An ultrathin multilayer TiN/SiN wear resistant coating for advanced magnetic tape drive heads

A titanium nitride/silicon nitride (TiN/SiN) multilayer coating as thick as 10 nm was developed to protect the magnetic tape drive read/write head against wear. Because of the sensitivity of the head components to the elevated temperatures, this coating was synthesized by alternatively sputtering titanium nitride (TiN) and silicon nitride (SiN) ultrathin films at room temperature. The structural, chemical, and tribological properties of the coating were analyzed by means of transmission electron microscopy, Auger electron microscopy, ball-on-disk, and functional tape drive tests and the results were compared to those of the monolithic TiN and SiN films of the same thickness. According to the results, formation of the TiN intrinsic columnar grain structure which is the main source of crack formation and propagation in the film and catastrophic failure of the coating was prevented by the amorphous SiN layer. This structural modification improved the wear resistance and durability of the TiN/SiN coating as compared to that of the single layer TiN coating. According to the functional wear tests in the actual head/tape interface, while the TiN coating failed to protect the head surface (the TiN coating was completely removed from the surface after the running of 1000 km tape), about 4 nm of the TiN/SiN multilayer coating was still protecting the head surface against wear.