We proposed a new method, electroplating followed by spark plasma sintering（SPS）, to fabricate laminated TiB2-B4 C/Cu-Ni composites with high strength and high toughness. It is found that a thin intermediate Cu laye...We proposed a new method, electroplating followed by spark plasma sintering（SPS）, to fabricate laminated TiB2-B4 C/Cu-Ni composites with high strength and high toughness. It is found that a thin intermediate Cu layer can effectively enhance the strength of the interface between the ceramics and the metals, resulting in a high flexural strength and toughness of the laminated TiB2-B4 C composites simultaneously. A flexural strength and fracture toughness of 651 MPa and 11.6 MPam^（1/2） respectively,are achieved, an approximately 90% improvement over TiB2-B4 C bulk.展开更多
Ultrasonic-assisted hot pressing(UAHP)has shown significant potential in enhancing both the densification and mechanical performance of metallic materials.However,the poor hightemperature stability of ultrasonic syste...Ultrasonic-assisted hot pressing(UAHP)has shown significant potential in enhancing both the densification and mechanical performance of metallic materials.However,the poor hightemperature stability of ultrasonic systems severely limits its application in the fabrication of high-melting-point materials.To fill this gap,UAHP was operated at temperatures exceeding 2000℃ and employed in the preparation of monolithic boron carbide(B4C)ceramics for the first time.The densification behavior,microstructure evolution,and mechanical properties of B4C fabricated via UAHP were systematically investigated and compared with those prepared by conventional hot pressing(HP).It was demonstrated that the introduction of high-frequency ultrasonic vibration in UAHP can not only accelerate the densification rate but also reduce the densification temperature and enhance the mechanical properties of B4C.Specifically,the relative density of B4C increased from 90.90% to 97.22% at 1900℃ under UAHP,which was comparable to that achieved by HP at 1950℃,indicating a 50℃ reduction in densification temperature.In addition,a significant increase in densification efficiency by reducing the densification time during UAHP endowed B4C with both near-full density and superior mechanical properties.The B4C ceramics prepared by UAHP at 1950℃ for 20 min and at 2050℃ for 5 min exhibited flexural strengths of 669.3±19.4 and 688.3±32.5 MPa,respectively,and fracture toughnesses of 4.37±0.23 and 4.22±0.29 MPa·m^(1/2),respectively.These results suggest that UAHP is a promising strategy for efficient densification and optimization of the mechanical properties of B4C ceramic and opens a new avenue for the preparation of difficult sintering ceramics.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51502220, 51521001, 51672197)the Ministry of Science and Technology of China (No. 2015DFR50650)+1 种基金the Self-determined and Innovative Research Funds of WUT (166899005, 2017II17XZ)the Open Project Program of Key Laboratory of Inorganic Functional Materials and Devices, Chinese Academy of Sciences (Grant No.: KLIFMD201606)
文摘We proposed a new method, electroplating followed by spark plasma sintering（SPS）, to fabricate laminated TiB2-B4 C/Cu-Ni composites with high strength and high toughness. It is found that a thin intermediate Cu layer can effectively enhance the strength of the interface between the ceramics and the metals, resulting in a high flexural strength and toughness of the laminated TiB2-B4 C composites simultaneously. A flexural strength and fracture toughness of 651 MPa and 11.6 MPam^（1/2） respectively,are achieved, an approximately 90% improvement over TiB2-B4 C bulk.
基金supported by the National Natural Science Foundation of China(No.52205492)the Fundamental Research Program of Shanxi Province,China(No.202303021221037)the Scientific and Technological Achievements Transformation Guidance Project of Shanxi Province,China(No.202204021301039).
文摘Ultrasonic-assisted hot pressing(UAHP)has shown significant potential in enhancing both the densification and mechanical performance of metallic materials.However,the poor hightemperature stability of ultrasonic systems severely limits its application in the fabrication of high-melting-point materials.To fill this gap,UAHP was operated at temperatures exceeding 2000℃ and employed in the preparation of monolithic boron carbide(B4C)ceramics for the first time.The densification behavior,microstructure evolution,and mechanical properties of B4C fabricated via UAHP were systematically investigated and compared with those prepared by conventional hot pressing(HP).It was demonstrated that the introduction of high-frequency ultrasonic vibration in UAHP can not only accelerate the densification rate but also reduce the densification temperature and enhance the mechanical properties of B4C.Specifically,the relative density of B4C increased from 90.90% to 97.22% at 1900℃ under UAHP,which was comparable to that achieved by HP at 1950℃,indicating a 50℃ reduction in densification temperature.In addition,a significant increase in densification efficiency by reducing the densification time during UAHP endowed B4C with both near-full density and superior mechanical properties.The B4C ceramics prepared by UAHP at 1950℃ for 20 min and at 2050℃ for 5 min exhibited flexural strengths of 669.3±19.4 and 688.3±32.5 MPa,respectively,and fracture toughnesses of 4.37±0.23 and 4.22±0.29 MPa·m^(1/2),respectively.These results suggest that UAHP is a promising strategy for efficient densification and optimization of the mechanical properties of B4C ceramic and opens a new avenue for the preparation of difficult sintering ceramics.
