The MPN dielectric and magnetic properties measurement systems are suited to most types of sample materials, including powders, solids, liquids.
The measurement systems use a long, high purity amorphous silica tube (with a “base” in it) to rapidly transport the sample back and forth between the furnace and the cavity ( see the section on “Cavity Perturbation Technique Details”). The high frequency system uses a 4 mm inside diameter (ID) sample holder tube, while the low frequency range system uses a 6 mm ID tube.There are two fundamental requirements on the sample:
- The "bulk" sample volume must be well defined and known.
- It must be possible to insert the sample down into the bottom of the holder tube, into the measurement position, without wetting or contaminating the walls of the holder above the sample position.
MPN has a punch/die set for pressing powder materials into pellets of the required sample size. Usually, three pellets, each ~ 4 mm long, are stacked to form a sample. Some powders will not press into pellets, and are simply poured into the holder and tamped down to the required density.
For solid materials, we do custom diamond core-drilling or honing to produce solid samples ( eg., ceramics, glasses), although the customer is urged to do his own sample preparation, when feasible.
For thick jells and very viscous mixtures ( eg., putty), a cork-borer can be used to form the required long rod-like sample.
For low-viscosity liquids, a commercially calibrated pipette system is attached to a long polyethylene tube to transfer a known amount of fluid into the bottom of the holder without contaminating the walls.
For highly viscous liquids, such as heavy oils, a Teflon tube is inserted into the oil, and a vacuum applied to suck the material into the tube. The tube is removed from the oil, and the outside of the tube is carefully cleaned. Then the tube is inserted down into the holder, and gas pressure applied to extrude the material. Teflon has been found to be less susceptible to wetting by the fluid, which reduces the tendency of the material to flow up the outside of the tube and contaminate inner wall of the holder.
The sample volume and mass are carefully measured before and after measurements, so that sample density is monitored. In special cases, postmeasurement sample treatment is done to determine sample moisture content.
Our measurement cost depends on the time required for sample preparation and transfer. These can be a significant part of the whole measurement process, so it needs to be discussed in some detail before costing measurements.
Please feel free to phone or e-mail and discuss possible measurements. We treat all communications as confidential unless advised otherwise.