“Investigations into the plasma-assisted production of thin functional layers on porous components using PE-CVD”

Status: ongoing

Particle composites are processed into high-quality components by means of sintering, among other things. The material and form-fit structure of several materials means that the porosity changes in each production step. This is largely dependent on the parameters of the production processes, has a significant influence on the properties of the finished product and therefore makes it necessary to test the density of the workpieces between the individual production steps before tempering/sintering.

Up to now, the density of workpieces has typically been measured in the laboratory, which is time-consuming and cost-intensive. The laboratory measurement methods that represent the state of the art (e.g. micrograph analysis, gas pycnometry) therefore entail practical process times of 1-2 days.

In contrast, the Archimedes' principle measurement method allows non-destructive and rapid density measurement and can also be integrated directly into production processes. However, the application of this method to porous objects that are unstable to moisture, such as green and brown bodies, i.e. ceramic components before the firing or sintering process, has so far been made difficult or impossible by their absorption of liquid during the measurement. This can be remedied by a thin functional coating whose barrier effect effectively suppresses the liquid absorption of the measurement object.

The aim of the joint project with the partners

• Dimensionics Density GmbH
• University of Rostock, Chair of Microfluidics
• Leibniz Institute for Plasma Science and Technology e. V.

is the development of an automated system for the deposition of such a thin functional layer on porous components using plasma-enhanced chemical vapor deposition (PECVD) for non-destructive, production-integrated density measurement according to Archimedes' principle.

The project objective of the Leibniz Institute for Plasma Science and Technology e. V. is the development of such functional layers by means of PECVD, which allow the application of the measurement principle also for porous and sensitive components.

In order to achieve the project goal, different coating processes, plasma sources and chemical starting compounds for coating are being examined for their suitability. In addition to the proven low-pressure processes, the suitability of a locally effective atmospheric pressure plasma for this application is being researched in particular, for which a laboratory model is being set up as part of the project. The results will be evaluated and compared by characterizing the chemical composition and measuring the wettability of the functional layers.