Ni-Cr Powders Modified with Rhenium as a Novel Coating Material-Physical Properties, Microstructure, and Behavior in...

Area of Science:

• Materials Science
• Surface Engineering
• Metallurgy

Background:

• Nickel-chromium (Ni20Cr) alloys are widely used in demanding applications.
• Developing advanced coatings with improved properties is crucial for enhanced performance.
• Rhenium (Re) addition can significantly alter material characteristics.

Purpose of the Study:

• To create a novel Ni20Cr alloy coating material modified with up to 50% wt. rhenium.
• To characterize the resulting rhenium-modified Ni20Cr powders.
• To investigate the behavior of these powders during plasma spraying.

Main Methods:

• Mechanical mixing of Ni20Cr powder with ammonium perrhenate.
• Thermoreduction in a hydrogen (H2) atmosphere to form a rhenium shell.
• Comprehensive powder characterization (microstructure, phase, composition, density, flowability, particle size, surface area).
• In-flight diagnostics of particle temperature and velocity during plasma spraying.

Main Results:

• Successfully produced Ni20Cr powder with a rhenium shell, showing interdiffusion and solid solution formation.
• Modified powders exhibited increased specific surface area and decreased flowability.
• Plasma spraying parameters (current, H2 flow) influenced in-flight particle temperature and velocity.
• Higher rhenium content led to increased particle temperature but reduced particle velocity.

Conclusions:

• The rhenium-modified Ni20Cr powders are suitable for plasma spraying feedstock.
• Rhenium addition alters powder characteristics and in-flight behavior during plasma spraying.
• This new coating material offers potential for advanced surface engineering applications.