Porous ceramics are lightweight materials with diverse pore structures and are widely applied in areas such as thermal insulation, sound absorption, filtration, catalysis, and energy storage. However, excessive shrink...Porous ceramics are lightweight materials with diverse pore structures and are widely applied in areas such as thermal insulation, sound absorption, filtration, catalysis, and energy storage. However, excessive shrinkage during the sintering process of porous ceramics leads to cracking and deterioration, posing significant challenges for achieving complex shapes. Despite its importance, the field of low sintering shrinkage porous ceramics has not received sufficient attention. This review systematically discusses the principles and progress in the development of low sintering shrinkage porous ceramics. First, we introduce the characteristics of various preparation methods, including partial sintering, particle-stabilized foaming, gel-casting, foam-gelcasting, and additive manufacturing (AM). We then explain three primary principles of low sintering shrinkage from the perspectives of the volume effect and mass transfer processes. This review focuses on the properties and applications of typical low sintering shrinkage ceramics such as mullite and alumina, particularly their mechanical properties and thermal conductivity as thermal insulation and ceramic cores. Finally, we summarize the current state and present future perspectives on low sintering shrinkage porous ceramics.展开更多
ZrO2 was added into CaO-Al2O3-SiO2 glass-ceramics and the effect of ZrO2 on sintering and crystallization of CaO-Al2O3-SiO2 glass ceramics was investigated. The results show that the sintering shrinkage ratio of glass...ZrO2 was added into CaO-Al2O3-SiO2 glass-ceramics and the effect of ZrO2 on sintering and crystallization of CaO-Al2O3-SiO2 glass ceramics was investigated. The results show that the sintering shrinkage ratio of glass particles decreases with the increase of the content of ZrO2. ZrO2 has an unfavourable effect on sintering shrinkage ratio of glass particles. The sintering shrinkage ratio of glass particles increases with the increase of sintering temperature. The increase of sintering temperature favors the decrease of the liquid phase viscosity of glass particles. ZrO2 has little effect on crystallization of main crystalline phase （β-wollastonite）. However, it promotes the crystallization at relatively low temperature.展开更多
Ceramic cores are important in the fabrication of superalloy hollow blades,which are increasingly characterized by intricate internal cavity channels.This complexity poses significant challenges to traditional manufac...Ceramic cores are important in the fabrication of superalloy hollow blades,which are increasingly characterized by intricate internal cavity channels.This complexity poses significant challenges to traditional manufacturing processes.The vat photopolymerization 3D printing technology provides a new choice for ceramic cores with complex structures.However,the lamellar structure of the vat photopolymerization 3D printed ceramic cores leads to the anisotropy.Meanwhile,the low strength and high shrinkage of ceramic cores restrict their industrial application.In this study,using Al_(2)O_(3)powder as the main material,the effects of zircon content on the sintering shrinkage,open porosity,fiexural strength,and other properties of Al_(2)O_(3)-based ceramic cores were studied to address the aforementioned issues.The influencing mechanism of zircon distribution on sintering shrinkage was analyzed,and the strengthening mechanism of mullite on ceramic cores was discussed from both thermodynamics and dynamics aspects.Through the comprehensive evaluation of ceramic core properties,the Al_(2)O_(3)-based ceramic core with 15vol.%zircon exhibites the optimal performance.Compared with the core samples without zirconium addition,the fiexural strength of the Al_(2)O_(3)-based ceramic core with 15vol.%zircon increases from 14.80 MPa to 61.54 MPa at 25°C,an increase of 315.8%;and from 4.91 MPa to 11.59 MPa at 1,500°C,an increase of 136.0%.The shrinkage in the Z-axis is reduced by 21%,which better weakens the anisotropy of the shrinkage of 3D printed Al_(2)O_(3)-based ceramic cores.ZrO_(2)phase and mullite phase are formed by zircon,which improve the comprehensive properties of Al_(2)O_(3)-based ceramic cores.The successful 3D printing of high-performance Al_(2)O_(3)-based ceramic cores via vat photopolymerization has promoted its industrial application for fabricating ceramic cores with complex structures.展开更多
Alumina ceramics are crucial for high-performance applications,such as turbine blades,due to their excellent thermal stability and mechanical properties.However,existing fabrication methods often fail to balance stren...Alumina ceramics are crucial for high-performance applications,such as turbine blades,due to their excellent thermal stability and mechanical properties.However,existing fabrication methods often fail to balance strength,porosity,and dimensional precision.This study partially fills this research gap through a systematic investigation of calcium oxide(CaO)doping effects on alumina ceramic cores fabricated via ceramic stereolithography,with controlled doping ratios and sintering parameters.A ceramic paste was prepared using coarse and fine Al_(2)O_(3) particles mixed with CaO as a sintering aid,followed by debinding and sintering to achieve optimal mechanical properties.The results show that CaO doping significantly enhances the fiexural strength of alumina cores while maintaining porosity levels between 20%and 30%and controlling the sintering shrinkage rate to about 5%.Additionally,CaO doping alters the microstructure by inhibiting the transformation of spherical fine particles into fiaky grains,improving sintering activity.However,as the CaO doping content increases,the bending strength increases,while the shrinkage rate of the material also tends to increase,resulting in a reduction in the overall porosity.This has a negative impact on the control of the manufacturing precision of turbine blades.Thus,although CaO doping improves strength and microstructure,achieving necessary dimensional control requires further optimization of doping content and sintering conditions.展开更多
Sintering shrinkage, compressive strength, bending strength, chemical composition and their relationships with mi-crostructure of HA-Ti and HA-BG-Ti biomaterials were studied. The results show that sintering shrinkage...Sintering shrinkage, compressive strength, bending strength, chemical composition and their relationships with mi-crostructure of HA-Ti and HA-BG-Ti biomaterials were studied. The results show that sintering shrinkage curve of HA-BG-Ti composite changes just like S shape (23.1%-16.2%-21.8%-17.1%) with increase of Ti content, and sintering shrinkage of HA-BG-Ti composite is always higher than that of HA-Ti composite. The approach also indicates that compressive strength and bending strength of HA-BG-Ti composite are always higher than that of HA-Ti composite. Basically, with its compressive strength and bending strength equaling to 211.5 MPa and 132.1 MPa respectively, HA-10 vol. pct BG-60 vol. pct Ti composite can meet the mechanical properties requirements of the outer dense bulk. Furthermore, microstructure analysis shows that interfacial integration of HA-BG-Ti composite is better than that of HA-Ti composite. From X-ray diffraction (XRD) and SEM-EDAX analysis, brittle new phases including calcium titanate and calcium carbonate are detected in HA-Ti composite. New phases in HA-Ti composite and complex strong binding force accompanied by elemental diffusion of Si, Ti in HA-BG-Ti composite can explain theoretically the great difference of mechanical properties of HA-Ti and HA-BG-Ti composites.展开更多
基金supported by the Guangxi Science and Technology Plan Project(No.Gui Ke AB22035043)the National Natural Science Foundation of China(Nos.52072301,52472078,52072202,and 52102058)+3 种基金the National Key R&D Program of China(No.2022YFB3504901)the Beijing Natural Science Foundation(No.2242046)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011609)the State Key Laboratory of Materials Processing and Die and Mold Technology,Huazhong University of Science and Technology(No.P2023-003).
文摘Porous ceramics are lightweight materials with diverse pore structures and are widely applied in areas such as thermal insulation, sound absorption, filtration, catalysis, and energy storage. However, excessive shrinkage during the sintering process of porous ceramics leads to cracking and deterioration, posing significant challenges for achieving complex shapes. Despite its importance, the field of low sintering shrinkage porous ceramics has not received sufficient attention. This review systematically discusses the principles and progress in the development of low sintering shrinkage porous ceramics. First, we introduce the characteristics of various preparation methods, including partial sintering, particle-stabilized foaming, gel-casting, foam-gelcasting, and additive manufacturing (AM). We then explain three primary principles of low sintering shrinkage from the perspectives of the volume effect and mass transfer processes. This review focuses on the properties and applications of typical low sintering shrinkage ceramics such as mullite and alumina, particularly their mechanical properties and thermal conductivity as thermal insulation and ceramic cores. Finally, we summarize the current state and present future perspectives on low sintering shrinkage porous ceramics.
文摘ZrO2 was added into CaO-Al2O3-SiO2 glass-ceramics and the effect of ZrO2 on sintering and crystallization of CaO-Al2O3-SiO2 glass ceramics was investigated. The results show that the sintering shrinkage ratio of glass particles decreases with the increase of the content of ZrO2. ZrO2 has an unfavourable effect on sintering shrinkage ratio of glass particles. The sintering shrinkage ratio of glass particles increases with the increase of sintering temperature. The increase of sintering temperature favors the decrease of the liquid phase viscosity of glass particles. ZrO2 has little effect on crystallization of main crystalline phase （β-wollastonite）. However, it promotes the crystallization at relatively low temperature.
基金financially supported by the National Natural Science Foundation of China(Nos.52402094,U234120139,and U22A20129)the National Defense Basic Scientific Research Program of China(No.JCKY2022130C005)+8 种基金the China Postdoctoral Science Foundation(No.2023M743571)the Postdoctoral Fellowship Program of CPSF(N o.GZC20232743)the Innovation Project of IMR(2024-PY11)the Open Research Fund of National Key Laboratory of Advanced Casting Technologies(No.CAT2023-006)the Graduate Education Quality Engineering Project of Anhui Province(No.2023cxcysj015)the Science and Technology Plan Project of Liaoning Province(No.2024JH2/101900011)the Nationa Key Research and Development Program of China(Nos2024YFB3714500 and 2018YFB1106600)the China United Gas Turbine Technology Co.Ltd.under the project of J790。
文摘Ceramic cores are important in the fabrication of superalloy hollow blades,which are increasingly characterized by intricate internal cavity channels.This complexity poses significant challenges to traditional manufacturing processes.The vat photopolymerization 3D printing technology provides a new choice for ceramic cores with complex structures.However,the lamellar structure of the vat photopolymerization 3D printed ceramic cores leads to the anisotropy.Meanwhile,the low strength and high shrinkage of ceramic cores restrict their industrial application.In this study,using Al_(2)O_(3)powder as the main material,the effects of zircon content on the sintering shrinkage,open porosity,fiexural strength,and other properties of Al_(2)O_(3)-based ceramic cores were studied to address the aforementioned issues.The influencing mechanism of zircon distribution on sintering shrinkage was analyzed,and the strengthening mechanism of mullite on ceramic cores was discussed from both thermodynamics and dynamics aspects.Through the comprehensive evaluation of ceramic core properties,the Al_(2)O_(3)-based ceramic core with 15vol.%zircon exhibites the optimal performance.Compared with the core samples without zirconium addition,the fiexural strength of the Al_(2)O_(3)-based ceramic core with 15vol.%zircon increases from 14.80 MPa to 61.54 MPa at 25°C,an increase of 315.8%;and from 4.91 MPa to 11.59 MPa at 1,500°C,an increase of 136.0%.The shrinkage in the Z-axis is reduced by 21%,which better weakens the anisotropy of the shrinkage of 3D printed Al_(2)O_(3)-based ceramic cores.ZrO_(2)phase and mullite phase are formed by zircon,which improve the comprehensive properties of Al_(2)O_(3)-based ceramic cores.The successful 3D printing of high-performance Al_(2)O_(3)-based ceramic cores via vat photopolymerization has promoted its industrial application for fabricating ceramic cores with complex structures.
基金financially supported by the National Key R&D Program of China(No.2023YFB4606101)the National Key R&D Program of China(No.2022YFB4601404)+3 种基金the Innovative and Entrepreneurial PhD Program of Jiangsu Province(No.JSSCBS20210836)the youth program of Jiangnan University(No.JUSRP121038)the Taihu Talent Program of Wuxi Citythe Innovative and Entrepreneurial Talent Program of Jiangsu Province(No.JSSCRC2021531)。
文摘Alumina ceramics are crucial for high-performance applications,such as turbine blades,due to their excellent thermal stability and mechanical properties.However,existing fabrication methods often fail to balance strength,porosity,and dimensional precision.This study partially fills this research gap through a systematic investigation of calcium oxide(CaO)doping effects on alumina ceramic cores fabricated via ceramic stereolithography,with controlled doping ratios and sintering parameters.A ceramic paste was prepared using coarse and fine Al_(2)O_(3) particles mixed with CaO as a sintering aid,followed by debinding and sintering to achieve optimal mechanical properties.The results show that CaO doping significantly enhances the fiexural strength of alumina cores while maintaining porosity levels between 20%and 30%and controlling the sintering shrinkage rate to about 5%.Additionally,CaO doping alters the microstructure by inhibiting the transformation of spherical fine particles into fiaky grains,improving sintering activity.However,as the CaO doping content increases,the bending strength increases,while the shrinkage rate of the material also tends to increase,resulting in a reduction in the overall porosity.This has a negative impact on the control of the manufacturing precision of turbine blades.Thus,although CaO doping improves strength and microstructure,achieving necessary dimensional control requires further optimization of doping content and sintering conditions.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(No.50174059).
文摘Sintering shrinkage, compressive strength, bending strength, chemical composition and their relationships with mi-crostructure of HA-Ti and HA-BG-Ti biomaterials were studied. The results show that sintering shrinkage curve of HA-BG-Ti composite changes just like S shape (23.1%-16.2%-21.8%-17.1%) with increase of Ti content, and sintering shrinkage of HA-BG-Ti composite is always higher than that of HA-Ti composite. The approach also indicates that compressive strength and bending strength of HA-BG-Ti composite are always higher than that of HA-Ti composite. Basically, with its compressive strength and bending strength equaling to 211.5 MPa and 132.1 MPa respectively, HA-10 vol. pct BG-60 vol. pct Ti composite can meet the mechanical properties requirements of the outer dense bulk. Furthermore, microstructure analysis shows that interfacial integration of HA-BG-Ti composite is better than that of HA-Ti composite. From X-ray diffraction (XRD) and SEM-EDAX analysis, brittle new phases including calcium titanate and calcium carbonate are detected in HA-Ti composite. New phases in HA-Ti composite and complex strong binding force accompanied by elemental diffusion of Si, Ti in HA-BG-Ti composite can explain theoretically the great difference of mechanical properties of HA-Ti and HA-BG-Ti composites.
