Zirconia Foam Filters These are used in molten steel and other alloys filtration. They can sustain very high temperatures up to 1700 C. Typical characteristics include: a) Yellow Color b) Application Temperature: < or Equal to 1,700 C c) ZrO3 Content > or Equal to 70% d) Typically Used in Molten Stainless Steel and Alloy Filtration in Precision Molding. e) Pore Size: 10 - 35 PPI