Abstract: An improved method is proposed for providing a coating film of diamond on the surface of, for example, a cutting tool as the substrate by the plasma jet deposition method, in which the deposited diamond film has, different from the cubic crystalline structure formed under conventional conditions, a predominantly hexagonal crystalline structure so as to greatly enhance the advantages obtained by the diamond coating of the tool in respect of the hardness and smoothness of the coated surface. The improvement comprises: using hydrogen alone as the plasma-generating gas; controlling the pressure of the plasma atmosphere not to exceed 300 Torr; keeping the substrate surface at a temperature of 800.degree.-1200.degree. C.; and making a temperature gradient of at least 13,000.degree. C./cm within the boundary layer on the substrate surface.

Abstract: An apparatus for abrasive cleaning comprising a truck adapted to run on the surface to be cleaned and at least one abrasive cleaner supported by a supporting mechanism on the truck and limitedly movable toward or away from the surface, the abrasive cleaner having an abrasive cleaning tool at its lower end, said or each abrasive cleaner being supported by the supporting mechanism so as to be limitedly tiltable in every direction with respect to an axis approximately perpendicular to the surface, the supporting mechanism being provided with a compression spring for biasing the abrasive cleaner away from the surface. Even when the surface to be cleaned has an undulation, the abrasive cleaner tilts with respect to the axis to hold the cleaning tool in uniform contact with the surface and assure a stable and uniform cleaning operation.

Abstract: An abrasive cleaning apparatus comprising a truck adapted to run on the first surface to be cleaned, a first abrasive cleaner adapted to be pressed against the first surface and mounted on the truck by a first support assembly so as to be limitedly movable in the direction of a first axis substantially perpendicular to the first surface and and limitedly tiltable in every direction with respect to the first axis, and a second abrasive cleaner adapted to be pressed against the second surface to be cleaned and substantially perpendicular to the first surface and mounted on the truck by a second support assembly so as to be limitedly movable in the direction of a second axis substantially parallel to the first surface and to be limitedly tiltable in every direction with respect to the second axis.

Abstract: Disclosed are graphitized hollow spheres and a method for the manufacture thereof which comprises coating a spherical core of foamed polystyrene with carbonaceous powder and a binder, heating the coated core under controlled conditions to decompose the spherical core of foamed polystyrene, and further heating the resultant carbonaceous body at a high temperature.