Magnetic head materials

In order to use Mn Zn ferrites as magnetic head materials, the materials have to show the following characteristics ... 

This chapter provides experimental data for the magnetic head material removal rate and surface finish. These two parameters were considered as the important factors for the magnetic head manufacturer as it reflects the needs of the customers. In this step, where we super polish the magnetic heads, we are trying to obtain a direct relationship between slurry type and material removal rate. Other characteristics to be included are particle size, concentration, and amoimt more parameters will be included in future experiments. 

In many cases of traditional tribology, friction and wear are regarded as the results of surface failure of bulk materials, the solid surface has severe wear loss under high load. Therefore, the mechanical properties of bulk material are important in traditional friction and wear. However, in microscale friction and wear, the applied load on the interactional surface is light and the contact area is also under millimeter or even micrometer scale, such as the slider of the magnetic head whose mass is less than 10 mg and the size is in micrometer scale. Under this situation, the physical and chemical properties of the interactional surface are more important than the mechanical properties of bulk material. Figure 1 shows the general differences between macro and micro scale friction and wear. 

Partially fluorinated X-IP has been used for a number of years as an additive in the inert lubricant PFPE film on the surface of a magnetic hard disk to enhance start/stop durability of PFPE lubricants [29,30]. Recently it has been used as a vapor lubricated film on the surface of the disks [31 ]. In order to avoid the PFPE being catalyzed to decomposition by the slider material AI2O3 (refer to Section 3.4), XI -P was also examined as a protective film on the surface of the magnetic heads [25,32]. The results of CSS tests indicate that the thermal stability of the lubricant was greatly improved in the presence of X-1P, and the thickness of X-1P film on the slider surface has an important influence on HDD lubrication properties. 

Magnetic materials can be classified into two groups metal and alloy materials, and metal oxide materials represented by ferrites. We here describe the Mn-Zn ferrites, which are used, for example, as the magnetic heads in magnetic recording, focusing on the preparative processes and physical properties, which are closely related to the oxygen non-stoichiometry. 

Figure 2 shows the two hysteresis loops for a medium and a head material. The coercivity, FT, the saturation magnetization, M or induction, Bs, remanent magnetization, M or induction, B and the permeability, JJ, differ for the two materials. 

Broz JS, Braun HB, Brodbeck O, Baltenspeiger W, Helman JS (1990) Nncleation of magnetization reversal via creation of pairs of Bloch walls. Phys Rev Lett 65 787-789 Brag JA, Anthony TC, Nickel JH (1996) Magnetic recording head materials. Mater Res Soc Bnll, September 1996 23-27... 

Takahashi S et al (2005) Magnetic recording head for patterned medium with 1 Tbit/inch. Abs intT symp. creation of magnetic recording materials with nano-interfacial technologies, Waseda University, Tokyo, PS08 27... 

Intermetallics were used in this century first and primarily for applications as functional materials, as is exemplified in Table 1. Indeed the first industrial applications relied on the special magnetic behavior of certain phases, and respective materials developments led e.g. to Sendust, which shows outstanding magnetic properties and wear resistance and is widely used for magnetic heads in tape recorders (Yamamoto, 1980 Brock, 1986). In the second... 

Kugimiya, K. (1990). Ceramic materials for magnetic heads. American Ceramic Society Bulletin, 69, 696-702. 

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