添加Ag_(2)Nb_(4)O_(11)的NiAl基复合材料的高温摩擦学性能及高温润滑机理研究

High Temperature Tribological Properties and High-Temperature Lubrication Mechanism of NiAl-Based Composites with the Addition of Ag_(2)Nb_(4)O_(11)

首先采用高温固相反应法合成了由纳米球状结构紧密堆积的微米级粉体Ag_(2)Nb_(4)O_(11),然后通过粉末冶金技术制备了添加铌酸银(Ag_(2)Nb_(4)O_(11))的NiAl基复合材料(NABO20,NiAl-20%Ag_(2)Nb_(4)O_(11)),考察其对复合材料显微结构、力学及摩擦学性能的影响.结果表明:热压烧结过程中,Ag_(2)Nb_(4)O_(11)发生高温分解及与C发生氧化还原反应,形成了NbC和Ag相.铌酸银(Ag_(2)Nb_(4)O_(11))的添加使得复合材料的密度略有增加,并且显著改善了NiAl基复合材料的显微硬度.在高温摩擦条件下(800℃),由于NABO20磨损表面和Al2O3对偶球表面均形成完整光滑的润滑膜(Nb_(2)O_(5)、Al_(2)O_(3)、Ag_(2)Nb_(4)O_(11)、AgNbO_(3)和AgNb_(3)O_(8)),两层膜的存在阻隔了对偶球和复合材料的直接接触,抑制了磨损进程,从而有效地提高了复合材料的耐磨性能.

The Ag_(2)Nb_(4)O_(11) powders with micro grade particle were synthesized by high-temperature solid state reaction method,then NiAl-based composites with the addition of Ag_(2)Nb_(4)O_(11)(NABO20,NiAl-20%Ag_(2)Nb_(4)O_(11))were prepared by powder metallurgy technology.The influence of silver niobates(Ag_(2)Nb_(4)O_(11))on the microstructure,mechanical properties and tribological behaviors of NiAl-based composites at elevated temperatures was investigated.The results showed that the Ag_(2)Nb_(4)O_(11) phase was decomposed and reacted with C element to form NbC and Ag phase in hotpressing sintering process.The addition of Ag_(2)Nb_(4)O_(11) slightly increased the density of composite and significantly increased the microhardness of composites.At 800℃,because the complete and smooth lubrication films(Nb_(2)O_(5),Al_(2)O_(3),Ag_(2)Nb_(4)O_(11),AgNbO_(3) and AgNb_(3)O_(8))on worn surfaces of NABO20 composite and Al2O3 counterpart ball prevented the direct contact of the composite and its counterpart,the wear-resistance of the composite was improved effectively.