Synthesis and Characterization of the 312 and H-Phases

拟议的研究将研究两种新型陶瓷材料的物理性质。这两类是“312”相和“h”相（分别为M3BC2和M2BX，其中M是过渡金属，B是B族元素，如Si、Al、Ge、Sn、Pb、In、Ga， X是碳或氮）。这两类化合物都具有层状六边形结构，由b族元素和过渡金属碳化物（或氮化物）交替紧密堆积的层构成。这些物质在60年代末首次被发现，但后来被忽视了，直到PI和他的团队最近的初步工作表明它们具有不同寻常的性质。它们具有高导热性和导电性，不容易受到热冲击，并且像金属一样可加工。像陶瓷一样，它们是耐火和抗氧化的。各种成分的全致密、单相、散装样品将被制造和表征，以确定这些化合物的弹性、热学和电学性能作为温度和各向异性的函数。这项研究的目的是为了更好地了解这些化合物的键合性质，特别是b族元素与过渡金属碳化物或氮化物层之间的键合性质。这两类新陶瓷的物理性质将进行研究。这些物质在60年代末首次被发现，但后来被忽视了，直到PI和他的团队最近的初步工作表明它们具有不同寻常的性质。它们具有高导热性和导电性，不容易受到热冲击，并且像金属一样可加工。像陶瓷一样，它们是耐火和抗氧化的。这些材料具有多种潜在的结构和功能应用。＊＊＊

9705237 Barsoum The proposed research will study the physical properties of two new classes of ceramic material. The two classes are the `312' and the `H-phase' (M3BC2 and M2BX, respectively, where M is a transition metal, B is a group B-element such as Si, Al, Ge, Sn, Pb, In, Ga, and X is either carbon or nitrogen). Both classes have layered hexagonal structures, with alternating close-packed layers of the B-group elements and transition metal carbides (or nitrides). These materials were first identified in the late sixties, but then were ignored until recent preliminary work by the PI and his group showed that they had unusual properties. They have high thermal and electrical conductivity, are not susceptible to thermal shock, and are machinable like metals. Like ceramics, they are refractory and oxidation resistant. Fully dense, single phase, bulk samples of a variety of compositions will be fabricated and characterized to determine the elastic, thermal, and electrical properties of these compounds as a function to temperature and anisotropy. The objective of the research is to better understand the nature of the bonding in these compounds, especially that between the B-group elements and the transition metal carbide or nitride layers. %%% These two new classes of ceramics will be examined for their physical properties. These materials were first identified in the late sixties, but then were ignored until recent preliminary work by the PI and his group showed that they had unusual properties. They have high thermal and electrical conductivity, are not susceptible to thermal shock, and are machinable like metals. Like ceramics, they are refractory and oxidation resistant. These materials have a variety of potential structural and functional applications. ***