不同Ni含量的合金钢在高温水蒸气中的氧化行为研究

Oxidation Behavior of Alloyed Steel with Different Ni Contents in High-temperature Steam

为了探究Ni含量与温度对合金钢氧化腐蚀行为的影响,对3.5%Ni、5%Ni和9%Ni钢在540℃高温水蒸气中的氧化行为进行了研究,并与9%Ni钢在600℃高温水蒸气中的氧化行为进行了对比。采用非连续称量法测定其动力学曲线,通过扫描电子显微镜(SEM)观察氧化膜形貌,用能谱仪(EDS)和X射线衍射(XRD)对元素成分和相组成进行了分析。结果表明,在540℃氧化时,3种合金钢的氧化动力学均符合抛物线规律;Ni含量增加,氧化速率下降,但有促进氧化膜脱落的倾向;3种合金钢的氧化膜均由Fe_3O_4、Fe_2O_3和NiFe_2O_4组成,Ni元素增多可以促进产物中Fe_3O_4向Fe_2O_3转化。氧化膜分为两层,层间存在孔洞;内层富含Ni Fe2O4的尖晶石氧化物,外层以Fe_3O_4和Fe_2O_3为主。温度升高时,9%Ni钢的氧化速率提高,氧化膜脱落时间提早;表面氧化物形貌发生了改变,从片状组织转化为颗粒状组织,但温度升高并未改变9%Ni钢的氧化产物类别。

The oxidation behavior of 3.5%Ni,5%Ni and 9%Ni steels in steam at 540 ℃ was investigated in order to investigate the effect of Ni content and temperature on the oxidation behavior,by comparing with that of 9% Ni steel in the steam at 600 ℃. The oxidation kinetic curves of three steels were analyzed by non-continuous weighing method. The morphofogy of oxide film was observed with SEM,and the elemental compositions and phase compositions of oxide film were tested by EDS and XRD. Results show that the oxidation kinetics curves of three steels are all parabofa at 540 ℃. With the increase of Ni content, the oxidation rate of the steels decreased, while there was a tendency of oxide lilm deterioration. The oxide films of three steels mainly consisted of Fe3O4, Fe2O3 and NiFe2 O4. An increase of Ni element can promote the transformation of Fe3O4 into Fe2O3. The oxide film consisted of two layers,between which there were voids. The inner layer was rich in spinel NiFe204,while the outer layer was mainly Fe3O4 and Fe2O. The oxidation rate of 9%Ni steel increased and the oxide film shed early with the rising temperature. The morphofogy of the oxide surface changed from lamellar structure to granulated structure, but an increased temperature didn＇t change the type of the oxidation products of 9%Ni steel.