Back
 MSA  Vol.9 No.12 , November 2018
Green Microstructural Visualization of Dry-Pressed Spray-Dried Alumina (Al2O3)
Abstract: Slurry parameters were controlled prior to spray-drying to visualize and govern an understanding of which parameters govern hollow coring and granule morphology during spray-drying. An aqueous alumina using a polyvinyl alcohol binder (PVA) system was analyzed and granules were processed by altering the slurry specific gravity and viscosity value prior to spray-drying. Spray-dried granules were uniaxial dry-pressed at varying moisture contents to show the plasticizing effects of moisture during compaction. A novel characterization method using a field emission electron microscope (FESEM) was implemented to image the green microstructures of the granules and compacted samples. Slurries with a higher specific gravity and viscosity resulted in denser granules with spherical shapes. Viscosity affected the binder segregation during the spray-drying process. Granules stored at higher moisture contents resulted in denser compacts with fewer intergranular pores and cracks along granule boundaries. Using a FESEM resulted in higher resolution for green microstructural characterization.
Cite this paper: Maher, I. and Haber, R. (2018) Green Microstructural Visualization of Dry-Pressed Spray-Dried Alumina (Al2O3). Materials Sciences and Applications, 9, 936-948. doi: 10.4236/msa.2019.912067.
References

[1]   Uematsu, K., Kim, J. Y., Miyashita, M., Uchida, N. and Saito, K. (1990) Direct Observation of Internal Structure in Spray-Dried Alumina Granules. Journal of the American Ceramic Society, 73, 2555-2557.
https://doi.org/10.1111/j.1151-2916.1990.tb07635.x

[2]   Zhang, Y., Uchida, N. and Uematsu, K. (1995) Direct Observation of Non-Uniform Distribution of PVA Binder in Alumina Green Body. Journal of Materials Science, 30, 1357-1360.
https://doi.org/10.1007/BF00356144

[3]   Uematsu, K. (1996) Immersion Microscopy for Detailed Characterization of Defects in Ceramic Powders and Green Bodies. Powder Technology, 88, 291-298.
https://doi.org/10.1016/S0032-5910(96)03133-6

[4]   Zhang, Y., Tang, X., Uchida, N. and Uematsu, K. (1998) Binder Surface Segregation during Spray Drying of Ceramic Slurry. Journal of Materials Research, 13, 1881-1887.
https://doi.org/10.1557/JMR.1998.0267

[5]   Hotta, T., Nakahira, K., Naito, M., Shinohara, N., Okumiya, M. and Uematsu, K. (1999) Origin of Strength Change in Ceramics Associated with the Alteration of Spray Dryer. Journal of materials research, 14, 2974-2979.
https://doi.org/10.1557/JMR.1999.0398

[6]   Shinohara, N., Okumiya, M., Hotta, T., Nakahira, K., Naito, M. and Uematsu, K. (1999) Formation Mechanisms of Processing Defects and Their Relevance to the Strength in Alumina Ceramics Made by Powder Compaction Process. Journal of Materials Science, 34, 4271-4277.
https://doi.org/10.1023/A:1004611105281

[7]   Shinohara, N., Okumiya, M., Hotta, T., Nakahira, K., Naito, M. and Uematsu K. (1999) Seasonal Variation of Microstructure and Sintered Strength of Dry-Pressed Alumina. Journal of the American Ceramic Society, 82, 3441-3446.
https://doi.org/10.1111/j.1151-2916.1999.tb02262.x

[8]   Uematsu, K., Uchida, N., Kato, Z., Tanaka, S., Hotta, T. and Naito M. (2001) Infrared Microscopy for Examination of Structure in Spray-Dried Granules and Compacts. Journal of the American Ceramic Society, 84, 254-256.
https://doi.org/10.1111/j.1151-2916.2001.tb00646.x

[9]   Shinohara, N., Katori, S., Okumiya, M., Hotta, T., Nakahira, K., Naito, M., et al. (2002) Effect of Heat Treatment of Alumina Granules on the Compaction Behavior and Properties of Green and Sintered Bodies. Journal of the European Ceramic Society, 22, 2841-2848.
https://doi.org/10.1016/S0955-2219(02)00059-6

[10]   Saito, Y., Nyumura, J., Zhang, Y., Tanaka, S., Uchida, N. and Uematsu, K. (2002) Kinetics of Property Change Associated with Atmospheric Humidity Changes in Alumina Powder Granules with PVA Binder. Journal of the European Ceramic Society, 22, 2835-2840.
https://doi.org/10.1016/S0955-2219(02)00041-9

[11]   Saito, Y., Nyumura, J., Fukai, K., Zhang, Y., Uchida, N. and Uematsu, K. (2002) Moisture Diffusion in Alumina Green Compact Containing Polyvinyl Alcohol Binder. Journal of the Ceramic Society of Japan, 110, 237-242.
https://doi.org/10.2109/jcersj.110.237

[12]   Tanaka, S., Pin, C.C. and Uematsu, K. (2006) Effect of Organic Binder Segregation on Sintered Strength of DRY-Pressed Alumina. Journal of the American Ceramic Society, 89, 1903-1907.
https://doi.org/10.1111/j.1551-2916.2006.01057.x

[13]   Tanaka, S., Chia-Pin, C., Kato, Z. and Uematsu, K. (2007) Effect of Internal Binder on Microstructure in Compacts Made from Granules. Journal of the European Ceramic Society, 27, 873-877.
https://doi.org/10.1016/j.jeurceramsoc.2006.04.038

[14]   Imran, Z.M., Tanaka, S. and Uematsu, K. (2009) Effect of Polyacrylic Acid (PAA) Binder System on Particle Orientation during Dry-Pressing. Powder Technology, 196, 133-138.
https://doi.org/10.1016/j.powtec.2009.07.003

[15]   Zainuddin, M.I., Tanaka, S., Furushima, R. and Uematsu, K. (2010) Correlation between Slurry Properties and Structures and Properties of Granules. Journal of the European Ceramic Society, 30, 3291-3296.
https://doi.org/10.1016/j.jeurceramsoc.2010.07.004

[16]   Uematsu, K., Miyashita, M., Kim, J.Y. and Uchida, N. (1992) Direct Study of the Behavior of Flaw-Forming Defect in Sintering. Journal of the American Ceramic Society, 75, 1016-1018.
https://doi.org/10.1111/j.1151-2916.1992.tb04178.x

[17]   Hondo, T., Kato, Z., Yasuda, K., Wakai, F. and Tanaka, S. (2016) Coarse Pore Evolution in Dry-Pressed Alumina Ceramics during Sintering. Advanced Powder Technology, 27, 1006-1012.
https://doi.org/10.1016/j.apt.2016.04.009

[18]   Saito, Y., Tanaka, S. and Uchida, N. (2002) CLSM for Ceramic Green Microstructure. American Ceramic Society Bulletin, 81, 35-38.

[19]   Saito, Y., Tanaka, S., Uchida, N. and Uematsu, K. (2001) Direct Evidence for Low-Density Regions in Compacted Spray-Dried Powders. Journal of the American Ceramic Society, 84, 2454-2456.
https://doi.org/10.1111/j.1151-2916.2001.tb01035.x

[20]   Tanaka, S. (2006) Design of Packing Structures through Direct Characterization of Ceramics Green Bodies. Journal of the Ceramic Society of Japan, 114, 141-146.
https://doi.org/10.2109/jcersj.114.141

[21]   Tanaka, S., Kato, Z., Uchida, N. and Uematsu, K. (2003) Direct Observation of Aggregates and Agglomerates in Alumina Granules. Powder Technology, 129, 153-155.
https://doi.org/10.1016/S0032-5910(02)00226-7

[22]   Kato, Z., Tanaka, S., Uchida, N. and Uematsu, K. (2006) Observation of the Granule Packing Structure Using a Confocal Laser-Scanning Microscope. Journal of the European Ceramic Society, 26, 683-687.
https://doi.org/10.1016/j.jeurceramsoc.2005.07.005

[23]   Tanaka, S., Kuwano, Y. and Uematsu, K. (2007) Packing Structure of Particles in a Green Compact and Its Influence on Sintering Deformation. Journal of the American Ceramic Society, 90, 3717-3719.
https://doi.org/10.1111/j.1551-2916.2007.01975.x

[24]   Hondo, T., Kato, Z. and Tanaka, S. (2014) Enhancing the Contrast of Low-Density Packing Regions in Images of Ceramic Powder Compacts Using a Contrast Agent for Micro-X-Ray Computed Tomography. Journal of the Ceramic Society of Japan, 122, 574-576.
https://doi.org/10.2109/jcersj2.122.574

[25]   Deis, T.A. and Lannutti, J.J. (1998) X-Ray Computed Tomography for Evaluation of Density Gradient Formation during the Compaction of Spray-Dried Granules. Journal of the American Ceramic Society, 81, 1237-1247.
https://doi.org/10.1111/j.1151-2916.1998.tb02474.x

[26]   Cottrino, S., Jorand, Y., Maire, E. and Adrien, J. (2013) Characterization by X-Ray Tomography of Granulated Alumina Powder during in Situ Die Compaction. Materials Characterization, 81, 111-123.
https://doi.org/10.1016/j.matchar.2013.04.004

[27]   Lu, P., Lannutti, J.J., Klobes, P. and Meyer, K. (2000) X-Ray Computed Tomography and Mercury Porosimetry for Evaluation of Density Evolution and Porosity Distribution. Journal of the American Ceramic Society, 83, 518-522.
https://doi.org/10.1111/j.1151-2916.2000.tb01227.x

[28]   Ku, N. (2015) Evaluation of the Behavior of Ceramic Powders under Mechanical Vibration and Its Effect on the Mechanics of Auto-Granulation. Ph.D. Thesis, Rutgers University, New Brunswick.

[29]   Alazzawi, M.K., Murali, S. and Haber, R.A. (2017) Visualizing the Effect of Extrusion Velocity on the Spatial Variation of Porosity in a Titanium Dioxide/Binder System. Materials Sciences and Applications, 8, 933.
https://doi.org/10.4236/msa.2017.813068

[30]   Promdej, C., Areeraksakul, S., Pavarajarn, V., Shigetaka, W., Wasanapiarnpong, T. and Charinpanitkul, T. (2008) Preparation of Translucent Alumina Ceramic Specimen Using Slip Casting Method. Journal of the Ceramic Society of Japan, 116, 409-413.
https://doi.org/10.2109/jcersj2.116.409

[31]   Yu, B., Feng, Y.J., Wohn, L.S., Huang, C., Li, Y.F. and Jia, Z. (2011) Spray-Drying of Alumina Powder for APS: Effect of Slurry Properties and Drying Conditions upon Particle Size and Morphology of Feedstock. Bulletin of Materials Science, 34, 1653-1661.
https://doi.org/10.1007/s12034-011-0373-0

 
 
Top