A new advanced non-copper coating for steel cord has been developed in the laboratory to improve the durability of the wire/rubber adhesion bond. Laboratory testing has shown that this coating gives : - equal initial adhesion to rubber - a reduction in the degradation rate of rubber by two times - a lower corrosion rate of the wire by fifty times. The prime objective of this project is to verify the improved safety and life of truck tyres using this new advanced coating made in a commercial manufacturing process.
The main conclusion of the work is that a steel cord with a new advanced coating has been produced (3 tonnes) in a commercial manufacturing process with equal performance as brass benchmark. Passenger tyres, incorporating this coating, confirm that the new wire/rubber adhesion bond is at least equal to that of brass/rubber and has superior corrosion resistance to the brass benchmark. This superior corrosion resistance reduces the possibility of adhesion loss between the steel and rubber thus improving the tyre safety and life. The tyre verification has shown that although the wire/rubber bond is at least equal to the benchmark, the rubber compound in contact with the wire needs to be modified for improved fatigue performance. These modifications have been made and Pirelli is currently running a truck tyre program to measure the improvement before further exploitation.
The new plating process uses less than 80% energy compared to the brass benchmark and a comparison of the current and new processes show a potential cost saving of 30%.
A new lubricant which allows the drawing of the coating without die wear has been developed by Rhone Poulenc based on knowledge gained in this work. The lubricant performance has been verified in the Pirelli pilot plant. Rhone Poulenc is currently evaluating this lubricant on traditional brass drawing lines in order to expand its market.
In order to meet the prime objective the following sub-objectives need to be achieved in tandem : - development of an electroplating system which can deposit a coating of two types of zinc alloy at industrial speeds and efficiencies - development of lubricants which allow for an efficient/effective fine wire drawing process using a coating meeting the first sub-objective criteria. These sub-objectives, in turn, require the evaluation and use of surface analysis techniques which can be used to : - develop the physical chemical model of the drawing and wire/rubber adhesion/degradation processes - control the quality of the wire.
NG7 2RD Nottingham