热浸镀Al-10Si-1Ce的HP40Nb钢微观组织及高温氧化行为研究

摘要

In order to improve the high temperature oxidation and carburization resistance of HP40Nb steel, experiment of steel was coated by hot-dipping into a molten bath containing Al-10Si-Ce.The effect of dif-fuse treatment on hot-dip aluminizing steel microstructure and oxidation resistance behavior at high tem-perature was studied by means of SEM,EDS and XRD.The results show that after hot-dip Al-10Si-1Ce treatment,the coating layer consisted of inner layer[(Fe,Cr,Ni)2 (Al,Si)5 ]and outer layer[primaryα-Al, (α+Si)eutectic structure].After diffusion at 800,900,1 000℃ for 4h,the coatings had different micro-structure characteristics ,different oxides were formed on the surface:θ-Al2 O3 ,θ-Al2 O3+α-Al2 O3 ,α-Al2 O3 .After the cyclic oxidation test at 1 000℃ for 360h,the coatings consisted of outer layer(NiAl+Cr3 Si) and inner layer(σ,α+Ni3 Al).In the oxidation,the hot dipped Al-10Si-1Ce HP40Nb steel with the diffuse treatment of 1 000℃/4h had the minimum oxidation rate and best oxidation resistance .The reason was that the compactα-Al2 O3 layer of the coating surface hindered the continuous oxidation.%采用 SEM、EDS和 XRD等方法,研究了 HP40Nb钢热浸镀 Al-10Si-1Ce 合金的初始镀层、扩散处理渗层、高温氧化渗层的微观组织特征和抗高温氧化性能。结果表明：热浸镀层由初生α-Al,(α-Al+Si)共晶组织的外层和(Fe,Cr,Ni)2(Al,Si)5相的内层组成。热浸镀试样分别在800、900、1000℃下进行4h扩散处理后,渗层中各层呈现不同的显微组织特征,且表面生成了不同氧化物：θ-Al2 O3,θ-Al2 O3+α-Al2 O3,α-Al2 O3。不同温度扩散处理的试样经1000℃/360h高温氧化后,渗层均由外层(NiAl+Cr3 Si)和内层(σ、α+Ni3 Al)组成。1000℃/4h 扩散处理的试样在高温氧化过程中平均氧化速率最小、抗氧化性能最好,其原因是表面致密的单一α-Al2 O3阻碍了氧化的进行。