Analysis of powders and powder dispersions
Various forms of powder, i.e. tiny particles, can form both the raw material and the final product in many fields. Particle size, chemical composition etc., together with their behaviour in many media are frequently completely decisive for a process or product. Swerea IVF has long experience of powder handling and powder characterisation, particularly in the ceramics field, but also for other applications.
Powders are handled in many industrial processes, and in many different ways. The properties of a powder influence both its utility in a process and the final product/material characteristics. Manufacture of ceramics and sintered metallic materials are examples where knowledge of the physical properties (particle size, particle shape etc.) and chemical properties (chemical formula, surface chemistry etc.) of the original powder is very important for optimising a shaping process or a property of the material. Powder characterisation at Swerea IVF can be done via:
• Density via helium pycnometry
• Particle size measurement with a Sedigraph (X-ray sedimentation)
• Specific surface area via gas adsorption (BET)
• Image analysis in a Scanning Electron Microscope (SEM) for particle size, particle shape (morphology) and chemical composition.
In many cases, the powders are going to be handled in a fluid and the flow properties (rheology) of the dispersion will be of decisive importance for the result of the process in question. Rheological measurement (viscosity, visco-elastic characteristics) provides answers to various effects related to the properties of the powder and how well the particles are separated (dispersed) in the fluid. Rheological measurement can also be linked to the process in question if the conditions are known and can be defined. i.e. the rheology can be simulated. Swerea IVF has access to an advanced rotation-rheometer with considerable capacity for shear/stress and temperature ranges. Examples of rheological measurements are:
- Equilibrium viscosity at different shear rates
- Yield point measurement
- Oscillation for visco-elastic characterisation; the relationship between viscous and elastic properties.
Please contact us if you are interested in more information about different methods of analysis, and/or a discussion about your specific requirements. For questions related to SEM analyses, please contact Lars Eklund (+46 31-706 62 93, firstname.lastname@example.org).
Surface chemistry and rheology