Hiroyuki Kitsunai

The transitions between microscopic wear modes during repeated sliding friction observed by a scanning electron microscope tribosystem

Abstract In order to analyse the microscopic wear mechanism in repeat-pass sliding, the wear process was observed successively over ten cycles of sliding in a newly developed scanning electron microscope tribosystem. The wear process was recorded with a video tape recorder. The type of wear test was pin-on-disk. The pin specimen was made of tungsten carbide. The hemispherical pin tip radius was 30 μm. The disk specimen was made of SUS 304 stainless steel. The sliding velocity was 40 μm s −1 . The normal load could be varied from 0.07 to 1.5 N. The following principal results were obtained. 1. (1) Wear mode transition during repeated sliding progresses from cutting, to wedge forming, to shear-tongue forming and then to ploughing. 2. (2) The critical conditions for the transitions between wear modes are expressed as follows: 0.27 D p cutting; 0.09 D p D p D p D p is the ratio of the depth of penetration to the length of contact parallel to the sliding direction. It is expressed as a function of normal load, disk specimen hardness, pin specimen radius and number of friction cycles. 3. (3) The conditions for wear mode transition can be explained theoretically by using a wear mode diagram.

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 .

In situ characterization of residues formed on a plasma-etching chamber

The chemical reaction of residues formed on a quartz surface in an electron cyclotron resonance plasma during the etching of Al and resist film by Cl2 and BCl3 plasma was characterized in situ by infrared reflection absorption (IRA) spectroscopy and quadrupole mass spectrometry (QMS). The plasma was generated in a chamber with a structure similar to a conventional production machine. Incident ions and molecules impacting onto a quartz surface at the chamber wall were analyzed by QMS. Then the residue formed on a quartz film on a sample mounted on the chamber wall was analyzed by IRA spectroscopy. The residue was identified as B2O3 which is formed by incident boron chloride ions that diffuse down through the B2O3 residue to the quartz surface and, there, thermally react with OH in the quartz. The residue film produced on the quartz surface could be identified by etching a 1-μm-thick Al film ten times at the etching rate of 12 nm/s. This combination of IRA and QMS is a promising technique for refining on-li...

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.

Transitions of microscopic wear mode of silicon carbide coatings by chemical vapor deposition during repeated sliding observed in a scanning electron microscope tribosystem

Abstract The purpose of this investigation is to analyze microscopic wear mechanisms of silicon carbide coatings by chemical vapor deposition (CVD). For this purpose, the wear processes during one hundred sliding cycles were observed successively in a scanning electron microscope (SEM) tribosystem. The results were compared with those of uncoated silicon carbide. The following results were obtained. (1) Wear modes are classified into four, they are ploughing, powder formation, crack formation and flake formation. These wear modes except for ploughing are mainly caused by surface crack propagation. (2) Silicon carbide coatings showed higher wear resistance than uncoated silicon carbide, because there are less initial surface cracks in the silicon carbide coatings. (3) The condition for wear mode transition can be explained theoretically by using the parameters of severity of contact, S c , S c , S* c , and the friction coefficient μ, where S c =P max (R max ) 1/2 /K 1c and S c * =H v (R max) 1/2 /K 1c .