TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing Ti...TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.展开更多
Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,a...Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.展开更多
Silicide coatings have proven to be promising for improving the high-temperature oxidation resistance of niobium alloy.However,the long-term protective property of single silicide coating remains a long-time endeavor ...Silicide coatings have proven to be promising for improving the high-temperature oxidation resistance of niobium alloy.However,the long-term protective property of single silicide coating remains a long-time endeavor due to the deficiency of oxygen-consuming phases,as well as the self-healing ability of the protective layer.Herein,a silicide-based composite coating is constructed on niobium alloy by incor-poration of nano-SiC particles for enhancing the high-temperature oxidation resistance.Isothermal oxi-dation results at 1250℃ for 50 h indicate that NbSi_(2)/Nb_(2)O_(5)-SiO_(2)/SiC multilayer coated sample with a low mass gain of 2.49 mg/cm^(2) shows an improved oxidation resistance compared with NbSi_(2) coating(6.49 mg/cm^(2)).The enhanced high-temperature antioxidant performance of NbSi_(2)/Nb_(2)O_(5)-SiO_(2)/SiC multi-layer coating is mainly attributed to the formation of the protective SiO_(2) self-healing film and the high-temperature diffusion behavior of NbSi_(2)/substrate.展开更多
A Cr/CoNiCrAlTaY bilayer coating was prepared on the Ti-45Al-8.5Nb alloy by plasma surface metallurgy technique.The as-prepared coating with a grain size of~2μm exhibited a dense microstructure and strong adhesion du...A Cr/CoNiCrAlTaY bilayer coating was prepared on the Ti-45Al-8.5Nb alloy by plasma surface metallurgy technique.The as-prepared coating with a grain size of~2μm exhibited a dense microstructure and strong adhesion due to metallurgical bonding,consisting of outermost Cr layer and CoNiCrAlTaY transition layer.The typical power-law relationship between mass gain and time was obtained for the coated specimens with a rate exponent of 3.18 following oxidation at 1173 K.The top Cr_(2)O_(3)film and spinel oxides(i.e.,NiCr_(2)O_(4)and CoCr_(2)O_(4))exhibited a protective effect with a low oxidation reaction rate.Interfacial analysis identified Ta precipitates(Cr_(2)Ta and TaAl_(3))and Ta oxides(Ta_(2)O_(5)and Ta_(2)O_(3)),which played an essential role in retarding rapid diffusion and enhancing adhesion and oxidation resistance.展开更多
To improve the oxidation resistance of HfB_(2)-SiC coatings on carbon/carbon composites at 1700°C in air,CeO_(2) was introduced to improve oxygen blocking and its mechanism was investigated.During the rapid oxida...To improve the oxidation resistance of HfB_(2)-SiC coatings on carbon/carbon composites at 1700°C in air,CeO_(2) was introduced to improve oxygen blocking and its mechanism was investigated.During the rapid oxidation stage,CeO_(2) accelerated the formation of a multiphase glass layer on the coating surface.The maximum oxidation rates of CeO_(2)-HfB2-SiC coatings with 1%,3%,and 5%CeO_(2) were 24.1%,20.3%,and 53.2%higher than that of the unmodified HfB2-SiC coating,respectively.In the stable oxidation stage,the maximum oxidation rates of coatings with 1%and 3%CeO_(2) decreased by 31.4%and 21.9%,respectively,demonstrating adequate inert protection.CeO_(2) is a“coagulant”and“stabilizer”in the composite glass layer.However,increasing the CeO_(2) content accelerates the reaction between the SiO_(2) glass phase and SiC,leading to a higher SiO_(2) consumption and reduced self-healing ability of the glass layer.The 1%CeO_(2)-60%HfB2-39%SiC coating showed improved glass layer viscosity and stability,moderate SiO_(2) consumption,and better self-healing ability,significantly boosting the oxidation protection of the coating.展开更多
To improve the high-temperature oxidation resistance of TiAlNb9 alloy,a Cr-Al-Y co-deposition coating was prepared on the alloy surface by the pack cementation method.The microstructure of the coating was analyzed by ...To improve the high-temperature oxidation resistance of TiAlNb9 alloy,a Cr-Al-Y co-deposition coating was prepared on the alloy surface by the pack cementation method.The microstructure of the coating was analyzed by scanning electron microscope,energy dispersive spectrometer,and X-ray diffractometer,and the high-temperature oxidation properties of the substrate and coating at 1273 K were compared and studied.The results show that the Cr-Al-Y coating is about 30μm in thickness,and it has a dense structure and good film-substrate bonding.The coating includes an outer layer composed of TiCr_(2),TiCr,Ti_(4)Cr,and(Ti,Nb)Cr_(4) phases as well as an inner layer composed of Ti_(2)Al,and Nb-richγ-TiAl interdiffusion zone.The TiAlNb9 substrate forms an oxide layer composed of TiO_(2) and Al_(2)O_(3) at 1273 K.Due to its loose and porous structure,TiO_(2) oxide film cannot effectively isolate the internal diffusion of element O,resulting in continuous oxidation damage to the substrate.The Cr-Al-Y co-deposition coating forms a dense Cr_(2)O_(3) and Al_(2)O_(3) oxide layer during oxidation,effectively preventing the internal diffusion of element O and significantly improving the high-temperature oxidation resistance of the substrate alloy.展开更多
Cr coatings,as protective coatings of Zr-alloy fuel claddings,inevitably suffer from irradiation damage before they would possibly run into the accident condition.This study evaluates the radiation and oxidation toler...Cr coatings,as protective coatings of Zr-alloy fuel claddings,inevitably suffer from irradiation damage before they would possibly run into the accident condition.This study evaluates the radiation and oxidation tolerance of three Cr-based coatings with different microstructures(Cr,CrAlSi,and CrAlSiN)through He2+ion irradiation and 1200℃ steam oxidation.The Cr and CrAlSi coatings experienced significant structural degradation,characterized by He bubble aggregation and amplified Kirkendall effects at elevated temperatures.In contrast,the irradiated CrAlSiN coating maintained structural integrity without measurable irradiation hardening.Following annealing at 800℃ for 30 min,approximately 40%of injected He atoms were released,indicating a“self-healing”mechanism.The mechanism is attributed to uniformly distributed,low-density channels that act as sinks and release paths for irradiation-induced defects.Density functional theory simulations suggest that N atoms promote significant rearrangement of ions surrounding the free volume,inhibiting the formation of sites capable of trapping He atoms.Moreover,the CrAlSiN coating exhibited superior oxidation resistance compared to the Cr and CrAlSi coatings,even under high-temperature steam conditions.Notably,the irradiated CrAlSiN sample displayed a significantly thinner oxide scale compared to the pristine one(almost half),owing to a more protective oxide scale and rapid outward diffusion of Cr,Al,and Si through nanochannel veins.These findings illuminate the effects of structure and composition on irradiation and oxidation behavior in Cr-based coatings,offering insights for developing new-generation accident-tolerance fuel coatings for Zr-alloy claddings.展开更多
The effects of niobium on the high-temperature oxidation resistance of austenitic stainless steel were systematically investigated.Two austenitic stainless steels with different Nb contents were prepared and exposed t...The effects of niobium on the high-temperature oxidation resistance of austenitic stainless steel were systematically investigated.Two austenitic stainless steels with different Nb contents were prepared and exposed to air at 850℃for 200 h.Results show that Nb positively affects the high-temperature oxidation resistance of austenitic stainless steels.The matrix organization of austenitic stainless steels with added niobium does not change,while the austenitic grain size is significantly refined,and it also promoted the release of internal stresses in the oxide film,which in turn improved the integrity of the oxide film and adhesion to the substrate.In addition,with the addition of Nb element,a large number of Nb(C,N)particles are diffusely distributed in the matrix.Nb(C,N)phase distributed in the matrix and the niobium-rich layer formed by the diffusion of niobium into the interface between the metal matrix and the oxide film during the high-temperature oxidation process effectively prevents the diffusion of iron into the outer layer and enhances the oxidation resistance at high temperatures.展开更多
Laser shock peening(LSP)was used to enhance the high-temperature oxidation resistance of laser melting deposited Ti45Al8Nb alloy.The microstructure and high-temperature oxidation behavior of the as-deposited Ti45Al8Nb...Laser shock peening(LSP)was used to enhance the high-temperature oxidation resistance of laser melting deposited Ti45Al8Nb alloy.The microstructure and high-temperature oxidation behavior of the as-deposited Ti45Al8Nb alloy before and after LSP were investigated by scanning electron microscopy,X-ray diffraction,and electron backscatter diffraction.The results indicated that the rate of mass gain in the as-deposited sample after LSP exhibited a decrease when exposed to an oxidation temperature of 900℃,implying that LSP-treated samples exhibited superior oxidation resistance at high temperatures.A gradient structure with a fine-grain layer,a deformed-grain layer,and a coarse-grain layer was formed in the LSP-treated sample,which facilitated the diffusion of the Al atom during oxidation,leading to the formation of a dense Al_(2)O_(3)layer on the surface.The mechanism of improvement in the oxidation resistance of the as-deposited Ti45Al8Nb alloy via LSP was discussed.展开更多
To improve the high-temperature service properties of coppery tuyere,Co06 coating with a Ni60A interlayer was prepared on copper by plasma cladding.Ni60A interlayer acted as a bridge to promote the element diffusion,t...To improve the high-temperature service properties of coppery tuyere,Co06 coating with a Ni60A interlayer was prepared on copper by plasma cladding.Ni60A interlayer acted as a bridge to promote the element diffusion,thus achieving metallurgical bonding.Due to the strengthening effect ofγ-Co,Cr_(23)C_(6)and Cr_(7)C_(3)phases,the wear resistance of Co06–Ni60A coating was much higher than that of copper substrate.As the temperature increased,the wear resistance of coating decreased first and then increased.The coating exhibited better wear resistance at 600℃ due to the oxidation wear mechanism.Compared with copper substrate and Ni60A,the oxidation resistance of Co06 was increased by 6.0 and 1.9 times,respectively.For melting loss resistance,Co06–Ni60A coating was superior to Ni60A single-layer coating,but the molten iron can still form a micro-metallurgical bonding with the coating surface.展开更多
The high-temperature oxidation resistance of AISI 321 stainless steel used in solar thermal power heat exchangers determines its service life.In this study,aluminizing and subsequent laser shock peening(LSP)treatments...The high-temperature oxidation resistance of AISI 321 stainless steel used in solar thermal power heat exchangers determines its service life.In this study,aluminizing and subsequent laser shock peening(LSP)treatments were employed to improve the high-temperature oxidation resistance of AISI 321 stainless steel at 620°C.These two treatments decreased the oxidation rate of AISI 321 steel.Specifically,the optimal oxidation resistance was observed in aluminized steel before oxidation for 144 h owing to the increased entropy of the LSP-treated specimen.After 144 h,LSP-treated steel achieved the best oxidation resistance because of the formation of a protectiveα-Al2O3film.Moreover,the large amount of subgrain boundaries formed on the aluminized layer of the LSP-treated samples could act as short-circuit paths for the outward diffusion of Al,facilitating the rapid nucleation ofα-Al2O3.Meanwhile,the aluminized layer could isolate the contact between the oxidation environment and matrix,thereby decreasing the oxidation rate.Furthermore,the minimum oxidation parabolic constant was calculated for LSP-treated steel(6.45787×10^(-14)),which was 69.18%and 36.36%that of aluminized and 321 steel,respectively,during the entire oxidation process.Therefore,the combination of aluminizing and LSP treatments can improve the high-temperature oxidation resistance of 321 stainless steel,providing a new idea for its surface treatment to achieve a long service life at high temperatures.展开更多
To protect carbon materials from oxidation, mullite/SiC coatings were prepared on graphite by chemical vapor reaction (CVR) and slurry sintering. The XRD analyses show that the phase of the outer-layer coating is comp...To protect carbon materials from oxidation, mullite/SiC coatings were prepared on graphite by chemical vapor reaction (CVR) and slurry sintering. The XRD analyses show that the phase of the outer-layer coating is composed of SiO2 and mullite, and the inner-layer coating is mainly composed of β-SiC. The anti-oxidation behavior of the coating and the Rockwell hardness (HRB) of the coating after oxidation were investigated. The oxidation test shows that the as-prepared multi-layer coating exhibits excellent antioxidation and thermal shock resistance at high temperature. After oxidation at 1150 ℃ for 109 h and thermal shock cycling between 1150 ℃ and room temperature for 12 times, the mass gain of the coated sample is 0.085%. Meanwhile, the indentation tests also demonstrate that the as-prepared coating has good bonding ability between the layers.展开更多
To improve the oxidation resistance of carbon/carbon （C/C） composites in air at high temperatures, a SiC- MoSi2/ZrO2-MoSi2 coating was prepared on the surface of C/C composites by pack cementation and slurry method....To improve the oxidation resistance of carbon/carbon （C/C） composites in air at high temperatures, a SiC- MoSi2/ZrO2-MoSi2 coating was prepared on the surface of C/C composites by pack cementation and slurry method. The microstructures and phase compositions of the coated C/C composites were analyzed by scanning electron microscopy and X-ray diffraction, respectively. The result shows that the SiC-MoSi2/ZrO2-MoSi2 coating is dense and crack-free with a thickness of 250-300 μm. The preparation and the high temperature oxidation property of the coated composites were investigated. The as-received coating has excellent oxidation protection ability and can protect C/C composites from oxidation for 260 h at 1773 K in air. The excellent anti-oxidation performance of the coating is considered to come from the formation of ZrSiO4, which improves the stability of the coating at high temperatures.展开更多
Microstructure, mechanical property and oxidation resistance of MCrAlYX coatings prepared by detonation gun (D-gun) and HVOF spraying were investigated. Lamellar microstructure and uniform microstructure formed in D-g...Microstructure, mechanical property and oxidation resistance of MCrAlYX coatings prepared by detonation gun (D-gun) and HVOF spraying were investigated. Lamellar microstructure and uniform microstructure formed in D-gun sprayed MCrAlYX coating and HVOF sprayed coating, respectively. Element redistribution and formation of new phase took place during the detonation process. Besides, the porosity of D-gun sprayed coating was much lower than that of HVOF sprayed coating. On the mechanical property, the micro-hardnesses of the two coatings were in the same level (~HV 910). However, D-gun sprayed MCrAlYX coating exhibited larger standard deviation of microhardness due to its lamellar microstructure, and exhibited better bend bonding strength owing to the existence of residual compressive stress between the layers and particles. Meanwhile, due to the much more compact microstructure, D-gun sprayed MCrAlYX coating showed superior oxidation resistance to the HVOF sprayed coating. The continuous dense protective layer can form earlier in D-gun sprayed coating and thus suppress further oxidation and control the oxide thickness at a relatively low level.展开更多
In order to protect C/C composites from oxidation, SiC-MoSi2 composite coating was synthesized by chemical vapor infiltration /reaction （CVI/CVR） technology. A porous Mo layer was prefabricated on SiC coated C/C com...In order to protect C/C composites from oxidation, SiC-MoSi2 composite coating was synthesized by chemical vapor infiltration /reaction （CVI/CVR） technology. A porous Mo layer was prefabricated on SiC coated C/C composites, and then MoSi2 and SiC were subsequently prepared in a CVI /CVR process using methyltrichlorosilane （MTS） as precursor. The deposition and reaction mechanism of the MoSi2-SiC composite coating was investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The oxidation behavior of SiC-MoSi2 coated specimens was tested. The results show that the porous Mo layer can be densified with SiC phase decomposed from MTS, and transformed into SiC-MoSi2 by reacting with MTS as well. A dense composite coating was prepared with optimized deposition parameters. The coated specimen exhibits a good oxidation resistance with a little mass loss of 1.25% after oxidation at 1500 °C for 80 h.展开更多
The outermost coating with single phase Ni2Al3 was obtained on copper surface by electrodepositing nickel followed by slurry pack aluminizing at 800 °C for 12 h. The oxidation resistance and microstructure of the...The outermost coating with single phase Ni2Al3 was obtained on copper surface by electrodepositing nickel followed by slurry pack aluminizing at 800 °C for 12 h. The oxidation resistance and microstructure of the coating oxidized in ambient air at 1000 °C for 25-250 h were investigated using SEM, X-ray diffraction and optical microscope methods. The results show that the copper with single phase Ni2Al3 coating possesses the best high temperature oxidation resistance, and the mass gain of the coating is 1/15 that of pure copper and 1/2 that of nickel coating, respectively. The specimen surface after being oxidized for 25 h still comprises Ni2Al3 phase. However, when the time of oxidizing treatment increases to 50 h, the Ni Al phase is formed. It is also found that the Ni2Al3 phase completely turns into Ni Al phase after oxidizing treatment for 100 h and above. The Ni Al coating shows excellent high temperature oxidation resistance when oxidation time is 250 h.展开更多
[Objective] The aim was to study on the oxidation resistance of flavonoids in Chinese jujube stone. [Method] The extract of flavonoids from Chinese jujube stone was added to fresh rapeseed oil and lard to explore the ...[Objective] The aim was to study on the oxidation resistance of flavonoids in Chinese jujube stone. [Method] The extract of flavonoids from Chinese jujube stone was added to fresh rapeseed oil and lard to explore the oxidation resistance of flavonoids; the removal rates of it to O2-·,DPPH· and ·OH were also studied. [Result] The flavonoids from Chinese jujube stone had good oxidation resistance on rapeseed oil and lard,and the effects showed dose-dependent; citric acid and vitamin C appeared synergistic effects to the flavonoids; in free-radical reaction experiment,the flavonoids from Chinese Jujube stone also showed strong scavenging ability on O2-·,DPPH· and ·OH,in addition,the scavenging ability increased with concentration increasing. [Conclusion] The result of this study had provided theoretical basis for the further development and utilization of Chinese jujube resource.展开更多
Yttrium silicate （Y2Si2O7） coating was fabricated on C/SiC composites through dip-coating with silicone resin ＋ Y2O3 powder slurry as raw materials. The synthesis, microstructure and oxidation resistance and the an...Yttrium silicate （Y2Si2O7） coating was fabricated on C/SiC composites through dip-coating with silicone resin ＋ Y2O3 powder slurry as raw materials. The synthesis, microstructure and oxidation resistance and the anti-oxidation mechanism of Y2Si2O7 coating were investigated. Y2Si2O7 can be synthesized by the pyrolysis of Y2O3 powder filled silicone resin at mass ratio of 54.2：45.8 and 800 °C in air and then heat treated at 1400 °C under Ar. The as-fabricated coating shows high density and favorable bonding to C/SiC composites. After oxidation in air at 1400, 1500 and 1600 °C for 30 min, the coating-containing composites possess 130%-140% of original flexural strength. The desirable thermal stability and the further densification of coating during oxidation are responsible for the excellent oxidation resistance. In addition, the formation of eutectic Y-Si-Al-O glassy phase between Y2Si2O7 and Al2O3 sample bracket at 1500 °C is discovered.展开更多
Al2O3/Au nano-laminated composite coatings were prepared by means of magnetron sputtering. The coating was compact and comprised of nano-laminated Al2O3 and Au layers. High temperature cyclic oxidation test was employ...Al2O3/Au nano-laminated composite coatings were prepared by means of magnetron sputtering. The coating was compact and comprised of nano-laminated Al2O3 and Au layers. High temperature cyclic oxidation test was employed to investigate the oxidation resistance of the composite coatings. The results revealed that the applied Al2O3/Au nano-laminated composite coatings improved the oxidation and spallation resistance of the stainless steel substrate significantly. The mechanism accounting for oxidation resistance was related with the suppression of inward oxygen diffusion and selective oxidation of Cr in the substrate. The mechanism accounting for spallation resistance was attributed to the relaxation of thermal stress by the nano-laminated structure.展开更多
To improve the oxidation resistance of boron-modified carbon foams, the B2O3 coating was prepared on boron-modified carbon foams by low-cost slurry method. The microstructures and phase compositions of the coated carb...To improve the oxidation resistance of boron-modified carbon foams, the B2O3 coating was prepared on boron-modified carbon foams by low-cost slurry method. The microstructures and phase compositions of the coated carbon foams were characterized by scanning electron microscopy and X-ray diffraction, respectively. Oxidation resistances of uncoated and coated boron-modified carbon foams were investigated at 873 K in air. The results showed that as-received B2O3 coating could protect boron-modified carbon foams from oxidation at 873 K. B2O3-coated carbon foam doped with 7% B2O3 （mass fraction） （BO-7） had better oxidation resistance, exhibiting mass loss of 17.40% after oxidation at 873 K for 120 min. The melting glass layer formed on the surface of BO-7 could prevent oxygen from diffusing into boron-modified carbon foams substrate during oxidation to some extent.展开更多
基金supported by the Original Exploratory Program of the National Natural Science Foundation of China(No.52450012)。
文摘TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.
基金National Natural Science Foundation of China(52071126)Natural Science Foundation of Tianjin City,China(22JCQNJC01240)+2 种基金Central Guidance on Local Science and Technology Development Fund of Hebei Province(226Z1009G)Special Funds for Science and Technology Innovation in Hebei(2022X19)Anhui Provincial Natural Science Foundation(2308085ME135)。
文摘Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.
基金supported by the National Natural Science Foundation of China(Nos.U21B2053,52071114,52001100,and 523B2010)Outstanding Youth Project of Natural Science Foundation of Heilongjiang Province(No.YQ2023E008)+1 种基金Young Elite Scientists Sponsorship Program by CAST(NO.2021QNRC001)Heilongjiang Touyan Team Program.
文摘Silicide coatings have proven to be promising for improving the high-temperature oxidation resistance of niobium alloy.However,the long-term protective property of single silicide coating remains a long-time endeavor due to the deficiency of oxygen-consuming phases,as well as the self-healing ability of the protective layer.Herein,a silicide-based composite coating is constructed on niobium alloy by incor-poration of nano-SiC particles for enhancing the high-temperature oxidation resistance.Isothermal oxi-dation results at 1250℃ for 50 h indicate that NbSi_(2)/Nb_(2)O_(5)-SiO_(2)/SiC multilayer coated sample with a low mass gain of 2.49 mg/cm^(2) shows an improved oxidation resistance compared with NbSi_(2) coating(6.49 mg/cm^(2)).The enhanced high-temperature antioxidant performance of NbSi_(2)/Nb_(2)O_(5)-SiO_(2)/SiC multi-layer coating is mainly attributed to the formation of the protective SiO_(2) self-healing film and the high-temperature diffusion behavior of NbSi_(2)/substrate.
基金financial supports from Shanxi Provincial Natural Science Foundation,China(No.20210302123162)Shanxi Scholarship Council of China(No.2024-057)+2 种基金State Key Laboratory of Advanced Metal Materials,China(No.2019-ZD02)Science and Technology Achievement Transformation and Cultivation Project of Shanxi,China(No.2020CG011)Shanxi“1331 Project”Quality Improvement and Efficiency Project,China。
文摘A Cr/CoNiCrAlTaY bilayer coating was prepared on the Ti-45Al-8.5Nb alloy by plasma surface metallurgy technique.The as-prepared coating with a grain size of~2μm exhibited a dense microstructure and strong adhesion due to metallurgical bonding,consisting of outermost Cr layer and CoNiCrAlTaY transition layer.The typical power-law relationship between mass gain and time was obtained for the coated specimens with a rate exponent of 3.18 following oxidation at 1173 K.The top Cr_(2)O_(3)film and spinel oxides(i.e.,NiCr_(2)O_(4)and CoCr_(2)O_(4))exhibited a protective effect with a low oxidation reaction rate.Interfacial analysis identified Ta precipitates(Cr_(2)Ta and TaAl_(3))and Ta oxides(Ta_(2)O_(5)and Ta_(2)O_(3)),which played an essential role in retarding rapid diffusion and enhancing adhesion and oxidation resistance.
文摘To improve the oxidation resistance of HfB_(2)-SiC coatings on carbon/carbon composites at 1700°C in air,CeO_(2) was introduced to improve oxygen blocking and its mechanism was investigated.During the rapid oxidation stage,CeO_(2) accelerated the formation of a multiphase glass layer on the coating surface.The maximum oxidation rates of CeO_(2)-HfB2-SiC coatings with 1%,3%,and 5%CeO_(2) were 24.1%,20.3%,and 53.2%higher than that of the unmodified HfB2-SiC coating,respectively.In the stable oxidation stage,the maximum oxidation rates of coatings with 1%and 3%CeO_(2) decreased by 31.4%and 21.9%,respectively,demonstrating adequate inert protection.CeO_(2) is a“coagulant”and“stabilizer”in the composite glass layer.However,increasing the CeO_(2) content accelerates the reaction between the SiO_(2) glass phase and SiC,leading to a higher SiO_(2) consumption and reduced self-healing ability of the glass layer.The 1%CeO_(2)-60%HfB2-39%SiC coating showed improved glass layer viscosity and stability,moderate SiO_(2) consumption,and better self-healing ability,significantly boosting the oxidation protection of the coating.
基金National Natural Science Foundation of China(52161009)Innovation Project of Postgraduate Students in North Minzu University(YCX24104)。
文摘To improve the high-temperature oxidation resistance of TiAlNb9 alloy,a Cr-Al-Y co-deposition coating was prepared on the alloy surface by the pack cementation method.The microstructure of the coating was analyzed by scanning electron microscope,energy dispersive spectrometer,and X-ray diffractometer,and the high-temperature oxidation properties of the substrate and coating at 1273 K were compared and studied.The results show that the Cr-Al-Y coating is about 30μm in thickness,and it has a dense structure and good film-substrate bonding.The coating includes an outer layer composed of TiCr_(2),TiCr,Ti_(4)Cr,and(Ti,Nb)Cr_(4) phases as well as an inner layer composed of Ti_(2)Al,and Nb-richγ-TiAl interdiffusion zone.The TiAlNb9 substrate forms an oxide layer composed of TiO_(2) and Al_(2)O_(3) at 1273 K.Due to its loose and porous structure,TiO_(2) oxide film cannot effectively isolate the internal diffusion of element O,resulting in continuous oxidation damage to the substrate.The Cr-Al-Y co-deposition coating forms a dense Cr_(2)O_(3) and Al_(2)O_(3) oxide layer during oxidation,effectively preventing the internal diffusion of element O and significantly improving the high-temperature oxidation resistance of the substrate alloy.
基金supported by the National Natu-ral Science Foundation of China(No.U2230126)the Natural Science Foundation of Zhejiang Province(No.LZ23E010001)+1 种基金This work was co-funded by the European Union under the Project Robotics and Advanced Industrial Production(Reg.No.CZ.02.01.01/00/22_008/0004590)supported by the Ministry of Education,Youth and Sports of the Czech Repub-lic through the e-INFRA CZ grant number ID:90140.Access to the computational infrastructure of the OP VVV funded Project No.CZ.02.1.01/0.0/0.0/16_019/0000765“Research Center for Informat-ics”and the use of the VESTA software[https://doi.org/10.1107/S0021889808012016]are also acknowledged.The authors thank the staffof HIRFL for the help with the irradiation experiment and the support of the Sharing Service Platform of CAS Large Re-search Infrastructures(2022-HIRFL-ZD-002017)。
文摘Cr coatings,as protective coatings of Zr-alloy fuel claddings,inevitably suffer from irradiation damage before they would possibly run into the accident condition.This study evaluates the radiation and oxidation tolerance of three Cr-based coatings with different microstructures(Cr,CrAlSi,and CrAlSiN)through He2+ion irradiation and 1200℃ steam oxidation.The Cr and CrAlSi coatings experienced significant structural degradation,characterized by He bubble aggregation and amplified Kirkendall effects at elevated temperatures.In contrast,the irradiated CrAlSiN coating maintained structural integrity without measurable irradiation hardening.Following annealing at 800℃ for 30 min,approximately 40%of injected He atoms were released,indicating a“self-healing”mechanism.The mechanism is attributed to uniformly distributed,low-density channels that act as sinks and release paths for irradiation-induced defects.Density functional theory simulations suggest that N atoms promote significant rearrangement of ions surrounding the free volume,inhibiting the formation of sites capable of trapping He atoms.Moreover,the CrAlSiN coating exhibited superior oxidation resistance compared to the Cr and CrAlSi coatings,even under high-temperature steam conditions.Notably,the irradiated CrAlSiN sample displayed a significantly thinner oxide scale compared to the pristine one(almost half),owing to a more protective oxide scale and rapid outward diffusion of Cr,Al,and Si through nanochannel veins.These findings illuminate the effects of structure and composition on irradiation and oxidation behavior in Cr-based coatings,offering insights for developing new-generation accident-tolerance fuel coatings for Zr-alloy claddings.
基金support of this work by the Major Program of Science and Technology in Shanxi Province(202202050201019)the National Natural Science Foundation of China(52271067)Shaanxi Outstanding Youth Fund Project(2021JC-45).
文摘The effects of niobium on the high-temperature oxidation resistance of austenitic stainless steel were systematically investigated.Two austenitic stainless steels with different Nb contents were prepared and exposed to air at 850℃for 200 h.Results show that Nb positively affects the high-temperature oxidation resistance of austenitic stainless steels.The matrix organization of austenitic stainless steels with added niobium does not change,while the austenitic grain size is significantly refined,and it also promoted the release of internal stresses in the oxide film,which in turn improved the integrity of the oxide film and adhesion to the substrate.In addition,with the addition of Nb element,a large number of Nb(C,N)particles are diffusely distributed in the matrix.Nb(C,N)phase distributed in the matrix and the niobium-rich layer formed by the diffusion of niobium into the interface between the metal matrix and the oxide film during the high-temperature oxidation process effectively prevents the diffusion of iron into the outer layer and enhances the oxidation resistance at high temperatures.
基金supported by the Class Ⅲ Peak Discipline of Shanghai,China-Materials Science and Engineering(High-Energy Beam Intelligent Processing and Green Manufacturing).
文摘Laser shock peening(LSP)was used to enhance the high-temperature oxidation resistance of laser melting deposited Ti45Al8Nb alloy.The microstructure and high-temperature oxidation behavior of the as-deposited Ti45Al8Nb alloy before and after LSP were investigated by scanning electron microscopy,X-ray diffraction,and electron backscatter diffraction.The results indicated that the rate of mass gain in the as-deposited sample after LSP exhibited a decrease when exposed to an oxidation temperature of 900℃,implying that LSP-treated samples exhibited superior oxidation resistance at high temperatures.A gradient structure with a fine-grain layer,a deformed-grain layer,and a coarse-grain layer was formed in the LSP-treated sample,which facilitated the diffusion of the Al atom during oxidation,leading to the formation of a dense Al_(2)O_(3)layer on the surface.The mechanism of improvement in the oxidation resistance of the as-deposited Ti45Al8Nb alloy via LSP was discussed.
基金supported by the University Synergy Innovation Program of Anhui Province(Grant Nos.GXXT-2023-025 and GXXT-2023-026)Natural Science Foundation of Anhui Province(Grant Nos.2008085ME149,2308085QE132 and 2308065ME171)Anhui University Scientific Research Project(Grant Nos.2022AH040247,2023AH051660,2023AH051670 and 2023AH051671).
文摘To improve the high-temperature service properties of coppery tuyere,Co06 coating with a Ni60A interlayer was prepared on copper by plasma cladding.Ni60A interlayer acted as a bridge to promote the element diffusion,thus achieving metallurgical bonding.Due to the strengthening effect ofγ-Co,Cr_(23)C_(6)and Cr_(7)C_(3)phases,the wear resistance of Co06–Ni60A coating was much higher than that of copper substrate.As the temperature increased,the wear resistance of coating decreased first and then increased.The coating exhibited better wear resistance at 600℃ due to the oxidation wear mechanism.Compared with copper substrate and Ni60A,the oxidation resistance of Co06 was increased by 6.0 and 1.9 times,respectively.For melting loss resistance,Co06–Ni60A coating was superior to Ni60A single-layer coating,but the molten iron can still form a micro-metallurgical bonding with the coating surface.
基金Supported by National Natural Science Foundation of China(Grant Nos.52075048,51675058,12232004)Hunan Provincial Excellent Youth Project of the Education Department(Grant No.21B0304)+2 种基金Natural Science Foundation of Hunan Province(Grant No.2023JJ30025)Science and Technology Innovation Program of Hunan Province(Grant No.2023RC1058)Scientific Research Innovation Project for Graduate Student of Changsha University of Science and Technology(Grant No.CLSJCX22096)。
文摘The high-temperature oxidation resistance of AISI 321 stainless steel used in solar thermal power heat exchangers determines its service life.In this study,aluminizing and subsequent laser shock peening(LSP)treatments were employed to improve the high-temperature oxidation resistance of AISI 321 stainless steel at 620°C.These two treatments decreased the oxidation rate of AISI 321 steel.Specifically,the optimal oxidation resistance was observed in aluminized steel before oxidation for 144 h owing to the increased entropy of the LSP-treated specimen.After 144 h,LSP-treated steel achieved the best oxidation resistance because of the formation of a protectiveα-Al2O3film.Moreover,the large amount of subgrain boundaries formed on the aluminized layer of the LSP-treated samples could act as short-circuit paths for the outward diffusion of Al,facilitating the rapid nucleation ofα-Al2O3.Meanwhile,the aluminized layer could isolate the contact between the oxidation environment and matrix,thereby decreasing the oxidation rate.Furthermore,the minimum oxidation parabolic constant was calculated for LSP-treated steel(6.45787×10^(-14)),which was 69.18%and 36.36%that of aluminized and 321 steel,respectively,during the entire oxidation process.Therefore,the combination of aluminizing and LSP treatments can improve the high-temperature oxidation resistance of 321 stainless steel,providing a new idea for its surface treatment to achieve a long service life at high temperatures.
基金Project (2012M511752) supported by China Postdoctoral Science FoundationProject (2011CB605801) supported by the National Basical Research Program of China+3 种基金Project (2012QNZT004) supported by the Fundamental Research Funds of the Central Universities, ChinaProject supported by the Freedom Explore Program of Central South University, ChinaProject (CSUZC2012026) supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University, ChinaProject supported by the Postdoctoral Science Foundation of Central South University, China
文摘To protect carbon materials from oxidation, mullite/SiC coatings were prepared on graphite by chemical vapor reaction (CVR) and slurry sintering. The XRD analyses show that the phase of the outer-layer coating is composed of SiO2 and mullite, and the inner-layer coating is mainly composed of β-SiC. The anti-oxidation behavior of the coating and the Rockwell hardness (HRB) of the coating after oxidation were investigated. The oxidation test shows that the as-prepared multi-layer coating exhibits excellent antioxidation and thermal shock resistance at high temperature. After oxidation at 1150 ℃ for 109 h and thermal shock cycling between 1150 ℃ and room temperature for 12 times, the mass gain of the coated sample is 0.085%. Meanwhile, the indentation tests also demonstrate that the as-prepared coating has good bonding ability between the layers.
基金Projects(51221001,51222207)supported by the National Natural Science Foundation of ChinaProject(090677)supported by the Program for New Century Excellent Talents in University of ChinaProject(B08040)supported by Program of Introducing Talents of Discipline to Universities,China
文摘To improve the oxidation resistance of carbon/carbon （C/C） composites in air at high temperatures, a SiC- MoSi2/ZrO2-MoSi2 coating was prepared on the surface of C/C composites by pack cementation and slurry method. The microstructures and phase compositions of the coated C/C composites were analyzed by scanning electron microscopy and X-ray diffraction, respectively. The result shows that the SiC-MoSi2/ZrO2-MoSi2 coating is dense and crack-free with a thickness of 250-300 μm. The preparation and the high temperature oxidation property of the coated composites were investigated. The as-received coating has excellent oxidation protection ability and can protect C/C composites from oxidation for 260 h at 1773 K in air. The excellent anti-oxidation performance of the coating is considered to come from the formation of ZrSiO4, which improves the stability of the coating at high temperatures.
基金Project(51201156)supported by the National Natural Science Foundation of China
文摘Microstructure, mechanical property and oxidation resistance of MCrAlYX coatings prepared by detonation gun (D-gun) and HVOF spraying were investigated. Lamellar microstructure and uniform microstructure formed in D-gun sprayed MCrAlYX coating and HVOF sprayed coating, respectively. Element redistribution and formation of new phase took place during the detonation process. Besides, the porosity of D-gun sprayed coating was much lower than that of HVOF sprayed coating. On the mechanical property, the micro-hardnesses of the two coatings were in the same level (~HV 910). However, D-gun sprayed MCrAlYX coating exhibited larger standard deviation of microhardness due to its lamellar microstructure, and exhibited better bend bonding strength owing to the existence of residual compressive stress between the layers and particles. Meanwhile, due to the much more compact microstructure, D-gun sprayed MCrAlYX coating showed superior oxidation resistance to the HVOF sprayed coating. The continuous dense protective layer can form earlier in D-gun sprayed coating and thus suppress further oxidation and control the oxide thickness at a relatively low level.
基金Projects(51221001,51272213,51072166)supported by the National Natural Science Foundation of ChinaProject(GBKY1021)supported by the Fundamental Research Foundation of Northwestern Polytechnical University,ChinaProject(B08040)supported by Program of Introducing Talents of Discipline to Universities,China
文摘In order to protect C/C composites from oxidation, SiC-MoSi2 composite coating was synthesized by chemical vapor infiltration /reaction （CVI/CVR） technology. A porous Mo layer was prefabricated on SiC coated C/C composites, and then MoSi2 and SiC were subsequently prepared in a CVI /CVR process using methyltrichlorosilane （MTS） as precursor. The deposition and reaction mechanism of the MoSi2-SiC composite coating was investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The oxidation behavior of SiC-MoSi2 coated specimens was tested. The results show that the porous Mo layer can be densified with SiC phase decomposed from MTS, and transformed into SiC-MoSi2 by reacting with MTS as well. A dense composite coating was prepared with optimized deposition parameters. The coated specimen exhibits a good oxidation resistance with a little mass loss of 1.25% after oxidation at 1500 °C for 80 h.
基金Projects(CKJB201205,QKJB201202,YJK201307)supported by the Nanjing Institute of Technology,China
文摘The outermost coating with single phase Ni2Al3 was obtained on copper surface by electrodepositing nickel followed by slurry pack aluminizing at 800 °C for 12 h. The oxidation resistance and microstructure of the coating oxidized in ambient air at 1000 °C for 25-250 h were investigated using SEM, X-ray diffraction and optical microscope methods. The results show that the copper with single phase Ni2Al3 coating possesses the best high temperature oxidation resistance, and the mass gain of the coating is 1/15 that of pure copper and 1/2 that of nickel coating, respectively. The specimen surface after being oxidized for 25 h still comprises Ni2Al3 phase. However, when the time of oxidizing treatment increases to 50 h, the Ni Al phase is formed. It is also found that the Ni2Al3 phase completely turns into Ni Al phase after oxidizing treatment for 100 h and above. The Ni Al coating shows excellent high temperature oxidation resistance when oxidation time is 250 h.
基金Supported by Tarim University President Fund for Innovation Group Program (TDZKCX08001)~~
文摘[Objective] The aim was to study on the oxidation resistance of flavonoids in Chinese jujube stone. [Method] The extract of flavonoids from Chinese jujube stone was added to fresh rapeseed oil and lard to explore the oxidation resistance of flavonoids; the removal rates of it to O2-·,DPPH· and ·OH were also studied. [Result] The flavonoids from Chinese jujube stone had good oxidation resistance on rapeseed oil and lard,and the effects showed dose-dependent; citric acid and vitamin C appeared synergistic effects to the flavonoids; in free-radical reaction experiment,the flavonoids from Chinese Jujube stone also showed strong scavenging ability on O2-·,DPPH· and ·OH,in addition,the scavenging ability increased with concentration increasing. [Conclusion] The result of this study had provided theoretical basis for the further development and utilization of Chinese jujube resource.
基金Project supported by the Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province,ChinaProject(CJ12-01-01)supported by the Innovative Group of National University of Defense Technology,ChinaProject(SAST2015043)supported by the Science Innovation Foundation of Shanghai Academy of Spaceflight Technology,China
文摘Yttrium silicate （Y2Si2O7） coating was fabricated on C/SiC composites through dip-coating with silicone resin ＋ Y2O3 powder slurry as raw materials. The synthesis, microstructure and oxidation resistance and the anti-oxidation mechanism of Y2Si2O7 coating were investigated. Y2Si2O7 can be synthesized by the pyrolysis of Y2O3 powder filled silicone resin at mass ratio of 54.2：45.8 and 800 °C in air and then heat treated at 1400 °C under Ar. The as-fabricated coating shows high density and favorable bonding to C/SiC composites. After oxidation in air at 1400, 1500 and 1600 °C for 30 min, the coating-containing composites possess 130%-140% of original flexural strength. The desirable thermal stability and the further densification of coating during oxidation are responsible for the excellent oxidation resistance. In addition, the formation of eutectic Y-Si-Al-O glassy phase between Y2Si2O7 and Al2O3 sample bracket at 1500 °C is discovered.
基金Project (50771021) supported by the National Natural Science Foundation of China
文摘Al2O3/Au nano-laminated composite coatings were prepared by means of magnetron sputtering. The coating was compact and comprised of nano-laminated Al2O3 and Au layers. High temperature cyclic oxidation test was employed to investigate the oxidation resistance of the composite coatings. The results revealed that the applied Al2O3/Au nano-laminated composite coatings improved the oxidation and spallation resistance of the stainless steel substrate significantly. The mechanism accounting for oxidation resistance was related with the suppression of inward oxygen diffusion and selective oxidation of Cr in the substrate. The mechanism accounting for spallation resistance was attributed to the relaxation of thermal stress by the nano-laminated structure.
基金Projects(51072107,51272213,51221001)supported by the National Natural Science Foundation of ChinaProject(B08040)supported by the Program of Introducing Talents of Discipline to Universities of China("111" Project)
文摘To improve the oxidation resistance of boron-modified carbon foams, the B2O3 coating was prepared on boron-modified carbon foams by low-cost slurry method. The microstructures and phase compositions of the coated carbon foams were characterized by scanning electron microscopy and X-ray diffraction, respectively. Oxidation resistances of uncoated and coated boron-modified carbon foams were investigated at 873 K in air. The results showed that as-received B2O3 coating could protect boron-modified carbon foams from oxidation at 873 K. B2O3-coated carbon foam doped with 7% B2O3 （mass fraction） （BO-7） had better oxidation resistance, exhibiting mass loss of 17.40% after oxidation at 873 K for 120 min. The melting glass layer formed on the surface of BO-7 could prevent oxygen from diffusing into boron-modified carbon foams substrate during oxidation to some extent.
