In the master's thesis, we investigated the influence of time on the mechanical properties of a bonded magnet based on NdFeB magnetic powder with a thermoplastic polymer matrix polyphenylene sulfide (PPS).
We made a premix of magnetic powder, thermoplastic polymer matrix and additive. A granulate was produced through the process of compounding and granulation. Test pieces were made on an injection molding machine and aged. After predetermined aging, magnetic and mechanical properties were measured. We compared the results with each other and drew graphs showing changes in these properties as a function of time.
We made six different sample materials with different parameters, e.g. drying and moistening of granulate, production in an inert atmosphere, tempering of samples and material produced with serial parameters, as it is usually produced in production. Our hypothesis was that the main influence for changes in the properties of the material is the presence of moisture, which causes oxidation and consequently worse adhesion between the magnetic powder particles and the polymer particles. That is why we use different parameters in the production of granulate or later on the samples for measurements wanted to eliminate the influence of moisture in order to achieve better results during aging.
In addition to the aging of the test subjects, we also performed an aging test of the granulate in order to determine whether there is a drop in mechanical properties already within the granulate. After aging of the granulate, the test specimens were injected and measurements were taken.
|
