一种新型经济高效非晶涂层的制备与性能表征

Preparation and Properties of A New Cost-effective Amorphous Composite Coating

摘要:

利用火焰喷涂技术喷涂自制的气雾化合金粉末取代非晶粉末,制备了NiFeBSiNb非晶纳米晶涂层。分别对粉末和涂层的微观组织结构和热力学性能进行了表征。结果表明,自制的合金粉末球形度较好,大多为球形或椭球形；主要为晶体结构,由Nb₂Ni₂₁B₆晶体相和(Ni,Fe)₂₃B₆固溶体组成。而经过火焰喷涂制备的涂层,形成了非晶相和纳米晶相。通过公式计算此合金体系粉末和涂层形成非晶相的临界冷却速率分别为6.01×10₅K/s和4.56×10₃K/s,解释了在粉末制备过程中较难形成非晶相而喷涂过程中形成非晶结构比较容易。对涂层的摩擦磨损性能进行了测试,涂层摩擦系数仅为0.17,具有优异的耐磨性能。

关键词:非晶涂层,合金粉末,火焰喷涂,摩擦磨损

Abstract:

A NiFeBSiNb amorphous/nanocrystalline composite coating was prepared through flame thermal spraying, where a gas atomized alloy powder substituted an amorphous powder. The microstructure and thermal behavior of the laboratory-produced powders and the produced as-sprayed coating were characterized. The results demonstrated that the powder, which was spherical or ellipsoidal, was mainly consisted of the Nb₂Ni₂₁B₆ and (Ni,Fe)₂₃B₆ crystalline phases, whereas the as-sprayed coating was consisted of a glassy structure and certain nanocrystalline phases. It was observed through calculations that the Rc (critical cooling rate) of the powder and the as-sprayed coating for the amorphous phases formations were 6.01×10₅ K/s and 4.56×10₃ K/s, respectively. A probable explanation for the amorphous structure, as it occurred in the as-sprayed coating, was rapid quenching from the melt at the cooling rates which exceeded the critical cooling rate Rc. The prepared coating of these as-sprayed amorphous coatings displayed the properties of a 0.17 low friction coefficient and excellent wear resistance.

Key words:amorphous coating; alloy powder; flame spraying; wear