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Localized Mechanical Property Characterization of Composites
Manufacturing and researching composite materials comes with a host of interesting and challenging problems. Reinforcement and matrix materials often have significant differences in their material properties that affect the behavior of the composite material as a whole. Composites researchers and manufacturers may seek to understand:
- Mechanical properties of each constituent material
- Distribution of constituent materials
- Interfacial characteristics between matrix and reinforcement material
- Behavior at elevated or reduced temperature
- Dynamic mechanical properties
Hysitron offers a suite of instruments to meet the mechanical testing needs for composites researchers and manufacturers. With our recently developed XPM (Accelerated Property Mapping) indentation technique, users can quickly obtain the mechanical properties of each material in their composites. Coupled with in-situ SPM Imaging, distribution of constituent materials can be easily measured. An electronic underfill material was characterized using XPM. The results are shown in Figure 1.
Figure 1. The topography and modulus of an electronic underfill material consisting of glass beads imbedded in a polymer matrix was mapped in a 10 x 10 µm area. 400 indents were performed in less than two minutes.
The Hysitron 2D Transducer is a useful tool for studying material behavior at the interface of constituents in a composite. For example, a researcher was interested in observing the behavior of boron carbide particles in an aluminum matrix when scratched at a constant force. One of the results is shown in Figures 2 and 3.
Figure 2. The researcher was interested in studying the characteristics of a composite consisting of boron carbide particles in an aluminum alloy matrix. A Hysitron 2D transducer was used to scratch an exposed particle. The topographical SPM images are 20 x 20 µm (left) and 10 x 10 µm (right)
Figure 3. The topography over the exposed particle was traced before and after the scratch. The particle was unmoved by a 1 mN constant load scratch.
Equipped with a nanoDMA® III transducer, users can measure the dynamic mechanical properties of polymeric composites. Often this technique is most useful when coupled with the xSol® High Temperature Stage so that the temperature dependent properties (such as storage or loss moduli) can be characterized. The glass transition temperature (Tg) can also be measured with a high degree of accuracy by performing a continuous DMA test while sweeping the temperature of the sample.
Figure 4. Tan(delta) curves of an electronic underfill composite tested at 10 and 220 Hz over a 40°C range.
The TriboIndenter line is equipped with several tools needed to properly characterize a variety of composite samples. In-situ SPM imaging and property mapping are powerful tools used to understand the distribution and mechanical properties of individual components in a composite material. These, in combination with the xSol system and nanoDMA technique, make a Hysitron TriboIndenter an indispensable tool for composite researchers and manufacturers.