Bright nitriding using atmospheric-pressure pulsed-arc plasma jet based on NH emission characteristics

Abstract

Bright nitriding of a steel surface is demonstrated by an atmospheric-pressure pulsed-arc plasma jet, keeping the original metallic luster and low roughness. As the hydrogen fraction in the nitrogen-hydrogen gas mixture increases, the optical emission intensity of NH radicals decreases. Following this fact, we examine a method to suppress the formation of a compound layer, in which the hydrogen fraction increases from the conventional value of 1% to larger values for suppressing excess nitrogen supply. The hydrogen fraction of 4% provides a nitrided surface without a compound layer, where surface reflectance is largest and surface roughness is lowest. However, the nitriding treatment produces a dark spot several millimeters in diameter at the sample center due to local oxidization.

Surface Treatment of Boron Doped Diamond by Atmospheric-Pressure Nitrogen Plasma Jet: Effects on the Electrochemical Characteristics

“…1. [15][16][17][18] Here, the pulsed-arc plasma jet is utilized as the atmospheric-pressure plasma source. In brief, the plasma jet nozzle equipped with coaxial cylindrical electrodes was used as shown in Fig.…”

“…As shown in Fig. 9 a), the aggressive species such as NH and nitrogen-related radicals are generated at high density during APN2PJ treatment [15][16][17][18] . These species violently attack C-C bond (including C-B bond at some minor extent) and scission of the bond takes place [Fig.…”

“…In particular, atmosphericpressure nitrogen plasma jet (APN2PJ) procedure is an interesting technology to produce NH and nitrogen-related radicals at high density as it has been demonstrated for nitriding and hardening in the case of steel surface. [15][16][17][18] Based on these features, we considered APN2PJ as a potential technology for functionalization of BDD via. etching and nitrogen doping.…”