Hiroshi Mishina

Surface deformation and formation of original element of wear particles in sliding friction

Abstract This paper describes a microscopic investigation of the deformation in the surface crystal grains and the initial step of wear mechanism in sliding friction using a metallographic microscope integrated in a pin-on-flat apparatus (frictional surface microscope). The in situ observation of the change in the surface crystal grains is performed during the sliding frictional process to reveal the generation proces of the ‘original element of wear debris’ from the solid surface. The results suggest that the plastic deformation which is generated at the contacting point in the surface crystal grains spreads into the inner part of the crystal grain and an original element of wear debris is generated from the surface crystal grains when a transgranular fracture occurs in it during sliding frictional process.

Chemisorption of diatomic gas molecules and atmospheric characteristics in adhesive wear and friction of metals

Abstract Atmospheric characteristics in adhesive wear and friction of pure metals tested in a pin and disk configuration are determined in the conditions of controlled gas environment. The relationship between wear (or friction) and atmospheric pressure, i.e. the atmospheric characteristics, is studied for three kinds of diatomic gas molecules (oxygen, hydrogen and nitrogen) in the pressure range from 2 × 10 −5 to 1 × 10 5 Pa. The atmospheric wear characteristics are divided into three kinds of specific types which depend on the strength of the chemisorption activity of gas molecules to the metals surfaces. Furthermore when the atmospheric gas strongly chemisorbs on to the metal surface the condition of mild wear development is defined by the chemisorption activities of each gas molecules.

Mechanism of surface magnetization by friction of ferromagnetic materials

Experiments showed that in the absence of an external magnetic field, the ferromagnetic materials Ni and Co undergo spontaneous magnetization of their frictional sliding surfaces as a result of tribological actions such as friction and wear. The magnetization phenomenon on the sliding surface was confirmed by measurements of the magnetic flux density and measurements of magnetic forces with a magnetic force microscopy. The mechanism of spontaneous magnetization by tribological action (tribomagnetization) is discussed in relation to the formation of elemental wear debris with a size of a few tens of nanometers, a size that is of the same order as that of a single magnetic domain particle, and of transfer particles that are formed by accumulation of debris adhering to the sliding surface in tribological processes.

Microscopic real time observation of failure, wear and deformation on coating/subsurface

Abstract The deposition of surface coatings on industrial component is widely used for reducing wear and friction in the tribological application. Tribological properties of various kinds of coatings have been systematically analyzed. This paper mainly deals with the investigation of failure mechanism of the coating/subsurface through the microscopic observation in real time through the repetition of sliding friction. The results of observations suggest that the mechanical failure is characterized by the intrinsic properties of coating and substrate materials, e.g. the relation between the thickness of coating and the depth of the plastically deformed region in the substrate. In the present study the microscopic real time observation is performed to investigate the failure of coating/subsurface by use of ‘frictional surface microscope system’, which is assembled by combining a metallographic microscope and a frictional device operated in the field of view of the microscope.