DEBACOAT · Development of high-performance barrels with innovative gradient coatings

A large amount of plastic raw material is processed by screw extrusion and by screw injection moulding techniques. The degree of equipment wear for these techniques represents one of the issues of greater concern since it determines the economic feasibility of processing, especially in view of increasing filler content of plastics, processing temperatures and throughputs of plants.The main objective of the project is the development of a set of barrels with innovative internal thick coatings, featuring a compositional gradient along their length to optimise the coating behaviour and better face the different tribological and corrosive environments encountered during service in the specific sections of the extruder.DEBACOAT aims to face important challenges:- to overcome the current trial-error approach for applied research and development of new coating solutions- to understand the relationship existing between materials and process parameters for obtaining high-quality coatings and improving their properties- to guarantee reliability and repeatability on the productionThe expected improved performance of the barrels can be specifically achieved by investigating and optimizing the following scientific issues:- R&D feedstock powder formulation for each specific working condition experienced in each section of the extruder;- R&D the chemical composition of the coating both along thickness (radially - as governed by dilution with backing steel) and also along the length of barrel (as governed by differentiated powder composition and specific melting processes);- Processing the barrels by induction heating and spin casting to achieve controlled zone-melting and solidification of the thick coating with a compositional gradient along its length;- Alternative novel processing of the barrels by laser cladding or Plasma Transferred Arc (PTA) deposition, to produce compositional gradients along their lengths, especially in twin-screw barrel configuration