GALLAND, Jacques
Ecole Centrale Paris, Dep. C.F.H., Grande Voie des Vignes, 92295 Chatenay-Malabry, France
Abstract: The principal criteria taken into account for solving corrosion problems and the training of men, oriented in this specific field, are discussed. Two categories of men are trained: those who know that corrosion exists and those who are "specialists" and "corrosion experts". The connection between the corrosion expert and other partners involved into the fight against corrosion is the most important for solving industrial problems. Thus, to meet the needs of industry, Ecole Centrale Paris and VSB-Technical University of Ostrava, and Vitkovice a.s. are associated in research with joint management of Ph.D. students.
Keywords: training of men, teaching, corrosion
The fight against corrosion must be considered constantly by manufacturers. The notions of durability, quality, reliability, security, cost, serviceableness are closely linked to this action (Figure 1).
Figure 1: Requirements for equipment and industrial productions
The economies of production and maintenance costs are not always directly calculable, but a relevant policy of corrosion fighting may lead to a 30% decrease in the cost of a given production.
The principal criteria taken into account for solving corrosion problems are the following ones:
To answer to a need
Not to stop production
To maintain a reasonable requirement for the quality
To maintain a minimum production cost
To minimise the maintenance cost
To choose the most competitive solution for the planned working conditions
To specify better the limits of use of the materials
To homogenise the quality of the different compounds
To take into account the long term durability
To improve maintenance (production and product)
To define the real need (marketing)
Dependence in raw materials (chromium, ...)
Energetic behaviour for productions (wood/aluminium, for instance)
Recycling of products (waste disposal)
New materials (composites, ...)
Environmental problems (pollution, ...)
Normative activities (internationalisation, ...)
The fight against corrosion requires therefore a multidisciplinary approach, implying knowledge in electrochemistry, chemistry, metallurgy, plastic industry, physical-chemistry of surfaces, mechanical and rheological properties of materials, assembling, etc. Corrosion mechanisms for metals being very often relevant to aqueous environments are of an electrochemical kind: it explains that only electrochemical knowledge may lead to identify simple behaviour laws and, consequently, also simple prevention rules. The corrosion interactions between materials and environments could be summarised in Figure 2.
Figure 2 - Interactions between materials and environments solving the fight against corrosion
The training of men, oriented to valuable competencies in a specific field, is always related to education. This training could take various sights, notably scientific or technologic. So, the fight against corrosion is a necessary part of the knowledge given to men with regards to the degradability of materials, in relation to raw materials or well finished products.
In this way, we have to reply to these questions related to students' education in corrosion:
Teaching for whom?
Why teaching?
What would be teaching?
How teaching?
Which results could be expected from teaching?
Corrosion teaching can be achieved at different training levels: during courses in colleges (more particularly technical ones, but even in grammar schools upper Sixth classes), during the training of senior technicians - already more important aspect - then in the training of graduate students in Engineering High Schools, and lastly in universities training, up to the postgraduate level. This enumeration shows that the problem of such a training is complicated since the basic knowledge of the students is very different according to their origins, and the objectives can also vary very much: it goes from a simple awareness of the 'honest man', to the training of 'generalists in corrosion' or of 'specialists in corrosion'.
This survey would not be complete without considering also continuing education, that is to say periodic recycling of the staff of the firms compared with such problems and this, once more, at different levels of competencies.
Corrosion fighting is an economically very important challenge. It is usual to mention, as corrosion cost, 3 to 4% of the Gross National Product, or for a country like France, about 30 billion euros in 1999. In such estimation, 90% are indirect expenses (plant stopping, production losses, ...) and only 10% are direct expenses (surface treatments, ...). Thus, it appears that, for industry, knowledge leading to abilities in corrosion and anticorrosion is necessary, not only at the level of design offices but also for production or maintenance workshops, or after sale services. Corrosion problems often involve non-specialists, that is to say imply the 90% of indirect expenses.
Thus two different objectives appear in corrosion teaching: either a sensitisation to these problems in the form of a general and superficial teaching, near to 'popularisation', or a deeper training, in the form of a 'specialisation ' base on advanced courses and practical works.
The difference between 'popularisation' and 'specialisation' depends more on the quantity and the level of knowledge we wish to see to be acquired, than on 'the state of mind 'with which corrosion problems must be solved. On this last point, analogies can be made with the therapeutic approach of diseases: 'prevention is better than cure'. Corrosion is a shameful disease, we do not want to talk of it, since we feel somewhat guilty and because it deteriorates the outlook of the firm. It is only when we face a situation that we have not wished that we are forced to solve this problem. Corrosion raises 'case studies' which imply many parameters which cannot always be quantified or modelled and cannot be solved by equations, and which respective value depends on the case study considered: to this end, let us mention notions such as quality, durability, reliability, ability for service, cost ... which requirements are sometimes contradicting.
On the other hand, it is easier to define the basic knowledge, either initial or to be acquired, to understand and solve corrosion problems.
To solve a corrosion case study, the following steps would have occurred and consequently would be analysed by engineers, but also by students :
Documentation on the corrosion case
Hypotheses on the reasons of the corrosion
Verification of these hypotheses by additional studies (laboratory)
Modification or approval of the suggested hypotheses
Determination of a suitable solution
Experimental check-up and periodical inspections
However, there are also case studies, for which the solving of the raised problem implies a critical and relevant analysis of the phenomenon, qualitative and not always quantitative, and for which the 'time' parameter is not always under control. It requires a compromise solution, which validity is justified by knowledge and experiences that only specialists accustomed since long to solve such problems, can formulate.
Is it valid to extrapolate (generally by a linear law as a function of time) the corrosion behaviour of an equipment or a production? Usually, it is not possible, and it raises the problem of accelerated tests (for instance, salt spray tests or other ones).
The educational project must satisfy the two requirements defined above. The knowledge to be communicated may be transmitted either by university specialised teachers, or by professionals coming from industry. Both solutions have their own respective advantages.
Initial training must most often be the responsibility of university teachers since they are more sensitive to the scientific and theoretical bases of the subject, and their students have received a pretraining which makes them more receptive to such concepts. On the other hand, in continuing education, professionals, having however pedagogical capacities, can better inform their audience on case studies to which one and others will have been confronted, in a given industry.
Whatever it may be, the ideal teacher is the one who takes into account these two training, that is to say who knows how to solve case studies with strong scientific and technological knowledge, the first knowledge being relatively 'unchanging ', whereas the second one requires a permanent retraining: such retraining are easy for professionals, due to their activities, but it often concerns a too limited field of knowledge and methodologies, whereas it requires a voluntary and opened attitude from the university teacher, which, however, will lead him to a more general and often more objective, view of the situation.
It is clear that the teaching must not include only courses but also exercises and practical work as soon as it outpasses the level of 'popularisation '. Probation periods in firms are also very formative, not only at the level of the acquaintance of the industrial world from the student, but also at the level, more specific, of a development and an applying of the knowledge previously acquired on corrosion. To research and follow such probation periods give also an excellent opportunity to have university teachers and industrials meet and dialogue, and to feel better their respective approaches to corrosion problems.
Anybody, but not specialist, being confronted to corrosion problems, will apparently describe this phenomenon by the corresponding corrosion damages and aspects, characteristic of a case study. This person will more seldom know its cause:
if such is the case, the solution of anticorrosion will be easier to find. The damage will imply a kinetics concept, thus not obviously valuable on the long term, since this corrosion rate may slowly decrease or even be annihilated spontaneously, or on the contrary may accelerate progressively. As for corrosion aspects, not only macroscopic and microscopic observations of surfaces are necessary, but also chemical analyses of the surface and the aggressive environment near it, are essential to determine the origin of corrosion.
In these conditions, we could expect that the better compromise solution would be found, with the best evaluation of the different parameters as mentioned in the introduction.
Initial training in corrosion and anticorrosion studies relies on university teachers who have shown their interest in educating students, according to the objectives and means defined above. They must introduce on the market of professional activities, men (and women) of rapid performance for a company, after a short period of specific professional training.
Two categories of men are thus trained:
Those who know that corrosion exists, that it must be controlled but above all avoided, and that it costs money, time, energy and human means. The training given to them, must enable them to dialogue with the 'specialists' that is to say to know how to observe and synthesize the case study to which they are confronted. Afterwards, they must understand the answer of the expert and apply the solution, which will have been retained, most often on the basis of an agreement, or even a compromise, between 'expert' and 'user'.
Those who are 'specialists' and especially 'corrosion-experts'. This notion is more difficult to be detailed since it concerns different levels, on one side of responsibilities (technician, engineer, researcher) and on the other, of competencies: metallurgist, mechanic, chemist, electrochemist, physician, economist, ..., according to cases to be studied.
Figure 3 shows the connections between the corrosion expert and the other partners involved into the fight against corrosion.
Figure 3. The position of a "corrosion expert" in industry
Technical universities, within their pedagogic plan of training their students and their scientific and technological research activities for industrial companies, must be able to deal successfully with these subjects; under such conditions, it is necessary, for their students, to move from an analysis approach to a synthesis one, in solving corrosion problems. Under such conditions, what is the interest to go up to the level of higher training, that is to say to reach a doctorate level in view to become a corrosion-expert? First of all, a doctoral training is the forming in and by research, that is to say the development of a certain number of qualities of the individual: acquirements of new knowledge, mastering of theoretical and experimental competencies, judicious interpretations of results, team spirit, group work, opening to dialogue and constructive critics, international relations, etc... After that, such a researcher will often be led to manage a research team, but after his career will take various directions... In the great majority of cases, the staff of Research Centres had developed their capacities in achieving a thesis.
Thus, to meet the needs of industry, Ecole Centrale Paris and the Technical University of Ostrava, with the help of their respective industrial partners, and especially Vitkovice a.s. which participates in studies with these two establishments, are associated in the achievement of theses with joint management doctorates, on the topics of corrosion, metallurgy, hydrogen embrittlement and surface treatments of metals. These doctorate degrees (Ph.D. diplomas), defended in France or in Czech Republic with regard to an international jury, received a common agreement and are financially supported by French and Czech public authorities.
So, in 98 two doctorate degrees have been delivered:
In France (Ecole Centrale Paris). "Behaviour of passivable alloys, duplex stainless steel and iron-nickel alloy, under simultaneous conditions of friction and corrosion". by: Petr KUBECKA
In Czech Republic (Technical University Ostrava). "Materials and technical properties of intermetallic alloys Ni3Al". by: Monika LOSERTOVA.