Research Topics

Kohei ITO(Professor)

Faculty of Engineering

Faculty of Engineering

Fuel Cell System Laboratory

Tribology Laboratory

Tatsumi KITAHARA

Hironori NAKAJIMA(Associate Professor)(Assistant Professor)

Joichi SUGIMURA(Professor)

Kazuyuki YAGI

Hiroyoshi TANAKA(Associate Professor)(Assistant Professor)▶http://tribo1.mech.kyushu-u.ac.jp/TR/index-j.html▶http://www.mech.kyushu-u.ac.jp/~fcsl/index.html
Electrochemical energy converters, such as fuel cells andTribology in High Pressure Hydrogenelectrolyzers, can work at higher efficiency and an excellent
reliability with lower noise. These outstanding features of fuel cells

Tribology, a term born in the UK in 1966, is a name of the field ofand electrolyzers motivate us to utilize them as a main energy“the science and technology of various phenomena occurring between

converter in the next generation. Although commercialization

two interacting surfaces in relative motion, and of related subjects andis already underway, a more cost-reduction, durability andpractices*”such as lubrication technology for reducing friction and wear.

performance are required to be addressed. Against this background,

We are studying tribology in hydrogen. It is well known that tribological

our laboratory conducts R&D for fuel cell and electrolyzer based on

phenomena are often affected by the surrounding gas. If the gas isa mechanical engineering approach as shown:hydrogen, surface phenomena are quite different from those in air,because it does not contain oxygen and water, or contains only very small● Elucidation of mass, heat and charge transport in cell：amounts of oxidative substances that are known to form protective films● Development of diagnostic and visualization techniques：on surfaces. It is not only chemical reactions on the surfaces that depend● New proposals :optimization, sophisticated systems：

on environmental gas, but a number of physical and chemical processes
occurring at or near the surfaces, adsorption, diffusion, deformation, wear

As a recent topic, our team succeeded to obtain 3D temperature

and adhesion depends on the gas. Machines to produce, store, transfer anddistribution with thin in-line thermocouples (TCs) with fineutilize hydrogen have a number of machine elements including bearings,positioning. It figured out that the temperature under channel was

valves and seals which are exposed to hydrogen. In order to ensure theirhigher than that under rib. This result connects to the understanding

long and reliable operation, it is necessary to establish the methods toof water behavior, leading to appropriate water management.

understand and design materials and lubrication for hydrogen. However,In addition, humidifier-less technique is being developed for cost-

little is known about effects of gaseous hydrogen in tribology.

reduction. We built in a gas circulation and humidity recovery

Since tribological phenomena include a number of different phenomena

system into a cell, with newly designed GDL which contains bothaccording to applications and conditions, our project includes a number ofhydrophobic and hydrophilic MPL as shown in the photograph.

different sub topics. They include sliding friction and wear of materials used

These efforts realize a high performance PEFC without humidifier.

in bearings, valves and seals, rolling contact fatigue of materials, fretting

Moreover, our analysis skill of impedance helps to grasp thewear at contacts under reciprocation with small amplitudes. The materialsheat sources in the SOFC during operation. The heat sources

being tested include steels and other metals and alloys, carbon-based

obtained is formulated as the thermal modeling, which can estimate

coatings, polymers, elastomers and ceramics. Experiments are conducted

temperature and current distribution in unit cell. This result isin different gas environments including hydrogen, argon, nitrogen andaccessible for the control of thermal stress and the effective use ofair, and also with materials exposed to high pressure hydrogen. In orderelectrodes. Contact us: kohei@mech.kyushu-u.as.jp

to understand tribology in hydrogen, it is necessary to understand thebehavior of hydrogen, chemical reactions, and transportation at and nearsolid surfaces, and the subsequent changes in chemical and mechanicalproperties of surface layers. We continue to study these fundamental
mechanisms in order to contribute to future tribology technology to ensure
the reliability of hydrogen systems.
★ from Glossary of OECD

Fig.1 Temp. distribution in a PEEC with thin TCs.

Fig.2 Tailor-made MPLs fabricated on a GDL.

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