| 272 | 11 | 25 |
| 下载次数 | 被引频次 | 阅读次数 |
采用粉煤灰、烧铝矾土和球黏土为原料,通过原位反应烧结合成球形多孔莫来石质支撑体。考察了烧结温度对多孔莫来石质支撑体相转变、晶粒尺寸、孔径分布和气孔率的影响,并对其莫来石化的机理进行了探讨。研究表明:在1300℃烧结温度下,二次莫来石在硅铝酸盐液相中通过溶解-沉淀机制开始成核,并于1400℃烧结发育成针状的晶粒;当烧结温度升至1500℃时,溶解在液相中的莫来石进行结构调整和生长,并最终在1550℃发生原位反应并形成刚性交错网络结构的柱状莫来石。在低温(<1400℃)烧结阶段,二次莫来石的成核和生长引起体积膨胀,导致气孔率随温度的升高而增大;在高温(≥1500℃)烧结阶段,大量玻璃相的存在使液相烧结占主导,气孔率因体积收缩呈下降趋势。支撑体的平均孔径随烧结温度的升高而增大,其原因是在高温烧结时莫来石生长消耗过多的SiO2使大量微孔联接形成大孔。
Abstract：Sphere porous mullite-based support for lightweight proppant was fabricated by in situ reaction sintering from a powder mixture of coal fly ash,calcined bauxite and ball clay.The effects of sintering temperature on phase evolution,grain size,pore size distribution and porosity were investigated.Moreover,the mullitization mechanism is discussed.The secondary mullite nucleate inchoately through a solution-precipitation mechanism via amorphous aluminosilicate phase at 1 300 ℃.The needle-like mullite grains were formed at 1 400 ℃.The dissolution of mullite in the permanent liquid phase could improve the growth of mullite at >1 500 ℃.The stiff skeleton net-structure mullite can be formed in situ.At low sintering temperature(<1 400 ℃),the volume expan-sion resultes from the formation and growth of secondary mullite,leading to the enhancement of porosity with increasing temperature.At ≥1 500 ℃,the presence of excess liquid glassy phase and the occurrence of liquid phase sintering are dominant,which results in the shrinkage of specimen and the decrease of porosity.The mean pore size for the support increased with increasing temperature.This is due to the consumption of excess SiO2 and the formation of larger size pores.
[1] MA X,YAO X,HUA S D,et al. Effects of MnO2 and Fe2O3 on micro- structure and crush resistance of alumina matrix fracturing proppant [J]. J Chin Ceram Soc (in Chinese),2009,37(2): 280-284.
[2] HAMMOND P S. Settling and slumping in a newtonian slurry,and implications for proppant placement during hydraulic fracturing of gas wells [J]. Chem Eng Sci,1995,50(20): 3247-3260.
[3] WEN Q Z,ZHANG S C,WANG L,et al. The effect of proppant em-bedment upon the long-term conductivity of fractures [J]. Petrol Sci Eng,2007 (55): 221-222.
[4] KONG L B,GAN Y B,ZHANG T S,et al. Mullite phase formation and reaction sequence with the presence of pentoxides [J]. J Alloys compd,2003 (351): 264-272.
[5] BARTSCH M,SCHMüCKER S B. Novel low- temperature processing route of dense mullite ceramics by reaction sintering of amorphous SiO2-coated γ-Al2O3 particle nanocomposites [J]. J Am Ceram Soc, 1999 (82): 1 388-1 392.
[6] ALEKSANDER J P,CLIFFORD S T,CHAN H. Formation mechanism and microstructure development in acicular mullite ceramics fabricated by controlled decomposition of fluorotopas [J]. J Eur Ceram Soc,2008 (28): 383-391.
[7] ZHANG G M,WANG Y C,FU Z Y,et al. Synthesis of mullite at low temperature and its chemical composition [J]. J Chin Ceram Soc (in Chinese),2008,11(36): 1 542-1 547.
[8] China National Petroleum Corporation. SY/T5108-1997 Recommended practice for testing proppants used in hydraulic fracturing operations [S]. Beijing: China National Petroleum Corporation,1997.
[9] GOMES S,FRANCOIS M,Characterization of mullite in silicoalumi- nous fly ash by XRD,TEM,and 29Si MAS NMR [J]. Cem Concr Res, 2000,30(2): 175-181.
[10] DONG Y C,FENG X Y,FENG X F,et al. Preparation of low-cost mullite ceramics from natural bauxite and industrial waste fly ash [J]. J Alloys compd,2008,460(1/2): 599-606.
[11] SAINZ M A,SERRANO F J,AMIGO J M,et al. XRD microstructural analysis of mullites obtained from kaolinite-alumina mixtures [J]. J Eur Ceram Soc,2000,20(4): 403-412.
[12] LIU K C,THOMAS G,CABALLERO A,et al. Mullite formation in kaolinite - α-alumina [J]. Acta Metall Mater,1994,42(2): 489-495.
[13] JOHNSON S M,PASK J A. Pole of impurities on formation of mullite up to 1 800 ℃ and microstructural development of ceramics [J]. Am Ceram Soc Bull,1982,61(8): 838-842.
[14] CHEN Y F,CHANG Y H,WANG M C,et al. Effects of Al2O3 addition on the phases,flow characteristics and morphology of the porous kao- lin ceramics [J]. Mater Sci Eng,2004,373(1/2): 221-228.
[15] SHE J H,OHJI T. Fabrication and characterization of highly porous mullite ceramics [J]. Mater Chem Phys,2003,80(3): 610-614.
[16] LIU Y F,LIU X Q,LI G,et al. Low cost porous mullite-corundum ceramics by gelcasting [J]. J Mater Sci,2001,36(15): 3687-3692.
基本信息:
中图分类号:TQ174.1
引用信息:
[1]马雪,姚晓,华苏东.原位反应合成多孔莫来石质支撑体及其显微结构(英文)[J].硅酸盐学报,2009,37(10):1777-1781.
基金信息:
南京工业大学博士论文创新基金(BSCX200706)资助项目
2009-10-15
2009-10-15