Low-Temperature Synthetic Route for Boron Carbide Powder from Boric Acid-Citric Acid Gel Precursor

Abstract

Boron carbide powder was synthesized by sol-gel polycondensation of boric acid with citric acid. The starting materials of Serbian origin were dissolved in water and mixed homogeneously until a precomposite gel was formed, which was converted into cryogels after freeze-drying. Pyrolysing and subsequent heat treatment of these cryogels resulted in boron carbide materials. Characterization by nitrogen adsorption showed that the precomposite cryogels and the composite powders were micro and mesoporous materials with large surface areas. Materials have been analyzed by means of X-ray diffraction and scanning electron microscopy. The Rietveld refinement was employed to get the structural information of the synthesized powder. The results show that the obtained carbide powder is composed of nearly equiaxed particles of narrow size distribution.

Ethylene glycol assisted low-temperature synthesis of boron carbide powder from borate citrate precursors

“…Fig. 4 also indicates that the formation of B 4 C is accomplished at 1350 • C for samples with EG additions, which is around 100-300 • C, a lower temperature than that reported for B 4 C synthesis using a condensed product with CA [15][16][17][18]. Fig.…”

“…An alternative to above processes is the utilization of polymer precursors, e.g. sucrose and glucose, glycerin, polyols, and phenolic resin, as low-temperature synthetic route to B 4 C facilitated by improving the homogeneity and dispersibility of B 2 O 3 and carbon [11][12][13][14][15][16][17][18][19][20][21][22]. Nevertheless, the disadvantage of using organic precursors is the presence of residual carbon in the products synthesized at lower temperatures.…”

“…Nevertheless, the disadvantage of using organic precursors is the presence of residual carbon in the products synthesized at lower temperatures. Citric acid (CA) has been employed to produce B 4 C with significant residual carbon at 1500-1900 • C [15][16][17][18]. Recently, it is indicated that the addition of tartaric acid to boric acid (BA)-glycerin ameliorates the dispersion of B 2 O 3 /C [21].…”

Optimization of the decarbonizing ratio of boron carbide powders by reverse flotation using response surface methodology

“…Heating a mixture of boric acid and carbon in an electric arc furnace at a temperature close to the melting point of B 4 C. [21][22][23][24][25][26][27] However, as the reaction progresses, there are large temperature differences in different areas of the electric arc furnace. The reaction is not complete at low temperatures (473-273 K) away from the central area, which results in the presence of large amounts of free carbon.…”

Recycling of Hazelnut Shell: Synthesis of Boron Carbide by Carbothermic Reaction

“…The metallothermic method is not favorable because of the high cost of reactant (elemental boron). The carbothermic process includes cheaper raw materials, for example, boron oxide and boric acid which is reduced by carbon to give boron carbide [5,6]. There are several studies for the usage of different types of carbon sources, such as citric acid gel [6][7][8][9], sucrose [10][11][12][13] and organic polymer precursor [14,15].…”