サブマイクロメーターサイズ粉体を用いた SiC のプロセッシングと力学特性へ及ぼすナノメーターサイズ SiC 粉体の混合効果
サブマイクロメーターサイズ粉体を用いた SiC のプロセッシングと力学特性へ及ぼすナノメーターサイズ SiC 粉体の混合効果
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混合纳米 SiC 粉末对亚微米 SiC 加工和机械性能的影响
DOI：
10.2109/jcersj.113.466
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发表时间：
2005
影响因子：
1.1
通讯作者：
好洋 平田
中科院分区：
文献类型：
--
作者：
宣浩 日高;好洋 平田
将800 nm-SiC粉末（75体积%）与30 nm-SiC粉末（25体积%）在pH 5的含有中值尺寸为0.2 μm的Al 2 O3粉末的0.05-0.3 M-Y（NO3）3溶液中混合，以使烧结添加剂（Al 2 O3+钇离子）均匀地分布在SiC颗粒周围。在20体积%的SiC悬浮液中，通过带正电荷的Al 2 O3和钇离子的异相凝聚，形成了带负电荷的SiC颗粒的网络结构。聚丙烯酸的加入增加了胶体SiC颗粒的润湿性，并由于带负电荷的聚合物、钇离子和SiC表面之间的静电相互作用，增加了钇离子在SiC表面的固定量。SiC（800 nm SiC 75%-30 nm SiC 25%）-Al 2 O3（1.2体积%）-Y3+离子（1.2-3.2体积% Y2 O3）体系的水悬浮液通过在石膏模具中浇铸而固结，并形成理论密度为36-38%的绿色压块。这些SiC压块在Ar气氛中在1950°C下热压至相对密度96.8-100%。在800 nm SiC中加入30 nm SiC，减小了热压SiC的晶粒尺寸和裂纹尺寸，提高了材料的抗弯强度和断裂韧性。由该混合粉末体系制备的平均晶粒尺寸为2.0 μm的致密SiC具有如下优异的力学性能：平均四点弯曲强度为812 MPa，断裂韧性为6.0 MPa·m1/2，维氏硬度为18-20 GPa。
An 800 nm-SiC powder (75 vol%) was mixed with a 30 nm-SiC powder (25 vol%) in a 0.05-0.3 M-Y(NO3)3 solution containing an Al2O3 powder of median size 0.2 μm at pH 5 to distribute homogeneously the sintering additives (Al2O3+ yttrium ions) around the SiC particles. In a 20 vol% SiC suspension, the network structure of negatively charged SiC particles was formed by the heterocoagulation through the positively charged Al2O3 and yttrium ions. Addition of polyacrylic acid increased the dispersibility of colloidal SiC particles and the amount of yttrium ion fixed to the SiC surfaces owing to the electrostatic interaction among negatively charged polymer, yttrium ions and SiC surfaces. The aqueous suspension of the SiC (800 nm SiC 75%-30 nm SiC 25%)-Al2O3 (1.2 vol%)-Y3+ ions (1.2-3.2 vol% Y2O3) system was consolidated by casting in a gypsum mold and formed green compacts of 36-38% theoretical density. These SiC compacts were hot-pressed to relative density 96.8-100% at 1950°C in an Ar atmosphere. The addition of 30 nm-SiC to 800 nm-SiC decreased the grain size and flaw size of the hot-pressed SiC and improved the flexural strength and fracture toughness. The dense SiC with 2.0 μm of average grain size, prepared from the mixed powder system, showed the following excellent mechanical properties: average four-point flexural strength of 812 MPa, fracture toughness of 6.0 MPa•m1/2 and Vickers hardness of 18-20 GPa.