Introduction

The IRP (LIA) FOCOMAT “Functional Composite Material” (started in 2013 and renewed in 2017) is managed by Dr. Nadine Pébère (CIRIMAT) in France and Dr. Tran Dai Lam (VAST) in Vietnam.

Missions and research themes

The project aims at developing new composites materials (bulk or thin films systems). The scientific program is divided in three axes:

1. Development of greener organic coatings
2. Electrodeposited biomimetic apatite coatings
3. Polymer composites with reinforcing plant fibers

1. Development of greener organic coatings

Organic coatings are widely used to prevent corrosion of metallic structures because they are easy to apply and cost effective. Corrosion inhibitors are incorporated in organic coatings to provide active corrosion protection. In the past, chromates were the most commonly used inhibitive pigments. However, due to their high toxicity, many studies have been devoted to the development of more environmentally acceptable organic coatings. In this context, our project aims to incorporate non-toxic corrosion inhibitors in organic coatings via natural clays (montmorillonite – MMT or layered double hydroxides – LDH), acting as nano-reservoirs for green inhibitors. The complementary effects of MMT and LDH on the microstructure of the coatings are investigated to search for synergistic effects by using different inhibitors. The study of the inhibitor leaching from the clays and their healing action in the case of damaged coatings will be specifically considered.

2. Biomimetic apatite coatings

A proper design of a bone implant material is aimed to provide the necessary durability, functionality, and biological response for long-term use. In this context, metallic materials, among which stainless steels, are most commonly implemented for load bearing implants. Durability and functionality of the implant are governed not only by the mechanical properties of the bulk material but also by the biological response, i.e. osteointegration that depends mainly on the surface/chemical characteristics of the implantable device. The challenges for electrodeposited coatings are twofold: (i) to be able to co-dope the apatite coating and to control the release kinetics and (ii) to produce coatings in lattices structures made from additive manufacturing (3D approaches), that is becoming the most usual method to produce the implants.

 3. Polymer composites with reinforcing plant fibers

The tailoring of polymer composites with long reinforcing plant fibers is a major issue of research in the domain of structural organic composite. The main advantage of such materials is weight saving. The other issue is to design recyclable materials. This explain that the choice must be restricted to linear polymers i.e. thermoplastics. Now, the difficult point is to be able to make the processing at a temperature that is sufficiently low for avoiding the degradation of the plant fiber. Finally, we focus on biosourced polymers. The reinforcing long fibers are bamboo fibers growing in North Vietnam: Dendrocalamus barbatus. The major interest of bamboo fiber is to possess the highest Young modulus among vegetal fibers. The first keys point is to define a treatment allowing the handling of the fiber during the processing of the composite. Moreover, it must allow a satisfactory interface with the polymeric matrix: the interfacial region is insuring the stress transfer from the matrix to the reinforcing fiber.

Some important dates for the collaboration on the topic “Corrosion and protection” 

November 1999: Do Son School “Corrosion protection”.

1997-2004: FSP “Espoir” Project (financial support for PhD thesis and for equipment).

2005-2012: Cooperation agreement VAST/CNRS “Corrosion and protection of materials”.

2013-2020: LIA “FOCOMAT”.

Organization of international Workshops on Corrosion and Protection of Materials in Hanoi: December 2012, October 2015, September 2018 and the next one planed in September 2020 (shifted in 2021, due to the Covid outbreak).

institutions and laboratories involved

France

• Dr. Nadine Pébère, CIRIMAT Laboratory, Université de Toulouse

Vietnam

• Dr. Tran Dai Lam, Director of the Institute of Tropical Technology (Vietnam Academy of Science and Technology) in Hanoi.

Participants to the Workshop CPM 2018, ITT, Hanoi

After the ceremony of the Friendship Medal.