Development of Zn-Mg alloy coatings by JVD

To promote continuous dry coatings for steel strip by PVD, CRM develops its own JVD (jet vapour deposition) simulator and applies an economical integration strategy combining continuous annealing of steel and vapour deposition by JVD. The JVD system is a very compact system, characterised by a high productivity, a very high metal yield, possibility of working at high partial pressure (up to 1 mbar), homogeneous metal distribution and alloy composition and good coating adherence. It was verified that continuous annealing is a very efficient surface pre-treatment for steel strip in a wide range of industrial dew points. No additional thermal energy is needed for strip heating since this PVD system is introduced in the end section just after continuous annealing. Application to the Zn-Mg system is described. Influence of annealing parameters, residual gas pressure, coating speed, steel strip temperature and chemistry are discussed.