Effects of Different Plasma Nitrided Layers on the Tribological Performance of DLC Coatings

Shioga, Pedro Henrique Teshima; Binder, Cristiano; Hammes, Gisele; Klein, Aloı́sio Nelmo; Mello, José Daniel Biasoli de

doi:10.1590/1980-5373-mr-2015-0455

Cited by 19 publications

(13 citation statements)

References 31 publications

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“…Peak 1 could correspond to ferrite or martensite, but considering the hardness and microstructure of the specimens, it was assigned to martensite. For the specimen with plasma nitriding + DLC, peak 1 was no longer present, while peaks for the Fe2-3N (ε) and Fe4N (γ´) phases were found, as reported in previous works using similar nitriding conditions [30]. For the nitrided + DLC specimen, the penetration depth of the X-ray was estimated using the Beer-Lambert equation (I/Io = e −μx ) [39], where I/Io is the ratio between absorbed and transmitted beam; x is the penetration depth; μ is the linear absorption coefficient that can be calculated by μm = μ/ρ, ρ is the density; and μm is the mass absorption coefficient.…”

Section: Structure and Mechanical Properties Of The Modified Surfacessupporting

confidence: 85%

“…Plasma nitriding of the substrate is another approach to improve load-bearing capacity before DLC deposition [29]. It allows progressively increase surface hardness, creating mechanical support for the DLC coating [30]. The adhesion between the DLC coating and the softer substrate is particularly relevant for a textured surface, since the surface topography affects this adhesion [31].…”

Section: Introductionmentioning

confidence: 99%

“…Significant changes have been observed in surface topography due to nitriding for compound layers predominantly of γ' phase [27,34]. This occurs because the nitride layer is obtained by accelerating N + ions against the substrate, responsible for cleaning, heating and providing active N to diffuse into the material, but at the same time modifying the surface topography of the substrate [30].…”

Section: Introductionmentioning

confidence: 99%

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Combined Use of Surface Texturing, Plasma Nitriding and DLC Coating on Tool Steel

et al. 2021

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In cold rolling, a textured roll can be used to imprint a desired surface topography onto the sheet during rolling. This work proposes the use of diamond-like carbon (DLC) coatings to protect the surface topography of the rolls in replacement of the carcinogenic hard chrome. For that, hydrogenated amorphous carbon (a-C:H) was deposited on plasma nitrided tool steel, both for ground and textured specimens. Changes in surface topography due to DLC coating were assessed using a confocal microscope. Coating adhesion was evaluated using the method VDI 3198. The specimens were characterized using X-ray diffraction (XRD), microhardness test and scanning electron microscopy (SEM). The coating was characterized using Raman spectroscopy (RS) and X-ray photoelectron spectroscopy (XPS). The results showed a soft multilayer coating consisting of a plasma nitrided layer for load support, a Si-rich interlayer to improve adhesion and an a-C:H top layer. DLC deposition reduced the roughness of the textured specimens. The coating resulted in relatively stable friction and good durability, with small damage and negligible wear even under dry sliding.

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Section: Structure and Mechanical Properties Of The Modified Surfacessupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Combined Use of Surface Texturing, Plasma Nitriding and DLC Coating on Tool Steel

et al. 2021

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“…It has been reported that a-C:H has been successfully produced in industrial scale with lower discharge frequencies, ranging between 1 and 500 kHz [10][11][12][13][14][15]. In addition, this reactor configuration is frequently used for nitriding soft substrates assuring mechanical support and anchoring, enabling deposition of DLC in such materials [14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Effect of soft substrate topography on tribological behavior of multifunctional DLC coatings

Soprano

Salvaro

Giacomelli

et al. 2018

J Braz. Soc. Mech. Sci. Eng.

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In this study, the influence of soft substrate surface finishing (5 distinct conditions) on tribological properties of hydrogenated amorphous carbon (a-C:H) films is investigated. Low carbon steel substrates were plasma-nitrided and DLCcoated in a single PECVD batch. Topographical evolution was investigated through white light interferometry (WLI) and scanning electron microscopy (SEM). The substrate topography leads to a negligible impact on bonding structure and mechanical properties of a-C:H films, which were analyzed by Raman spectroscopy (RS) and nano-indentation. The nitriding and deposition process resulted in two groups of samples regarding the topographic features: (A) RoughS q coated & 0.17-0.23 lm; (B) SmoothS q coated & 0.08-0.11 lm. Tribological performance of multifunctional coatings under incremental normal load reciprocating dry sliding tests in ambient air revealed friction coefficients of 0.09 (Rough) and 0.05 (Smooth). Wear scars were analyzed by WLI, SEM and RS. The results suggest that rougher substrates inhibit tribolayer formation and stability, leading to higher friction coefficients.

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“…To further understand the influence of the nature of the loadbearing layer, we developed, using Plasma Enhanced Chemical Vapor Deposition (PECVD), an in house proprietary coating registered as CHИ R (Shioga et al, 2016). The multifunctional coating consisted of a load-bearing layer (plasma nitride layer), and a low friction layer (DLC) deposited onto soft, low carbon steel (AISI 1,020).…”

Section: Layers Nature and Thicknessesmentioning

confidence: 99%

In situ Tribo-Fluorination for Oil-Less Hermetic Compressor Applications

et al. 2021

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In the present work, we overview the multidisciplinary development of a regular, lubricated, hermetic compressor which works in an on-off cycle, circular motion, single-speed, many tribological contacts, into an innovative, linear motion, variable displacement, single tribological contact, oil-less hermetic compressor presenting high versatility in terms of refrigerator design, sustainability and improved efficiency. The original approach encompassed the development of new surface engineering procedures applying purpose-oriented phases to soft substrates. Particular emphasis is given to the in situ fluorination of the tribolayer formed in the piston-cylinder tribopair. Although chlorinated halocarbons (CFC) are efficient refrigerants from a thermodynamic point of view, they do have serious environmental implications that have forced the refrigeration industry to switch to more environmentally friendly hydrofluorocarbon (HFC) based refrigerants. The first and most successful alternative to the CFCs was tetrafluorocarbon, particularly tetrafluoroethane (CF3CH2F), aka R134a refrigerant. The current trend to downsizing mechanical systems, smaller clearances, and increased speeds leading to greater energy efficiencies associated with miscibility issues imposing the use of costly, fully synthetic lubricants with the R134a refrigerant gas led to the introduction of a new hermetic compressor design, the Wisemotion®, the first, and until now, unique, oil-free hermetic compressor on the world market. In this context different types of multi-layers, their thickness, substrate material, processing routes, etc., have been studied and optimized. Si-rich hydrogenated DLC (a:C-H) presented enhanced tribological properties when tested under fluorine-rich atmospheres, and semi-industrial scale tests have been carried out to understand this point further. A homemade tribological emulator was developed allowing close-to-real tribopair, atmosphere, and imposed mechanical conditions used in an oil-free commercial hermetic compressor. The tests were carried under different stroke frequencies (5, 20, and 40 Hz) and atmospheres (R134a, ambient air, and argon). Results showed a strong influence of both atmosphere and stroke frequencies. The friction coefficients were significantly lower (~3.8X) for the refrigerant gas atmosphere, attributed to the fluorine and highly disordered graphitic structures rich tribolayers. Under the high frequency (40 Hz), the energy input seems to be a deterrent to the formation of stable tribolayers, and the DLC coating shatters on the first few sliding meters.

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Effects of Different Plasma Nitrided Layers on the Tribological Performance of DLC Coatings

Cited by 19 publications

References 31 publications

Combined Use of Surface Texturing, Plasma Nitriding and DLC Coating on Tool Steel

Combined Use of Surface Texturing, Plasma Nitriding and DLC Coating on Tool Steel

Effect of soft substrate topography on tribological behavior of multifunctional DLC coatings

In situ Tribo-Fluorination for Oil-Less Hermetic Compressor Applications

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