Shi-jia GU , Han-lin CHEN , Jun-zhuo WANG , Xiao-fang LU , Lian-jun WANG , Wan JIANG
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引用次数: 0
Abstract
High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance. Their traditional production method relies on repeated impregnation-carbonization and graphitization, and is plagued by lengthy preparation cycles and high energy consumption. Phase transition-assisted self-pressurized self-sintering technology can rapidly produce high-strength graphite materials, but the fracture strain of the graphite materials produced is poor. To solve this problem, this study used a two-step sintering method to uniformly introduce micro-nano pores into natural graphite-based bulk graphite, achieving improved fracture strain of the samples without reducing their density and mechanical properties. Using natural graphite powder, micron-diamond, and nano-diamond as raw materials, and by precisely controlling the staged pressure release process, the degree of diamond phase transition expansion was effectively regulated. The strain-to-failure of the graphite samples reached 1.2%, a 35% increase compared to samples produced by fullpressure sintering. Meanwhile, their flexural strength exceeded 110 MPa, and their density was over 1.9 g/cm3. The process therefore produced both a high strength and a high fracture strain. The interface evolution and toughening mechanism during the two-step sintering process were investigated. It is believed that the micro-nano pores formed have two roles: as stress concentrators they induce yielding by shear and as multi-crack propagation paths they significantly lengthen the crack propagation path. The two-step sintering phase transition strategy introduces pores and provides a new approach for increasing the fracture strain of brittle materials.
期刊介绍：
New Carbon Materials is a scholarly journal that publishes original research papers focusing on the physics, chemistry, and technology of organic substances that serve as precursors for creating carbonaceous solids with aromatic or tetrahedral bonding. The scope of materials covered by the journal extends from diamond and graphite to a variety of forms including chars, semicokes, mesophase substances, carbons, carbon fibers, carbynes, fullerenes, and carbon nanotubes. The journal's objective is to showcase the latest research findings and advancements in the areas of formation, structure, properties, behaviors, and technological applications of carbon materials. Additionally, the journal includes papers on the secondary production of new carbon and composite materials, such as carbon-carbon composites, derived from the aforementioned carbons. Research papers on organic substances will be considered for publication only if they have a direct relevance to the resulting carbon materials.
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