Hot-Dip Aluminising of Ferrous materials-A Resume of two decades of R & D efforts at NML

Abstract

Starting from bench scale experiments on evolving the process techniques of hot-dip aluminising in fifties the author recapitulates the scaling up of aqueous flux process to pilot plant scale for wire aluminising. The laboratory technology was successfully transferred to a commercial scale plant. Technological soundness alone is however not enough. Cost and economic are still the prime moves in industry. The process has so far reminded been difficult. New users are therefore suggested in the field of heat, oxidation and scaling resistance or where the corrosion resistance properties are marked by superior e.g. marine atmospheres, sulphurous atmospheres and where superior conductivity will be asset e.g. telecommunication and power transmission .Data collected on sheet panels, wire, hardware for P&T, high tension transmission towers, tubes and fittings thereof, 18:8 types and Forritic stainless steels and malleable cast irons are briefly touched upon. For detailed know-how the reader is referred to Annexure –I original list of published papers. Commercial exploitation is however possible after executing licence agreement with N.R.D.C. The very recent hike in price of aluminium as a result of enhanced power tariffs has caused a serious set back to the economic viability of aluminising as compared to galvanizing. Current open market quotations (29.7.75) of Al at Rs.1450/- per quintal as compared to Zn at Rs.14600/- make it rather difficult to promote aluminised materials as substitutes for galvanized materials solely on merits of corrosion resistance, as hard speller and dross in galvanizing industry sometimes fetch a higher price compared to virgin zinc supplied by MMTC through imports.