The search for novel, superhard materials

Abstract

The recent development in the field of superhard materials with Vickers hardness of ⩾40 GPa is reviewed. Two basic approaches are outlined including the intrinsic superhard materials, such as diamond, cubic boron nitride, C3N4, carbonitrides, etc. and extrinsic, nanostructured materials for which superhardness is achieved by an appropriate design of their microstructure. The theoretically predicted high hardness of C3N4 has not been experimentally documented so far. Ceramics made of cubic boron nitride prepared at high pressure and temperature find many applications whereas thin films prepared by activated deposition from the gas phase are still in the stage of fundamental development. The greatest progress has been achieved in the field of nanostructured materials including superlattices and nanocomposites where superhardness of ⩾50 GPa was reported for several systems. More recently, nc-TiN/SiNx nanocomposites with hardness of 105 GPa were prepared, reaching the hardness of diamond. The principles of design for these materials are summarized and some unresolved questions outlined.

High-pressure studies with x-rays using diamond anvil cells

“…Light element compounds in the B-C-N-O system are the most appealing materials for novel superhard materials; inspiring extensive studies e.g. [22,655,[668][669][670].…”

Электронная структура, механическая и динамическая стабильность гексагональных субкарбидов M-=SUB=-2-=/SUB=-C (M = Tc, Ru, Rh, Pd, Re, Os, Ir, Pt): ab initio расчеты

“…), см. [60][61][62]. Указанные упругие параметры тесно связаны с дру-гими фундаментальными физическими свойствами мате-риалов, таких как температура Дебая (θ D ) и скорость звука (ν m ).…”

Potensi Pembentukan Lapisan Super Dan Ultra Keras Senyawa Komposit Nitrida Menggunakan Kaidah Elektrodeposisi

“…Namun pembentukan lapisan TiAlN yang dikombinasikan dengan Si3N4 mampu mempertahankan kekerasan meskipun pada aplikasi suhu tinggi. Hal ini disebabkan oleh pengaturan sendiri (self-organization) struktur nano lapisan sebagai hasil dari segregasi fase secara termodinamika [7]. Selain itu lapisan TiAlN memiliki kestabilan terhadap oksidasi hingga suhu 800 0 C melalui pembentukan lapisan pasif oksida (AlTiO) [8] Senyawa nitrida keras lain adalah senyawa Si3N4 yang merupakan senyawa keramik dengan sifat mekanik, kestabilan kimia, dan konduktivitas termal yang baik khususnya pada suhu tinggi.…”