Synthesis of boron carbide powders from mono- and polysaccharides

Surface Properties and Morphology of Boron Carbide Nanopowders Obtained by Lyophilization of Saccharide Precursors

“…In the first method, boric acid (H 3 BO 3 ) and mono- or polysaccharides were dissolved in distilled water in a molar ratio providing a boron to carbon ratio in the final powder of 1:9. After mixing the precursor in distilled water, the solutions were prepared as described in our earlier article [ 16 ], and then, they were dried overnight at 90 °C in a vacuum oven to obtain them in solid states. In the second method, the powders of boron carbide were prepared using a similar procedure as in the first method, but the only difference was that the solutions of boric acid mixed with different saccharides were freeze-dried to remove water from the precursor’s powders.…”

“…Powders obtained from carbothermal reduction are strongly agglomerated and aggregated, so they require intensive crushing and grinding so that they become suitable for further use. The main problem is to reduce the cost of synthesis; many researchers have attempted to lower the synthesis temperature using various organic carbon precursors such as phenolic resin, citric acid, polyvinyl alcohol (PVA), and carbohydrates (cellulose, glucose, and sucrose) with boric acid (H 3 BO 3 ) [ 16 ]. When the boron carbide is synthesized from an organic precursor, the main problem during synthesis is the removal of water from precursors, which avoids the aggregation of particles in precursors, thereby significantly affecting the size and morphology of the boron carbide after synthesis.…”

“…Freeze-drying, also known as lyophilization or cryodesiccation, is a method of removing water by the sublimation of ice crystals from frozen material. Lyophilization is an effective method of drying materials without harming them and is commonly used mainly in the food and pharmaceutical industries [ 16 , 17 , 18 ]. Freeze-drying is also an effective method of removing water from the precursor obtained by the mixed solvent of boric acid and saccharides.…”

“…Previous work by our research group [ 16 ] only focused on synthesized boron carbide from different types of saccharide precursors as the carbon precursor in carbothermal reduction and studied the influence of the used saccharide precursor with a molar ratio of carbon to boron of 9:1 on the morphology of the obtained boron carbide powders (B 4 C). In the present work, we aimed to verify the idea that the freeze-drying of mixed precursors (boric acid and different saccharides) has an important influence on the morphology and obtained size of boron carbide after synthesis.…”

Boron-Rich Boron Carbide Nanoparticles as a Carrier in Boron Neutron Capture Therapy: Their Influence on Tumor and Immune Phagocytic Cells

“…The most popular method is the carbothermal or magnesiothermic reduction of boric acid at a temperature over 2000 • C, but the powders produced by this method require intensive grinding and purification [11]. Fine-grained boron carbide powders can be obtained by the direct reaction between B 2 O 3 or H 3 BO 3 and organic carbon precursors, such as saccharose, cellulose, glycerine, and poly(vinyl) alcohol [12,13]. Such methods are timeconsuming and labor-intensive and require temperatures over 1600 • C, and carbon becomes an unavoidable impurity.…”