Experimental Design Applied to the Chemical Durability of Sol–Gel‐Derived Zirconias

A statistical design was used to investigate the effects of various processing conditions on the chemical durability of sol–gel‐derived zirconias. Eight processing variables were investigated: water:alkoxide molar ratio, alcohol:alkoxide molar ratio, nitric acid:alkoxide molar ratio, mixing temperature during hydrolysis, firing temperature, heating rate, soak at firing temperature, and firing atmosphere. Processing variables were set at high and low limits in a main‐effects statistical design. The design identified four critical processing variables (listed in descending order of significance): firing temperature, firing atmosphere, water:alkoxide ratio, and nitric acid:alkoxide ratio. Sol–gel‐derived zirconias were characterized by differential scanning calorimetry, X‐ray diffractometry, and mercury intrusion. Suggestions are offered that may help to explain why these particular processing conditions influenced the chemical durability of sol–gel‐derived zirconias.