Application and evaluation of nitriding treatment using active screen plasma

Ichimura, Susumu; Takashima, Seigo; Tsuru, Ippei; Ohkubo, Daichi; Matsuo, Hideaki; Goto, Mineo

doi:10.1016/j.surfcoat.2019.05.075

Cited by 17 publications

(7 citation statements)

References 32 publications

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“…Thus, it is expected that high-quality diamond films can be deposited directly onto plasma-nitrided WC-Co substrates by tuning the content and distribution of Co4N in the surface layer. Similar to the nitriding of ferrous alloys [23,24], Ar + , N + , and H + , with high energy and present in the plasma produced at a bias voltage of 400 V, bombard the surface of the substrate and sputter-out the Co atoms; the sputtering efficiency of the ions increases in the order Ar + > N + > H + . A fraction of the sputtered Co atoms reacts with the active nitrogen in the plasma to form Co4N, which redeposits on the surface to form the white Co-rich particles.…”

Section: Effect Of the Conversion Layer On Hfcvdmentioning

confidence: 99%

“…A Co-boride layer in the surface is able to delete the Co catalysis, then how about Co-nitrides? Plasma nitriding has been successfully used for hardening ferrous alloys [23,24]; however, there are significant challenges when plasma nitriding is used in the surface modification of WC-Co cermets. According to the W-Co-C ternary phase diagram, the solubility of Co with the other constituents, the decomposition of WC phases, and the constituent phase structure vary with temperature and the media atmosphere [25][26][27].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Low-Pressure Plasma Nitriding with Hollow Cathode Discharge on the Surface Microstructure of WC-Co Cermet

et al. 2021

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WC-Co cermet was plasma-nitrided with the assistance of a hollow cathode ion source at 400 °C under a vacuum of 3–8 Pa. Hot film chemical vapor deposition (HFCVD) of a diamond coating was carried out on the nitrided specimen, without chemical etching. Scanning electronic microscopy, electron probing microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were used to characterize the surface microstructure of the nitride specimens and the coatings. A thin surface conversion layer with a specific structure was formed, in which the primary Co binder was transformed into Co-rich particles. The Co-rich particles consisted of a γ-Co core and a Co4N outer layer. This specific surface conversion layer significantly suppresses the out-diffusion and catalytic graphitization of Co during HFCVD. The existent phase, morphology, and density distribution of Co compounds can be tuned by varying the nitriding parameters, such as gas media, ionization ratio, bombardment energy flux, and nitriding duration.

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Section: Effect Of the Conversion Layer On Hfcvdmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Low-Pressure Plasma Nitriding with Hollow Cathode Discharge on the Surface Microstructure of WC-Co Cermet

et al. 2021

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“…Active screen plasma nitriding (ASPN) is an excellent method for the further utilization of active species and the generation of uniform heating regions. The screen suppresses the edge effect by increasing the supply of active species such as N + , N 2 + and H + and by heating the sample surface uniformly [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. However, nitriding on small-diameter thin pipes has not been reported yet [30].…”

Section: Introductionmentioning

confidence: 99%

Application of Active-Screen Plasma Nitriding to an Austenitic Stainless Steel Small-Diameter Thin Pipe

Sumiya¹,

Tokuyama²,

Nishimoto

et al. 2021

Metals

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Low-temperature active-screen plasma nitriding (ASPN) was applied in this study to improve the bending rigidity and corrosion resistance of a small-diameter thin pipe composed of austenitic stainless steel (SUS 304). The inner and outer diameters of the pipe were ϕ0.3 and ϕ0.4 mm, respectively, and the pipe length was 50 mm. The jig temperature was measured using a thermocouple and was adopted as the nitriding temperature because measuring the temperature of a small-diameter pipe is difficult. The nitriding temperature was varied from 578 to 638 K to investigate the effect of temperature on the nitriding layer and mechanical property. The nitriding layer thickness increased with an increase in nitriding temperature, reaching 15 μm at 638 K. The existence of expanded austenite (S phase) in this nitriding layer was revealed using the X-ray diffraction pattern. Moreover, the surface hardness increased with the nitriding temperature and took a maximum value of 1100 HV above 598 K. The bending load increased with an increase in the nitriding temperature in relation to the thicker nitriding layer and increased surface hardness. The nitrided samples did not corrode near the center, and corrosion was noted only near the tip at high nitriding temperatures of 618 and 638 K in a salt spray test. These results indicated that the bending rigidity of the small-diameter thin pipe composed of austenitic stainless steel was successfully improved using low-temperature ASPN while ensuring corrosion resistance.

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“…As the cathode of the metal screen is bombarded by ions, iron particles are continuously sputtered and deposited on the workpiece, and nitrogen atoms diffuse into the inner part of the suspended workpiece to avoid the above problems during CPN treatment. Since the plasma is formed by the glow discharge generated by the active screen, the workpiece should be closer to the active screen [17][18][19] .…”

Section: Introductionmentioning

confidence: 99%

Mechanical and Wear Properties of 42CrMo Steel by Plasma Nitriding assisted Hollow Cathode Ion Source

et al. 2021

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Plasma nitriding is a plasma-activated thermochemical method widely used to increase the fatigue strength, hardness and wear resistance of low-alloy steels. In this work, a new structure consisting of a hollow cathode metal plate can produce a hollow cathode discharge and heat the workpiece by radiation. This principle is used to perform hollow cathode source plasma nitriding (HCSPN). Herein, 42CrMo steels were treated by conventional plasma nitriding (CPN) and HCSPN treatments. The 42CrMo steels were nitrided at 525 °C for 6 h in NH 3 atmosphere. The mechanical and dry wear properties were measured by nano-indentation, Vickers micro-indentation and ball-on-disk tribometer, respectively. The H 3 /E ⁎2 ratio was 0.0274 GPa (H=11.51 GPa and E ⁎ =235.84 GPa) for the CPN sample and 0.0276 GPa (H=10.87 GPa and E ⁎ =215.54 GPa) for the HCSPN sample. Compared with the untreated 42CrMn steel, all the nitrided samples possess increased fracture toughness. Because the workpiece was not used as a discharge cathode, this HCSPN treatment overcame the disadvantages of the conventional CPN treatment. Additionally, results showed that the surface of the HCSPN sample was smoother than that of the CPN sample, and its tribological performance was better.

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Application and evaluation of nitriding treatment using active screen plasma

Cited by 17 publications

References 32 publications

Effect of Low-Pressure Plasma Nitriding with Hollow Cathode Discharge on the Surface Microstructure of WC-Co Cermet

Effect of Low-Pressure Plasma Nitriding with Hollow Cathode Discharge on the Surface Microstructure of WC-Co Cermet

Application of Active-Screen Plasma Nitriding to an Austenitic Stainless Steel Small-Diameter Thin Pipe

Mechanical and Wear Properties of 42CrMo Steel by Plasma Nitriding assisted Hollow Cathode Ion Source

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