Precision investment casting, also known as the lost wax casting process, is an ancient metal forming technology. The technique is several thousand years old, originally producing ornaments and jewelry. Today, many high tech components are fabricated to tight tolerances using this technology.
Colloidal silica is used as an investment casting binder with refractory grains such as alumina, aluminosilicates, fused silica and zircon. These systems are used for the casting of many types of metals. NexSil 8, an eight nm alkaline sol, is a preferred binder for these systems.
For the higher alloys, reactive metals, or super alloys, NYACOL® offers colloidal zirconia and colloidal yttria binders. These binders are used for the prime coat layer only, with the subsequent backup layers using colloidal silica such as NexSil 8.
NYACOL® Zirconia Acetate is a preferred binder for the casting of titanium. When properly used with an appropriate refractory, titanium castings with reduced surface “alpha case” can be prepared. NYACOL® can provide guidance on how to use this binder including maintenance of the investment casting slurry.
NYACOL® Colloidal Yttria sol is finding increasing use as a binder for the casting of titanium, nickel and cobalt super alloys. Yttria sol used with yttria refractory as the prime coat can provide a very low reactivity surface for the casting of these metals.
NYACOL® sols have many uses in ceramics. They can function as high temperature binders for bricks and other monolithic applications. In certain ceramics, they can act as sintering aids to improve or control microstructure and physical properties.