As with investigating tribology, it is important to evaluate the corrosive properties of the material. From the viewpoint of material utilization, it is required to evaluate them in an actual environment. Corrosion degradation may be affected by physical properties such as tribology and strength. The explanation focuses on the corrosion reaction, and especially since corrosion is an electrochemical phenomenon, it is explained electrochemically. In the corrosion evaluation, the mechanical load and corrosion reaction, the basics of electrochemical for understanding corrosion, the interpretation of corrosion and corrosion protection of galvanized steels, the electrochemical measurement method and the evaluation of atmospheric corrosion will be explained.

Our research group devised a technology to create a coating layer with fine powder by continuously sending hard fine powder mixed with carrier powder between the substrate and the tool and rubbing it under local high surface pressure. This is called friction reforming. In addition, we are also working on the combined use of heat treatment for the purpose of hardening the friction reforming layer, improving the adhesion between the friction reforming layer and the substrate, and improving the corrosion and wear resistance associated with these. This paper introduces efforts to develop friction materials that can be used in marine environments by providing corrosion resistance and low friction / wear resistance to high-strength metals using friction reforming technique and heat treatment in combination.

Reducing auto body weight by use of high strength steel is an important issue. Although it is necessary to increase the strength of steel sheets for chassis parts, use of high strength steel sheets has not progressed sufficiently due to the problems of fatigue and corrosion. Corrosion of chassis parts mainly occurs in arc welded joints. This review describes the corrosion behavior of arc welded joints in detail. It also describes the improvement technique based on the corrosion mechanism.

Several Japanʼs infrastructure facilities are degrading with time. These facilities need to be efficiently maintained in a good condition by implementing appropriate maintenance and introducing various techniques. This paper concentrates on the application of cathodic protection for repairing concrete structures. The cathodic protection controls the corrosion current of steel bars in concrete by polarizing the steel potential. Besides, due to spin-off reactions, cathodic protection improves the corrosion environment of steel bars, such as increase in the pH and decrease in the chloride ion concentration near the steel barʼs surface. The behaviors induced by these effects were explained from experimental data and polarization curves. In addition, the current issues and prospects of cathodic protection were summarized.

Magnesium alloys have high specific strength and specific stiffness, so they are expected to be a lightweight material in the field of transportation equipment, and their application is increasing year by year. However, magnesium has a low electrochemical potential and corrodes easily. Therefore, in order to apply magnesium alloy, it is necessary to provide corrosion protection by surface treatment. This paper outlines the main surface treatments such as conversion treatment, anodization, and electroplating etc. for magnesium alloys and their characteristics, as well as the phosphate anodization developed by the authors and its anticorrosion mechanism.

Electrochemical machining (ECM) is a machining method with a long history, especially applied in parts manufacturing in airplane and automobile industries. Although the advantages of ECM is very clear and attractive comparing to other machining methods, its lower machining accuracy and bad environmental impact hindered the expansion of its application. Due to realization of high-precision machining with new technologies, electrochemical machining came to be noted again. In this paper, after the outline and features of electrochemical machining is explained, the mechanism of anodic dissolution and ECM model are briefly introduced. Then, the applications in parts manufacturing and surface texturing for tribological purposes are introduced.

To reduce the maintenance cost of current collecting materials such as contact wires and contact strips in electric railways, it is necessary to propose wear reduction measures based on wear mechanisms. Conventionally, the wear mechanisms of current collecting materials have been divided into two major categories: mechanical wear, which is considered to be solely adhesive wear, and electrical wear caused by arc discharges. However, there are some phenomena in the field that have not been explained by the conventional wear mechanism. Therefore, to clarify the mechanical wear mechanism of current collecting materials, which especially has not yet been clarified, we developed a rotating wear tester that can measure contact temperature during sliding tests,and wear tests were carried out. As a results, the mechanical wear was classified into four modes: “adhesive wear,” “seizure,” “abrasive wear,” and “softening flow and delamination wear”. In addition, from the measurement results of contact temperature and hardness on wear surfaces, we clarified that the transition of these wear modes is caused by the softening of material due to frictional heat.

This study clarifies the effect of coating hydrogenated DLC film to Carbon Fiber Reinforced PEEK (CFRP) on the sliding characteristics under dry conditions. The sliding distance to reach the glass-transition temperature, Tg , and specific wear of the coated CFRP are evaluated based on frictional heat and wear resistance. Generally, hydrogenated Diamond-like carbon (DLC) films have a significant fraction of sp³-hybridized carbon atoms with a remarkable fraction of hydrogen atoms bonded to the network. In this experiment, the negative bias voltage was varied to change the sp³-hybridized carbon atoms and hydrogen content of the CFRP samples. The results show that hydrogenated DLC films with a ratio of about half sp³-hybridized carbon atoms increased the sliding distance more than six times while decreasing the specific wear rate to about one-fourth of the DLC film synthesized at the minimum bias voltage necessary for the synthesis of DLC film. Furthermore, the typical operating range for the DLC-coated CFRP samples based on the PV-product is predicted to be less than 0.25 MPa・m/s. The results suggest that DLC-coated CFRP materials are good candidates for sliding mechanical parts that work under lower normal loads and velocities.