The last 25 years has witnessed a wealth of publications on the creation of carbon materials whose compression bulk modulus and hardness are much higher than those of diamond. This review presents a critical analysis of these studies. Three groups of myths that have emerged lately are discussed. The first is related to the possibility of creating materials whose bulk moduli are significantly higher than those of diamond. The second group is devoted to 'experimentally measured' values of hardness, much higher than that of diamond. The third includes alleged 'theoretical' grounds for a several-fold (!) increase in the hardness of covalent substances due to the effects of quantum confinement. It is shown that materials whose elastic moduli significantly exceed those of diamond cannot in principle be produced under normal conditions. Issues surrounding the quantitative measurement of hardness are discussed; it is noted that the creation of obstacles to the movement of dislocations in nanomaterials may allow a 20–40% increase in the effective measured hardness of ultrahard materials. It is emphasized that alternative hypothetical approaches to increase hardness, for example, due to quantum confinement, actually have no physical grounds whatsoever. The highest mechanical characteristics of diamond are associated with reliably established physical laws, and any assertions regarding possible obtainment of materials whose elastic characteristics or hardness are several times greater than those of diamond may not be regarded as reliable to any extent or even science-based.

中文翻译：

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超硬纳米材料——神话与现实

在过去的 25 年里，已经有大量关于碳材料的发表，其压缩体积模量和硬度远高于金刚石。本综述对这些研究进行了批判性分析。讨论了最近出现的三组神话。第一个与创造体积模量明显高于金刚石的材料的可能性有关。第二组致力于“实验测量”的硬度值，远高于钻石的硬度值。第三个包括所谓的“理论”基础，即由于量子限制的影响，共价物质的硬度增加了几倍（！）。结果表明，弹性模量明显超过金刚石的材料在正常条件下原则上不能生产。讨论了有关硬度定量测量的问题；值得注意的是，纳米材料中位错运动的障碍可能会使超硬材料的有效测量硬度增加 20-40%。需要强调的是，增加硬度的替代假设方法，例如，由于量子限制，实际上没有任何物理依据。金刚石的最高机械特性与可靠建立的物理定律有关，任何关于可能获得弹性特性或硬度比金刚石高几倍的材料的断言在任何程度上都不能被视为可靠，甚至不能被视为科学依据。值得注意的是，纳米材料中位错运动的障碍可能会使超硬材料的有效测量硬度增加 20-40%。需要强调的是，增加硬度的替代假设方法，例如，由于量子限制，实际上没有任何物理依据。金刚石的最高机械特性与可靠建立的物理定律有关，任何关于可能获得弹性特性或硬度比金刚石高几倍的材料的断言在任何程度上都不能被视为可靠，甚至不能被视为科学依据。值得注意的是，纳米材料中位错运动的障碍可能会使超硬材料的有效测量硬度增加 20-40%。需要强调的是，增加硬度的替代假设方法，例如，由于量子限制，实际上没有任何物理依据。金刚石的最高机械特性与可靠建立的物理定律有关，任何关于可能获得弹性特性或硬度比金刚石高几倍的材料的断言在任何程度上都不能被视为可靠，甚至不能被视为科学依据。需要强调的是，增加硬度的替代假设方法，例如，由于量子限制，实际上没有任何物理依据。金刚石的最高机械特性与可靠建立的物理定律有关，任何关于可能获得弹性特性或硬度比金刚石高几倍的材料的断言在任何程度上都不能被视为可靠，甚至不能被视为科学依据。需要强调的是，增加硬度的替代假设方法，例如，由于量子限制，实际上没有任何物理依据。金刚石的最高机械特性与可靠建立的物理定律有关，任何关于可能获得弹性特性或硬度比金刚石高几倍的材料的断言在任何程度上都不能被视为可靠，甚至不能被视为科学依据。