Four kinds of ceramics (silicon carbide, boron carbide, aluminum oxide and tungsten carbide) were added into Ni base self-fluxing alloy as reinforcing materials in order to obtain metalceramic composite coating by mea...Four kinds of ceramics (silicon carbide, boron carbide, aluminum oxide and tungsten carbide) were added into Ni base self-fluxing alloy as reinforcing materials in order to obtain metalceramic composite coating by means of laser cladding. A lot of experiments have been carried out to test the processability of the four kinds of ceramics with different sizes and contents. The microstructures of sintered tungsten carbide (S-WC) and cast tungsten carbide (C-WC) reinforced Ni base alloy coatings were analysed, the distortion regulation of laser clad specimens was revealed. The wear resistance of the composite coating has been tested.展开更多
The fracture toughness (KIC) values determined by indentation microfracture method (IM ) for SiC whisker reinforced Al2O3 and ZrO2 based composites were calculated with different IM equations and compared with those o...The fracture toughness (KIC) values determined by indentation microfracture method (IM ) for SiC whisker reinforced Al2O3 and ZrO2 based composites were calculated with different IM equations and compared with those obtained by singte edge notched beam (SENB) technique. Experimental results show that the KIC (IM) values calculated with different equations are quite different one from another. For composites without phase transformable components the KIC (IM) and KIC (SENB) values are practically on the same level, but for composites with phase transformable components (partially stabilized zirconia) the KIC (SENB) values are always higher than KIC (IM). This is because that the IM method can not reveal sensitively the toughening effect due to dynamic t-m transformation of ZrO2 as the SENB method does. The accuracy of the IM method depends on the Suitability of the IM equations and was evaluated for the materials used in this investigation. Two new IM equations are suggested with which the KIC (IM ) values can be obtained very close to KIC (SENB) values for composites having phase transformable components.展开更多
In this study,C_(f)/SiC composites with excellent mechanical and thermal properties were prepared by combining binder jetting(BJ)additive manufacturing with liquid silicon infiltration(LSI)process.The introduction of ...In this study,C_(f)/SiC composites with excellent mechanical and thermal properties were prepared by combining binder jetting(BJ)additive manufacturing with liquid silicon infiltration(LSI)process.The introduction of C_(f)into the C_(f)/SiC mixed powder reduced its spreading ability,which reduced the density,strength,and precision of the C_(f)/SiC green parts.However,phenolic resin infiltration and pyrolysis(PRIP)treatment compensated for the decrease in the density of the green parts resulting from the introduction of C_(f).By optimizing the number of PRIP cycles to increase the pyrolytic carbon(PyC)content in the carbonized parts,the C_(f)in the green parts successfully prevented the reaction with molten Si in the LSI and played an important role in strengthening and toughening the composites.The flexural strength,fracture toughness,and thermal conductivity of the C_(f)/SiC composites reached the maximum values of 316±16 MPa,4.81±0.12 MPa·m^(1/2),and 140 W/m·K,respectively.This study presents future opportunities for the cost-effective and efficient industrial manufacturing of C_(f)/SiC complex structures.展开更多
Graphene-incorporated ceramics are recognized as promising candidates for various tribological applications,including machining tools,nozzles,mechanical seals,bearings,and gears.Generally,graphene-incorporated ceramic...Graphene-incorporated ceramics are recognized as promising candidates for various tribological applications,including machining tools,nozzles,mechanical seals,bearings,and gears.Generally,graphene-incorporated ceramics exhibit lower friction coefficients and wear rates compared to ceramic composites reinforced by other lubricants,including CaF5,MoS2,h-BN,carbon fiber,and CNTs.This review comprehensively summarizes the current knowledge of the tribological performance of graphene-reinforced ceramics,highlighting the effects of in situ grown graphene,core-shell structured graphene,three-dimensional assembled graphene,and functionally graded graphene on the friction and wear properties of ceramics.In situ graphene forms stable lubrication films,effectively reducing the friction coefficient of the ceramic matrix.Core-shell structured graphene ceramics achieve outstanding wear resistance through rolling friction mechanisms and crack inhibition.Three-dimensional assembled graphene enhances the stability of lubrication films and contributes to superior friction reduction.Functionally graded graphene ceramics optimize internal structures,improving impact resistance and tribological stability.Furthermore,the challenges and future development directions of graphene-incorporated ceramics are discussed,highlighting their promising applications in high-temperature,extreme environments,and precision mechanical systems.展开更多
Fiber reinforced ceramic matrix composites(FRCMCs)are the preferred materials for safety critical components in the fields of aerospace,nuclear engineering,and transportation,with broad market and application prospect...Fiber reinforced ceramic matrix composites(FRCMCs)are the preferred materials for safety critical components in the fields of aerospace,nuclear engineering,and transportation,with broad market and application prospects.However,due to the characteristics of multiphase,heterogeneity,and anisotropy,key issues such as poor adhesion,high porosity,and crack propagation urgently need to be addressed in the fabrication and machining of FRCMCs.With the increasing demand for FRCMCs parts,high-quality and reliable design and fabrication,performance evaluation,and precision manufacturing have become a series of hot issues.There is a lack of systematic review in capturing the current research status and development direction of FRCMCs fabrication and machining.This research aims to comprehensively review and critically evaluate the existing understanding of the fabrication and machining of FRCMCs.This study can provide scientists with a deeper understanding of the shape control mechanism of FRCMCs fabrication and machining,the theoretical basis of material synchronous removal,machining performance,and development direction.Firstly,the basic characteristics and application background of FRCMCs are introduced.Secondly,by comparing and analyzing the typical fabrication process of FRCMCs,the advantages,disadvantages,and performance evaluation of different processes are comprehensively evaluated.Thirdly,the material removal mechanisms and machining performance evaluation standards of traditional mechanical machining technologies(drilling,milling,grinding)and non-traditional mechanical machining technologies(ultrasonic,laser,water jet,discharge,wire saw,and multi-field hybrid machining)are discussed and analyzed.Finally,the challenges,development trends,and prospects faced by FRCMCs in the fields of fabrication,machining,and application are analyzed.This study not only elucidates the basic processes and key difficulties in the fabrication of FRCMCs,but also provides valuable insights for low-damage machining.展开更多
Alumina whisker reinforced zirconia ceramic composite was prepared by both hot oscillatory pressing(HOP)and conventional hot pressing(HP).The results show that compared with HP,HOP can significantly increase the final...Alumina whisker reinforced zirconia ceramic composite was prepared by both hot oscillatory pressing(HOP)and conventional hot pressing(HP).The results show that compared with HP,HOP can significantly increase the final density and densification rate of the material.Analysis of densification kinetics reveals that the predominant densification mechanism transits from grain boundary sliding in the beginning to the diffusion in the later stage.The main effect of the oscillating pressure is to increase the densification rate in the process of grain boundary sliding.The current study suggests that HOP is a promising technique for densifying whisker reinforced ceramics.展开更多
Model composites consisting of SiC fiber and Yb_(2)SiO_(5)were processed by the spark plasma sintering(SPS)method.The mechanical compatibility and chemical stability between Yb_(2)SiO_(5)and SiC fiber were studied to ...Model composites consisting of SiC fiber and Yb_(2)SiO_(5)were processed by the spark plasma sintering(SPS)method.The mechanical compatibility and chemical stability between Yb_(2)SiO_(5)and SiC fiber were studied to evaluate the potential application of Yb monosilicate as the interphase of silicon carbide fiber reinforced silicon carbide ceramic matrix composite(SiC_(f)/SiC CMC).Two kinds of interfaces,namely mechanical and chemical bonding interfaces,were achieved by adjusting sintering temperature.SiC_(f)/Yb_(2)SiO_(5)interfaces prepared at 1450 and 1500℃exhibit high interface strength and debond energy,which do not satisfy the crack deflection criteria based on He-Hutchison diagram.Raman spectrum analyzation indicates that the thermal expansion mismatch between Yb_(2)SiO_(5)and SiC contributes to high compressive thermal stress at interface,and leads to high interfacial parameters.Amorphous layer at interface in model composite sintered at 1550℃is related to the diffusion promoted by high temperature and DC electric filed during SPS.It is inspired that the interfacial parameters could be adjusted by introducing Yb_(2)Si_(2)O_(7)-Yb_(2)SiO_(5)interphase with controlled composition to optimize the mechanical fuse mechanism in SiC_(f)/SiC CMC.展开更多
文摘Four kinds of ceramics (silicon carbide, boron carbide, aluminum oxide and tungsten carbide) were added into Ni base self-fluxing alloy as reinforcing materials in order to obtain metalceramic composite coating by means of laser cladding. A lot of experiments have been carried out to test the processability of the four kinds of ceramics with different sizes and contents. The microstructures of sintered tungsten carbide (S-WC) and cast tungsten carbide (C-WC) reinforced Ni base alloy coatings were analysed, the distortion regulation of laser clad specimens was revealed. The wear resistance of the composite coating has been tested.
文摘The fracture toughness (KIC) values determined by indentation microfracture method (IM ) for SiC whisker reinforced Al2O3 and ZrO2 based composites were calculated with different IM equations and compared with those obtained by singte edge notched beam (SENB) technique. Experimental results show that the KIC (IM) values calculated with different equations are quite different one from another. For composites without phase transformable components the KIC (IM) and KIC (SENB) values are practically on the same level, but for composites with phase transformable components (partially stabilized zirconia) the KIC (SENB) values are always higher than KIC (IM). This is because that the IM method can not reveal sensitively the toughening effect due to dynamic t-m transformation of ZrO2 as the SENB method does. The accuracy of the IM method depends on the Suitability of the IM equations and was evaluated for the materials used in this investigation. Two new IM equations are suggested with which the KIC (IM ) values can be obtained very close to KIC (SENB) values for composites having phase transformable components.
基金supported by National Defense Basic Scientific Research Program of China(Grant No.JCKY2022213C008)Fundamental Research Funds for the Central Universities of China(Grant No.YCJJ20230353)。
文摘In this study,C_(f)/SiC composites with excellent mechanical and thermal properties were prepared by combining binder jetting(BJ)additive manufacturing with liquid silicon infiltration(LSI)process.The introduction of C_(f)into the C_(f)/SiC mixed powder reduced its spreading ability,which reduced the density,strength,and precision of the C_(f)/SiC green parts.However,phenolic resin infiltration and pyrolysis(PRIP)treatment compensated for the decrease in the density of the green parts resulting from the introduction of C_(f).By optimizing the number of PRIP cycles to increase the pyrolytic carbon(PyC)content in the carbonized parts,the C_(f)in the green parts successfully prevented the reaction with molten Si in the LSI and played an important role in strengthening and toughening the composites.The flexural strength,fracture toughness,and thermal conductivity of the C_(f)/SiC composites reached the maximum values of 316±16 MPa,4.81±0.12 MPa·m^(1/2),and 140 W/m·K,respectively.This study presents future opportunities for the cost-effective and efficient industrial manufacturing of C_(f)/SiC complex structures.
基金the National Natural Science Foundation of China(52375451,52005396)Shandong Provincial Natural Science Foundation(ZR2023YQ052)+6 种基金Young Taishan Scholars Program of Shandong Province(tsqn202306041)Guandong Basic and Applied Basic Research Foundation(2023A1515010044)Shandong Provincial Youth Innovation Team(2022KJ038)Open Project of State Key Laboratory of Solid Lubrication(LSL-22-11)Shandong Provincial Technological SME Innovation Capability Promotion Project(2023TSGC0848)Instrument Improvement Funds of Shandong University Public Technology Platform(20230113)Qilu Youth Scholar Project Funding of Shandong University。
文摘Graphene-incorporated ceramics are recognized as promising candidates for various tribological applications,including machining tools,nozzles,mechanical seals,bearings,and gears.Generally,graphene-incorporated ceramics exhibit lower friction coefficients and wear rates compared to ceramic composites reinforced by other lubricants,including CaF5,MoS2,h-BN,carbon fiber,and CNTs.This review comprehensively summarizes the current knowledge of the tribological performance of graphene-reinforced ceramics,highlighting the effects of in situ grown graphene,core-shell structured graphene,three-dimensional assembled graphene,and functionally graded graphene on the friction and wear properties of ceramics.In situ graphene forms stable lubrication films,effectively reducing the friction coefficient of the ceramic matrix.Core-shell structured graphene ceramics achieve outstanding wear resistance through rolling friction mechanisms and crack inhibition.Three-dimensional assembled graphene enhances the stability of lubrication films and contributes to superior friction reduction.Functionally graded graphene ceramics optimize internal structures,improving impact resistance and tribological stability.Furthermore,the challenges and future development directions of graphene-incorporated ceramics are discussed,highlighting their promising applications in high-temperature,extreme environments,and precision mechanical systems.
基金supported by Key Laboratory of Higheffciency and Clean Mechanical Manufacture at Shandong University,Ministry of Education,the National Natural Science Foundation of China(Nos.52305484,52305475,and U23A20632)the China Postdoctoral Science Foundation(No.2024M761876)+7 种基金the Youth Innovation Team Program of Universities in Shandong Province(No.2024KJH166)the National Key Research and Development Program of China(No.2023YFC2413301)the Taishan Scholars Program(No.tsqn202408242)the Shandong Provincial Natural Science Foundation(Nos.ZR2022QE053 and ZR2022QE159)the Guangdong Basic and Applied Basic Research Foundation(No.2022A1515111124)the Major Scientific and Technological Innovation Project of Shandong Province(No.2023CXGC010207)the Major Basic Research of Shandong Provincial Natural Science Foundation(No.ZR2023ZD34)the talent research project for the pilot project of integrating science,education,and industries of Qilu University of Technology(Shandong Academy of Sciences)(No.2024RCKY009)。
文摘Fiber reinforced ceramic matrix composites(FRCMCs)are the preferred materials for safety critical components in the fields of aerospace,nuclear engineering,and transportation,with broad market and application prospects.However,due to the characteristics of multiphase,heterogeneity,and anisotropy,key issues such as poor adhesion,high porosity,and crack propagation urgently need to be addressed in the fabrication and machining of FRCMCs.With the increasing demand for FRCMCs parts,high-quality and reliable design and fabrication,performance evaluation,and precision manufacturing have become a series of hot issues.There is a lack of systematic review in capturing the current research status and development direction of FRCMCs fabrication and machining.This research aims to comprehensively review and critically evaluate the existing understanding of the fabrication and machining of FRCMCs.This study can provide scientists with a deeper understanding of the shape control mechanism of FRCMCs fabrication and machining,the theoretical basis of material synchronous removal,machining performance,and development direction.Firstly,the basic characteristics and application background of FRCMCs are introduced.Secondly,by comparing and analyzing the typical fabrication process of FRCMCs,the advantages,disadvantages,and performance evaluation of different processes are comprehensively evaluated.Thirdly,the material removal mechanisms and machining performance evaluation standards of traditional mechanical machining technologies(drilling,milling,grinding)and non-traditional mechanical machining technologies(ultrasonic,laser,water jet,discharge,wire saw,and multi-field hybrid machining)are discussed and analyzed.Finally,the challenges,development trends,and prospects faced by FRCMCs in the fields of fabrication,machining,and application are analyzed.This study not only elucidates the basic processes and key difficulties in the fabrication of FRCMCs,but also provides valuable insights for low-damage machining.
基金We thank the financial support from the National Natural Science Foundation of China(Grant Nos.52072344 and U1904180)Excellent Young Scientists Fund of Henan Province(Grant No.202300410369)Henan Province University Innovation Talents Support Program(Grant No.21HASTIT001).
文摘Alumina whisker reinforced zirconia ceramic composite was prepared by both hot oscillatory pressing(HOP)and conventional hot pressing(HP).The results show that compared with HP,HOP can significantly increase the final density and densification rate of the material.Analysis of densification kinetics reveals that the predominant densification mechanism transits from grain boundary sliding in the beginning to the diffusion in the later stage.The main effect of the oscillating pressure is to increase the densification rate in the process of grain boundary sliding.The current study suggests that HOP is a promising technique for densifying whisker reinforced ceramics.
基金supported by the National Key R&D Program of China(No.2017YFB0703201)the National Natural Science Foundation of China(No.51772302)CAS International Cooperation Key Program(No.174321KYSB20180008)。
文摘Model composites consisting of SiC fiber and Yb_(2)SiO_(5)were processed by the spark plasma sintering(SPS)method.The mechanical compatibility and chemical stability between Yb_(2)SiO_(5)and SiC fiber were studied to evaluate the potential application of Yb monosilicate as the interphase of silicon carbide fiber reinforced silicon carbide ceramic matrix composite(SiC_(f)/SiC CMC).Two kinds of interfaces,namely mechanical and chemical bonding interfaces,were achieved by adjusting sintering temperature.SiC_(f)/Yb_(2)SiO_(5)interfaces prepared at 1450 and 1500℃exhibit high interface strength and debond energy,which do not satisfy the crack deflection criteria based on He-Hutchison diagram.Raman spectrum analyzation indicates that the thermal expansion mismatch between Yb_(2)SiO_(5)and SiC contributes to high compressive thermal stress at interface,and leads to high interfacial parameters.Amorphous layer at interface in model composite sintered at 1550℃is related to the diffusion promoted by high temperature and DC electric filed during SPS.It is inspired that the interfacial parameters could be adjusted by introducing Yb_(2)Si_(2)O_(7)-Yb_(2)SiO_(5)interphase with controlled composition to optimize the mechanical fuse mechanism in SiC_(f)/SiC CMC.
