Alproof®: the New Family of Castables for the Aluminium Industry
With the hundreds of propri-etary formulations of own inven-tion in the catalogue, the com-pany believed that, over time, it was built up an offering broad enough to guarantee the best solution for all – or almost all – customers’ needs in the alu-minium industry. However, since it is not in the nature to “rest on our laurels”, observing the changes in the market, Eredi Scabini real-ised that one could do even more, and even better.
So, about three years ago, a project to re-assess the products specifically for alu-minium was launched, which involved the performance of more than 600 corrosion tests on 49 refractory castables, with four different alloys (46000/46100;5083;7075; 2196) at four different temperatures (815 – 1100 – 1200 and 1300 °C respectively). An analysis of the huge amount of data generated by the tests, revealed that the portfolio guaranteed excellent coverage of both standard and heavy-duty applications, but from the commercial point of view, it was less competitive in intermediate ap-plications (e.g. reverberatory furnaces with medium-power regenerative burners). There was therefore a gap in this range for a more specific product for these applications, which would enable Eredi Scabini to offer customers an alternative to the existing “high-end” products. Fig. 1a Fig. 1a-b: Alproof® compared to standard products at different temperatures Therefore, starting from this product fam-ily, which provided a well tried and tested base, the R&D department developed a new technology, capable of delivering bet-ter performances in terms of resistance to thermal shock and corrosion resistance at higher-than-standard temperatures. A better compromise, if possible at the same price as the existing refractory. This was not an easy task: the alumina content was not to be increased in order to avoid higher reversible linear changes and lower thermal shock resistance, and the exclusive use of “non-wetting” additives in the matrices to reduce corrosion and provide better resistance to high temperatures had to be avoided. Without a doubt, efforts had to be concentrated on the matrix, which in these castables accounts for 40–50 % of the total weight. Once again nanotechnology, which was al-ready used for more than 15 years, was the solution. The combination of techniques and know-ledge of chemistry and physics which en-ables to manipulate matter at the atomic level to create structures with size meas-ured in nanometres enabled the researchers to add neutral, solid nanoparticles to the matrix, to block the pathways in the matrix by means of which the molten metals usually saturate the refractory, thus making it “aluminium-proof”. These particles have immense specific coverage: just one gram of material is able to cover an area of 800 m2. Since the number of particles needed to obtain our required result is minimal and our produc-tion know-how allows them to be evenly distributed even through large masses, their effect on the final cost of the product is negligible.
This technique has provided the basis of new products with protection against cor-rosion and corundum penetration at high-temperature up to 90 % higher than the equivalent standard product. Corrosion resistance is so high and the quality-price ratio so excellent that we have decided to create a whole family of these products: Alproof®. The following is the comparison between the corrosion resistance of Alproof® and the equivalent standard product. As the data show, in normal conditions (at 815 °C) both products give excellent results, but from 1100 °C to 1200 °C there is 90 % less corrosion on Alproof®. However, the regu-lar customers should note that its physical properties and installation procedures are very similar to those of the well-established Flustone® products. Eredi Scabini expects that this new, bene ficial discovery will prove very popular with its customers. D. Scabini
Eredi Scabini s.r.l.
Siziano (PV), Italy