2.1. — Direct coating

In the hole of the samples equiatomic amounts of Ni and Al powder are introduced and is pressed uniaxially. Several amounts are added and press several times up to introduce ca. 2 g.

When the sample is in position on the focal point the cover of the Fresnel lens is put out and the NiAl begin to be heated. When the ignition temperature is achieved the reaction starts and in 0,2 sec. is completed. A wave is visible starting in the center of the sample, the heatest spot, where the melt of NiAl happens as a consequence of the high evolution of heat. going to the outside and back. A second wave returns because the outside of the samples is the coolest and then the solidification of the melted NiAl happens in the opposite sense.

The melted NiAl produces a coating on the steel when the amount of NiAl is higher than 0,6 g. The reason, as explained in a previous paper, is that when the amount of reactive powder increases temperature increases and there is more time to produce de mutual diffusion of Ni and Fe to have good adherence [8]

To increase this adherence some other tests were made. They consist in the introduction of a layer of Ni powder under the mixture of AlNi powder. When the SHS reaction was performed, the adherence was better except in the sides because in the vertical walls there were not the intermediate layer of Ni [9] The coating consists in a layer of Ni, reach in Fe in the lower part and poor in Ni in the upper part because of the diffusion.

2.2. — Saving in energy

The main advantage of this combination of SCE and SHS is that of no fuel consumption in the preparation of a coating of a intermetallic whose melting point is over 1600 K. The only
energy consumption in the whole process is that of electroplating and that of equipment following the sun.

Another advantage of this kind of combined processes is that the time of reaction is very small, ca.0,2 sec; that means

Conclusion

This paper demonstrate the possibility to produce coatings with a high temperature performance on steel obtained without any consumption of energy except free solar energy and exothermic chemical energy that is also non polluting energy.

Materials obtained are high temperature materials whose fabrication obliges to a high energetic consumption according traditional production routes.

This presentation try to encourage the imagination of scientific and engineers to identify and develop all possibilities we have at hand to follow in industrial development with a strong reduction in non renewable polluting energetic materials without CO2 production.

Additionally this equipment is presented as the most suitable to perform research a pilot research working with materials. Due to its lower total cost it can be buy by any department in materials of any university or research centre as an ordinary research tool but mainly as a way to show students and post graduate and industrials the possibilities of CSE, combined or not with SHS, in the near future.

It is only a matter of imagination and, certainly, a matter of complementary work to be done mainly in the field of control to obtain a automatic equipment.

Literature

[1] I Garcia, G. P. Rodriguez, J. J. Damborenea, A. J. Vazquez, , (2002), ”CSEFL (concentrated Solar Energy with Fresnel Lenses): an Ecological Option for Surface Modification of Materials”. International Forum on Renewable Energies FIER’2002 Tetouan, Maroc, pp. 228-234

[2] I. Garcia, J. Sanchez Olias and. A. J. Vazquez, (1999) "A new method for materials synthesis: Solar energy concentrated by Fresnel lens", Journal de Physique IV, France 9, 435-440

[3] I. Garcia, J. Sanchez-Olias, J. de Damborenea y A. J. Vazquez, (1998), "Sintesis de nitruro de titanio mediante laser y energia solar concentrada", Rev. Metal. Madrid 34,2, 109-113.

[4] Quncheng Fan, Huifen Chai and Zhihao Jin, (2001), “Dissolution-precipitation mechanism of self-propagating high-temperature synthesis of mononickel aluminide”, In Intermetallics, 9 pp. 609-619

[5] J. J. Moore, H. J. Feng (1995) “Combustion synthesis of advanced materials: Part I. reaction parameters”, Progress in Materials Science 39 (4-5), pp. 243-273.

[6] J. J. Moore, H. J. Feng, (1995) “Combustion synthesis of advanced materials: Part II. Classification, applications and modelling”, Progress in Materials Science 39 (4-5) pp. 275-316.

[7] J. Sanchez Olias, I. Garcia, A. J. Vazquez, (1999), "Synthesis of TiN with solar energy concentrated by a Fresnel lens”. Materials Letters 38 379-385

[8] C. Sierra and Vazquez A. J., (2004)“NiAl coatings on carbon steel by SHS assisted with Concentrated Solar Energy: mass influence on adherence”, International Conference on the Physics, Chemistry and Engineering of Solar Cells (SCELL-2004),in press

[9] C. Sierra and Vazquez, A. J. (2004), “NiAl coatings on carbon steel by SHS assisted with concentrated Solar Energy. Influence of powder”, in press