Variations in a boehmite gel and oleic acid emulsion under calcination

In this paper, we describe variations in a boehmite (AlOOH) and oleic acid emulsion during the process of forming superfine alpha-Al2O3 crystallites from the mixture of oleic acid and a boehmite gel precursor. We also propose that the oleic acid decomposes under calcination, generating carbon, which can effectively prevent agglomeration of Al2O3 particles. Calcination for the present study was conducted under a reduced oxygen atmosphere, in the temperature range 25degrees-1100degreesC. Phase variations of the mixture under calcination were identified by Fourier transform infrared spectrometry (FTIR), X-ray diffractometry (XRD), and transmission electron microscopy (TEM). The FTIR spectra were used when the mixed emulsion of oleic acid and boehmite gel was heated, to investigate the adsorption reaction of the aluminum oleate; the C-O-C cross-linking structure of oxygenation, which aided in carbon formation; and the ability of the carbon generated with alpha-Al2O3 during phase transformation to prevent agglomeration (vermicularity). The products were analyzed by XRD at different temperatures, and TEM was used to examine the individual diameters of the alpha-Al2O3 crystallites.