The Influence to Thermal Conductivity of a High Emissivity Coating to a Fused Silica Shell System

摘要

This study is a refinement of a previous presentation (2010 ICI Conference) on theinfluence to thermal conductivity of a high emissivity coating applied to a fused silicashell system.Heat transfer modifying treatments are commonly used in the investment casting industryas an attempt to influence the progression of solidification in a direction that feeds thevolumetric contraction. Complex parts with marginally designed gating systems oftensuffer from a “latent defect” of internal shrinkage that may only be revealed aftermachining or failure in service.While the high emissivity coating aids in the selective cooling of a fused silica shell, avariety of insulating techniques are also utilized to improve casting quality as they tochange the heat transfer characteristics of a fused silica shell and the quality of theinvestment casting.This paper will describe the heat transfer test method utilized by Bescast, Inc. to reporttemperature loss as a function of time as well as the cooling rate difference as a functionof time.The selective application of coating and insulating blankets provide the casting engineermore tools in the quest to provide the customer with casting that meet the internalsoundness requirements for reliable performance.