Evaluation of Dispersion State of Fine Particle by Scanning Tunneling Microscope

Dispersion of magnetic powder was carried out by a wet type bead mill in order to evaluate a dispersion condition of fine particles. The three-dimensional surface condition of magnetic paint film was surveyed by a Scanning Tunneling Microscope (STM). Observation of film by a Scanning Electron Microscope (SEM) and measurement of glossity were also conducted. By applying the STM, the microscopic dispersion state of fine particles was able to be evaluated because the three dimensional surface condition of magnetic paint film could be obtained quantitatively. So, the evaluation method by STM is superior to that of the glossity or by SEM.From the experimental results of STM, the operational end-point of dispersion was found to be determind by the measurement of power consumption or viscosity of the paint. The STM evaluation method should be adoptable to other fine particles.