Oxide Reduction and Oxygen Removal in Water-atomized Iron Powder and Its Influence on Sintering
Conventional press-and-sinter powder metallurgy commonly uses water-atomized iron powder as a base to which alloying elements are added.The initial conditions of the powder,for example its surface characteristics,will influence the sintering behavior.A crucial aspect of sintering is the formation of strong sinter necks between the metal particles.This process is facilitated by removal of the surface iron oxide layer covering all metal particles,whereby diffusion of metal atoms can proceed to the neck region without hindrance.Inadequate control of the atmosphere and failure to remove the iron oxide layer will impede and delay the sinter neck formation.Additionally,the surfaces of the metal particles also contain minor amounts of oxide particulates rich in chromium,manganese and silicon,with thermodynamic stabilities higher than those of the iron oxides present in the oxide layer.In this study,three different sieve fractions(-20,-45 and-75 μm)of water-atomized iron powder were investigated by means of thermogravimetric analysis using different processing parameters.The mass loss events related to the reduction of the surface iron oxide layer,internal oxides,and thermodynamically stable oxide particulates were analyzed.A kinetic analysis was performed to determine the activation energies for the different reduction and oxygen removal events.Auger electron spectroscopy was applied to perform a surface chemical analysis to acquire details regarding the characteristics of the surface oxides and to correlate their removal with the thermogravimetric analyses.
Water-atomized iron powder surface analysis thermogravimetric analysis reduction sintering
Wendel Johan Manchili Swathi Cao Yu Hryha Eduard Nyborg Lars
Department of Industrial and Materials Science,Chalmers University of Technology,R(a)nnv(a)gen 2A,Gothenburg,SE-41296,Sweden
国际会议
北京
英文
526-532
2018-09-16（万方平台首次上网日期，不代表论文的发表时间）