Self-catalytic reactions have consistently been implicated in the high-temperature corrosion mechanism of NiAl-phase coatings in NaCl-or Na_(2)SO_(4)-containing mediums,with little discussion concerning the adsorption...Self-catalytic reactions have consistently been implicated in the high-temperature corrosion mechanism of NiAl-phase coatings in NaCl-or Na_(2)SO_(4)-containing mediums,with little discussion concerning the adsorption and competitive behavior of complex environmental molecules.This study investigated the adsorption and dissociation behavior of a series of gas-phase molecules(O_(2),H_(2)O,SO_(3),S_(2),H_(2)S,Cl_(2)and HCl)on the NiAl(110)surface using first-principles calculations.The findings reveal a mechanism of competitive adsorption and dissociation,with two distinct adsorption dissociation behaviors observed upon the introduction of Pt or Hf elements.Pt-doping inhibits the surface adsorption behavior of self-catalytic molecules,while Hf significantly enhances the adsorption and dissociation of oxygen-carrying molecules.By preparing three types of NiAl-phase coatings(β-NiAl,(Ni,Pt)Al,and Hf-(Ni,Pt)Al)and conducting corrosion tests in the presence of NaCl or Na_(2)SO_(4),it is determined that the excellent corrosion resistance of Hf-(Ni,Pt)Al can be attributed to the combined effects of Pt in delaying corrosion reactions and Hf in promoting the formation of a protective oxide scale.A comprehensive analysis,combining first-principles calculations and experimental observations,was conducted to elucidate the corrosion mechanisms of three coatings in different corrosion mediums.展开更多
Pt layers of 5 μm in thickness were electroplated before or after depositing NiCoCrAlY coating by arc ion plating(AIP) aiming for identifying the effect of Pt enriching position on microstructure and cyclic oxidation...Pt layers of 5 μm in thickness were electroplated before or after depositing NiCoCrAlY coating by arc ion plating(AIP) aiming for identifying the effect of Pt enriching position on microstructure and cyclic oxidation behavior of Pt modified NiCoCrAlY coatings. Al-rich zones formed at the same position of Ptrich zones for both modified coatings due to uphill diffusion of Al driven by Pt. Cyclic oxidation tests at 1000 and 1100?C indicated that oxidation resistance of NiCoCrAlY was improved by Pt modification via different mechanisms: at surface, Pt-rich zone promoted selective oxidation of Al to form α-Al_2O_3,whilst at coating/substrate interface Pt-rich zone acted as effective diffusion barrier for titanium. Roles of Pt played in enhancing the oxidation performance of various Pt-modified NiCoCrAlY coating were investigated.展开更多
A thermal barrier coating system comprising Pt-modified NiCoCrAlY bond coating and nanostructured 4mol.% yttria stabilized zirconia(4YSZ, hereafter) top coat was fabricated on a second generation Ni-base superalloy. T...A thermal barrier coating system comprising Pt-modified NiCoCrAlY bond coating and nanostructured 4mol.% yttria stabilized zirconia(4YSZ, hereafter) top coat was fabricated on a second generation Ni-base superalloy. Thermal cycling behavior of NiCoCrAlY-4 YSZ thermal barrier coatings(TBCs) with and without Pt modification was evaluated in ambient air at 1100?C up to 1000 cycles, aiming to investigate the effect of Pt on formation of thermally grown oxide(TGO) and oxidation resistance. Results indicated that a dual layered TGO, which consisted of top(Ni,Co)(Cr,Al)_2O_4 spinel and underlying α-Al_2O_3, was formed at the NiCoCrAlY/4 YSZ interface with thickness of 8.4μm, accompanying with visible cracks at the interface. In contrast, a single-layer and adherent α-Al_2O_3 scale with thickness of 5.6μm was formed at the interface of Pt-modified NiCoCrAlY and 4 YSZ top coating. The modification of Pt on NiCoCrAlY favored the exclusive formation of α-Al_2O_3 and the reduction of TGO growth rate, and thus could effectively improve overall oxidation performance and extend service life of TBCs. Oxidation and degradation mechanisms of the TBCs with/without Pt-modification were discussed.展开更多
A single-phase (Ni,Pt)Al coating with lean addition of Zr was prepared by co-electroplating of Pt-Zr com posite plating and subsequent gaseous alum inization treatm ents. Isotherm al and cyclic oxidation behavior of t...A single-phase (Ni,Pt)Al coating with lean addition of Zr was prepared by co-electroplating of Pt-Zr com posite plating and subsequent gaseous alum inization treatm ents. Isotherm al and cyclic oxidation behavior of the Zr-doped (Ni,Pt)Al coating sam ples was assessed at 1373K in static air in comparison with plain nickel alum inide (NiAl) and norm al (Ni,Pt)Al coatings. Results indicated th at Zr-doped (Ni,Pt)Al coating dem onstrated a lower oxidation rate constant and reduced tendency of oxide scale spallation as well as surface rumpling, in which the enhanced oxidation perform ance was m ainly attributed to the segregation of Zr at oxide scale grain boundaries and the im proved Young's modulus of the coating. Besides, the addition of Zr effectively delayed oxide phase transform ation of Al2O3 from θ phase to α phase in the early oxidation stage and coating degradation of β-NiAl to γ'-Ni3Al in the stable oxidation stage.展开更多
基金the sponsorship by the National Natural Science Foundation of China(Nos.51671202 and 52301116)the Fundamental Science Center for Aviation and Gas Turbine Engines(No.P2021-A-IV-002-001)+1 种基金supported by the National Science and Technology Major Project(No.J2019-IV-0006-0074)the Key Research Program of the Chinese Academy of Sciences(No.ZDRW-CN-2021-2-2).
文摘Self-catalytic reactions have consistently been implicated in the high-temperature corrosion mechanism of NiAl-phase coatings in NaCl-or Na_(2)SO_(4)-containing mediums,with little discussion concerning the adsorption and competitive behavior of complex environmental molecules.This study investigated the adsorption and dissociation behavior of a series of gas-phase molecules(O_(2),H_(2)O,SO_(3),S_(2),H_(2)S,Cl_(2)and HCl)on the NiAl(110)surface using first-principles calculations.The findings reveal a mechanism of competitive adsorption and dissociation,with two distinct adsorption dissociation behaviors observed upon the introduction of Pt or Hf elements.Pt-doping inhibits the surface adsorption behavior of self-catalytic molecules,while Hf significantly enhances the adsorption and dissociation of oxygen-carrying molecules.By preparing three types of NiAl-phase coatings(β-NiAl,(Ni,Pt)Al,and Hf-(Ni,Pt)Al)and conducting corrosion tests in the presence of NaCl or Na_(2)SO_(4),it is determined that the excellent corrosion resistance of Hf-(Ni,Pt)Al can be attributed to the combined effects of Pt in delaying corrosion reactions and Hf in promoting the formation of a protective oxide scale.A comprehensive analysis,combining first-principles calculations and experimental observations,was conducted to elucidate the corrosion mechanisms of three coatings in different corrosion mediums.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51671202 and 51301184)the Defense Industrial Technology Development Program (Grant No. JCKY2016404C001)sponsored by the "Guangdong Province Science and Technology Plan" (Grant No. 2017B090903005)
文摘Pt layers of 5 μm in thickness were electroplated before or after depositing NiCoCrAlY coating by arc ion plating(AIP) aiming for identifying the effect of Pt enriching position on microstructure and cyclic oxidation behavior of Pt modified NiCoCrAlY coatings. Al-rich zones formed at the same position of Ptrich zones for both modified coatings due to uphill diffusion of Al driven by Pt. Cyclic oxidation tests at 1000 and 1100?C indicated that oxidation resistance of NiCoCrAlY was improved by Pt modification via different mechanisms: at surface, Pt-rich zone promoted selective oxidation of Al to form α-Al_2O_3,whilst at coating/substrate interface Pt-rich zone acted as effective diffusion barrier for titanium. Roles of Pt played in enhancing the oxidation performance of various Pt-modified NiCoCrAlY coating were investigated.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51,671,202 and 51,301,184)the Defense Industrial Technology Development Program(Grant No. JCKY2016404C001)sponsored by the "Liaoning BaiQianWan Talents" Program
文摘A thermal barrier coating system comprising Pt-modified NiCoCrAlY bond coating and nanostructured 4mol.% yttria stabilized zirconia(4YSZ, hereafter) top coat was fabricated on a second generation Ni-base superalloy. Thermal cycling behavior of NiCoCrAlY-4 YSZ thermal barrier coatings(TBCs) with and without Pt modification was evaluated in ambient air at 1100?C up to 1000 cycles, aiming to investigate the effect of Pt on formation of thermally grown oxide(TGO) and oxidation resistance. Results indicated that a dual layered TGO, which consisted of top(Ni,Co)(Cr,Al)_2O_4 spinel and underlying α-Al_2O_3, was formed at the NiCoCrAlY/4 YSZ interface with thickness of 8.4μm, accompanying with visible cracks at the interface. In contrast, a single-layer and adherent α-Al_2O_3 scale with thickness of 5.6μm was formed at the interface of Pt-modified NiCoCrAlY and 4 YSZ top coating. The modification of Pt on NiCoCrAlY favored the exclusive formation of α-Al_2O_3 and the reduction of TGO growth rate, and thus could effectively improve overall oxidation performance and extend service life of TBCs. Oxidation and degradation mechanisms of the TBCs with/without Pt-modification were discussed.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51,671,202 and 51,301,184)the Defence Industrial Technology Development Program (Grant No. JCKY2016404C001)sponsored by “Liaoning BaiQianWan Talents” Program
文摘A single-phase (Ni,Pt)Al coating with lean addition of Zr was prepared by co-electroplating of Pt-Zr com posite plating and subsequent gaseous alum inization treatm ents. Isotherm al and cyclic oxidation behavior of the Zr-doped (Ni,Pt)Al coating sam ples was assessed at 1373K in static air in comparison with plain nickel alum inide (NiAl) and norm al (Ni,Pt)Al coatings. Results indicated th at Zr-doped (Ni,Pt)Al coating dem onstrated a lower oxidation rate constant and reduced tendency of oxide scale spallation as well as surface rumpling, in which the enhanced oxidation perform ance was m ainly attributed to the segregation of Zr at oxide scale grain boundaries and the im proved Young's modulus of the coating. Besides, the addition of Zr effectively delayed oxide phase transform ation of Al2O3 from θ phase to α phase in the early oxidation stage and coating degradation of β-NiAl to γ'-Ni3Al in the stable oxidation stage.
