On the hydrogenated silicon carbide (SiCx:H) interlayer properties prompting adhesion of hydrogenated amorphous carbon (a-C:H) deposited on steel

ACS Appl. Mater. Interfaces

Bim

Leidens

et al. 2015

Self Cite

Amorphous carbon (a-C) and several related materials (DLCs) may have ultralow friction coefficients that can be used for saving-energy applications. However, poor chemical bonding of a-C/DLC films on metallic alloys is expected, due to the stability of carbon-carbon bonds. Silicon-based intermediate layers are employed to enhance the adherence of a-C:H films on ferrous alloys, although the role of such buffer layers is not yet fully understood in chemical terms. The chemical bonding of a-C:H thin films on ferrous alloy intermediated by a nanometric SiCx:H buffer layer was analyzed by X-ray photoelectron spectroscopy (XPS). The chemical profile was inspected by glow discharge optical emission spectroscopy (GDOES), and the chemical structure was evaluated by Raman and Fourier transform infrared spectroscopy techniques. The nature of adhesion is discussed by analyzing the chemical bonding at the interfaces of the a-C:H/SiCx:H/ferrous alloy sandwich structure. The adhesion phenomenon is ascribed to specifically chemical bonding character at the buffer layer. Whereas carbon-carbon (C-C) and carbon-silicon (C-Si) bonds are formed at the outermost interface, the innermost interface is constituted mainly by silicon-iron (Si-Fe) bonds. The oxygen presence degrades the adhesion up to totally delaminate the a-C:H thin films. The SiCx:H deposition temperature determines the type of chemical bonding and the amount of oxygen contained in the buffer layer.

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Identification of the Chemical Bonding Prompting Adhesion of a-C:H Thin Films on Ferrous Alloy Intermediated by a SiC_x:H Buffer Layer

ACS Appl. Mater. Interfaces

Bim

Leidens

et al. 2015

Self Cite

“…Furthermore, the exponential decay (at T ≥100°C) of the interlayer thickness as a function of temperature, by using HMDSO as silicon precursor, is quite similar to those obtained by using TMS as silicon precursor. 20 The DLC deposition parameters were maintained constant for all the produced samples. Figure 4a shows the Raman spectra for the DLC films deposited at different temperatures of the SiC x :H interlayer deposition.…”

Section: Resultsmentioning

confidence: 99%

Physicochemical structure of SiC_x:H to improve DLC adhesion on steel

Petry

Boeira

et al. 2016

Surface Engineering

Self Cite

Diamond-like carbon (DLC) coatings show strident properties such as high wear resistance and ultra-low friction. However, a widespread use regarding energy efficiency issues is neglected due to the poor adhesion. Silicon adhesion interlayers (SiC x :H) were deposited at different temperatures from 50 to 500°C with hexamethyldisiloxane followed by DLC. The microstructure was analysed by atomic force microscopy, scanning electron microscopy and Raman spectroscopy. The chemical depth profiling and chemical mapping were performed by glow discharge optical emission spectroscopy and energy-dispersive spectroscopy, respectively. Hardness and critical loads were analysed by nanoindentation tests. At higher deposition temperatures the Si-containing interlayers show lower relative content of H, O and Si and higher relative content of C, allowing the formation of more C-C chemical bonds at the outermost DLC/ SiC x :H interface, which is correlated to better adhesion. Finally, an atomistic model is proposed in order to explain the DLC debonding and bonding mechanisms.

“…One can remark that even the highest hardness value is lower than those published in previous works due to the base roughing pressure of 2 Pa. This base pressure was intentionally used in order to explore the limitation of this technique in the hardness of a-C:H thin films and a recent publication from our group showed the chemical analysis of a-C:H thin films obtained under the same deposition conditions [32]. Moreover, these relatively low hardness values can be explained, partially, by the relatively high hydrogen content in our a-C:H thin films [10].…”

Section: Resultsmentioning

confidence: 99%

Hydrogenated amorphous carbon thin films deposition by pulsed DC plasma enhanced by electrostatic confinement

Dufrène

Surface and Coatings Technology

Soares

et al. 2014

Self Cite

Diamond-like carbon (DLC) is a metastable form of amorphous carbon with attractive properties such as high hardness, low friction, chemical inertness and high wear resistance. In this work, hydrogenated amorphous carbon (a-C:H) thin films were deposited using a plasma enhanced chemical vapor deposition technique by pulsed DC plasma with a simple, low-cost and efficient arrangement of multi-cathodes and multi-anodes in order to enhance the plasma by electrostatic confinement. The samples were characterized by Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Elastic Recoil Detection Analysis, Raman Spectroscopy, and nanoindentation measurements. a-C:H thin films show an homogeneous hydrogen profile along the films deposited at −600 V and −800 V and variable working pressure. According to Raman spectra, both the I D /I G ratio and the G-peak position increase at higher voltages (more remarkable dependence) and lower working pressures (less remarkable dependence). Moreover, the hardness depends on working conditions such as power supply voltage and total working pressure. The electrostatic confinement enhances the deposition rates of a-C:H thin films up to values of 0.9 μm·h −1 , which is almost double than those previously published by pulsed DC plasma in similar conditions. The Raman spectra follow the stage 2 of an established model and this structure transition may explain the hardness behavior.