High Density RF-DC Plasma Nitriding under Optimized Conditions by Plasma-Diagnosis

Abstract

This paper is concerned with plasma diagnosis on a N2-H2 gas mixture to determine the optimum parameters for the nitriding process. Plasma parameters such as pressure, RF-voltage, and DC-bias were varied for optimization. The active species such as N2+ and NH were identified in plasma diagnosis. In the N2-H2 gas mixture, hydrogen imposed a great influence on plasma generation. The small addition of a hydrogen molecule into the gas mixture resulted in the highest yield of N2+ ions and NH radicals; the optimum hydrogen content was 20% in the mixture. The austenitic stainless-steel type AISI304 was nitrided at 673 K and 623 K to experimentally demonstrate that hydrogen gas content optimization is necessary to improve the surface hardness and to describe low temperature nitriding under high nitrogen flux at the surface.

Micro-/Meso-Structure Control of Multi-Hostmetal Alloys by Massive Nitrogen Supersaturation

“…The RF (Radio-Frequency)-DC (Direct Current) plasma nitriding system (YS-Electrical Industry, Co., Ltd.; Kofu, Japan) with the use of the hollow cathode was utilized to prepare the nitrogen supersaturated AISI316 (NS-AISI316) specimen for its microscopic and mesoscopic analyses, as schematically illustrated in Figure 2a. Owing to the hollow cathode device, the nitrogen ion and NH (nitrogen-hydrogen) radical densities were enhanced in the hollow as studied in [16]. After its plasma diagnosis, the ion density reached 4 × 10 18 ions/m 3 under the gas flow ratio of nitrogen gas by 160 mL/min to hydrogen gas flow by 20 mL/min.…”

“…The screen printer was utilized to print the designed microtextures onto the AISI316 substrate as depicted in Figure 3. Owing to the hollow cathode device, the nitrogen ion and NH (nitrogen-hydrogen) radical densities were enhanced in the hollow as studied in [16]. After its plasma diagnosis, the ion density reached 4 × 10 18 ions/m 3 under the gas flow ratio of nitrogen gas by 160 mL/min to hydrogen gas flow by 20 mL/min.…”

Green Forging of Titanium and Titanium Alloys by Using the Carbon Supersaturated SKD11 Dies

“…The nitrogen and hydrogen gas mixture with the flow rate ratio of 160 mL/min for nitrogen and 30 mL/min for hydrogen was utilized to make plasma nitriding. The population of NH radicals and nitrogen ions was intensified under this gas flow mixture after the plasma diagnosis in [15]. The methane, hydrogen and argon mixture with the flow rate ratio of 20 mL/min both for methane and hydrogen and 160 mL/min for argon was used to make plasma carburizing.…”

Penning ion source based surface modification of titanium by nitrogen ion implantation

“…Titanium nitride thin film deposition is carried out by applying various techniques such as (i) thermochemical plasma nitriding and chemical vapor deposition performed at high temperature furnace and pressure [8][9][10], (ii) magnetron sputtering (RF-DC) requires a high RF and voltage power source [11][12][13], (iii) cathodic arc deposition needs bias voltage and high electrical power [14], (v) dense plasma focus (DPF) operated at high energy (kJ) [15], and (vi) pulsed laser nitriding faces microstrain and inhomogeneity and demands high laser power [16].…”

“…The main technological pursuits in current research include: generation of nitrogen ions with an economical, efficient and compact ion source operated at very low power as compared to a high power ion source reported in the literature [11][12][13][14][15][16], ions are accelerated to high energy (kilovolt range) with a simple high voltage pulsed transformer and extraction electrode as compared to a large accelerator used in previously reported research [21,[24][25][26]. In this work, we have successfully produced titanium nitride thin films using an economical and portable Penning ion source-based nitriding system.…”