ABSTRACT SiC particulates reinforced alumina matrix composites were fabricated using Directed Metal Oxidation (DIMOX) process. Continuous oxidation of an Al-Si-Mg-Zn alloy with different interlayers (dopents) as growth promoters, will encompasses the early heating of the alloy ingot, melting and continued heating to temperature in the narrow range of 950°C to 980°C in an atmosphere of oxygen. Varying interlayers (dopents) are incorporated to examine the growth conditions of the composite materials and to identification of suitable growth promoter. The process is extremely difficult because molten aluminum does not oxidize after prolonged duration at high temperatures due to the formation of a passivating oxide layer. It is known that the Lanxide Corporation had used a combination of dopents to cause the growth of alumina from molten metal. This growth was directed, i.e. the growth is allowed only in the required direction and restricted in the other directions. The react nature of the dopants was a trade secret. Though it is roughly known that Mg and Si in the Al melt can aid growth, additional dopents used, the temperatures at which the process was carried out, the experimental configurations that aided directed growth were not precisely known. In this paper we have evaluated the conditions in which composites can be grown in large enough sizes for evaluation application and have arrived at a procedure that enables the fabrication of large composite samples by determining the suitable growth promoter (dopant). Scanning electron microscopic, EDS analysis of the composite was found to contain a continuous network of Al2O3, which was predominantly free of grain-boundary phases, a continuous network of Al alloy. Fabrication of large enough samples was done only by the inventor company and the property measurements by the company were confirmed to those needed to enable immediate applications. Since there are a large number of variable affecting robust growth of the composite, fabrication large sized samples for measurements is a difficult task. In the present work, to identify a suitable window of parameters that enables robust growth of the composite has been attempted.
Cite this paper
M. Devaiah, T. Srihari and T. Rajasekharan, "Identification of Growth Promoter to Fabrication SiCp/Al2O3 Ceramic Matrix Composites Prepared by Directed Metal Oxidation of An Al Alloy," Journal of Minerals and Materials Characterization and Engineering, Vol. 11 No. 11, 2012, pp. 1063-1068. doi: 10.4236/jmmce.2012.1111111.
 M. S. Newkirk, A. W. Urquhart and H. R. Zwicker, “Formation of Lanxide Ceramic Composite,” Journal of Materials Research, Vol. 1, No. 1, 1986, pp. 81-89.
 M. S. Newkirk, H. D. Lesher and D. R. White, “Formation of Lanxide Ceramic Matrix Composites: Matrix Formation by the Directed Oxidation of Molten Metals,” Ceramic Engineering & Science Proceedings, Vol. 8, No. 7-8, 1987, pp. 879-885.
 P. Barron-Antolin, G. H. Schiroky, and C. A. Anderson, “Properties of Fiber-Reinforced Alumina Matrix Com- posites,” Ceramic Engineering & Science Proceedings, Vol. 9, No. 7-8, 1988, pp. 759-766.
 K. Aghajanian, N. H. MacMillan, C. R. Kennedy, S. J. Luszcz and R. Roy, “Properties and Microstructures of Lanxide Al2O3-Al Ceramic Composite Materials,” Journal of Materials Science, Vol. 24, No. 2, 1989, pp. 658- 670. doi:10.1007/BF01107457
 A. S. Nagelberg, “Growth Kinetics of Al2O3/Metal Com- posites from a Complex Aluminum Alloy,” Solid State Ionics, Vol. 32-33, 1989, pp. 783-788.
 A. S. Nagelberg, S. Antolin and A. W. Urquhart, “Formation of Al2O3/Metal Composites by the Directed Oxida- tion of Molten Aluminum-Magnesium-Silicon Alloys: Part II, Growth Kinetics,” Journal of the American Ceramic Society, Vol. 75, No. 2, 1992, pp. 455-462.
 O. Salas, H. Ni, V. Jayaram, K.C. Vlach, C.Q. Levi and R. Mehrabian, “Nucleation and Growth of Al2O3/Metal Composites by Oxidation of Aluminum Alloys,” Journal of Materials Research, Vol. 6, No. 9, 1991, pp. 1964-1981. doi:10.1557/JMR.1991.1964
 E. Monar, H. Ni, C.G. Levi. and R. Meharabin, “Formation of Al2O3/Metal Composites by the Directed Oxidation of Molten Aluminum-Magnesium-Silicon Alloys: Part II, Growth Kinetics,” Journal of the American Ceramic Society, Vol. 75, No. 2, 1992, pp. 455-462.
 A. S. Nagelberg, “The Effect of Processing Parameters on the Growth Rate and Microstructure of Al2O3/Metal Ma- trix Composites,” Materials Research Society Symposium Proceedings, Vol. 155, 1989, pp. 155-275.
 A. W. Urquhart. “Molten Metals Sire MMC’s, CMC’s,” Advanced Materials and Processes, Vol. 140, No. 1, 1991, pp. 25-29.
 E. Breval, M. Aghajanian and S. Luszcz, “Microstruc- ture and Composition of Alumina/Aluminum Composites Made by Directed Oxidation of Aluminum,” Journal of the American Ceramic Society, Vol. 73, No. 9, 1990, pp. 2610-2614. doi:10.1111/j.1151-2916.1990.tb06735.x
 S. Antolin and A. S. Nagelberg, “Formation of Al2O3/ Metal Composites by the Directed Oxidation of Molten Aluminum-Magnesium-Silicon Alloy: Part I, Microstructural Development,” Journal of the American Ceramic Society, Vol. 75, No. 2, 1992, pp. 447-454.
 A. S. Nagelberg and S. Antolin, “Formation of Al2O3/ Metal Composites by the Directed Oxidation of Molten Aluminum-Magnesium-Silicon Alloy: Part II, Growth Kinetics,” Journal of the American Ceramic Society, Vol. 75, No. 2, 1992, pp. 455-462.