微波混合加热法合成Cr_2AlC陶瓷粉体

Synthesis of Cr_2AlC Ceramic Powder by Microwave Hybrid Heating

以Cr、Al、Cr_3C_2粉为原料,采用微波混合加热法在700~1 050℃内保温3 min,氩气保护下,合成了Cr_2AlC陶瓷粉体。考察了物料比、烧结温度对产物的影响。采用XRD、SEM、DSC对样品的物相、形貌进行了表征。结果表明,当原始组分中Al非过量时,样品为Cr_2AlC单相;当n(Cr_3C_2)∶n(Al)∶n(Cr)=1∶(2.1~2.4)∶1时,样品主相为Cr_2AlC,另有少量杂质相C(石墨)和Cr8Al5。微波混合加热到700~1 000℃时,目标相快速增加伴随着Cr-Al金属间化合物、未反应的Cr和Cr_3C_2的减少;在1 050℃时保温3 min,可获得单相Cr_2AlC陶瓷粉体,其平均颗粒尺寸为5~8μm。

Highly pure Cr_2AlC ceramic powders were synthesized by microwave hybrid heating pure Cr,Al and Cr_3C_2 powders at a temperature between 700 and 1 050 ℃ for 3 min in argon atmosphere. The effects of material ratio and sintering temperature on the resulting Cr_2AlC were studied. The phase composition and microstructure of samples were characterized by XRD,SEM and DSC techniques. The results indicated that single phase Cr_2AlC in the sample was obtained for composition n（Cr_3C_2） ∶n（Al）∶ n（Cr） = 1∶2. 0∶1. When n（Cr_3C_2） ∶n（Al） ∶n（Cr） = 1∶（2. 1 ~ 2. 4） ∶1,single phase Cr_2AlC with small amount of graphiteand Cr8Al5 was obtained. The amount of Cr_2AlC phase was increased rapidly by the reaction between Cr-Al intermetallic compounds,and un-reacted Cr and Cr_3C_2 was decreased in the temperature range of 700 ℃ to 1 000 ℃ by microwave hybrid heating. However,single phase Cr_2AlC ceramic powders with an average particle size in the range of 5 μm to 8 μm were achieved at 1 050 ℃for 3 min.