GOALI: Investigation of Structure and Properties of Si Doped Boron Carbide

非技术性描述：由于其高硬度和低密度，碳化硼（标称为B4 C）是一种重要的技术材料。这些性能使其成为耐磨涂层以及安全、安保和防弹应用（即人员和车辆装甲）的潜在材料。令人惊讶的是，考虑到这些性能，已经发现碳化硼在承受高速冲击方面不是特别好。这项研究的目的是首先彻底了解B4 C的结构，然后通过添加少量硅对其进行修改，以提高其在高速冲击下的性能。提出的基础来自于这样一个事实，即我们根据计算得出的初步结果表明，通过添加1 - 5%的硅可以消除B4 C中的薄弱环节。该项目的成功结果将导致实现一种硬度值仅次于金刚石的材料。这种材料将在广泛的应用中有用，但特别是作为对抗高速威胁的装甲材料。该项目将涉及与几个工业合作伙伴谁是陶瓷装甲供应商的合作。此外，该项目还将涉及对女大学生或少数民族大学生的培训。我们还打算邀请一位小学或高中教师在暑假期间将我们的研究活动从实验室转化到课堂。技术支持：从头计算表明，B4 C是独一无二的，因为许多多型体可以同时共存，这是由于相似的晶格参数和稳定能。然而，这些多型体之一[B12（CCC）]具有非常低的抗冲击性，与其他多型体（40 GPa）相比，在低得多的压力（~ 7 GPa）下失效。因此，B12（CCC）多型体是B4 C中的薄弱环节，导致其在高冲击速度下过早失效。最近的计算表明，通过添加1 - 5%的Si，可以从B4 C中消除B12（CCC）多型体。通过使用溅射或等离子体熔化的远平衡处理，可以在不分离成SiC和B4 C的情况下进行结合。预计含Si的碳化硼的这种基本研究将为如何改善其机械性能以最大限度地减少高压冲击造成的损害提供见解。该项目还为研究生提供最新材料加工和表征技术的培训。

NON-TECHNICAL DESCRIPTION: Boron carbide (nominally B4C) is an important technological material because of its high hardness and low density. These properties make it a material of potential interest for wear resistant coatings as well as security, safety and ballistic applications (i.e. personnel and vehicular armor). Surprisingly, given these properties, it has been found that boron carbide is not particularly good at withstanding high velocity impacts. The aim of the proposed research is to initially thoroughly understand the structure of B4C and then modify it by adding a small amount of silicon in order to enhance its performance at high velocity impacts. The basis of the proposed comes from the fact that we have preliminary results based on calculations that the weak link in B4C can be eliminated by adding 1 - 5% silicon. The successful outcome of this project should lead to the realization of a material that has hardness values only second to those of diamond. Such a material will be useful in wide ranging applications but especially as an armor material against high velocity threats. The project will involve collaboration with several industrial partners who are ceramic armor providers. In addition, the project will involve training of undergraduate female or minority students. We also intend to invite an elementary or high school teacher over the summer in order to translate our research activity from the laboratory to the classroom.TECHNICAL DETAILS: Ab-initio calculations have shown that B4C is unique in that numerous polytypes can co-exist simultaneously due to similar lattice parameters and stability energies. One of these polytypes [B12(CCC)], however, has a very low impact resistance, failing at much lower pressure (~ 7 GPa) compared to other polytypes (40 GPa). Thus, the B12(CCC) polytype is the weak link in B4C which leads to its premature failure at high impact velocities. Calculations have recently revealed that it is possible to eliminate the B12(CCC) polytype from B4C by addition of 1 - 5% Si. The incorporation is possible, without separation in to SiC and B4C, through far-for-equilibrium processing using sputtering or plasma melting. It is anticipate that such a fundamental investigation of Si containing boron carbide will provide insights into how to improve its mechanical properties in order to minimize damage from high-pressure impacts. The project also provides training in latest materials processing and characterization techniques to graduate students.