NTT Energy and Environment Systems Laboratories

Project

• Environmental Systems Project

Up to now

• renew the currently used structural and paint materials with those that are adaptive to the environment
• prolong the life of their telecommunication facilities

At the NTT

The goal of our research is to develop a highly efficient maintenance method for telecommunication facilities. This method must contribute to better administration in NTT.

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Our approach uses a materials science method and has three parts: improving durability, taking measures against environmental problems, and clarifying the essential factor in material deterioration.
Details are as follows.

1) Development of paint materials highly adapted for environmental protection.

Fig and Table relating highly development of technique for
environmentally friendly telecommunications plant materials

2) 　To deal with corrosing facilities, it is necessary to develop criteria for efficient installation, inspection and renewal of facilities that are suffering from progressive corrosion. We are studying such criteria for different installation environments based on corrosion simulation. Since different installation environments cause materials, such as zinc and iron, to corrode in different rates, we take local conditions such as the weather into account. One of the research approaches is to focus on sea-salt corrosion, which is caused mainly by sea-salt particles. To gain a clearer understanding, we have developed a system that can visually present the risk of corrosion based on the multivariate analysis. This system can represent several factors, such as the amount of sea-salt particles (Note 1) and corrosion rate (Note 2), on maps of Japan.

Figure/Table Development of criteria for the installation, inspection, and renewal of facilities

Fig. 3 Sea-salt corrosion map system for corrosion simulation using weather database (DB), map DB, and facility DB.

Fig. 4 Example of a map showing corrosion rate around Choshi in Chiba Prefecture, Japan. Weather data from past months are used.

Note1: Amount of sea-salt particles in unit of mg/100 cm²/day. This represents the amount of attached particles per unit area per day at a point. The changes in the amount of sea-salt particles generated from a breaking wave are calculated by approximating the decline in the particles' density as an exponential function of the distance from the coastline to the analysis point, and also by taking wind vectors into account.

Note: 2 Corrosion rate in unit of μm/year. This represents the rate of decrease per year of a metallic material on the surface of structures. It is estimated using several factors comprising sea-salt particles, materials, and moisture and temperature levels obtained from weather observation stations. In particular, moisture is assumed to be a mixed model made up of the number of dew days and the amount of precipitation.

3) Clarification of the essential factor in material deterioration, especially hydrogen's behavior and reaction.

Clarification of the essential factor in material deterioration,
especially hydrogen's behavior and reaction.

Fig. 5 Pourbaix Diagram

Point！

In order to provide highly safe, secure and reliable facility maintenance, we are studying technologies to make facility materials more adaptive to the environment and facility maintenance more efficient.