纳米Fe-Al/Cr_3C_2复合涂层及其抗高温腐蚀性能

High-temperature corrosion resistance property of nano Fe-Al/Cr_3C_2 composite coating

制备纳米金属间化合物Fe-Al/Cr_3C_2复合涂层并测试其抗腐蚀性能,为利用热喷涂技术治理火电站易损部件腐蚀问题提供有效手段。运用自主研发的造粒系统,成功对高活性的纳米Fe-Al/Cr_3C_2复合喷涂粉体实施团聚造粒;运用高速火焰喷涂方法,在结构材料表面制备出了纳米Fe-Al/Cr_3C_2复合涂层,对比测试了微米、纳米Fe-Al/Cr_3C_2复合涂层的抗高温腐蚀性能,分别采用抛物线型和幂函数型对腐蚀动力学曲线进行拟合。纳米Fe-Al/Cr_3C_2复合喷涂材料的粒径由原始的50nm团聚到最终的114~178μm,团聚后的纳米颗粒呈圆形或椭圆形,各成分比例保持原始比例,团聚颗粒内部仍然保持纳米粉体状态;纳米Fe-Al/Cr_3C_2复合涂层表面致密、铺展均匀,截面元素过渡平缓、层片细小;运用幂函数方程对腐蚀动力学曲线的拟合效果更好。通过对腐蚀动力学拟合方程进行求导运算可推算出各复合涂层的腐蚀速率。团聚后的纳米颗粒满足热喷涂材料的相关要求,纳米Fe-Al/Cr_3C_2复合涂层的抗高温腐蚀性能显著高于微米Fe-Al/Cr_3C_2复合涂层。纳米Al、Cr优先氧化生成具有保护作用的氧化膜机理解释了纳米涂层抗高温腐蚀性能优异的原因。

Nano composite coatings of the intermetallic compound Fe-Al/Cr 3C 2 were prepared and their high-temperature corrosion resistance was tested,in order to overcome the corrosion problems of easily corroded parts in power plants by thermal spraying.Using the reunion-granulation system we developed independently,highly active nano Fe-Al/Cr 3C 2 composite spraying materials successfully underwent reunion-granulation.High-velocity flame spraying was employed to spray the nano Fe-Al/Cr 3C 2 composite coating on the structural materials.The high-temperature corrosion resistance of the micro and nano Fe-Al/Cr 3C 2 composite coatings was tested under the same corrosion conditions.Parabolic and power function curves were used to fit the corrosion kinetic curves.The particle sizes of the Fe-Al/Cr 3C 2 composite spraying materials changed from the nanometer scale to the micrometer scale.Post reunion-granulation,the nano-sprayed particles were spherical or elliptical,the chemical composition of the granulated particles was the same as that of the original,and the inner granulated particles maintained their nanometer sizes.The surface of the nano Fe-Al/Cr 3C 2 composite coating was compact,and the spreading is uniform.The element transition of section is smooth and the layer is fine.The power function curves fit the corrosion kinetic equation better.The corrosion rates of the coatings were calculated by deriving the fitted corrosion kinetic equation.The characteristics of the nano-sprayed particles meet the relevant requirements after reunion-granulation.The high-temperature corrosion resistance of the nano Fe-Al/Cr 3C 2 composite coating was significantly better than that of the micro coating.The mechanism by which the nano chromium and aluminum are preferentially oxidized and form protective oxide layers explains the excellent high-temperature corrosion resistance of the nano coating.