镍-铬合金与O2-SO2-SO3反应机理
Reaction Mechanism of Fe-Cr Alloy with O2-SO2-SO3 Reaction
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摘要: 本文研究了Ni16Cr,Ni16Cr3AI、Ni16Cr3Ti及Ni16Cr2Nb等合金在700℃,常压下于O2-10%(SO2+SO3)环境条件下硫化-氧化行为.通过X-射线衍射及扫描电镜技术对腐蚀产物组成及形貌进行了观察。在含有SO3的情况下,Nil6Cr合金腐蚀速度较快,加入2%的Nb,对其抗腐蚀性能无太大影响,加入3%的Al或Ti时的腐蚀速度明显下降。主要腐蚀产物以初始合金表面为界分为内、外两层。外层是NiO和Ni3S2的混合物,内层包括所有合金元素的氧化物和硫化物。整个反应中包含Ni由合金基体向腐蚀产物的外层扩散,以及硫和氧在相反方向上的迁移。腐蚀产物层中传质分析表明,氧化物-硫化物混合产物层的组织形态,对控制整个传质过程起着主要作用。Abstract: Sulfidation-oxidation behaviors of Ni16Cr, Nil6Cr3Ti, Ni16Cr 2Nb alloys have been studied at 700℃ in O2-10% (SO2+SO3). Corrosion products are observed and examined with X-ray diffraction and SEM. Under experimental condition, containing SO3 corrosion rate of Ni16Cr alloy is rapider. Nb has little effect on degradation of alloy. When alloy containes Al or Ti, the oxidation rate of these alloys is slower. Products of corrosion consist of two layers; external layer (NiO + Ni3S2) mixture and internal layer sulfids and oxides containing all test alloying elements.
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