂-Ni coating by two thermal spray technologies, atmospheric plasma spray(APS) and high velocity oxygen fuel spray(HVOF). The microstructure, phase constitution, porosity, hardness and fracture toughness of two sprayed TiB₂-Ni coatings were compared and analyzed. The results showed that the HVOF sprayed TiB₂-Ni coating had more compact structure, larger TiB₂ content, higher hardness and better fracture toughness than the APSed coating. The TiB₂ in two coatings had no obviously deboronization and oxidation. However, the TiB₂ in APS process was dissolved in metallic phase to form a large number of brittle Ni₂₀Ti₃B₆ phases. This dissolution reaction reduced the TiB₂ content in coating and it was the main reason for the lower hardness and worse fracture toughness of APSed TiB₂-Ni coating.