Product Description
PaperID: 1014
EventID: 20
Author: Dr. Grant Bradley, Remet Corporation
Abstract: Measuring the rheological properties of abrasive fluids such as ceramic slurries used in precision investment casting has always been hard on the rheometer leading to scored and abraded components along with drifts in calibration. Dynamic Mechanical Analysis (DMA) is a technique used to measure the mechanical properties of a wide range of materials. Many materials, including polymers used in ceramic slurries, behave both like an elastic solid and a viscous fluid, thus the term viscoelastic.
In this paper, use of DMA in a shearing mode is explored as a reliable, repeatable method of obtaining rheological information over a range of shear values without damaging the instrument. Various foundry slurries are measured and compared with laboratory and experimental slurry systems. We report on correlation of rheological properties obtained by DMA compared to Brookfield laboratory viscometer. Measurements in shear mode provides PIC foundry customers with advantages not provided by any other measuring systems. For instance, samples can be run from high to low stiffness without any drastic volume and geometry changes to ensure correct measurements of viscoelastic properties of binder slurry systems.
DMA differs from other mechanical testing devices in two important ways. First, typical tensile test devices focus only on the elastic component. In many applications, the inelastic, or viscous component, is critical. It is the viscous component that determines properties such as green strength in investment cast ceramic shells. Second, tensile test devices work primarily outside the linear viscoelastic range. DMA works primarily in the linear viscoelastic range and is therefore more sensitive to structure of polymer based binders.
Paper Pages: 26
Paper Year: 2015
Paper Index: 2:308
Paper Source: 82
