In his doctoral dissertation, MSc (Tech) Ville Matikainen studied the formation, properties, and performance of chromium carbide -based coatings, which were manufactured with the modern HVAF spray process. The goal was to produce coatings with improved properties and performance to provide a real alternative to the industry’s standard high-velocity oxygen-fuel (HVOF) sprayed tungsten carbide -based materials.
“In thermal spraying, hardmetal coatings are produced by injecting powder into a combustion spray process, which heats up the particles and accelerates them to high velocity before they impact on a surface and build up a coating. In the HVAF spray process, the particles are accelerated to higher impact velocities compared to other processes, which results in denser and mechanically stronger coatings,” Matikainen summarises his study.
This improved coating quality is one of the key factors determining the performance of the selected coating compositions. Moreover, improved performance enables using cheaper materials in the coatings, such as chromium carbide based hardmetals, while maintaining sufficient performance. In his study, Matikainen investigated several coating compositions and thoroughly tested them in several wear environments to assess their potential. The results showed improved mechanical properties and performance compared to HVOF sprayed coatings.
“Tampere Wear Center (TWC) provided an ideal environment to carry out the wear testing of manufactured coatings. In some wear conditions, the HVAF-sprayed chromium carbide -based coatings performed even better than HVOF sprayed WC-CoCr coatings, offering a cost-efficient alternative to the standard solution,” Matikainen says.
Chromium carbide -based coatings also provide an alternative for reducing the use of tungsten and cobalt, which are on the EU’s list of critical raw materials because they come with verified risks caused by their economic significance and high supply risks.
“In addition to the already existing supply risks, the current global situation is yet another factor and a real wake-up call for many companies to look for more optimised and tailored coating solutions because of increased costs. The results of the dissertation provide new insights into the HVAF spray process as well as to chromium carbide -based coatings, serving the thermal spray industry,” Matikainen explains.
Ville Matikainen lives in Jyväskylä where he is working for Valmet Technologies Oy as a R&D Engineer developing hard coatings for paper machine parts.
The doctoral dissertation of MSc (Tech) Ville Matikainen in the field of surface engineering titled Modern HVAF Spray Process and Cr3C2 -Based Coatings: Exploring the process, structure, properties and performance will be publicly examined at the Faculty of Engineering and Natural Sciences at Tampere University at 12 o’clock on Friday 13 May 2022, in lecture hall K1702, address: Korkeakoulunkatu 6, Tampere. The Opponents will be Professor Christian Moreau from Concordia University and Professor Michael Gasik from Aalto University. Professor Minnamari Vippola from the Faculty of Engineering and Natural Sciences will be the Custos.
The event can be followed via remote connection
The dissertation is available online at
http://urn.fi/URN:ISBN:978-952-03-2403-2
Photograph: Mika Kanerva