Small onion-like BN leads to ultrafine-twinned cubic BN
Small onion-like BN leads to ultrafine-twinned cubic BN
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小洋葱状氮化硼产生超细孪晶立方氮化硼
DOI：
10.1007/s40843-019-9409-1
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发表时间：
2019-08-01
影响因子：
8.1
通讯作者：
He, Julong
中科院分区：
文献类型：
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作者：
Luo, Kun;Zhang, Yang;He, Julong
纳米孪晶立方氮化硼(NT-CBN)具有优异的硬度、韧性和稳定性，因其独特的科学和工业意义而引起了人们的广泛关注。合成NT-CBN的关键是采用洋葱状的BN(OBN)纳米前驱体，并在高压下诱导相变。在这里，我们发现所用OBN的尺寸变化对产品的力学性能影响很大。随着前驱体尺寸从~320 nm减小到90 nm，纳米结构产物的维氏硬度从61 Gpa提高到108 Gpa，这是因为大尺寸的OBN纳米颗粒具有更平坦、有序和石墨状的壳层，这与小直径纳米颗粒的高度皱折和不完美的层形成鲜明对比，从而导致合成产物中超细结构的明显减少。研究表明，只有较小的OBN前驱体才能制备出性能优异的完全超细NT-CBN。为进一步提高这种重要材料的性能提出了一条可行的途径。
Nanotwinned cubic boron nitride (nt-cBN) with remarkable hardness, toughness, and stability has attracted widespread attention due to its distinct scientific and industrial importance. The key for nt-cBN synthesis is to adopt an onion-like BN (oBN) nano-precursor and induce phase transition under high pressure. Here, we found that the size change of oBN used greatly affected the mechanical performance of products. With the precursor size decreasing from~ 320 to 90 nm, the Vickers hardness of nanostructured products improved from 61 to 108 GPa, due to the fact that large oBN nanoparticles possessed more flattened, orderly and graphite-like shell layers, in sharp contrast to the highly wrinkled and imperfect layers in small-diameter nanoparticles, thus resulting in the apparent reduction of ultrafinetwin substructure in the synthetic products. This study reveals that only small oBN precursor could produce complete ultrafine nt-cBN with outstanding performance. A practical route was proposed to further improve the performance of this important material.