Abstract: A magnetic recording medium for use in making high-density computer hard disks. It contains: (a) an aluminum or Ni/P substrate; (b) a chromium underlayer on the substrate; (c) a four-component magnetic recording layer on the underlayer; and (d) a carbon protective layer on the magnetic recording layer. The magnetic recording layer comprises 66-78 atom percent of cobalt, 12-16 atom percent of chromium, 6-10 atom percent of nickel, and 4-8 atom percent of tantalum. The CoCrTiTa four-component exhibits a high coercivity (greater than 2,800 Oe), which results in many improved qualities, including increased recording density, reduced noise, improved off-track capability (OTC), and reduced on-track error rate (OTER). It also also allows the sputtering process to be conducted at a substantially lowered temperature.

Abstract: The present invention relates to high-coercivity magnetic recording media used in a hard disk drive. The magnetic recording medium comprises a nonmagnetic substrate, a seed layer comprising NiAl alloy sputtered onto the substrate, a sublayer comprising CrV alloy sputtered onto the seed layer, a magnetic layer comprising CoCrPtTaNb alloy sputtered onto the sublayer, and a carbon overcoat sputtered onto the magnetic layer. The magnetic recording medium of such a structure has improved signal-to-noise ratio, coercivity, overwrite capability, and orientation ratio thereby greatly improving the storage density and read/write capacity of the magnetic recording medium. Furthermore, the coercivity of the magnetic layer of CoCrPtTaNb alloy according to the present invention can be as high as 4000 Oersteds even without the use of the NiAl seed layer.

Abstract: The surface of stainless steel can be hardened by coating a silicon nitride gel and then scanning by CO.sub.2 laser to form a surface alloy layer thereon. The thickness and hardness of the surface alloy layer are both uniform. The Vicker's hardness of the layer can be as high as 1200 Hv. This method can be operated in a common atmosphere or nitride atmosphere at normal pressure, therefore it is more economic than ion nitriding or plasma nitriding.