| 摘要 |
PURPOSE:To obtain a magnetic disk substrate having an excellent recording characteristic, strength, corrosion resistance, etc. by forming an Al2O3, SiO2 or Si3N4 film having a specific value or below of surface roughness and having a poreless and strain-free surface on the surface of an SiC ceramic material having a specific value or below of fine pore diameter and approximately theoretical density. CONSTITUTION:A sputtered film of Al2O3, SiO2 or Si3N4 having 0.3-30mu film thickness is formed on the surface of the silicon carbide ceramic material which is the silicon carbide ceramic material having fine pores of <=5mu diameter and manufactured by a hot hydrostatic press and has >=96% relative theoretical density. The film surface is subjected to mechanochemical polishing by using a lapping machine under 0.05-2kg/cm<2> load in a liquid prepd. by suspending >=1 kinds among SiO2, MgO and Al2O3 fine particles having <=0.1mu grain size in pure water. The magnetic disk substrate which has the poreless and strain-free surface layer having <=80Angstrom surface roughness and has an excellent magnetic recording characteristic, substantial pressure resistance against machining, polishing and high-speed revolution and has excellent corrosion resistance, weatherability, heat resistance, etc. is thus obtd.
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