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| Abstract No.: |
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Scheduled at:
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Thursday, May 23, 2019, Saal Brüssel 9:40 AM
Application methods for brazing metals
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| Title: |
In situ chromium carbide formation in carbon modified brazed NiCrP-coatings
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| Authors: |
Ulrich Holländer* / Leibniz University Hannover, Germany
Hans Jürgen Maier / Leibniz Universität Hannover / Institut für Werkstoffkunde, Germany
Kai Möhwald/ Leibniz Universität Hannover / Institut für Werkstoffkunde, Germany
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| Abstract: |
NiCrP-based braze metals are preferably used for joining stainless steel components, which are made for operation at demanding temperatures and corrosive loads. Even with chromium contents >25%, melting temperatures <1000°C and a good wetting and spreading are achieved with this braze metals due to their significant content of phosphorus. This properties make NiCrP-braze metals suitable for brazing appropriate assemblies in a cost-efficient conveyor belt furnace process under protective gas. In contrast to that, the use of such alloys for coating by brazing is very limited, since the wear resistance of the phosphorus containing braze metals is rather poor. In the approach presented a modification of the braze metal with carbon containing material is suggested. During brazing, carbon is released and an in situ formation of chromium carbides in liquid NiCrP alloy takes place. The resulting carbide precipitations reinforce the microstructure of the braze alloy yielding a considerable increase of the hardness and the wear resistance of the brazed coating. Within the scope of the paper suitable material concepts and brazing conditions for in situ carbide-enhanced brazed coatings are presented and discussed with respect to an industrial feasibility.
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