Scratch resistance of double-layered particulate media

We have investigated the scratch resistance and the elastic modulus of the double-layered, the magnetic upper-layer and the under-layer films in order to clarify the scratch mechanism of the double-layered metal particulate media. The mechanical properties of the magnetic upper layer are superior to those of the under layer. The double-layered films were fractured by the generation and propagation of cracks. These results indicate that fractures in double-layered films can be attributed to the stress applied on the under layer through the magnetic layer. We concluded that the scratch resistance of double-layered films depends on the scratch resistance of the under layer and the elastic modulus of the magnetic layer.