INFLUENCE OF PROCESS PARAMETERS ON THE QUALITY OF CERAMIC SHELL MOULDS WITH AQUEOUS SILICA SOL BINDER GRADE VT-1302U11 Development by Vacuumtech LLC.

Abstract

The article presents an analysis of the shell mold formation process in investment casting using a silica sol binder. The investment casting method is significant for producing complex, precise, and critical components from ferrous metals and alloys. This is particularly important for industries such as aerospace, power engineering, and defense, where heat-resistant and stainless steels. The high requirements for mechanical properties and geometric stability of such castings necessitate improvements in mold formation technology.

Factors such as slurry viscosity, shear rate during application, and the granulometric composition of the filler were investigated. The study aims to achieve maximum stability of the production cycle and improve casting quality by minimizing defects. Using experimental modeling methodology, the influence of key controlled parameters in the ceramic formation process – viscosity, dwell time, and draining technology (input data) – on the properties of shell molds was examined. These properties include strength, edge thickness, thickness on curved surfaces, and cracking load (output data).

Using experimental modeling software, several distinct parameter combinations for the tested slurries were created. No interaction between factors was observed, meaning each factor produced a response independently of other input factors. A change in the viscosity of the tested systems by 4 s had no effect on the properties of the ceramic shell mold. None of the factors influenced cracking. The draining technology and dwell time did affect the properties of the control samples. Reducing the block's dwell time in the slurry by 10 s leads to a slight increase in thickness and an increase in the breaking load. The draining technology does not affect the thickness of the ceramic layer on flat surfaces but directly impacts the thickness on curved surfaces. When forming blocks with a complex gating system, an increase in dwell time may lead to a reduction in the thickness of the ceramic layer under the feeders (gates). In some cases, increasing the dwell time also eliminates the need for a pre-wetting agent. For foundries frequently facing the defect of edge cracking, reducing the draining time to achieve uniform edge coverage may be more effective than increasing viscosity. Reducing the dwell and draining times allows a foundry to enhance productivity by spending less time immersing the block in the slurry.