Superhydrophobicity endows various substrates with astonishing multifunctional properties and has received widespread praise in industrial production.However,the fragile connection between the coating and the substrat...Superhydrophobicity endows various substrates with astonishing multifunctional properties and has received widespread praise in industrial production.However,the fragile connection between the coating and the substrate not only limits the service life of superhydrophobic coatings,but also poses limitations.To address this issue,this study used 3-(perfluorooctyl)propanol and organic polysilazane(OPSZ)with universal anchoring properties as starting materials to obtain fluorine modified OPSZ through a one-step synthesis method,and then doped SiO_(2)micro nano particles to produce superhydrophobic coatings that can be widely applied to various substrates.Investigating the relationship between the hydrophobic properties of the coatings and the amounts of SiO_(2)microparticles and nanoparticles used to create the microscopic rough structure of the superhydrophobic coatings,it was discovered that the hydrophobic properties of the coatings tended to increase as the number of nanoparticles increased.The water contact angle of prepared coatings was still over 157°after 48 h of UV exposure or 180 days of exposure to air.The heat resistance of the created superhydrophobic coatings was tested in a muffle furnace at 400℃ for 2 h.The results revealed that the coatings maintained their water contact angle of 155.1°±3.01°and water sliding angle of 6.4°±1.98°,demonstrating their excellent heat resistance and suitability for use in a variety of high-temperatu re environme nts.The work provided a practical way for creating superhydrophobic composite coatings with excellent mechanical stability,acid and alkali corrosion resistance,and heat resistance,and had potential application in antifouling and anti-corrosion.展开更多
The performance of an aero-engine is closely related to the cooling ability of the hollow turbine blades.Ceramic core is an important component in the production of hollow turbine blades with a complex structure.As th...The performance of an aero-engine is closely related to the cooling ability of the hollow turbine blades.Ceramic core is an important component in the production of hollow turbine blades with a complex structure.As the pace of updating and iteration in turbine blade design continues to accelerate,the internal cavity structures of turbine blades have become increasingly complex.Traditional hot injection process is difficult to meet the production requirements of ceramic cores with complex structures.3D printing technology can manufacture ceramic cores without the need for moulds,significantly shortening the production cycle and providing a new technology for the production of ceramic cores with complex structures.To meet the technical requirements of the investment casting process,ceramic cores must possess adequate mechanical strength and appropriate porosity.In this work,the ceramic slurry with polysilazane(PSZ)precursor was successfully prepared,and the Al_(2)O_(3)-based ceramic cores with high performance were fabricated using 3D printing technology.The regulation mechanism of polysilazane on the performance of ceramic cores was investigated.The results show that with the increase of PSZ content,the fiexural strength of ceramic cores firstly increases and then decreases.When the content of PSZ is 5%,the fiexural strength at 25℃and 1,500℃are 31.5 MPa and 13.1 MPa,respectively,and the porosity is 36.7%.This work is expected to advance the research and practical application of high-performance ceramic cores fabricated via 3D printing.展开更多
Si_(3)N_(4)/SiCN ceramics have been extensively explored for applications in the aerospace,mechanical engineering,and biomedical fields.Recently,there has been significant focus on the additive manufacturing(AM)of pol...Si_(3)N_(4)/SiCN ceramics have been extensively explored for applications in the aerospace,mechanical engineering,and biomedical fields.Recently,there has been significant focus on the additive manufacturing(AM)of polymer-derived ceramic(PDC)technology for fabricating Si_(3)N_(4)/SiCN ceramics.The chemical structure and composition of the preceramic polymer precursors have a crucial influence on the performance of ceramic products.In this paper,recent advances in the use of polysilazane and polycarbosilazane precursors in AM are reviewed and an outlook for future development is presented.The findings of this study could spark inspiration and reflection regarding AM applications and synthetic technology.It is believed that the development of PDCs in ceramic fabrication will become more versatile and application-oriented and provide more freedom in the design of high-performance ceramics.展开更多
The gas barrier film formation technique using simultaneous photo-irradiation and heat-treatment has been researched on alicyclic polyimide film coated with a polysilazane solution. A fine SiO2 thin film on polyimide ...The gas barrier film formation technique using simultaneous photo-irradiation and heat-treatment has been researched on alicyclic polyimide film coated with a polysilazane solution. A fine SiO2 thin film on polyimide film was formed at low temperatures, which greatly improved the substrate’s gas barrier characteristics by this technique. The values of gas barrier characteristics depended on the substrate temperature at the time of photo-irradiation. For photo-irradiated thin film heat-treated to 150°C, the water vapor transmission rate and oxygen transmission rate fell below the equipment measurement limit of 0.02 g/m2/day and 0.02 cm3/m2/day, respectively. This polyimide film with a gas-barrier film coating has good transmittance in the region of visible light, heat resistance, and flexibility.展开更多
The effects of excimer light irradiation on polysilazane coatings formed on PET films with vacuum-evaporated SiO2 coatings and the effects of these coatings on gas barrier characteristics have been investigated. The t...The effects of excimer light irradiation on polysilazane coatings formed on PET films with vacuum-evaporated SiO2 coatings and the effects of these coatings on gas barrier characteristics have been investigated. The temperature during light irradiation has a large effect on the coating’s molecular structure and gas barrier characteristics. When irradiation was performed at 100℃, the polysilazane coating transformed into a silica coating, and a compact silica coating at a much lower temperature than with heat treatment alone was produced. Surface irregularities in the vapor-deposited silica coating were smoothed out by the formation of a polysilazane coating, which was transformed into a compact silica coating when irradiated with light, resulting in a significant improvement in the gas barrier characteristics. The water vapor permeability of the thin coating irradiated with excimer light at 100℃ showed only 0.04 g/m2•day (40℃, 90% RH). According to the results of investigation of temperature variation of water-vapor permeability, it is inferred that the developed film has an excellent gas barrier value, namely, 4.90 × 10–4 g/m2•day at 25℃. This gas barrier coated PET film is transparent and flexible, and can be used in the fabrication of flexible electronics. Also, the proposed fabrication method effectively provides a simple low-cost and low-temperature fabrication technique without the need for high vacuum facility.展开更多
A new kind of conjugated polymer, acetylenic polysilazane was prepared by ammono- lysis of acetylenic dimethylchlorosilane. The polymer was characterized by 29Si、13C NMR and elemental analysis.
Flexible electronics have been recently paid much attention. A flexible substrate (Organic resin film) is indispensable component for flexible devices. Though PET film is low-cost organic film, low heat-resistance of ...Flexible electronics have been recently paid much attention. A flexible substrate (Organic resin film) is indispensable component for flexible devices. Though PET film is low-cost organic film, low heat-resistance of PET film limits its application as a flexible device substrate. We have developed heat-resistant PET which does not deteriorate even at 190°C heat treatment for one hour. An excimer light was irradiated onto a polysi-lazane (PHPS: perhydropolysilane)-coated film to form a dense silicon-dioxide (SiO2) layer on a PET film, and the heat-resistance property of the formed film was examined. Changes of surface state and cross-sectional structure of the formed film due to heat treatment were investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). Compared to normal PET, which is deteriorated and whitened by heat treatment of about 110°C - 120°C, the SiO2-coated PET film maintains transparency and does not deteriorate after heat treatment at 180°C - 190°C for one hour. This high heat resistance is due to a dense SiO2 film formed on the surface that prevents surface precipitation and crystallization of low-molecular-weight oligomers (which are the cause of thermal degradation of PET). It is expected that enhancing the heat resistance of PET—which has high versatility and low cost—to about 180°C to 190°C will allow SiO2-film-coated PET to be developed as a film substrate for flexible devices.展开更多
Integrating thick/thin film sensors into component systems has emerged as a prevalent approach for monitoring in extreme environments.However,traditional vapor deposition methods face obstacles,including complex fabri...Integrating thick/thin film sensors into component systems has emerged as a prevalent approach for monitoring in extreme environments.However,traditional vapor deposition methods face obstacles,including complex fabrication processes and the degradation of sensitive materials at extremely high temperatures.This work delineates the development of a polysilazane composite dual-layer thick-film Negative Temperature Coefficient(NTC)thermistor characterized by its suitability for extreme temperatures and robust bond strength achieved through an advanced near-net-shape printing methodology.High-temperature resistant La(Ca)CrO_(3)/polysilazane films were printed as the sensitive layer,while a dense layer formed by Cr_(2)O_(3)/polysilazane was used as the protective layer.The bilayer structure resulted in a 2.5-fold increase in adhesion strength compared to the single-layer La(Ca)CrO_(3)/polysilazane films.Experimental results indicate that the dual-layer thick-film NTC thermistor can be operated long-term at 1300℃ with a resistance drift rate of 0.9%/h and survive short-term exposure to temperatures up to 1550℃.As a proof of concept,this work applied 3D printing technology to fabricate a polysilazane composite dual-layer thick-film NTC thermistor on the surface of turbine blades and demonstrated its functionality under flame impingement at nearly 1300℃.Such flexible 3D printing techniques pave the way for a new paradigm in manufacturing sensors capable of withstanding ultra-high temperatures.展开更多
High strength and high toughness are mutually exclusive in structural materials.In ceramic materials,increasing toughness usually depends on the introduction of a ductile phase that reduces the strength and high-tempe...High strength and high toughness are mutually exclusive in structural materials.In ceramic materials,increasing toughness usually depends on the introduction of a ductile phase that reduces the strength and high-temperature stability of the material.In this work,vat photopolymerization 3D printing technology was used to achieve toughening of ceramic composite material.The friction sliding of the 3D-printed ceramic macrolayer structure results in effective energy dissipation and redistribution of strain in the whole structure,and macroscale toughening of the ceramic material is realized.In addition,the bridging and elongation of the crack in situ amorphous ceramic whiskers were significant microscopic toughening results,coupled with the toughening of the crack tip of nano-ZrO_(2).Multiscale collaborative toughening methods based on 3D-printed ceramics should find wide applications for materials in service at extreme high temperatures.展开更多
基金supported by the National Key Research and Development Program of China(2022YFC3004901-3)the National Natural Science Foundation of China(21908109)+2 种基金the Open Project of Key Laboratory of Fire Emergency Rescue Equipment of Ministry of Emergency Management of People's Republic of China(2020XFZB05)the Fundamental Research Funds for the Central Universities(30919011272)the Natural Science Foundation of Jiangsu Province(BK20180816)。
文摘Superhydrophobicity endows various substrates with astonishing multifunctional properties and has received widespread praise in industrial production.However,the fragile connection between the coating and the substrate not only limits the service life of superhydrophobic coatings,but also poses limitations.To address this issue,this study used 3-(perfluorooctyl)propanol and organic polysilazane(OPSZ)with universal anchoring properties as starting materials to obtain fluorine modified OPSZ through a one-step synthesis method,and then doped SiO_(2)micro nano particles to produce superhydrophobic coatings that can be widely applied to various substrates.Investigating the relationship between the hydrophobic properties of the coatings and the amounts of SiO_(2)microparticles and nanoparticles used to create the microscopic rough structure of the superhydrophobic coatings,it was discovered that the hydrophobic properties of the coatings tended to increase as the number of nanoparticles increased.The water contact angle of prepared coatings was still over 157°after 48 h of UV exposure or 180 days of exposure to air.The heat resistance of the created superhydrophobic coatings was tested in a muffle furnace at 400℃ for 2 h.The results revealed that the coatings maintained their water contact angle of 155.1°±3.01°and water sliding angle of 6.4°±1.98°,demonstrating their excellent heat resistance and suitability for use in a variety of high-temperatu re environme nts.The work provided a practical way for creating superhydrophobic composite coatings with excellent mechanical stability,acid and alkali corrosion resistance,and heat resistance,and had potential application in antifouling and anti-corrosion.
基金supported by the National Natural Science Foundation of China(Nos.52402094,U234120139,and U22A20129)National Defense Basic Scientific Research Program of China(No.JCKY2022130C005)+7 种基金China Postdoctoral Science Foundation(No.2023M743571)Postdoctoral Fellowship Program of CPSF(No.GZC20232743)Innovation Project of IMR(No.2024-PY11)Open Research Fund of National Key Laboratory of Advanced Casting Technologies(No.CAT2023-006)Graduate Education Quality Engineering Project of Anhui Province(No.2023cxcysj015)Science and Technology Plan Project of Liaoning Province(No.2024JH2/101900011)National Key Research and Development Program of China(Nos.2024YFB3714500 and 2018YFB1106600)the China United Gas Turbine Technology Co.,Ltd.(No.J790)。
文摘The performance of an aero-engine is closely related to the cooling ability of the hollow turbine blades.Ceramic core is an important component in the production of hollow turbine blades with a complex structure.As the pace of updating and iteration in turbine blade design continues to accelerate,the internal cavity structures of turbine blades have become increasingly complex.Traditional hot injection process is difficult to meet the production requirements of ceramic cores with complex structures.3D printing technology can manufacture ceramic cores without the need for moulds,significantly shortening the production cycle and providing a new technology for the production of ceramic cores with complex structures.To meet the technical requirements of the investment casting process,ceramic cores must possess adequate mechanical strength and appropriate porosity.In this work,the ceramic slurry with polysilazane(PSZ)precursor was successfully prepared,and the Al_(2)O_(3)-based ceramic cores with high performance were fabricated using 3D printing technology.The regulation mechanism of polysilazane on the performance of ceramic cores was investigated.The results show that with the increase of PSZ content,the fiexural strength of ceramic cores firstly increases and then decreases.When the content of PSZ is 5%,the fiexural strength at 25℃and 1,500℃are 31.5 MPa and 13.1 MPa,respectively,and the porosity is 36.7%.This work is expected to advance the research and practical application of high-performance ceramic cores fabricated via 3D printing.
基金supported by Natural Science Basic Research Pro-gram of Shaanxi in China(Grant.No.2023-JC-YB-388)National Nat-ural Science Foundation of China(Grant.No.52005392)Fundamental Research Funds for the Central Universities in China,and the Youth In-novation Team of Shaanxi Universities in China.
文摘Si_(3)N_(4)/SiCN ceramics have been extensively explored for applications in the aerospace,mechanical engineering,and biomedical fields.Recently,there has been significant focus on the additive manufacturing(AM)of polymer-derived ceramic(PDC)technology for fabricating Si_(3)N_(4)/SiCN ceramics.The chemical structure and composition of the preceramic polymer precursors have a crucial influence on the performance of ceramic products.In this paper,recent advances in the use of polysilazane and polycarbosilazane precursors in AM are reviewed and an outlook for future development is presented.The findings of this study could spark inspiration and reflection regarding AM applications and synthetic technology.It is believed that the development of PDCs in ceramic fabrication will become more versatile and application-oriented and provide more freedom in the design of high-performance ceramics.
文摘The gas barrier film formation technique using simultaneous photo-irradiation and heat-treatment has been researched on alicyclic polyimide film coated with a polysilazane solution. A fine SiO2 thin film on polyimide film was formed at low temperatures, which greatly improved the substrate’s gas barrier characteristics by this technique. The values of gas barrier characteristics depended on the substrate temperature at the time of photo-irradiation. For photo-irradiated thin film heat-treated to 150°C, the water vapor transmission rate and oxygen transmission rate fell below the equipment measurement limit of 0.02 g/m2/day and 0.02 cm3/m2/day, respectively. This polyimide film with a gas-barrier film coating has good transmittance in the region of visible light, heat resistance, and flexibility.
文摘The effects of excimer light irradiation on polysilazane coatings formed on PET films with vacuum-evaporated SiO2 coatings and the effects of these coatings on gas barrier characteristics have been investigated. The temperature during light irradiation has a large effect on the coating’s molecular structure and gas barrier characteristics. When irradiation was performed at 100℃, the polysilazane coating transformed into a silica coating, and a compact silica coating at a much lower temperature than with heat treatment alone was produced. Surface irregularities in the vapor-deposited silica coating were smoothed out by the formation of a polysilazane coating, which was transformed into a compact silica coating when irradiated with light, resulting in a significant improvement in the gas barrier characteristics. The water vapor permeability of the thin coating irradiated with excimer light at 100℃ showed only 0.04 g/m2•day (40℃, 90% RH). According to the results of investigation of temperature variation of water-vapor permeability, it is inferred that the developed film has an excellent gas barrier value, namely, 4.90 × 10–4 g/m2•day at 25℃. This gas barrier coated PET film is transparent and flexible, and can be used in the fabrication of flexible electronics. Also, the proposed fabrication method effectively provides a simple low-cost and low-temperature fabrication technique without the need for high vacuum facility.
文摘A new kind of conjugated polymer, acetylenic polysilazane was prepared by ammono- lysis of acetylenic dimethylchlorosilane. The polymer was characterized by 29Si、13C NMR and elemental analysis.
文摘Flexible electronics have been recently paid much attention. A flexible substrate (Organic resin film) is indispensable component for flexible devices. Though PET film is low-cost organic film, low heat-resistance of PET film limits its application as a flexible device substrate. We have developed heat-resistant PET which does not deteriorate even at 190°C heat treatment for one hour. An excimer light was irradiated onto a polysi-lazane (PHPS: perhydropolysilane)-coated film to form a dense silicon-dioxide (SiO2) layer on a PET film, and the heat-resistance property of the formed film was examined. Changes of surface state and cross-sectional structure of the formed film due to heat treatment were investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). Compared to normal PET, which is deteriorated and whitened by heat treatment of about 110°C - 120°C, the SiO2-coated PET film maintains transparency and does not deteriorate after heat treatment at 180°C - 190°C for one hour. This high heat resistance is due to a dense SiO2 film formed on the surface that prevents surface precipitation and crystallization of low-molecular-weight oligomers (which are the cause of thermal degradation of PET). It is expected that enhancing the heat resistance of PET—which has high versatility and low cost—to about 180°C to 190°C will allow SiO2-film-coated PET to be developed as a film substrate for flexible devices.
基金supported by the National Key R&D Program of China(No.2022YFB3203900).
文摘Integrating thick/thin film sensors into component systems has emerged as a prevalent approach for monitoring in extreme environments.However,traditional vapor deposition methods face obstacles,including complex fabrication processes and the degradation of sensitive materials at extremely high temperatures.This work delineates the development of a polysilazane composite dual-layer thick-film Negative Temperature Coefficient(NTC)thermistor characterized by its suitability for extreme temperatures and robust bond strength achieved through an advanced near-net-shape printing methodology.High-temperature resistant La(Ca)CrO_(3)/polysilazane films were printed as the sensitive layer,while a dense layer formed by Cr_(2)O_(3)/polysilazane was used as the protective layer.The bilayer structure resulted in a 2.5-fold increase in adhesion strength compared to the single-layer La(Ca)CrO_(3)/polysilazane films.Experimental results indicate that the dual-layer thick-film NTC thermistor can be operated long-term at 1300℃ with a resistance drift rate of 0.9%/h and survive short-term exposure to temperatures up to 1550℃.As a proof of concept,this work applied 3D printing technology to fabricate a polysilazane composite dual-layer thick-film NTC thermistor on the surface of turbine blades and demonstrated its functionality under flame impingement at nearly 1300℃.Such flexible 3D printing techniques pave the way for a new paradigm in manufacturing sensors capable of withstanding ultra-high temperatures.
基金supported by the Natural Science Foundation of China(No.U22A20129)the National Science and Technology Major Project(No.2017-VI-0002-0072)+2 种基金the National Key Research and Development Program of China(No.2018YFB1106600)the Fundamental Research Funds for the Central Universities(No.WK5290000003)the Students’Innovation and Entrepreneurship Foundation of USTC(Nos.CY2022G10 and CY2022C24)。
文摘High strength and high toughness are mutually exclusive in structural materials.In ceramic materials,increasing toughness usually depends on the introduction of a ductile phase that reduces the strength and high-temperature stability of the material.In this work,vat photopolymerization 3D printing technology was used to achieve toughening of ceramic composite material.The friction sliding of the 3D-printed ceramic macrolayer structure results in effective energy dissipation and redistribution of strain in the whole structure,and macroscale toughening of the ceramic material is realized.In addition,the bridging and elongation of the crack in situ amorphous ceramic whiskers were significant microscopic toughening results,coupled with the toughening of the crack tip of nano-ZrO_(2).Multiscale collaborative toughening methods based on 3D-printed ceramics should find wide applications for materials in service at extreme high temperatures.
