Nobuo Tsumaki

Transitions of microscopic wear mechanism for Cr2O3 ceramic coatings during repeated sliding observed in a scanning électron microscope tribosystem

Abstract The purpose of this investigation is to analyse microscopic wear modes and their transitions for Cr 2 O 3 coatings in repeated sliding. For this purpose the wear processes during 100 sliding cycles were observed successively in a scanning electron microscope tribosystem. They were also compared with those of a metal, SUS304 stainless steel. The type of wear test was pin on disc. Cr 2 O 3 coatings on SUS304 stainless steel were used for the disc specimens. The thickness of the coatings was 400 μm. The pin specimen was made of single-crystal diamond with a hemispherical tip of radius 30 μm. The sliding velocity was 400 μm s −1 . The normal load was changed from 0.07 to 1.5 N. The following results were obtained. 1. (1) The wear modes are classified into crack and powder formation, flake formation and ploughing and powder formation. These wear modes are mainly caused by surface crack propagation. 2. (2) The wear modes change during repeated sliding as follows for loads from 0.2 to 1.5 N: crack and powder formation (low wear rate)→flake formation (high wear rate)→ploughing and powder formation (negligible wear rate). When W =0.07 N , the wear mode is ploughing and powder formation and there is no transition to other wear modes. 3. (3) The condition for wear mode transition can be explained theoretically by using the parameter of severity of contact, S c , and the friction coefficient μ, where S c = P max ( R max ) 1 2 /K Ic .

Vibration-controlling bearing

A vibration-controlling bearing for controlling vibration developing in a rotary shaft supported in a housing of a rotary machine including a bearing member of a cylindrical shape interposed between an outer peripheral surface of the rotary shaft and an inner peripheral surface of the housing and spaced apart therefrom by respective gaps. A dynamic pressure is generated between an inner peripheral surface of the bearing member and the outer peripheral surface of the rotary shaft. Communicating ducts are formed in the bearing member for transmitting a portion of the dynamic pressure generated to a gap between the outer peripheral surface of the bearing member and the inner peripheral surface of the housing.

In Situ Infrared Reflection Absorption Spectroscopy of Materials Formed on SiO2 in Inductively Coupled Plasma Etching Chamber

In situ infrared reflection absorption (IRA) spectroscopy was used to investigate materials formed on SiO 2 film coated on samples mounted on the inner surface of a process chamber for inductively coupled plasma etching. Aluminum wafers partially covered with photoresist film were etched using BCl 3 and Cl 2 plasma generated in a quartz chamber surrounded by a radio frequency (rf) coil. RF bias was applied to the aluminum wafers at the same time. This is the first time that, in order to predict the IRA spectra, the reflectivities of various inorganic multiple layers formed on metal substrates have been calculated using the optical constants of the materials. The experimental spectra for SiO 2 film and for the materials formed on it during a 2 μm deep etching process were well characterized by the calculated spectra of SiO 2 film and a B 2 O 3 layer on it, respectively.