Ag掺杂Mo-12Si-8.5B合金在25~600℃的摩擦学行为

Tribological Behavior of Ag-Doped Mo-12Si-8.5B Alloy from 25 to 600℃

本文中采用放电等离子烧结法制备了Mo-12Si-8.5B和Mo-12Si-8.5B-10%Ag这2种合金,通过高温真空摩擦磨损试验仪测试了2种合金与Al_(2)O_(3)摩擦副在25~600℃间的干摩擦学性能.结果表明:与Mo-12Si-8.5B合金相比,在25~600℃区间Mo-12Si-8.5B-10%Ag合金表现出更低的摩擦系数和磨损率.在600℃时,Mo-12Si-8.5B-10%Ag合金的摩擦系数和磨损率均可达到最小值,其值分别为0.41和1.14×10^(-5)mm^(3)/(N·m),此时Mo-12Si-8.5B-10%Ag合金的干摩擦性能表现最佳,这与Mo-12Si-8.5B-10%Ag合金磨损表面的MoO_(3)、SiO_(2)和Ag_(2)MoO_(4)等润滑相的存在及Ag在25~600℃范围内起到的润滑效果有关.此外,在25~200℃区间,Mo-12Si-8.5B-10%Ag合金的磨损机制主要为黏着磨损和剥层磨损,在400~600℃范围内,则以黏着磨损和氧化磨损为主.

With the continuous development of modern aerospace industry,the requirements for the operation temperature and service life of high-temperature materials are becoming higher.And the working conditions of materials are becoming more stringent.Therefore,the development and preparation of new ultra-high temperature structural materials is urgent.Mo-Si-B ternary alloys have become one of the promising new ultra-high temperature candidate materials because of their high melting point(2000℃),high strength,high hardness and excellent high-temperature oxidation resistance.The Mo-12Si-8.5B(atom fraction/%)alloy,consisted ofα-Mo-based,Mo_(3)Si,and Mo_(5)SiB_(2)intermetallic compound reinforcement phases,has been extensively researched due to its excellent high-temperature strength,excellent creep resistance,and balance between high-temperature oxidation resistance.What’s more,it is anticipated to be a key material in high-temperature applications.Al_(2)O_(3) ceramics are often used in hybrid bearing components of high-performance jet engines.As the moving parts,the Mo-12Si-8.5B alloy and Al_(2)O_(3) ceramics will experience dry friction relative sliding within a certain temperature range.However,according to the current research reports on the dry friction and wear characteristics of Mo-12Si-8.5B alloy at moderate temperatures(600℃)and below the two important indicators for evaluating its tribological properties,the friction coefficient and the wear rate are still relatively high.Therefore,at the moderate temperatures and below,how to reduce the friction coefficient and wear rate of Mo-12Si-8.5B alloy and ceramic pairing pairs,and how to improve the effective lubrication and self-lubricating function of the alloy both provides strong theoretical support for the practical application of Mo-12Si-8.5B alloy in engineering.In this article,Mo-12Si-8.5B and Mo-12Si-8.5B-10%Ag alloys were prepared by spark plasma sintering method and the dry friction and wear properties of the two alloys paired with Al_(2)O_(3) were tested at 25~600℃using a high-temperature vacuum friction and wear tester.The results showed that compared with Mo-12Si-8.5B alloy Mo-12Si-8.5B-10%Ag alloy exhibited lower friction coefficient and wear rate in the range of 25~600℃.The friction coefficient and wear rate of Mo-12Si-8.5B-10%Ag alloy could reach the minimum values of 0.41 and 1.14×10^(-5)mm^(3)/(N·m)respectively at 600℃.At this time the friction performance of Mo-12Si-8.5B-10%Ag alloy was the best,which was related to the presence of lubricating phases,such as MoO3,B_(2)O_(3),SiO_(2) and Ag_(2)MoO_(4) on the worn surface of Mo-12Si-8.5B-10%Ag alloy,as well as the lubricating effect of Ag in the range of 25~600℃.In addition the wear mechanism of Mo-12Si-8.5B-10%Ag alloy was mainly adhesive wear and peeling wear within the range of25~200℃.In the middle temperature range of 400~600℃,it was mainly adhesive wear and oxidation wear.This article provided basic data and theoretical support for in-depth research on the friction and wear theory of Mo-Si-B alloy realizing the self-lubricating function of Mo-Si-B alloy in a wide temperature range and practical applications.