Pseudo Output and Magnetic Properties of Fe-Al-Si Film in MIG Head

In Fe-Al-Si film deposited on ferrite material, there is a layer near the film-ferrite interface with inferior magnetic properties. This layer, which acts as a pseudo-gap in MIG heads, is caused by the nonuniform structure of the Fe-Al-Si film and by interdiffusion between film and ferrite. Improvement of the properties of these Fe-Al-Si films requires better crystal orientation, smaller grain sizes and a homogeneous film structure; these changes can be attained by selecting the optimum substrate. When a MIG head uses the (110) face of single-crystal ferrite as a gap surface, the head exhibits no pseudo-output, nor does a MIG head of polycrystalline ferrite with a Fe-Al-Si/Fe-Ni double-layer film, because both MIG heads have good crystal orientation and a homogeneous film structure.