Development of a ta-C Wear Resistant Coating with Composite Interlayer for Recording Heads of Magnetic Tape Drives

The effect of two different surface modification methods on the wear life of the coating of magnetic tape drive heads has been studied. In this research, the heads were coated with 10 nm tetrahedral amorphous carbon (ta-C) film using filtered cathodic vacuum arc (FCVA) technique. The surface of the heads was pretreated by bombarding with energetic carbon ions or by developing a Si–Al–C composite interlayer before deposition of the coating. The coated heads were tested at a real head/tape interface of a tape drive. Surface characterization and tribological behavior of the head coatings with and without surface modification has been studied by transmission electron microscopy (TEM), Auger electron spectroscopy (AES), and scanning electron microscopy (SEM). The results reveal that the ta-C coating without any surface modification is not durable and the coating fails due to delamination. Pre-treating the head surface with energetic carbon ions improves the durability of the coating, especially on the head read/write elements; however, the coating of the head ceramic substrate is still partially delaminated. The application of a Si–Al–C composite interlayer is shown to be able to solve the delamination problem effectively and increase the wear life of the coating up to six times in comparison with the sample pretreated with carbon ions. The formation of strong chemical bonds between the head surface and the overcoat is found to be an important factor in improving the durability of the ta-C head coating.