Adhesion Of Diamond-like Carbon Films Research Articles

Improving the adhesion of diamond-like carbon films on glass substrate by chemical etching and oxygen plasma treatment

The weak adhesion of diamond-like carbon (DLC) films on glass has hindered their widespread application. Despite extensive research on interlayers to enhance adhesion, the challenge of poor DLC adhesion on glass surfaces remains unresolved. In this study, a new strategy is proposed to improve DLC adhesion on glass. Initially, the glass was chemically etched to generate continuous and micrometer-sized pits on the surface. Subsequently, oxygen plasma treatment was employed on the etched glass to increase the Si–OH content on the surface. SiO2, SiOC and DLC were then sequentially deposited on the etched glass using magnetron sputtering. The film materials were embedded into the pits, resulting in a wavy 3D morphology. This morphology facilitated the distribution of applied force on the inclined planes of the pits and increased the contact area between the film and the glass surface, thereby improving the chemical bonding between the film and the substrate. The adhesion strength, Vickers hardness and pencil hardness of the films on the glass were 135.37 mN, 751.8 HV and 8H, respectively. These results demonstrate the effectiveness of the proposed approach in addressing the issue of weak DLC adhesion on glass. The findings of this study have potential applications in various fields.

Study of the influence of a gradient gas flow as an alternative to improve the adhesion of Diamond-Like Carbon film in the wear and corrosion resistance on the nitrided AISI 4340 steel

Diamond-Like Carbon (DLC) films have been widely studied due to their interesting properties, but this film presents low adhesion on metal surfaces. Interlayers have been performed, between the substrate and the DLC film, combined with previous surface treatment as plasma nitriding to improve film adhesion on the surface. This work aims to develop a multilayer treatment of nitriding, gradient treatment, and DLC film deposition without organosilicon interlayer to determine the synergic influence of treatments on multilayer adhesion, wear, and corrosion resistance of the AISI 4340 steel. Plasma surface treatments such as simple nitriding, simple DLC film deposition, which consists of treatments performed individually, multilayer treatment of nitriding + DLC with and without an organosilicon interlayer, and multilayer treatment of nitriding + gradient treatment + DLC without interlayer using gas flow gradient were carried out using a pulsed-DC power supply. The highest wear and corrosion resistance was obtained by the multilayer treatment with organosilicon interlayer due to the synergic effect of this interlayer with the DLC film and nitriding treatment, but the multilayer treatment without organosilicon interlayer performed with gas flow gradient presents better corrosion and wear properties compared with simple treatment. Results have shown that it is possible to perform multilayer treatments with the presence and the absence of an organosilicon interlayer, keeping wear, corrosion, and adhesion properties of the DLC film on nitrided AISI 4340 steel deposition.

Effect of rubber substrates on the flexibility and tribological properties of diamond-like carbon coatings

In this study, closed-field unbalanced magnetron sputtering was employed to deposit a diamond-like carbon (DLC) film with Cr as the middle layer on three elastomeric substrates, namely nitrile rubber (NBR), fluorine rubber (FKM), and ethylene propylene diene monomer (EPDM) rubber, respectively. In addition, effects of these rubber substrates on the structure and properties of DLC films were investigated. Results revealed that after the bending test, several new cracks are produced on the DLC-coated EPDM rubber and NBR rubber, while debonding is not observed, indicative of the good flexibility and adhesion of DLC films on EPDM rubber and NBR rubber. Furthermore, tribological properties of NBR rubber and EPDM rubber were significantly improved by the DLC film, and almost no film damage was observed on the wear track, while the DLC coated-FKM exhibited severe wear due to the gradual peeling of the coating. Film shedding was caused by the extremely smooth FKM substrate, which led to low film adhesion. Different tribological properties of the coated rubbers were closely related to the difference in surface roughness and mechanical properties of the rubber substrates. • Using unbalanced magnetron sputtering technology to deposit DLC with Cr as a interlayer on NBR, EPDM, FKM • The substrate roughness shows considerable influence on the adhesion. • The friction properties of coated NBR, EPDM and FKM are compared systematically.

Enhancing the adhesion of diamond-like carbon films to steel substrates using silicon-containing interlayers

Diamond-like carbon (DLC) films were deposited on AISI 316L stainless steel by using a unipolar pulsed-DC plasma assisted chemical vapor deposition (PACVD) system. In order to improve the adhesion of the DLC films to the substrate, three different silicon-containing interlayers (a-Si:H, a-SiCx:H, and a-SiNx:H) were deposited at two temperatures of 150 and 350 °C using silicon tetrachloride, methane, nitrogen, and hydrogen precursors. The DLC films with silicon-containing interlayers, deposited at 150 °C, did not show appropriate adhesion to the substrate due to the presence of a high amount of chlorine and hydrogen in the structure of the interlayers. By increasing the temperature of the interlayer deposition, the adhesion of DLC films improved significantly. The results of Raman spectroscopy, Nano indentation and adhesion tests showed that the DLC film with a-SiNx:H interlayer exhibited the lowest ID/IG ratio, highest hardness, and highest adhesion to the substrate.

Enhancement of mechanical, tribological and morphological properties of nitrogenated diamond-like carbon films by gradient nitrogen doping

Diamond-like carbon (DLC) films with gradient nitrogen (N) doping were synthesized by direct-current (DC) magnetron sputtering method. The effects of N doping on composition, adhesion, mechanical, tribological and morphological properties were investigated by Raman spectra, nano-scratch tester, nano-indenter and atomic force microscopy (AFM). The results of nano-scratch tester showed that the adhesion of DLC film was enhanced due to N introduction. The results of AFM, nano-scratch tester and nano-indenter showed that the doping method of gradient increased N component had a significant improvement in surface roughness and mechanical properties compared with the conventional N doping method. The gradient N doping (NG-DLC) films also exhibited better tribological properties compared to conventional N doping (NC-DLC) film. The adhesion and roughness were well achieved and improved simultaneously by utilizing a gradient N-doped deposition method for the first time. The relationship between tribological and mechanical properties was deduced and demonstrated. A model based on wave superposition theorem was built to interpret the relationship between surface roughness and N concentration during the deposition. The simulation results showed great agreement with the experimental results.

Influence of plasma nitriding treatment on the adhesion of DLC films deposited on AISI 4140 steel by PVD magnetron sputtering

Duplex surface treatments composed of diamond like carbon (DLC) coating followed by plasma nitriding have drawn attention for a while. In this study, AISI 4140 steel substrates were plasma nitrided at different treatment temperatures and times. Then, DLC films were deposited on both untreated and plasma nitrided samples using PVD magnetron sputtering. The effect of different plasma nitriding temperatures and times on the structural, mechanical and adhesion properties of DLC coatings was investigated by XRD, SEM, microhardness tester and scratch tester, respectively. It was found that surface hardness, intrinsic stresses, layer thickness values and phase distribution in modified layers and DLC coating were the main factors on adhesion properties of duplex coating system. The surface hardness and residual stress values of AISI 4140 steel substrates significantly increased with both DLC coating and duplex surface treatment (plasma nitriding + DLC coating). Increasing plasma nitriding temperature and time also increased the diffusion depth and the thickness of modified layers. Hard surface layers led to a significant improvement on load bearing capacity of the substrate material. However, it was also determined that the process parameters, which provided lower intrinsic stresses, improved the adhesion properties of the duplex coating system.

Linear Ion Source에 의해 증착된 Diamond-Like Carbon(DLC) 박막의 질화층 형성에 따른 밀착력 특성 연구

Diamond-like carbon (DLC) has many outstanding properties such as low friction, high wear resistance and corrosion resistance. However, it is difficult to achieve enough adhesion on the metal substrates because of weak bonding between DLC film and the metal substrate. The purpose of this study is to enhance an adhesion of DLC film. For improving adhesion, the substrate was treated by active screen plasma nitriding before DLC film deposing. Nitrided substrates were investigated by Glow Discharge Spectrometer (GDS), Micro-Vickers Hardness. DLC films were deposited on several metals by linear ion source, and characteristics of the films were investigated using nano-indentation, Field Emission Scanning Electron Microscope (FESEM). The adhesion was measured by scratch tester. The adhesion of DLC films was increased when nitriding layer was formed before DLC deposition. Therefore, the adhesion of DLC film can be enhanced as increasing the hardness of materials.

Investigation into the antibacterial property and bacterial adhesion of diamond-like carbon films

Diamond-like carbon films have unique properties for biological and medical applications due to their excellent biocompatibility, chemical inertness, and superior mechanical properties. In order to attend biomedical applications, there is an increasing interest in developing antibacterial coatings. In this paper, we investigated the bactericidal properties of diamond-like carbon films produced using plasma enhanced chemical vapor deposition. The films were deposited over 316L stainless steel substrates using a pulsed directly current discharge of methane gas. Diamond-like carbon structural quality was evaluated using Raman scattering spectroscopy. The bacterial adhesion and bactericidal activity of the coating was evaluated against Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Salmonella typhimurium ATCC 14028 and Staphylococcus aureus ATCC 25923. These tests show diamond-like carbon bactericidal activity ranged between 25 and 55%, depending on the kind of bacteria. The bacterial adhesion on diamond-like carbon surface was influenced by its structure, chemical bonds and hydrogen content. The low surface roughness did not have decisive effect on its antibacterial performance.

Influence of sputter rate and crystal orientation on the distribution of carbon in polycrystalline copper surfaces treated by plasma immersion ion implantation

The sputter rate influences the resulting thickness of the carbon containing layer within a surface that was treated by plasma immersion ion implantation. Choosing a polycrystalline substrate with rather large crystals and a material with an inherent high sputter rate, inhomogeneous distributions of carbon over the substrate area due to different thicknesses of the incorporated carbon can be detected. A correlation of three factors namely the carbon x-ray intensity in electron probe microanalysis, the thickness of the carbon layer, and the sputter rate in depth profiling measurements via secondary ion mass spectrometry can be shown. Essential for these factors is the crystal orientation that is visualized by mapping via electron backscatter diffraction. The differences in carbon content due to the orientation are most likely one of the reasons that the adhesion of diamond-like carbon films on copper does not improve with an interlayer of implanted carbon.

Plasma immersion ion implantation induced improvements of mechanical properties, wear resistance, and adhesion of diamond-like carbon films deposited on tool steel

Nitrogen-rich layers are formed on the surface of JIS-SKH51 tool steel substrates using the plasma immersion ion implantation (PIII) technique. An unbalanced magnetron sputtering (UBMS) system is then used to coat the steel substrates with diamond-like carbon (DLC) films of various thicknesses. The adhesive strength and wear resistance of the DLC films are then examined by performing nanoscratch and nanowear tests. Finally, the microstructures of the DLC films are analyzed using TEM and Raman spectroscopy. The nanoindentation test results show that the PIII treatment yields an effective improvement in both the hardness and the Young's modulus of the SKH51 substrates. Moreover, cross-sectional observations show that the implantation depth and microstructure of the nitrogen-rich surface layer are dependent on the nitrogen/hydrogen flow ratio used in the PIII process. The nanoscratch test results show that the PIII treatment improves the adhesion of the DLC film to the steel substrate. Furthermore, the Raman spectroscopy results indicate that the use of hydrogen in the PIII process limits the increase in the I(D)/ I(G) ratio by increasing the DLC film thickness. Finally, the nanowear test results show that the deposition of a DLC coating with a sufficient thickness yields a significant improvement in the wear resistance of the steel substrate.

The study of adhesion and nanomechanical properties of DLC films deposited on tool steels

In this study, thin diamond-like carbon (DLC) films were deposited onto a steel substrate. By using the plasma immersion ion implantation (PIII) technique, a nitrogen layer was formed on the steel surface before depositing the DLC films. This PIII formed nitrogen layer, which acts as the buffer layer, has apparently increased the adhesion between the DLC film and the steel substrate. The microstructures, the nanomechanical properties, and the adhesion of the DLC were investigated by the techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), nanoindentation, and nanoscratch. Results show that the hardness and Young's modulus were significantly improved, up to 2 to 9 times; while the implantation depth and the microstructure of the nitrogen layers vary with nitrogen/hydrogen ratio (N:H = 1:0, 1:1, 1:3). Raman analyses indicate that the I( D)/ I( G) ratio increases with the thickness of DLC film. By using the PIII technique in the steel substrate, the adhesion of the DLC film onto the substrate is greatly enhanced, and wear resistance is elevated if the DLC film is sufficiently thick.

Local Adhesion of Diamond-Like Carbon Films Coated on Substrates in a Trench-shaped Cathode

A negative potential is applied to an object in plasma consisting of methane or acetylene in order to coat a thin solid film, such as DLC (Diamond-like Carbon), on a material surface. The method is called Plasma-based Ion Implantation (PBII). Since mechanical objects commonly possess complex shapes, it may be difficult to coat DLC on them in a uniform manner. This non-uniformity in thickness has been studied in many papers, and it has been reported that it is improved by applying a pulse potential repeatedly to the coated material. A scratch test defined the local adhesion of DLC coated by PBII attached at several places to SUS304 thin plates in a trench-shaped cathode. It has been found that the adhesion increases in strength in the following order: the sides of the plates, the bottom of the groove in a trench, and the top of a trench. In order to interpret these results, the hardness of films is measured by a nano-indenter, and the Raman spectra are examined.

Effect of ion implantation layer on adhesion of DLC film by plasma-based ion implantation and deposition

High adhesive diamond-like carbon (DLC) film on SUS304 was obtained using carbon ion implantation between DLC film and substrate material by plasma-based ion implantation and deposition (PBIID). Implantation of mixed silicon and carbon ions to the substrate resulted in much higher adhesion strength than that of the epoxy resin. Effect of ion implantation on adhesion of DLC film was studied by cross sectional STEM observation and EDS element analysis. Enhancement in adhesive strength by ion implantation of mixed carbon and silicon was ascribed to the formation of the multilayer interface consisting of mixed carbon and silicon ion implanted layer and the amorphous layer of carbon and silicon.

Improvements of Wear Properties DLC Coated UHMWPE and PMMA for Biomaterial

Diamond-like carbon (DLC) films were deposited onto UHMWPE and PMMA substrates using plasma CVD process. To improve adhesion of DLC films, substrates were treated plasma before DLC deposition. Samples were analyzed by ball-on disk tester, atomic force microscopy (AFM), and scratch test. Wear and scratch resistance of DLC-coated each substrates were evaluated and showed good results.

Adhesion studies of diamond-like carbon films deposited on Ti6Al4V substrate with a silicon interlayer

Diamond-like carbon (DLC) films have proven quite advantageous in many tribological applications due to their low friction coefficient, their extreme hardness, and more recently their high adherence on different substrate materials. However, for many applications, DLC films as thick as 2 μm are required, which cause high residual stress. In order to overcome this problem, this study observed the behavior of different thicknesses of silicon interlayer between DLC films and Ti6Al4V substrates. The study also analyzed the relation of growth parameters to the mechanical properties of DLC films. Silicon and DLC films were grown by using a rf-PECVD at 13.56 MHz with silane and methane atmospheres, respectively. The contribution of an interlayer thickness to the adhesion between the DLC films and Ti6Al4V substrate was evaluated by using a micro-scratch technique. The hardness and friction coefficient were evaluated by using microindentation and lateral force microscopy (LFM), respectively. Raman scattering spectroscopy was used to characterize the film quality. A correlation was found between the intrinsic stress and adhesion of DLC film and the parameters of the silicon interlayer growth. The addition of a silicon interlayer successfully reduced intrinsic stress of the films, even as measured by using a perfilometry technique.

Pulsed laser deposition of hydroxyapatite-diamondlike carbon multilayer films and their adhesion aspects

We have developed a layered hydroxyapatite/diamondlike carbon/functionally gradient diamondlike carbon-silver/titanium carbide/titanium carbonitride/titanium nitride composite film using pulsed laser deposition. A diamondlike carbon interlayer between a hydroxyapatite coating and the Ti-6Al-4V alloy can serve several purposes, including preventing corrosion of Ti-6Al-4V alloy, overcoming poor adhesion between the hydroxyapatite coating and the titanium oxide surface, and reducing inflammation at the implant/tissue interface. Titanium nitride, titanium carbonitride (TiC x N y ), titanium carbide and functionally gradient diamondlike carbon-silver layers were used to improve the adhesion of diamondlike carbon films to Ti-6Al-4V alloy. We envision several potential medical applications for these multilayer materials, including use in orthopedic and dental devices.

Correlation between adhesion of diamond-like carbon film on LiTaO 3 substrate and SAW velocity

Coating diamond-like carbon (DLC) film to LiTaO 3 substrate is theoretically expected to stiffen the substrate surface so as to accelerate the surface acoustic wave (SAW) at the surface due to its high elastic constant and low mass density. However, it has been reported that DLC film on LiTaO 3 substrate led to a reduction of SAW velocity probably due to poor adhesion between the DLC film and LiTaO 3 substrate. In this study, the adhesion strength between DLC film and LiTaO 3 substrates has been enhanced by introducing a SiO 2 interlayer. Scratch test shows that relatively thick DLC films with an appropriated thickness SiO 2 interlayer exhibit a good adhesion. The increase in SAW velocity correlates with the adhesion strength of the DLC film to the LiTaO 3 substrate, indicating that the adhesion plays an important role of joining the two materials together. In addition, with an improved adhesion, SAW phase velocity in the DLC/SiO 2/LiTaO 3 structure increases with increasing DLC film thickness and with decreasing SiO 2 interlayer thickness.

Interfacial studies for improving the adhesion of diamond-like carbon films on steel

The adhesion of diamond-like carbon (DLC) films on steel is usually very poor. Adhesion of DLC on SKD11 steel was improved for tribological purposes in this study by applying chromium (Cr) metal intermediate layers using magnetron sputtering with substrate bias. DLC films were deposited by inductively coupled plasma (ICP) chemical vapor deposition. However, the adhesion was only at medium level. Intermixing at the Cr–steel interface was further achieved by ion bombardment and found to remarkably improve the adhesion. A reliable process was established to improve the adhesion to top level.

Pre-treatment of substrates for improved adhesion of diamond-like carbon films on surgically implantable metals deposited by saddle field neutral beam source

The saddle field neutral beam process is one of the most promising coating processes used for the production of diamond-like carbon (DLC) films. The films are deposited from a beam of energetic, largely neutral molecules obtained from a source gas of acetylene. For surgical implant uses, the films are deposited on substrates of the principal orthopaedic metal alloys: 316L stainless steel, CoCr and Ti6Al4V. Of paramount importance in these applications is the adhesion of the films. It is known that numerous parameters have an influence on coating adhesion including stress in the film, contamination and chemical bonding between the film and the substrate, and the physical properties and roughness of the substrate. The adhesion of the films has been measured as a function of the duration of in situ etching by a neutral argon beam. The studies were performed on DLC films with thickness ∼0.35 μm. Adhesion was measured using the pull-off and Rockwell C tests. Optimal adhesion was obtained for a limited range of argon etch times; longer or shorter times showed reduced adhesion. The relationship between etching time, adhesion and film structure (sp 3 content) was investigated. The effects of substrate temperature during etching and deposition on the adhesion and film structure were investigated.

Effect of surface treatment on the adhesion of DLC film on 316L stainless steel

Stainless steel type 316L is a material widely used for medical implant purposes, for example, for artificial hips. To improve their wear resistance and biocompatibility, these implants are coated with various materials, in particular diamond-like carbon (DLC). It is known that numerous parameters have an influence on coating adhesion including stress in the film, contamination and chemical bonding between the film and the substrate, and the physical properties and roughness of the substrate. DLC films have been deposited on to substrates of 316L stainless steel using a saddle field neutral beam deposition system with acetylene as the process gas. The adhesion of the films has been measured as a function of the duration of in situ etching by a neutral argon beam on DLC films with thickness ∼0.4 μm. It was measured using pull-off and Rockwell C tests. Argon pre-etching for 15 min is recommended to guarantee an optimal adhesion. The relationship between etching time and film adhesion, structure and stress was investigated. It was found that the adhesion was maximised with an etching period of 15 min and that the etching process also influenced the film structure in terms of the sp2/sp3 bonding ratio and stress. The nature of the surface oxide after etching was investigated by Fourier transform infrared spectroscopy and it was found that the adhesion is correlated with a change in the structure and thickness of the native oxide layer on the surface of the steel, being greatest when the surface oxide was nickel-rich.