The accurate evaluation of the elastic modulus of ceramic coatings at high temperature(HT)is of high significance for industrial application,yet it is not easy to get the practical modulus at HT due to the difficulty ...The accurate evaluation of the elastic modulus of ceramic coatings at high temperature(HT)is of high significance for industrial application,yet it is not easy to get the practical modulus at HT due to the difficulty of the deformation measurement and coating separation from the composite samples.This work presented a simple approach in which relative method was used twice to solve this problem indirectly.Given a single-face or double-face coated beam sample,the relative method was firstly used to determine the real mid-span deflection of the three-point bending piece at HT,and secondly to derive the analytical relation among the HT moduli of the coating,the coated and uncoated samples.Thus the HT modulus of the coatings on beam samples is determined uniquely via the measured HT moduli of the samples with and without coatings.For a ring sample(from tube with outer-side,inner-side,and double-side coating),the relative method was used firstly to determine the real compression deformation of a split ring sample at HT,secondly to derive the relationship among the slope of load-deformation curve of the coated ring,the HT modulus of the coating and substrate.Thus,the HT modulus of ceramic coatings can be evaluated by the substrate modulus and the load-deformation data of coated rings.Mathematic expressions of those calculations were derived for the beam and ring samples.CVD-SiC coatings on graphite substrate were selected as the testing samples,of which the measured modulus ranging from room temperature to 2100℃demonstrated the validity and convenience of the relative method.展开更多
ZrO_(2)ceramic coatings were directly prepared on the surface of ZrH_(1.8) in silicate and phosphate elec-trolytes by micro-arc oxidation(MAO)technique,respec-tively.The microstructure,chemical composition and phase c...ZrO_(2)ceramic coatings were directly prepared on the surface of ZrH_(1.8) in silicate and phosphate elec-trolytes by micro-arc oxidation(MAO)technique,respec-tively.The microstructure,chemical composition and phase composition of ZrO_(2)ceramic coatings were inves-tigated by X-ray diffraction(XRD),energy-dispersive spectrometry(EDS)and scanning electron microscopy(SEM).The anti-permeation effect was measured by means of vacuum dehydrogenation experiment.It is found that the coating fabricated in phosphate electrolyte is more compact than that in silicate electrolyte.The coatings fabricated on the surface of ZrH_(1.8) are composed of M-ZrO_(2),T-ZrO_(2) and C-ZrO_(2).EDS analysis indicates that the coatings are mainly composed of O and Zr.Vacuum dehydrogenation experiment shows that the permeation reduction factor(PRF)of coating prepared in phosphate electrolyte is su-perior to that in the silicate electrolyte,and the PRF value reaches up to 11.2,which can enhance the resistance effect of hydrogen significantly.展开更多
Micro-arc oxidation (MAO) method was used for the surface modification of an Mg-5wt.%Li alloy. Ceramic coatings were in-situ fabricated on the Mg-Li alloy. The morphology feature,phase composition,and corrosion-resist...Micro-arc oxidation (MAO) method was used for the surface modification of an Mg-5wt.%Li alloy. Ceramic coatings were in-situ fabricated on the Mg-Li alloy. The morphology feature,phase composition,and corrosion-resistance of the formed ceramic coatings were studied by SEM,XRD,and electrochemical methods,respectively. The results showed that the coatings produced in a sodium silicate solution system were composed of MgO and Mg2SiO4. The ceramic coating became thicker and the content of Mg2SiO4 phase increased as the concentration of Na2SiO3 increased in the solution. The coating was loose at the low concentration of Na2SiO3 and was compact at the high concentration of Na2SiO3. The coated samples had a better corrosion resistance than the Mg-Li substrate in terms of the Tafel polarization curves and the cyclic voltammetry curves (CV).展开更多
In this study,a Cr_(2)O_(3) nanosheet(Cr_(2)O_(3) NS)inserted Cr-Zr-O coating was developed as a hydrogen isotope permeation barrier.The Cr_(2)O_(3) NSs,fabricated by rapid heat treatment,were amorphous with a thickne...In this study,a Cr_(2)O_(3) nanosheet(Cr_(2)O_(3) NS)inserted Cr-Zr-O coating was developed as a hydrogen isotope permeation barrier.The Cr_(2)O_(3) NSs,fabricated by rapid heat treatment,were amorphous with a thickness of only several nanometers.These Cr_(2)O_(3) NSs were then incorporated into a Cr-Zr-O multi-metal oxide composite coating via a dip-coating method to form a coating.The effect of the Cr_(2)O_(3) NS concentration on the morphology,microstructure and deuterium permeation resistance of the coating was studied.With the addition of 1.0 g 1^(-1)Cr_(2)O_(3) NSs,compared with the Cr-Zr-O coating without NSs,the permeation reduction factor of the resultant coating was enhanced from 249℃to 575℃ at 500℃.The coating,with a thickness of nearly 193 nm,achieved a comparable deuterium resistance that was above two orders of magnitude higher than the steel substrate.The results show that ceramic NSs can serve as effective fillers for enhancing the coating performance when functioning as a hydrogen isotope barrier.展开更多
The self-lubricating ceramic coatings that can control friction and wear have attracted researchers’widespread attention.However,the poor interfacial bonding between lubricants and ceramics and the deterioration of m...The self-lubricating ceramic coatings that can control friction and wear have attracted researchers’widespread attention.However,the poor interfacial bonding between lubricants and ceramics and the deterioration of mechanical properties due to a tribological design limit their practical applications.Here,a robust self-lubricating coating was fabricated by an in-situ synthesis of MoS_(2)/C within inherent defects of thermally sprayed yttria-stabilized zirconia(YSZ)coatings.The edge-pinning by noncoherent endows hybrid coatings with excellent interfacial strength,increasing their hardness(HV)and cohesive strength.Furthermore,owing to the formation of a well-covered robust lubricating film at a frictional interface,a coefficient of friction(COF)can be reduced by 79.6%to 0.15,and a specific wear rate(W)drops from 1.36×10^(−3) to 6.27×10^(−7) mm^(3)·N^(−1)·m^(−1).Combining outstanding mechanical properties and tribological performance,the hybrid coating exhibits great application potential in controlling friction and wear.Importantly,this strategy of introducing the target materials into the inherent defects of the raw materials to improve the relevant properties opens new avenues for the design and preparation of composite materials.展开更多
To construct world-class iron and steel enterprises,Baosteel has adopted a strategy of environmental management that emphasizes environmental protection in the low-carbon and ecological manufacturing of steel products...To construct world-class iron and steel enterprises,Baosteel has adopted a strategy of environmental management that emphasizes environmental protection in the low-carbon and ecological manufacturing of steel products.In recent years,Baosteel has developed a series of advanced green refractory technologies(including composite refractory precast blocks with a unique ceramic glaze,and high-thermal-conductivity / high-density silica brick) for use in Baosteel coke ovens.The results of these applications not only reduce production costs and increase production efficiency,but also facilitate clean production by coke ovens.Baosteel's coke oven has become China's leading example of the application of green refractories.展开更多
Ablation resistance of monolithic LaB_6-doped ZrC coating for SiC-coated carbon/carbon composites by supersonic atmospheric plasma spray was investigated under an oxyacetylene torch with a heat flux of 4.18 MW/m^2. Re...Ablation resistance of monolithic LaB_6-doped ZrC coating for SiC-coated carbon/carbon composites by supersonic atmospheric plasma spray was investigated under an oxyacetylene torch with a heat flux of 4.18 MW/m^2. Result shows that ZrC coating with 10 vol.% LaB_6 has a good ablation resistance compared with pure ZrC, ZrC with 20 vol.% LaB_6 and SiC-doped ZrC coating. After ablation for 15 s, the weight is increased by 1.12 mg/s. The good ablation resistance is ascribed to the formation of a stabilized scale which consists of protective La_2Zr_2O_7-containing molten phase and ZrO_2 particles keeping the integrity of the coating.展开更多
As a solution for solar heating, the low-cost and long-life vanadium-titanium black ceramic solar absorbers have been used in rural construction. However, in contrast to its high absorptance(0.93-0.97), ceramic also h...As a solution for solar heating, the low-cost and long-life vanadium-titanium black ceramic solar absorbers have been used in rural construction. However, in contrast to its high absorptance(0.93-0.97), ceramic also has high emissivity(approximately 90%) and low thermal conductivity(1.3 W/(m·K)). Without a glaze covering, ceramic absorbers cannot meet the industrial standard. This paper assumes that glaze covering can be substituted by insulation film in a solar greenhouse. To verify this assumption, field experiments were conducted. First, a traditional greenhouse in the Tacheng Basin, a severely cold area in China, was renovated to improve its passive thermal performance. Then, 90 m^(2) of ceramic absorbers and floor coils as well as a water tank were installed inside the greenhouse, which made the entire construction act as an integrated solar collector. This heat collection and release system moderately increased the indoor air temperature(0.9℃-22.4℃) and substantially increased the soil temperature(15.5℃-31.2℃). The average daily useful heat gain under a daily solar insolation value of 17 MJ/m^(2) was 13.8 MJ, and the mean value of the collection efficiency was 0.81. Furthermore, the payback time of the project(7 years) is short, which is principally due to the low cost of ceramic materials and the financial savings of the shared construction components(e.g., transparent cover, metal frame and extra insulation). In conclusion, the main contribution of this study is the verification that it is feasible to replace glaze covering with insulation film in a novel greenhouse-integrated vanadium-titanium black ceramic solar system.展开更多
Laser-assisted gas nitriding of selective Ti-6Al-4V surfaces has been achieved during laser powder bed fusion fabrication by exchanging the argon build gas environment with nitrogen.Systematic variation of processing ...Laser-assisted gas nitriding of selective Ti-6Al-4V surfaces has been achieved during laser powder bed fusion fabrication by exchanging the argon build gas environment with nitrogen.Systematic variation of processing parameters allowed microdendritic Ti N surface coatings to be formed having thicknesses ranging from a few tens of microns to several hundred microns,with TiN dendrite microstructure volume fractions ranging from 0.6 to 0.75;and corresponding Vickers microindentation hardness values ranging from^7.5 GPa–9.5 GPa.Embedded TiN hard layers ranging from 50μm to 150μm thick were also fabricated in the laser-beam additively manufactured Ti-6Al-4V alloy producing prototype,hybrid,planar composites having alternating,ductile Ti-6Al-4V layers with a hardness of^4.5 GPa and a stiff,TiN layer with a hardness of^8.5 GPa.The results demonstrate prospects for fabricating novel,additively manufactured components having selective,hard,wear and corrosion resistant coatings along with periodic,planar or complex metal matrix composite regimes exhibiting superior toughness and related mechanical properties.展开更多
基金supported by the National Natural Science Foundation of China(No.51472227)National High-tech R&D Program of China(863 Program,No.2015AA034204).
文摘The accurate evaluation of the elastic modulus of ceramic coatings at high temperature(HT)is of high significance for industrial application,yet it is not easy to get the practical modulus at HT due to the difficulty of the deformation measurement and coating separation from the composite samples.This work presented a simple approach in which relative method was used twice to solve this problem indirectly.Given a single-face or double-face coated beam sample,the relative method was firstly used to determine the real mid-span deflection of the three-point bending piece at HT,and secondly to derive the analytical relation among the HT moduli of the coating,the coated and uncoated samples.Thus the HT modulus of the coatings on beam samples is determined uniquely via the measured HT moduli of the samples with and without coatings.For a ring sample(from tube with outer-side,inner-side,and double-side coating),the relative method was used firstly to determine the real compression deformation of a split ring sample at HT,secondly to derive the relationship among the slope of load-deformation curve of the coated ring,the HT modulus of the coating and substrate.Thus,the HT modulus of ceramic coatings can be evaluated by the substrate modulus and the load-deformation data of coated rings.Mathematic expressions of those calculations were derived for the beam and ring samples.CVD-SiC coatings on graphite substrate were selected as the testing samples,of which the measured modulus ranging from room temperature to 2100℃demonstrated the validity and convenience of the relative method.
基金financially supported by the National Natural Science Foundation (Nos. 51164023 and 513640236)the Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region (No. NJYT-13B10)the Program for New Century Excellent Talents in University (No. NCET-13-0847)。
文摘ZrO_(2)ceramic coatings were directly prepared on the surface of ZrH_(1.8) in silicate and phosphate elec-trolytes by micro-arc oxidation(MAO)technique,respec-tively.The microstructure,chemical composition and phase composition of ZrO_(2)ceramic coatings were inves-tigated by X-ray diffraction(XRD),energy-dispersive spectrometry(EDS)and scanning electron microscopy(SEM).The anti-permeation effect was measured by means of vacuum dehydrogenation experiment.It is found that the coating fabricated in phosphate electrolyte is more compact than that in silicate electrolyte.The coatings fabricated on the surface of ZrH_(1.8) are composed of M-ZrO_(2),T-ZrO_(2) and C-ZrO_(2).EDS analysis indicates that the coatings are mainly composed of O and Zr.Vacuum dehydrogenation experiment shows that the permeation reduction factor(PRF)of coating prepared in phosphate electrolyte is su-perior to that in the silicate electrolyte,and the PRF value reaches up to 11.2,which can enhance the resistance effect of hydrogen significantly.
文摘Micro-arc oxidation (MAO) method was used for the surface modification of an Mg-5wt.%Li alloy. Ceramic coatings were in-situ fabricated on the Mg-Li alloy. The morphology feature,phase composition,and corrosion-resistance of the formed ceramic coatings were studied by SEM,XRD,and electrochemical methods,respectively. The results showed that the coatings produced in a sodium silicate solution system were composed of MgO and Mg2SiO4. The ceramic coating became thicker and the content of Mg2SiO4 phase increased as the concentration of Na2SiO3 increased in the solution. The coating was loose at the low concentration of Na2SiO3 and was compact at the high concentration of Na2SiO3. The coated samples had a better corrosion resistance than the Mg-Li substrate in terms of the Tafel polarization curves and the cyclic voltammetry curves (CV).
基金supported by the National MCF Energy R&D Program of China(No.2018YFE0313300)National Natural Science Foundation of China(Nos.52273224,51402116)the Fundamental Research Funds for the Central Universities(Nos.2018KFYYXJJ028,2019KFYXMBZ045)
文摘In this study,a Cr_(2)O_(3) nanosheet(Cr_(2)O_(3) NS)inserted Cr-Zr-O coating was developed as a hydrogen isotope permeation barrier.The Cr_(2)O_(3) NSs,fabricated by rapid heat treatment,were amorphous with a thickness of only several nanometers.These Cr_(2)O_(3) NSs were then incorporated into a Cr-Zr-O multi-metal oxide composite coating via a dip-coating method to form a coating.The effect of the Cr_(2)O_(3) NS concentration on the morphology,microstructure and deuterium permeation resistance of the coating was studied.With the addition of 1.0 g 1^(-1)Cr_(2)O_(3) NSs,compared with the Cr-Zr-O coating without NSs,the permeation reduction factor of the resultant coating was enhanced from 249℃to 575℃ at 500℃.The coating,with a thickness of nearly 193 nm,achieved a comparable deuterium resistance that was above two orders of magnitude higher than the steel substrate.The results show that ceramic NSs can serve as effective fillers for enhancing the coating performance when functioning as a hydrogen isotope barrier.
基金support from the National Natural Science Foundation of China (51905212)Guangdong Key Laboratory of Modern Surface Engineering Technology (2020B1212060049)+2 种基金Science and Technology Project of Guangdong Academy (2021GDASYL-20210103062)Young Scientific and Technological Talents Promotion Project of Guangzhou Science and Technology Association (X20210201061)Foshan Taoyuan Institute of Advanced Manufacturing (TYKF202203003).
文摘The self-lubricating ceramic coatings that can control friction and wear have attracted researchers’widespread attention.However,the poor interfacial bonding between lubricants and ceramics and the deterioration of mechanical properties due to a tribological design limit their practical applications.Here,a robust self-lubricating coating was fabricated by an in-situ synthesis of MoS_(2)/C within inherent defects of thermally sprayed yttria-stabilized zirconia(YSZ)coatings.The edge-pinning by noncoherent endows hybrid coatings with excellent interfacial strength,increasing their hardness(HV)and cohesive strength.Furthermore,owing to the formation of a well-covered robust lubricating film at a frictional interface,a coefficient of friction(COF)can be reduced by 79.6%to 0.15,and a specific wear rate(W)drops from 1.36×10^(−3) to 6.27×10^(−7) mm^(3)·N^(−1)·m^(−1).Combining outstanding mechanical properties and tribological performance,the hybrid coating exhibits great application potential in controlling friction and wear.Importantly,this strategy of introducing the target materials into the inherent defects of the raw materials to improve the relevant properties opens new avenues for the design and preparation of composite materials.
文摘To construct world-class iron and steel enterprises,Baosteel has adopted a strategy of environmental management that emphasizes environmental protection in the low-carbon and ecological manufacturing of steel products.In recent years,Baosteel has developed a series of advanced green refractory technologies(including composite refractory precast blocks with a unique ceramic glaze,and high-thermal-conductivity / high-density silica brick) for use in Baosteel coke ovens.The results of these applications not only reduce production costs and increase production efficiency,but also facilitate clean production by coke ovens.Baosteel's coke oven has become China's leading example of the application of green refractories.
基金supported by the National Natural Science Foundation of China (Nos. 51521061,51502245,51472203)the "111" Project (Grant no. B08040)the Research Fund of State Key Laboratory of Solidification Processing (NWPU),China (Grant No.142-TZ-2016)
文摘Ablation resistance of monolithic LaB_6-doped ZrC coating for SiC-coated carbon/carbon composites by supersonic atmospheric plasma spray was investigated under an oxyacetylene torch with a heat flux of 4.18 MW/m^2. Result shows that ZrC coating with 10 vol.% LaB_6 has a good ablation resistance compared with pure ZrC, ZrC with 20 vol.% LaB_6 and SiC-doped ZrC coating. After ablation for 15 s, the weight is increased by 1.12 mg/s. The good ablation resistance is ascribed to the formation of a stabilized scale which consists of protective La_2Zr_2O_7-containing molten phase and ZrO_2 particles keeping the integrity of the coating.
基金supported by the National Natural Science Foundation of China(Grant No.51778350)The Research Center for Australia,Sichuan Province(Grant No.ADLY2021-006)the Chengdu Key Research Base of Philosophy and Social Science(CCRC2020-4)。
文摘As a solution for solar heating, the low-cost and long-life vanadium-titanium black ceramic solar absorbers have been used in rural construction. However, in contrast to its high absorptance(0.93-0.97), ceramic also has high emissivity(approximately 90%) and low thermal conductivity(1.3 W/(m·K)). Without a glaze covering, ceramic absorbers cannot meet the industrial standard. This paper assumes that glaze covering can be substituted by insulation film in a solar greenhouse. To verify this assumption, field experiments were conducted. First, a traditional greenhouse in the Tacheng Basin, a severely cold area in China, was renovated to improve its passive thermal performance. Then, 90 m^(2) of ceramic absorbers and floor coils as well as a water tank were installed inside the greenhouse, which made the entire construction act as an integrated solar collector. This heat collection and release system moderately increased the indoor air temperature(0.9℃-22.4℃) and substantially increased the soil temperature(15.5℃-31.2℃). The average daily useful heat gain under a daily solar insolation value of 17 MJ/m^(2) was 13.8 MJ, and the mean value of the collection efficiency was 0.81. Furthermore, the payback time of the project(7 years) is short, which is principally due to the low cost of ceramic materials and the financial savings of the shared construction components(e.g., transparent cover, metal frame and extra insulation). In conclusion, the main contribution of this study is the verification that it is feasible to replace glaze covering with insulation film in a novel greenhouse-integrated vanadium-titanium black ceramic solar system.
基金provided through the MSI STEM Research&Development Consortium sponsored by the U.S.Army via cooperative agreement#W911SR-14-2-0001 project number 0025。
文摘Laser-assisted gas nitriding of selective Ti-6Al-4V surfaces has been achieved during laser powder bed fusion fabrication by exchanging the argon build gas environment with nitrogen.Systematic variation of processing parameters allowed microdendritic Ti N surface coatings to be formed having thicknesses ranging from a few tens of microns to several hundred microns,with TiN dendrite microstructure volume fractions ranging from 0.6 to 0.75;and corresponding Vickers microindentation hardness values ranging from^7.5 GPa–9.5 GPa.Embedded TiN hard layers ranging from 50μm to 150μm thick were also fabricated in the laser-beam additively manufactured Ti-6Al-4V alloy producing prototype,hybrid,planar composites having alternating,ductile Ti-6Al-4V layers with a hardness of^4.5 GPa and a stiff,TiN layer with a hardness of^8.5 GPa.The results demonstrate prospects for fabricating novel,additively manufactured components having selective,hard,wear and corrosion resistant coatings along with periodic,planar or complex metal matrix composite regimes exhibiting superior toughness and related mechanical properties.
