The Effect of Acid concentration and temperature variation on α-Alumina Particle Size in acidic Method

Nanocrystalline alumina, which is the most widely used ceramic materials in the industrial applications, has several advantageous engineering properties such as high mechanical strength and hardness as well as wear, corrosion and heat resistance capability. Therefore, it has considerable potential for a wide range of applications including electronic ceramics, high strength materials and catalysts [1–3]. Conventional methods for the synthesis of alumina are mechanical milling, vapor phase reaction, precipitation, hydrothermal and sol-gel [4]. The formation of α -phase alumina usually occurs at around 1150°C. The temperature of complete transformation of γ alumina to α-Al2O3 is reported from 1000 to 1400°C depending on the employed synthesis techniques as well as different precursors [4-6]. Among these methods, sol–gel method is the most promising one for preparing highly pure powders with high specific surface area. However, high cost of precursors such as metal alkoxides and long gelation time are the main restrictions of this method. Recently, simple acetic acid gel method has been used to prepare nanocrystalline powders, which is a relatively easy process, less energy consumer and cost effective compared to the other sol-gel based methods. The focus of this study was to produce nanocrystalline α-alumina in different acid concentration solutions by acetic acids, which have various functional groups such as carboxyl (COOH) and hydroxyl (OH). Moreover, the phase transformation and morphology of the synthesized powders were investigated