Abstract No.:
5324

 Scheduled at:
Thursday, June 08, 2017, Hall 27 4:00 PM
HVOF Spraying


 Title:
Effect of nozzle-length, powder feed-rate and spray distance on HIPOJET 2700 HVOF sprayed Cr3C2-NiCr coatings.

 Authors:
Steven Matthews* / The University of Auckland, New Zealand
Joycelyn Woo / Department of Chemical and Materials Engineering, The University of Auckland, New Zealand
Jessica Daniel/ Department of Chemical and Materials Engineering, The University of Auckland, New Zealand

 Abstract:
The high wear resistance of Cr3C2-NiCr coatings is reliant on the formation of a dense coating containing a high percentage of carbide grains, with minimal carbide degradation. Such coating characteristics are typically achieved through the use of high velocity oxygen fuel (HVOF) spraying. The propane fuelled, manually operated HIPOJET 2700 HVOF system is one of a suite of smaller sized commercial HVOF systems recommended for smaller job shops. However, few works have characterised the properties of carbide composite coatings produced with this system. In this work a full factorial design of experiment analysis was used to assess the effect of key operating parameters on the quality of Cr3C2-NiCr coatings. The combustion parameters (fuel and oxygen flows) were fixed at the manufacturers recommended settings in order to focus on the effect of nozzle length (short, air cooled and long, water cooled nozzles), powder feed rate (25g/min and 40g/min) and spray distance (150mm and 200mm) for a conventional HVOF grade (-45/+5µm) agglomerated and sintered Cr3C2-25NiCr powder. The effect of these variables on the coating thickness, microhardness, oxide/porosity content and the extent of carbide phase degradation is discussed.

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