Thermal sprayed protective coatings for superplastic forming ceramic dies:A monitoring system of die condition

摘要

Superplastic forming (SPF) is an advanced sheet manufacturing process typically restricted to low volume and high value products. SPF ceramic dies have a lower production cost than conventional metal tools, and have short lead-times, but their brittle nature is a limiting factor for SPF applications. Suitable surface treatments have a remarkable effect on wear resistance; hence, the working surface of the die can be improved by the application of appropriate coatings, increasing the lifetime of the SPF ceramic dies. Thermal spray is a promising deposition method, since numerous coating solutions are achievable without expensive vacuum technology.This paper describes a method for the investigation of surface degradation mechanisms in ceramic dies during SPF process at laboratory scale. Greater emphasis is given to the application of thermal sprayed coatings and quantification of their protection properties. At the Advanced Forming Research Centre is been designed a dedicated test rig used for simulate the die part interface at SPF condition. The aim of this study is to develop and to implement a monitoring system of working surface condition by which it is possible to predict the ceramic dies lifetime improvement for different thermal sprayed coatings.