Synthesis of boron carbide from its elements at high pressures and high temperatures

Abstract

The formation of boron carbide under high pressures and from elemental reactants has been studied and optimum parameters have been determined by varying the (P, T, reactants) conditions.To this end, stoichiometric mixtures of commercial β rhombohedral boron and amorphous glassy carbon have been subjected to temperatures ranging from 1473 K to 2473 K at pressures of 2 GPa, 5 GPa and 13 GPa. Similar syntheses have been repeated for mixtures of β boron and graphite, and amorphous boron and amorphous carbon at 2 GPa and 5 GPa. The carbon concentration of boron carbide is shown to be affected by pressure at which it is synthesised from elements, and we propose pressure as a means to control the carbon content. The formation temperature is shown to be affected by the pressure and the choice of the reactants. The effect of temperature cycling on the formation temperature has also been studied. The formation of α boron as an intermediate phase is seen at 5 GPa before the formation of boron carbide.

Effect of Additives on the Reactive Sintering of Ti–B4C Composites Consolidated by Hot Pressing and Pressureless Sintering

“…Observation of grain size morphology strongly suggests that the most probable chemical reaction route was the presence of the liquid‐phase reaction. Thermodynamical calculations of free enthalpies for reactions possible in the investigated system indicate that the most favorable is the reaction between Ti and C. [ 48–59 ] …”

“…Observation of grain size morphology strongly suggests that the most probable chemical reaction route was the presence of the liquid-phase reaction. Thermodynamical calculations of free enthalpies for reactions possible in the investigated system indicate that the most favorable is the reaction between Ti and C. [48][49][50][51][52][53][54][55][56][57][58][59] Figure 7. The SEM images showing the microstructure of composites: a) 5% addition of titanium and boron and b) 20% addition of titanium and boron.…”

Boron carbide under torsional deformation: evidence of the formation of chain vacancies in the plastic regime

“…Three such experiments have been performed under a pressure of about 5 GPa, with various degrees of rotation of the anvils : 90°, 180°and 270°(table I). The pressure was determined by the value of the primary pressure on the press, which had been calibrated using in situ experiments at synchrotrons with pressure calibrants, similar to the calibration method for the conventional Paris-Edinburgh press [29][30][31]. In all of our experiments, only the lower anvil was rotated, while the upper one was kept fixed.…”

Performance of glucose, sucrose and cellulose as carbonaceous precursors for the synthesis of B4C powders

“…Therefore, acquiring the technical knowledge of B4C production, achieving its manufacturing technology from available raw materials, as well as using cost-effective fabrication methods are of special importance [8][9][10]. There are various techniques for synthesis of B4C ceramics including carbothermal reduction [11,12], synthesis from its elemental constituents [13,14], magnesiothermal reduction [15,16], chemical vapor deposition (CVD) [17][18][19], and synthesis from polymeric raw materials [20][21][22]. Among the above methods, the synthesis using constituent elements is not cost-effective due to the expensive pure raw materials required and is merely a research-based methodology for synthesis in the laboratory [23].…”