Characterization of Tribological and Mechanical Properties of the Si3N4 Coating Fabricated by Duplex Surface Treatment of Pack Siliconizing and Plasma Nitriding on AISI D2 Tool Steel

Mojtaba Najafizadeh,Pasquale Cavaliere,Mehran Ghasempour-Mouziraji,Behzad Sadeghi

doi:10.1007/s11661-021-06410-6

Abstract

Silicon nitride (Si3N4) coating was deposited on AISI D2 tool steel through employing duplex surface treatments—pack siliconizing followed by plasma nitriding. Pack cementation was performed at 650 °C, 800 °C, and 950 °C for 2 and 3 hours by using various mixtures to realize the silicon coating. X-ray diffraction analyses and scanning electron microscopy observations were employed for demonstrating the optimal process conditions leading to high coating adhesion, uniform thickness, and composition. The optimized conditions belonging to siliconizing were employed to produce samples to be further processed via plasma nitriding. This treatment was performed with a gas mixture of 75 pct H2-25 pct N2, at the temperature of 550 °C for 7 hours. The results showed that different nitride phases such as Si3N4-β, Si3N4-γ, Fe4N, and Fe3N can be recognized as coatings reinforcements. It was demonstrated that the described composite coating procedure allowed to obtain a remarkable increase in hardness (80 pct higher with respect to the substrate) and wear resistance (30 pct decrease of weight loss) of the tool steel.

Highlights

THE D-type is high carbon (1.4 to 1.6 wt pct) and high chromium (11 to 13 wt pct) tool steels
The D2 tool steel is mainly employed for cold extrusion dies production.[1,2,3,4]
The present study focused on the production and characterization of Si3N4 coating on AISI D2 tool steel through a duplex treatment via pack siliconizing followed by plasma nitriding

Summary

Introduction

THE D-type is high carbon (1.4 to 1.6 wt pct) and high chromium (11 to 13 wt pct) tool steels. They are characterized by very high strength and mechanical stability at elevated temperature, high hardness, good corrosion, and wear resistance. The D2 tool steel is mainly employed for cold extrusion dies production.[1,2,3,4] Obviously, their surface properties are normally improved through simple or complex case hardening processes. As a matter of fact, surface properties are Manuscript submitted May 18, 2021; accepted July 21, 2021.

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Results

Conclusion