低氧分压下β-Si3N4制品的氧化烧结

Oxidation sintering of β-Si_3N_4 products under low oxygen partial pressure

以闪速燃烧氮化法合成的β-Si3N4粉为主要原料,在w(β-Si3N4粉)为80%、w(α-Al2O3粉)和w(Y2O3粉)分别为10%的混合粉料中,外加3%金属铝粉,混练、成型后,在1 600℃的弱氧化气氛(氮气中配入体积分数分别为0、10%、20%、30%的空气)中实现了β-Si3N4制品的逆氮化反应烧结。结果表明:空气配入量为10%时,得到的Si3N4烧结体指标较好;金属铝粉首先发生氧化,新生成的高活性Al2O3可促进烧结的进行;弱氧化气氛烧成时,通过氧分压来控制氧化物的生成量,既避免了SiN的过度氧化,又形成了活性烧结。

The retrorse nitridation reaction was achieved using mixture of Si3N4 powder β-Si3N4 synthesized by flash combustion method） ,α-Al2O3 powder and Y2O3 powder （with 8：1 ：1 mass ratio） as main starting materials, extra adding 3% aluminum powder, then mixing and shaping, firing in weak oxidizing atmosphere （adding 0, 10%, 20% and 30% （volume percent） air into N2, respectively） at 1 600 ℃. The results showed that, when the volume percent of air was 10%, the performance of sintered Si3N4 was better; the aluminum powder was oxidized firstly, the newly formed high activity Al2O3 could accelerate sintering; when firing in weak oxidizing atmosphere, the excessive oxidation could be avoided by controlling the generation amount of oxide through oxygen partial pressure,and there were active sintering.