Wang Xiaonan, Wang Dianzhen, Rong Kaixuan, Tao Qiang, Zhu Pinwen
Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Changchun 130103, China.
Synergetic Extreme Condition High-Pressure Science Center, State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Qianjin Street, Changchun 130012, China.
Materials (Basel). 2024 Nov 28;17(23):5838. doi: 10.3390/ma17235838.
Introducing a second phase has been an effective way to solve the brittleness of boron carbide (BC) for its application. Though reduced graphene oxide (rGO) is an ideal candidate for reinforcing the BC duo's two-dimensional structure and excellent mechanical properties, the toughness is less than 6 MPa·m, or the hardness is lower than 30 GPa in BC-graphene composites. A barrier to enhancing toughness is the weak interface strength between rGO and BC, which limits the bridging and pull-out toughening effects of rGO. In this work, internal stress was introduced using a high-pressure and high-temperature (HPHT) method with BC-rGO composites. The optimal hardness and toughness values for the BC-2 rGO composite reached 30.1 GPa and 8.6 MPa·m, respectively. The improvement in toughness was 4 times higher than that of pure BC. The internal stress in the composite increased gradually from 2.3 GPa to 3.3 GPa with an increase in rGO content from 1 to 3 . Crack deflection, bridging, and rGO pull-out are responsible for the improvement in toughness. Moreover, the high internal stress contributed to the formation of good interface strength by embedding rGO into the BC matrix particles, which further enhanced the dissipation of the crack energy during the pull-out process and led to high toughness. This work provides new insights into synthesizing high-toughness BC matrix composites.
引入第二相是解决碳化硼（BC）应用中脆性问题的有效方法。尽管还原氧化石墨烯（rGO）是增强BC二维结构和优异力学性能的理想候选材料，但在BC-石墨烯复合材料中，韧性小于6MPa·m，或硬度低于30GPa。提高韧性的一个障碍是rGO与BC之间的界面强度较弱，这限制了rGO的桥接和拔出增韧效果。在这项工作中，通过高压高温（HPHT）方法在BC-rGO复合材料中引入内应力。BC-2rGO复合材料的最佳硬度和韧性值分别达到30.1GPa和8.6MPa·m。韧性的提高比纯BC高4倍。随着rGO含量从1增加到3，复合材料中的内应力从2.3GPa逐渐增加到3.3GPa。裂纹偏转、桥接和rGO拔出是韧性提高的原因。此外，高内应力通过将rGO嵌入BC基体颗粒中有助于形成良好的界面强度，这进一步增强了拔出过程中裂纹能量的耗散并导致高韧性。这项工作为合成高韧性BC基复合材料提供了新的见解。
