Preparation And Characterization Of CrN/ZrN Coating On1Cr10Co3MoWVNbNB Heat-resistant Steel

CrN/ZrN gradient hard coatings were deposited by RF magnetron sputtering on thesurface of1Cr10Co3MoWVNbNB heat-resistant steel in order to improve the performanceand service life of steam turbine blades.The coatings were observed by Scanning Electron Microscope (SEM) and Atomic ForceMicroscope (AFM). The composition was analysed by Energy Diffraction Spectrum (EDS). XRay Diffraction (XRD) was used for phase analysis. Nano-indentation system and Vickes’smicrohardness tester were used for measuring the hardness and elastic modulus. The adhesionstrength, abrasion and corrosion resistance of CrN/ZrN coatings were investigated by scratchtest, pin-on-disc wear and abrasion test machine and potentiodynamic polarization.The results indicated that CrN/ZrN coatings with good comprehensive properties can beprepared by selecting appropriate processing parameters of magnetron sputtering. They have agood protection effect on the heat-resistant steel substrate. Structures of CrN/ZrN coatings areuniform and compact, and there are few defects between the coatings and heat-resistant steelsubstrates. The layers are crystal, mainly consist of face-centered cubic (FCC) CrN, ZrN and acertain amount of pure Cr, Zr. Influences of different process parameters on coating structuresand properties are complicated. Mechanical property testing and corrosion resistance testresults show that, the best magnetron sputtering processing parameters are sputtering powerof100W, bias voltage of100V, N2flow of4sccm, Ar flow of16sccm, substrate at roomtemperature. The results of potentiodynamic polarization and wear and abrasion test show thatthe1Cr10Co3MoWVNbNB heat-resistant steel’ s corrosion resistance and abrasion resistanceboth can be improved significantly by the deposited CrN/ZrN coatings. Hardness and elasticmodulus are19GPa and260GPa, the film-substrate cohesion is52N, the friction coefficientis0.2, corrosion current is lower than that of the substrate. The rise of substrate temperaturepromotes the diffusion of atoms, contributes to obtain more dense coatings, further improvesthe corrosion resistance of the coatings, but it causes the wear resistance to decrease.Plasma nitriding before magnetron sputtering coatings can greatly improve the coatinghardness and elastic modulus, which are as high as31GPa and414GPa. Abrasion resistanceand corrosion resistance decline due to surface defects and the diminution of film-substratecohesion, but still better than the substrate.