埋炭气氛下热处理C-Al体系物相和显微结构的演变

Evolution of phase and microstructure of C-Al system in carbon-embedded atmosphere firing

为了研究含铝粉的碳复合耐火材料物相和显微结构的变化过程,以-195鳞片石墨和w(Al)=99%的铝粉(≤0.074 mm)为主要原料,按1:1的质量比配料后,加入约占粉料总质量15%的酚醛树脂混合均匀,在液压机上成型。试样经250℃烘干12 h后,分别经800、1 000、1 200、1 400、1 600℃保温3 h埋石墨热处理,用XRD测定烧后试样的物相,并用SEM观察其断口形貌。研究表明:800℃时,铝粉熔融,并和树脂碳在石墨边缘形成粒状Al4C3;1 000℃时,Al4C3增多并发育长大,同时开始出现AlN;1 200℃时,Al4C3发育,呈板状,同时部分氮化成纤维状的AlN;1400℃时,Al4C3生成量减少,氮化或氧化成纤维状的AlN或Al2O3;1 600℃时,Al4C3消失,Al2O3或AlN长大、粗化。

In order to investigate the evolution of phase and microstructure of aluminum containing carbon composites, -195 graphite flake and ≤0. 074 mm aluminum powder （99% AI,mass percent,similar herein- after） were used as main starting materials. The mixture with i ： 1 of graphite and aluminum was well mixed with additional 15% phenolic resin and then shaped in a hydraulic machine. The pressed specimens were first dried at 250 ℃ for 12 h,and then graphite-embedded fired at 800,1 000,1 200,1 400,and 1 600 ℃ for 3 h, respectively. XRD and SEM were used to characterize the phase composition and section microstruc- ture. The results show that at 800 ℃ aluminum powder melts and reacts with carbon in resin forming granu- lar AI4C3 at the edge of graphite;at 1 000 ℃,AI4C3 increases in number and grows in volume,and AIN com- mences to form;at 1 200 ℃,some AI4C3 grows to tabular shape,and other AI4C3 nitridizes forming fibrous AIN;at 1 400 ℃,AI4C3 decreases because it is nitridized or oxidized forming fibrous AIN or AI203 ;at 1 600 ℃,AI4C3 disappears,AIN or AI203 gets big and coarse.