Kenichi Kurihara

Carbon Nanotubes Filled with Gadolinium and Hafnium Carbides

High-resolution transmission electron microscopy (HREM) has been used to examine the effect of metals on the ordering of carbon during fullerene generation by the the DC electric arc discharge of metal-composite graphite rods. Investigations of the carbonaceous deposits formed on the top edge of the negative electrode confirmed the existence of graphitic polyhedra and carbon nanotubes filled with hafnium (Hf) carbide and gadolinium (Gd) carbide crystals. X-ray diffraction measurements indicate that the metals are incorporated in the form of HfC and GdC2. Possible mechanisms leading to the different stuctures formed in the presence of Hf and Gd are discussed. The continuous supply of sufficient numbers of metal atoms into the arc plasma and moderate suppression of diffusion of the arc plasma flow by increased He pressure was found to enhance the growth of the carbon nanotubes filled with metal carbides.

The influence of lubricant recovery on the coefficient of friction of lubricated metal-particulate flexible disks

We studied the relationship between the removal/recovery behavior and the chemical and physical properties of perfluoropolyether lubricants with different functional groups in metal-particulate flexible disk systems. The rotational speed dependence of the coefficient of sliding friction between disks and a spherical glass slider were measured. The dependence was found to be described by a simple equation in consideration of the removal/recovery behavior of the lubricant. The time constants in the equation were found to be almost proportional to the inverses of the extraction lifetimes estimated from the solvent-extraction profiles of lubricants on the disk surface. This result indicates that the affinity of the lubricant to the disk surface dominates the rate of recovery.

Removal of brown stain on magnetic head by a chelating agent on magnetic tapes

We found that a chelating agent on magnetic tape can drastically suppress the loss of signal amplitude caused by brown stains. After a streaming-mode test using MP tape on which a chelating agent was coated, we found no brown stain on the magnetic head. A chelating agent on magnetic tape is able to prevent from formation of brown stains. In addition, we found that a chelating agent on magnetic tapes can remove brown stain, already on the magnetic head. It is suggested that a chelating agent reacts with the iron oxide of brown stains to make metal complexes, and that the complexes can be removed easily by chemical lapping.

Development of highly reactive hardening agents for MP tapes

Abstract The reactivity of isocyanate groups was examined using molecular orbital calculations and magnetochemical measurements. We found a linear relationship between the logarithm of kinetic constants for the addition reaction of the phenylisocyanates with 2-ethylhexanol and the atomic charges of the carbon atoms in the isocyanate group. A linear relationship was also found between the kinetic constants and the 13 C chemical shifts of the same carbon. On the basis of these relationships, a new hardening agent consisting of Cl-substituted phenyldiisocyanates (CPDI) was synthesized. The degree of cross-linking of the binder film was improved by using the new highly reactive hardening agent. Furthermore, the loss of signal amplitude of MP tape using the new agent was less than that using the conventional agent in pause mode test.