Growth Kinetics and Some Mechanical Properties of Plasma Paste Borided Layers Produced on Nimonic 80A-Alloy

Natalia Makuch,Michał Kulka,Piotr Dziarski,Mourad Keddam

doi:10.3390/ma14185146

Natalia Makuch, Michał Kulka + Show 2 more

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https://doi.org/10.3390/ma14185146

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Abstract

Plasma paste boriding was employed in order to produce the boride layers on Nimonic 80A-alloy. The process was carried out at temperatures of 1023 K, 1073 K and 1123 K for 3, 4 and 6 h in a gas mixture of 50% H2-50% Ar. Borax paste was used as a boron source. The microstructure of the produced surface layers consisted of the mixture of nickel borides and chromium borides. The effect of processing temperature and duration on the thickness of the borided layers was observed. The theoretical thicknesses of the borided layers were estimated using an integral diffusion model. A good correlation was obtained between the theoretical (modeled) and experimental depths of the plasma paste borided layers. The boride layers were characterized by a high hardness ranging from 1160 HV to 2132 HV. The multiphase character of the produced layers resulted in differences in hardness. A significant improvement of the wear resistance of the plasma paste borided Nimonic 80A-alloy was observed in comparison with the non-borided alloy.

Highlights

Layers Produced on NimonicNickel alloys, including Nimonic 80A, are commonly known for their excellent resistance to oxidation and corrosion
Δm/mi ratio for the non-borided Nimonic 80A-alloy was 2.5-times higher compared to the plasma paste borided Nimonic 80A-alloy
The produced borided layer contained a mixture of nickel and chromium borides of high hardness

Summary

Introduction

Layers Produced on NimonicNickel alloys, including Nimonic 80A, are commonly known for their excellent resistance to oxidation and corrosion. Plasma-assisted surface treatment is a thermo-chemical treatment technique with great potential for industrial application. When compared to the conventional thermo-chemical boriding processes, plasma-assisted boriding has many advantages: shorter duration of process, lower temperature of process, relatively low gas consumption, lower activation energy for the formation of the boride layers, and reduction in emission of pollutants and toxic wastes [1,2]. Plasma-assisted boriding has become an interesting technique for producing the borided layers on various materials such as: steels [1,2,3,4,5,6,7], titanium alloys [8,9,10,11,12,13], nickel alloys [14,15], molybdenum alloys [16] and cobalt alloys [17]

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