Si粉和Si-Al复合粉加入量对原位合成Al_2O_3-SiC-SiAlON材料抗氧化性的影响

Effects of Si powder and Si-Al composite powder on oxidation resistance of in-situ formed Al_2O_3-SiC-SiAlON composites

以电熔白刚玉、α-Al2O3微粉、Si粉、Al粉为原料,在普通刚玉砖的配料中分别加入5%(质量分数,下同)和8%的Si粉或7%(Si)+1%(Al)、5%(Si)+3%(Al)和3%(Si)+5%(Al)的Si-Al复合粉,以树脂为结合剂,在150MPa下成型为25mm×25mm×125mm的5组试样,经150℃24h固化后,在埋炭条件下于1500℃保温3h烧成,冷却后在空气中进行常规热重分析和大试样热重分析,测量氧化后试样剖面的氧化层厚度和氧化面积百分数,并进行了相应的XRD和SEM分析。结果表明:1)原位合成的刚玉-SiC-SiAlON试样的氧化属于保护性氧化;2)随着Si粉加入量的增加,试样的抗氧化性增强;随着Al粉的加入及其加入比例的增大,试样的抗氧化性减弱。

Five groups specimens with the size of 25 mm×25 mm×125 mm were prepared using white fused alumina,ultra fine α-Al2O3,Si powder and Al powder as starting materials, resin as binder,adding Si powder （5%,8%,respectively） or Si-AI composite powders （7% Si＋1% Al,5% Si ＋3% Al and 3% Si ＋5% Al, respectively） ,pressing at 150 MPa,drying at 150℃（3 for 24 h,carbon-embedded firing at 1500 ℃ for 3 h, then cooling. The specimens were investigated by DTA and thermo-gravimetric apparatus for large size specimens. The thickness of oxidized layer and the oxidized area percentage of section of oxidized speci- mens were tested, and corresponding XRD and SEM analysis were conducted. The results show that= （ 1 ） The characteristic of oxidation of these composites belong to protective type;（2） The oxidation resistance is improved with increase of Si addition,and oxidation resistance is decreased with increase of Al addition.