HVOF喷涂Fe基非晶合金涂层的组织结构和耐腐蚀性能

Structure and Corrosion Properties of Fe-based Amorphous Coatings Deposited by HVOF

采用超音速火焰喷涂技术,制备了含Fe、Cr、Mo、Ni、P、Si、B的Fe基非晶合金涂层。利用显微硬度计、扫描电子显微镜、X射线衍射仪、电化学工作站、差示扫描量热仪等设备对涂层的组织结构、耐腐蚀性能和热稳定性进行了研究。喷涂工艺参数为:氧气压力0.6MPa,氧气流量166L·min-1,丙烷压力0.55MPa,丙烷流量24L·min-1,喷涂距离350mm。制备的涂层孔隙率和显微硬度分别为1.8%和823HV0.1,其非晶化程度较高;微观结构分析表明涂层由熔化变形成扁平粒子、未熔化的粉末颗粒以及孔隙、裂纹等缺陷组成的波浪层状组织。相组织结构分析表明涂层主要由非晶相组成,含有少量的纳米晶相组织。差示扫描量热仪测试表明所制备涂层的晶化区间为532℃～580℃。电化学测试表明,Fe基非晶合金涂层在1mol·L-1的H2SO4、10%NaOH和3.5%NaCl溶液中都经历了活性溶解—钝化—过钝化的过程,涂层在NaOH溶液中的耐腐蚀性能最强,其次为NaCl溶液,在H2SO4溶液中的耐腐蚀性能较差。

Fe-based amorphous alloy coating(Containing Fe,Cr,Mo,Ni,P,Si,B)was deposited by High Velocity Oxy-Fuel(HVOF)technique. The structure,corrosion resistance and thermal stability of the deposited coating were investigated by means of microhardness tester,optical metallographic microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM),corrosion resistance evaluation set-up,differential scanning calorimetry(DSC). Through orthogonal experimental design,the optimized were obtained. The parameters of spraying is O2 pressure was 0.6 MPa,the O2 flow rate was 166 L·min-1,the C3H8 pressure was 0.6 MPa,the C3H8 flow rate was 24 L·min-1 and stand-off distance was 350 mm. The porosity of deposited coating was as low as 1.8% the microhardness was as high as 823 HV0.1. A dense,homogeneous and lamellar coatings with high fraction of amorphous phase was obtained,which was composed of deformed strip shaped particles,un-melted particles,some pores and cracks. The DSC test showed that the crystallized temperature of coating began at 532℃ and ended at 580℃. It was found through electrochemical test that the amorphous coating undergo the processes of active solution-passivation-repassivation in 1 mol·L-1 H2SO4,10%NaOH and 3.5%NaCl solutions. The amorphous coating exhibited the best corrosion resistant capacity in NaOH solution,the worst in H2SO4 solution in the three kinds of solutions.