Powders
At CERAM, our extensive experience of powders extends from powders to powder suspensions and different processing routes. Used as coatings, fillers in shaped components or, indeed, to form shaped products in their own right, powders find use in many industries - pharmaceuticals, advanced ceramics, food and aerospace.
Where powders are dry and fine (particle sizes 50 microns and less), handling and processing can be problematic. By using powder suspensions however (powder dispersed but not dissolved in water or solvent), a range of different process routes then become available. For example, a suspension can be spray-dried to make a granulate (an agglomeration of fine powder particles) that can be subsequently pressed into a shape. Alternatively, a suspension can be cast in a porous mould. Suspensions can also be sprayed as a coating. Conversely, very high solids content suspensions possess a plasticity and so can be extruded.
The Importance of Powder Control
Regardless of industrial sector, the production and manipulation of powders invariably represent early stages in the full production process. Failure to optimise at this stage can have knock-on consequences in terms of intermediate and final product yields. Even if yields are not affected, product quality can be compromised.
At CERAM, our experts can assist in optimising powder processing through a combination of analytical testing and consultancy know-how. Consultancy associated with inorganic (ceramic, metal, glass) powders is a particular strength, although the same principles can be applied to virtually all powder processing.
Any investigation normally begins with analytical testing to provide baseline data. For powders, an assessment of particle size, particle shape, composition (via X-Ray Fluorescence) and crystal structure (X-Ray Diffraction) provides useful information. When powders are dispersed in water, measurement of rheology and zeta potential compliment the above techniques.
Armed with baseline test data, our experts can then apply their knowledge of factory processing and suggest and provide solutions via a number of routes. These include:
- use of additives, pH changes to optimise zeta potential and so rheology for subsequent processing
- making key measurements on intermediate products "downstream" (for example, strength measurements on items pressed from granulate; appraisal of powder coating thickness)
- use of Factorial Experimental Design (FED) to demonstrate strong correlations between a given powder property and key end-product properties
- recommendations for QC tests and associated protocols.
Applications
| Industrial Sector | Application Examples |
|---|---|
| Aerospace | Generation of stable, Cr-free coatings for turbines used in engines |
| Minerals | Assisting mineral suppliers in assessing and optimising primary or waste mineral materials for use on ceramics |
| Biomedical | Optimising refractory slurries to minimise losses in investment casting of alloy implants |
| Biomedical | Maximising yields of calcium phosphate phases subsequently processed as dental/bone cements |
| Electronics & Petrochemical | An investigation into nano-structured zirconia and barium titanate components for improved performance in drilling valve and capacitor applications respectively |
| Ceramics | Creation of a web-based knowledge system to assist SME producers in identifying, then optimising, additives for yield gains |
| Electronics | Controlling glass-powder stability in aqueous suspensions prior to spray-drying and pressing "performs" |
Powders Expertise - Investment Casting Control
CERAM's expertise sought regarding ceramic slurries for investment casting.