Analysis of Acoustic Emission waveform signals produced in test on ceramo-metallics interfaces

The study of ceramic-metal interface is of special importance in odontology area by the current demand about dental prostheses, so it is very important to be more and more similar to natural teeth and with a long service life. With the aim of assessing in detail the behavior of ceramic-metal interface used in dental restorations systems, in this work the adherence between ceramic (feldspathic porcelain) and metal (chrome-based alloys frequently used in odontology) is characterized through a non-destructive tests method called Acoustic Emission (AE). For this, samples were made under a Standard, with a Ni-Cr alloy substrate and feldspathic porcelain layer. The substrates were subjected to different surface treatments, such as sand blasting and thermal treatments, before applying the ceramic layer. These treatments take part of the manufacturing process and allow improving the bonding between porcelain and alloy. Each sample was tested under a specific Standard with bending on a three-point device until the ceramic became detached. The detachment was studied with AE in real time. The AE waveforms and the parameters load signal were obtained during the tests. The analysis of the AE signal waveforms was made by studying the events resulting from the most important moments of the interface-debonding process. In this case, waveform features of the AE signals were used, in particular a parameter proportional to the energy of the P waves in order to classify them as different conditions of adhesion.