ZrO2-Y2O3 ceramic coating was produced by plasma electrolytic oxidation （PEO） on ZAlSil2Cu3Ni2 alloy. The microstructure and phase composition of the coating were investigated by SEM and XRD.： The results show that...ZrO2-Y2O3 ceramic coating was produced by plasma electrolytic oxidation （PEO） on ZAlSil2Cu3Ni2 alloy. The microstructure and phase composition of the coating were investigated by SEM and XRD.： The results show that adding an appropriate amount of yttrium ion can improve the growing rate of ceramic coating at different oxidation stages and decrease arc voltage. The thickness of ZrO2-Y2O3 coating is 16 μn thicker than that of ZrO2 coating and the maximum oxidation rate improves by 0.6 μm/min. In addition, the arc voltage decreases from 227 to 172 V. It can be seen that the rate of oxidation firstly increases to some extent and then decreases with the content of yttrium ion increasing. The growth rate reaches the maximum while the content of yttrium ion is 0.05 g-L-1The maximum thickness is 90 μm.Compared to ZrO2 coating, the micropores of ZrO2-Y2O3 coating are less and the ceramic layer is repeatedly deposited by ZrO2 and Y2O3 ceramic particles. Meanwhile, the binding force between coating and substrate is better and the coating is uniform and compact. The ceramic layer is mainly composed of c-Y0.15Zr0.85O1.93□0.07, m-ZrO2, α-Al2O3, ,γ-Al2O3 and Y2O3. It is indicated that ZrO2 has beert fully stabilized by yttrium ion through the formation of solid solution.展开更多
Al2O3-13%TiO2 （mass fraction） coatings, prepared by laser cladding on nickel-based alloy, were heated using high frequency induction sources. The coating microstructure and the interface between bond coating and cer...Al2O3-13%TiO2 （mass fraction） coatings, prepared by laser cladding on nickel-based alloy, were heated using high frequency induction sources. The coating microstructure and the interface between bond coating and ceramic coating were characterized by SEM, XRD and EDS. The results show that two-layer substructure exists in the ceramic coating： one layer evolving from fully melted region where the sintered grains grow fully; another layer resembling the liquid-phase-sintered structure consisting of three-dimensional net where the melted Al2O3 particles are embedded in the TiO2-rich matrix. The mechanism of the two-layer substructure formation is also explained in terms of the melting and flattening behavior of the powders during laser cladding processing. The spinel compounds NiAl2O4 and acicular compounds Cr2O3 are discovered in the interface between bond coating and ceramic coating. It proves that the chemical reactions in the laser cladding process will significantly enhance the coating adhesion.展开更多
A newly developed method is introduced for producing Cr 2O 3 base ceramic coating on aluminum alloys. On the basis of properly selecting base reactions, slurry is prepared and then applied onto the substrate surface...A newly developed method is introduced for producing Cr 2O 3 base ceramic coating on aluminum alloys. On the basis of properly selecting base reactions, slurry is prepared and then applied onto the substrate surface. By chemical reactions taken place in situ on the surface of aluminum alloy at relative low temperature, Cr 2O 3 base ceramic coating is formed. By means of scanning electron microscopy, the coating microstructure and the bonding mechanism are studied. X ray diffraction analysis is also used to investigate the chemical composition of the coating. The coating formation mechanism is further discussed. With a pin on disk tester, wear test is made to evaluate the wear performances of the coating. The results show that by applying the coating on aluminum alloy, the wear decreases 5 times in comparation to that without coating.展开更多
ZrO2, Al2O3, ZrO2/Al2O3 and Al2O3/ZrO2 coatings were fabricated on low carbon steel using atmospheric plasma spraying technique. The microstructure and phase composition of the as-sprayed coatings were examined by sca...ZrO2, Al2O3, ZrO2/Al2O3 and Al2O3/ZrO2 coatings were fabricated on low carbon steel using atmospheric plasma spraying technique. The microstructure and phase composition of the as-sprayed coatings were examined by scanning electron microscopy （SEM） and X-ray diffraction （XRD）, respectively. The polarization test, salt spray test and immersion test were used to investigate the corrosion behavior of the coatings in 3.5% NaCl solution. The results suggested that the bilayered Al2O3/ZrO2 coating exhibits superior corrosion resistance when compared with the other coatings. This is ascribed to the presence of very few interconnected pores and stable phases in the coating.展开更多
The high-temperature oxidation resistance behavior of 7% （mass fraction） Y203-ZrO2 thermal barrier coatings （TBCs） irradiated by high-intensity pulsed ion beam （HIPIB） was investigated under the cyclic oxidation...The high-temperature oxidation resistance behavior of 7% （mass fraction） Y203-ZrO2 thermal barrier coatings （TBCs） irradiated by high-intensity pulsed ion beam （HIPIB） was investigated under the cyclic oxidation condition of 1 050 ℃ and 1 h. The columnar grains in the TBCs disappear after the HIPIB irradiation at ion current densities of 100-200 A/cm^2 and the irradiated surface becomes smooth and densified after remelting and ablation due to the HIPIB irradiation. The thermally grown oxide （TGO） layer thickness of the irradiated TBCs is smaller than that of the original TBCs. After 15 cycles, the mass gains of the original TBCs and those irradiated by ion current densities of 100 and 200 A/cm^2 due to the oxidation are found to be 0.8-0.9, 0.6-0.7, and 0.3-0.4 mg/cm^2, respectively. The inward diffusion of oxygen through the irradiated TBCs is significantly impeded by the densified top layer formed due to irradiation, which is the main reason for the improved overall oxidation resistance of the irradiated TBCs.展开更多
Low thermal conductivity, matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings(EBCs/TBCs) and interphases for Al2O3 f/Al2O3 composites. I...Low thermal conductivity, matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings(EBCs/TBCs) and interphases for Al2O3 f/Al2O3 composites. In this work, a novel high-entropy(HE) rare-earth phosphate monazite ceramic (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is designed and successfully synthesized. This new type of HE rare-earth phosphate monazite exhibits good chemical compatibility with Al2O3, without reaction with Al2O3 as high as 1600℃ in air. Moreover, the thermal expansion coefficient(TEC) of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4(8.9 × 10^-6/℃ at 300–1000℃) is close to that of Al2O3. The thermal conductivity of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 at room temperature is as low as 2.08 W·m^-1·K^-1, which is about 42% lower than that of La PO4. Good chemical compatibility, close TEC to that of Al2O3, and low thermal conductivity indicate that HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is suitable as a candidate EBC/TBC material and an interphase for Al2O3 f/Al2O3 composites.展开更多
Agglomeration-free nanosized ZrO2-HfO2-Y2O3-Sc2O3 composite powders were successfully synthesized by Sol-Gel technique in heated aqueous solution of alcohol, using analytically pure ZrOCl2 · 8H2O, HfOCl2·8H2...Agglomeration-free nanosized ZrO2-HfO2-Y2O3-Sc2O3 composite powders were successfully synthesized by Sol-Gel technique in heated aqueous solution of alcohol, using analytically pure ZrOCl2 · 8H2O, HfOCl2·8H2O, Y（NO3）3·6H2O, and Sc2O3 as raw materials. The effect of synthesis condition on the size and dispersity of the composite powders was investigated by means of XRD, TEM, and TG-DSC techniques. The results showed that well-dispersed predecessor of ZrO2-HfO2-Y2O3-Sc2O3 composite nanopowders could be obtained. The optional condition ： PEG6000 as dispersant was 1%, alcohol/H2O ratio was 5/1, metallic ion concentration in whole solution was 0.5 mol·L^-1 and the pH value of the solution was 12. After calcined at 620 ℃, the powder obtained was in uniform cubic structure, and its average particle size was about 13 nm, which was good for producing nanocrystalline solid electrolyte.展开更多
The composite coating was prepared by thermal spray welding after making composite powder,which is composed of Ni-based self-melted alloy and AlOceramic powder including nano,sub-micron and micron powders.The influenc...The composite coating was prepared by thermal spray welding after making composite powder,which is composed of Ni-based self-melted alloy and AlOceramic powder including nano,sub-micron and micron powders.The influences of contents and sizes of AlOon the structure and wearability were investigated.The results show that the wear resistance of the coating would be increased greatly by adding AlO,but the spray weldability decreases with increasing AlOcontent.So there is an optimal content of AlOpowder.The composite coating with AlOnano or sub-micron powder of 0.5% has the best abrasive resistance,while the optimal content of AlOmicron powder is 1 %.展开更多
以纳米ZrO 、微米Al O 为原料,采用无压烧结方式制备了ZTA 复相陶瓷。结果表明:nano-ZrO 的 2 2 3 2加入有利于制备细晶ZTA 复相陶瓷。此外,nano-ZrO 的加入对 Al O 陶瓷的显微结构也产生影响,ZrO ...以纳米ZrO 、微米Al O 为原料,采用无压烧结方式制备了ZTA 复相陶瓷。结果表明:nano-ZrO 的 2 2 3 2加入有利于制备细晶ZTA 复相陶瓷。此外,nano-ZrO 的加入对 Al O 陶瓷的显微结构也产生影响,ZrO 颗粒以 2 2 3 2“晶内型”和晶界型两种形式存在。合理的配方组成及制备工艺有利于 Z r O 以四方亚稳相存在。Z r O 含量为 2 23 0 w t % 时,其四方相含量可达 6 9 %,有利于应力诱导相变增韧,该 Z T A 复相陶瓷的抗弯强度、断裂韧性分别达到 604MPa、6.87MPa·m1/2。展开更多
基金Funded by the National Natural Science Foundation of China(No.51401155)the School Foundation(No.XAGDXJJ1012)The Open Fund of Shaanxi Key Laboratory of Photoelectric Functional Materials and Devices(No.ZSKJ201416)
文摘ZrO2-Y2O3 ceramic coating was produced by plasma electrolytic oxidation （PEO） on ZAlSil2Cu3Ni2 alloy. The microstructure and phase composition of the coating were investigated by SEM and XRD.： The results show that adding an appropriate amount of yttrium ion can improve the growing rate of ceramic coating at different oxidation stages and decrease arc voltage. The thickness of ZrO2-Y2O3 coating is 16 μn thicker than that of ZrO2 coating and the maximum oxidation rate improves by 0.6 μm/min. In addition, the arc voltage decreases from 227 to 172 V. It can be seen that the rate of oxidation firstly increases to some extent and then decreases with the content of yttrium ion increasing. The growth rate reaches the maximum while the content of yttrium ion is 0.05 g-L-1The maximum thickness is 90 μm.Compared to ZrO2 coating, the micropores of ZrO2-Y2O3 coating are less and the ceramic layer is repeatedly deposited by ZrO2 and Y2O3 ceramic particles. Meanwhile, the binding force between coating and substrate is better and the coating is uniform and compact. The ceramic layer is mainly composed of c-Y0.15Zr0.85O1.93□0.07, m-ZrO2, α-Al2O3, ,γ-Al2O3 and Y2O3. It is indicated that ZrO2 has beert fully stabilized by yttrium ion through the formation of solid solution.
基金Project (59975046) supported by the National Natural Science Foundation of China
文摘Al2O3-13%TiO2 （mass fraction） coatings, prepared by laser cladding on nickel-based alloy, were heated using high frequency induction sources. The coating microstructure and the interface between bond coating and ceramic coating were characterized by SEM, XRD and EDS. The results show that two-layer substructure exists in the ceramic coating： one layer evolving from fully melted region where the sintered grains grow fully; another layer resembling the liquid-phase-sintered structure consisting of three-dimensional net where the melted Al2O3 particles are embedded in the TiO2-rich matrix. The mechanism of the two-layer substructure formation is also explained in terms of the melting and flattening behavior of the powders during laser cladding processing. The spinel compounds NiAl2O4 and acicular compounds Cr2O3 are discovered in the interface between bond coating and ceramic coating. It proves that the chemical reactions in the laser cladding process will significantly enhance the coating adhesion.
文摘A newly developed method is introduced for producing Cr 2O 3 base ceramic coating on aluminum alloys. On the basis of properly selecting base reactions, slurry is prepared and then applied onto the substrate surface. By chemical reactions taken place in situ on the surface of aluminum alloy at relative low temperature, Cr 2O 3 base ceramic coating is formed. By means of scanning electron microscopy, the coating microstructure and the bonding mechanism are studied. X ray diffraction analysis is also used to investigate the chemical composition of the coating. The coating formation mechanism is further discussed. With a pin on disk tester, wear test is made to evaluate the wear performances of the coating. The results show that by applying the coating on aluminum alloy, the wear decreases 5 times in comparation to that without coating.
文摘ZrO2, Al2O3, ZrO2/Al2O3 and Al2O3/ZrO2 coatings were fabricated on low carbon steel using atmospheric plasma spraying technique. The microstructure and phase composition of the as-sprayed coatings were examined by scanning electron microscopy （SEM） and X-ray diffraction （XRD）, respectively. The polarization test, salt spray test and immersion test were used to investigate the corrosion behavior of the coatings in 3.5% NaCl solution. The results suggested that the bilayered Al2O3/ZrO2 coating exhibits superior corrosion resistance when compared with the other coatings. This is ascribed to the presence of very few interconnected pores and stable phases in the coating.
基金Projects supported by The 2nd Stage of Brain Korea and Korea Research Foundation
文摘The high-temperature oxidation resistance behavior of 7% （mass fraction） Y203-ZrO2 thermal barrier coatings （TBCs） irradiated by high-intensity pulsed ion beam （HIPIB） was investigated under the cyclic oxidation condition of 1 050 ℃ and 1 h. The columnar grains in the TBCs disappear after the HIPIB irradiation at ion current densities of 100-200 A/cm^2 and the irradiated surface becomes smooth and densified after remelting and ablation due to the HIPIB irradiation. The thermally grown oxide （TGO） layer thickness of the irradiated TBCs is smaller than that of the original TBCs. After 15 cycles, the mass gains of the original TBCs and those irradiated by ion current densities of 100 and 200 A/cm^2 due to the oxidation are found to be 0.8-0.9, 0.6-0.7, and 0.3-0.4 mg/cm^2, respectively. The inward diffusion of oxygen through the irradiated TBCs is significantly impeded by the densified top layer formed due to irradiation, which is the main reason for the improved overall oxidation resistance of the irradiated TBCs.
基金financially supported by the National Natural Science Foundation of China (Nos. 51672064 and U1435206)
文摘Low thermal conductivity, matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings(EBCs/TBCs) and interphases for Al2O3 f/Al2O3 composites. In this work, a novel high-entropy(HE) rare-earth phosphate monazite ceramic (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is designed and successfully synthesized. This new type of HE rare-earth phosphate monazite exhibits good chemical compatibility with Al2O3, without reaction with Al2O3 as high as 1600℃ in air. Moreover, the thermal expansion coefficient(TEC) of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4(8.9 × 10^-6/℃ at 300–1000℃) is close to that of Al2O3. The thermal conductivity of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 at room temperature is as low as 2.08 W·m^-1·K^-1, which is about 42% lower than that of La PO4. Good chemical compatibility, close TEC to that of Al2O3, and low thermal conductivity indicate that HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is suitable as a candidate EBC/TBC material and an interphase for Al2O3 f/Al2O3 composites.
基金Project supported by the National Natural Science Foundation of China (20101006)Nano Technology Special Foundationof Shanghai Science and Technology Committee (0452nm073) and Shanghai Education Committee
文摘Agglomeration-free nanosized ZrO2-HfO2-Y2O3-Sc2O3 composite powders were successfully synthesized by Sol-Gel technique in heated aqueous solution of alcohol, using analytically pure ZrOCl2 · 8H2O, HfOCl2·8H2O, Y（NO3）3·6H2O, and Sc2O3 as raw materials. The effect of synthesis condition on the size and dispersity of the composite powders was investigated by means of XRD, TEM, and TG-DSC techniques. The results showed that well-dispersed predecessor of ZrO2-HfO2-Y2O3-Sc2O3 composite nanopowders could be obtained. The optional condition ： PEG6000 as dispersant was 1%, alcohol/H2O ratio was 5/1, metallic ion concentration in whole solution was 0.5 mol·L^-1 and the pH value of the solution was 12. After calcined at 620 ℃, the powder obtained was in uniform cubic structure, and its average particle size was about 13 nm, which was good for producing nanocrystalline solid electrolyte.
基金Item Sponsored by Provincial Natural Science Foundation of Jiangsu of China(BK2000012)
文摘The composite coating was prepared by thermal spray welding after making composite powder,which is composed of Ni-based self-melted alloy and AlOceramic powder including nano,sub-micron and micron powders.The influences of contents and sizes of AlOon the structure and wearability were investigated.The results show that the wear resistance of the coating would be increased greatly by adding AlO,but the spray weldability decreases with increasing AlOcontent.So there is an optimal content of AlOpowder.The composite coating with AlOnano or sub-micron powder of 0.5% has the best abrasive resistance,while the optimal content of AlOmicron powder is 1 %.
文摘以纳米ZrO 、微米Al O 为原料,采用无压烧结方式制备了ZTA 复相陶瓷。结果表明:nano-ZrO 的 2 2 3 2加入有利于制备细晶ZTA 复相陶瓷。此外,nano-ZrO 的加入对 Al O 陶瓷的显微结构也产生影响,ZrO 颗粒以 2 2 3 2“晶内型”和晶界型两种形式存在。合理的配方组成及制备工艺有利于 Z r O 以四方亚稳相存在。Z r O 含量为 2 23 0 w t % 时,其四方相含量可达 6 9 %,有利于应力诱导相变增韧,该 Z T A 复相陶瓷的抗弯强度、断裂韧性分别达到 604MPa、6.87MPa·m1/2。
