Z 0036 (OTTO) Zirconium pieces, 1-10 mm, 99.99% Cas 7440-67-7 - used in space vehicles where resistance to heat is needed. Z 0036 (OTTO) Zirconium pieces, 1-10 mm, 99.99% Cas 7440-67-7 - used in space vehicle parts for their resistance to heat, an important quality given the extreme heat associated with atmospheric reentry.