TEM and DSC studies on the synthetic diamond grown from Fe–Ni–C–B system under HPHT

Abstract

Diamond was synthesized by the static pressure catalyst method may contain many kinds of impurities [1], which can affect the color, hardness, strength, thermal conductivity, optical absorption, and other physical properties of diamonds [2]. Evergrowing requirements imposed on thermal management materials in applications such as microelectronics; optical communications and semiconductor processing equipment drive the development of new materials with enhanced thermal conductivity [3]. The boron and nitrogen were two important impurities that could control the electronic properties of diamond through playing roles of donor and acceptor [4]. The reports on boron in the synthetic diamond grown at high-pressure high-temperature (HPHT) has not been found compared to that on nitrogen, which was ever studied extensively [5, 6]. Besides the effect on the electronic resistance of diamond, born could influence the outset temperature of oxidation resistance, i.e., the thermal stability of diamond crystals [7]. Further studies of the boron effect on thermal stability of diamond would have great significance in mechanical industry. In present paper, investigation was focused on both the microstructure and chemical composition of boron compounds in the diamond and their influence on the thermal stability of diamond crystals synthesized using Fe–Ni–B metal catalyst under HPHT conditions. In addition, we examined the effect of boron compounds on the outset temperature of oxidation resistance of synthetic diamond grown using boron-contained catalyst by different scanning calorimetry (DSC) techniques. Four alloys: Fe–Ni, Fe–Ni–0.01wt%B, Fe–Ni– 0.1 wt%B and Fe–Ni–0.4 wt%B, sampled as A, B, C, and D, respectively, were used as metal catalysts. They were placed alternately with graphite discs (purity 99.9%) to synthesize four types of boron-content diamond. In order