Densification is achieved only at temperatures >2000 ºC by grain boundary and volume diffusion .At higher temperatures,Exaggerated grain growth also takes place resulting in poor mechanical properties, so densification in lower temperature is Important and in dispensable for preparing B4C. Introducing sintering aids is a usual method to achieve this goal. Selection of the additive and the method of consolidation are dedicated by the end use of the product and the finally required properties . The additive by itself or expected to in situ reaction with main phase would form a nonvolatile second phase aiding in densification and property improvement. Hence ,selection of the additive should be focused on forming of a suitable structure which can provide the correct properties for use.