This study is a refinement of a previous presentation (2010 ICI Conference) on the influence to thermal conductivity of a high emissivity coating applied to a fused silica shell system.

Heat transfer modifying treatments are commonly used in the investment casting industry as an attempt to influence the progression of solidification in a direction that feeds the volumetric contraction. Complex parts with marginally designed gating systems often suffer from a "latent defect" of internal shrinkage that may only be revealed after machining or failure in service.

While the high emissivity coating aids in the selective cooling of a fused silica shell, a variety of insulating techniques are also utilized to improve casting quality as they change the heat transfer characteristics of a fused silica shell and the quality of the investment casting.

This paper will describe the heat transfer test method utilized by Bescast, Inc. to report temperature loss as a function of time as well as the cooling rate difference as a function of time.

The selective applicaton of coating and insulating blankets provide the casting engineer more tools in the quest to provide the custoemr with casting that meet the internal soundness requirements for reliable performance.