CFF-Z based on partially stabilized zirconia withstand temperatures up to 1700â. CFF-Z is used in the filtration of steel grades from carbon to stainless and super alloys. There are many benefits to the steel foundry including fewer reoxidation and subsurface defects and a higher casting yield. CFF-Z is highly thermal shock resistant, a must for the steel foundry.CFF-Z are available in many standard and custom sizes, shapes, and pore sizes.