The Effect of Silicon Particle Size on the Nitriding Behaviour of Reaction Bonded Si3N4 Compacts

Silicon Carbide–Silicon Nitride Refractory Materials: Part 1 Materials Science and Processing

“…Per [14][15][16] there is information as to what modification of silicon nitride gives Reaction (1) of liqu with nitrogen. Another thing is that the α-Si3N4 structure can accommodate smal of oxygen atoms [5,[14][15][16] and is more likely to occur via volatilization and satu resulting silicon nitride. Nitrogen can react with solid silicon, with molten silicon, and with gaseous silicon.…”

“…It is considered that at low temperatures, a film of silicon nitride is formed on the surfaces of solid particles of silicon. The formation of a film may stop the reaction, but it is believed [14,15] that the silicon nitride film is not continuous, and there are gaps and cracks through which nitrogen can penetrate to solid or liquid silicon. Silicon may evaporate through these gaps and cracks.…”

“…One point of view suggests [5] that the main product of the reaction of solid silicon with gaseous nitrogen is β-Si 3 N 4 (marked "3" in Figure 2), and the main product of the reaction of gaseous silicon with gaseous nitrogen is α-Si 3 N 4 (marked "2" in Figure 2). Per [14][15][16] there is no direct information as to what modification of silicon nitride gives Reaction (1) of liquid silicon with nitrogen. Another thing is that the α-Si 3 N 4 structure can accommodate small amounts of oxygen atoms [5,[14][15][16] and is more likely to occur via volatilization and saturation of resulting silicon nitride.…”

“…Per [14][15][16] there is no direct information as to what modification of silicon nitride gives Reaction (1) of liquid silicon with nitrogen. Another thing is that the α-Si 3 N 4 structure can accommodate small amounts of oxygen atoms [5,[14][15][16] and is more likely to occur via volatilization and saturation of resulting silicon nitride. Due to the positive weight effect of Reaction ( 1), the weight of the sintered materials is bigger than the weight the green shapes.…”

“…Per [14][15][16] there is no direct information as to what modification of silicon nitride gives Reaction (1) of liquid silicon with nitrogen. Another thing is that the α-Si3N4 structure can accommodate small amounts of oxygen atoms [5,[14][15][16] and is more likely to occur via volatilization and saturation of resulting silicon nitride. The average grain size of isometric crystals of silicon nitride is from 1 µm to 3-5 µm, the average diameter of needle like crystals of silicon nitride is from 0.5 µm to 2-3 µm, and the length of needle-like crystals is from 7-10 to 50 µm (Figure 2).…”