Domain and grain observations using a colloid technique for grain-oriented Si-Fe with coatings

New effective domain and grain observation methods using a ferromagnetic-colloid technique are presented for highly-oriented Si-Fe with the tensile coating. A dc field of about 50 Oe is applied perpendicular to the sheet plane for domain observations, while a dc field of about 90 Oe is applied parallel to the sheet plane for grain and grain-boundary observations on the coating. These simple observation techniques are considered to be suitable for product inspections because there are no limitations to the sample size or the observed area on the coating as is the case with domain observation using a high-voltage scanning electron microscope (SEN).