Sintered ceramic body of large dimension and method of making

A method of making a sintered ceramic body, the method comprising the following process steps:

• a. disposing at least one ceramic powder inside an inner volume of a spark plasma sintering tool, wherein the spark plasma sintering tool comprises:
• a die comprising a sidewall comprising an inner wall and an outer wall, wherein the inner wall has a diameter that defines the inner volume;
• an upper punch and a lower punch operably coupled with the die, wherein each of the upper punch and the lower punch have an outer wall defining a diameter that is less than the diameter of the inner wall of the die thereby creating a gap between each of the upper punch and the lower punch and the inner wall of the die when at least one of the upper punch and the lower punch are moved within the inner volume of the die, wherein the sintering tool has a central axis and the gap is from 10 μm to 100 μm wide, wherein the inner wall of the die comprises at least one conductive foil which has a minimum thickness of 25 μm and wherein the gap is measured from an inwardly facing surface of the conductive foil closest to the upper and lower punches to the outer wall of each of the upper and lower punches;
• b. creating vacuum conditions inside the inner volume;
• c. moving at least one of the upper punch and the lower punch to apply pressure to the ceramic powder while heating the ceramic powder to a sintering temperature and sintering the ceramic powder to form the sintered ceramic body;
• and
• d. lowering the temperature of the sintered ceramic body,
• wherein the at least one ceramic powder has a specific surface area of from 1 to 18 M2/g as measured according to ASTM C1274 and
• the inner diameter of the die is greater than or equal to 100 mm.