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By LZH | 05 July 2023 | 0 Comments

Pristine structure characterization of boron carbide

What is Boron carbide?
Boron carbide (B4C) is an important ceramic material because of its low density, high Hugoniot elastic limit, super-high hardness, and good electric conductivity. It has been used in various important applications with critical hardness, weight, and conductivity. However, the low toughness, strength, and poor damage tolerance have limited their widespread use as structural and functional materials. As the strength and plasticity of brittle materials are sensitive to the fabrication flaws that may act as stress concentrators or weak points for crack initiation and, thereby, catastrophic failure, various attempts have been made to improve the sintering density of B4C ceramics with different sintering additives. Although those sintering aids can increase the specific density of B4C, the fracture toughness, flexibility, and strength were only improved marginally. Nanocrystalline ceramics are known to exhibit numerous outstanding properties compared with conventional polycrystals. In particular, these ceramics are expected to have high strength and enhanced flexibility. However, avoiding grain coarsening during high-temperature sintering remains challenging.
Enhanced mechanical properties of nanocrystalline boron carbide by nanoporosity and interface phases
Ceramics typically have very high hardness but low toughness and plasticity. Besides intrinsic brittleness associated with rigid covalent or ionic bonds, porosity and interface phases are the foremost characteristics that lead to their failure at low-stress levels in a brittle manner. Here we show that, in contrast to the conventional wisdom that these features are adverse factors in the mechanical properties of ceramics, the compression strength, plasticity, and toughness of nanocrystalline boron carbide can be noticeably improved by introducing nanoporosity and weak amorphous carbon at grain boundaries. Transmission electron microscopy reveals that the unusual nanosize effect arises from the deformation-induced elimination of nanoporosity mediated by grain boundary sliding with the assistance of the soft grain boundary phases. This study has important implications for developing high-performance ceramics with ultrahigh strength and enhanced plasticity and toughness.

Pristine structure characterization of boron carbide
Nanocrystalline B4C powders containing slightly excessive carbon, namely 2–3 vol. % higher than stoichiometric, were sintered at a relatively lower temperature to obtain a fine-grained microstructure. The relative density of the bulk n-B4C is 92.8% of the theoretical value; assuming 2–3 vol. % free carbon, the porosity of the sintered sample is ~8–10%. The X-ray diffraction (XRD) pattern indicates that the sample is highly crystallized B4C with a rhombohedral structure (space group: R 166), and a detectable secondary phase cannot be seen as amorphous carbon is inaccessible by XRD. The typical scanning electron microscopy (SEM) image of the fractured surface of n-B4C reveals nearly equiaxed grains with sizes in the range of ~40 to 150 nm (Fig. 1a). Figure 1b shows the bright-field transmission electron microscopy (TEM) image of the sample, in which a high number densities of nanopores are distributed homogenously throughout the sample. The nanopores have an irregular shape with a size ranging from 20 to 70 nm at GBs and GB triple junction points. The mean diameter is estimated at ~32±7 nm, about half the average grain size. High-resolution TEM (HRTEM) images show a thin layer of amorphous carbon at most GBs and the internal surface of nanopores. The fast Fourier transform pattern further confirms the amorphous nature of the interface phase. In addition, clean GBs without detectable interface phases can also be observed by HRTEM.

Price of Boron carbide
Boron carbide particle size and purity will affect the product's Price, and the purchase volume can also affect the cost of Boron carbide. A large amount of large amount will be lower. The Price of Boron carbide is on our company's official website.

Boron carbide supplier
Luoyang Tongrun Nano Technology Co. Ltd.  (TRUNNANO) Luoyang City, Henan Province, China, is a reliable and high-quality global chemical material supplier and manufacturer. It has more than 12 years of experience providing ultra-high quality chemicals and nanotechnology materials, including Boron carbide, nitride powder, graphite powder, sulfide powder, and 3D printing powder. If you are looking for high-quality and cost-effective Boron carbide, you are welcome to contact us or inquire at any time.

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