Papers by Keyword: DLC Film

Abstract: In this study, DLC films were deposited using IBED with various CH₄/H₂ ratio, gas flow rates and accelerating voltages. The composition and mechanical properties of the DLC coatings were characterized using SEM, Raman spectroscopy and nanoindentor. The tribological properties of the coating were also investigated using a frictional surface microscope with an in situ observation system and friction force measurements. The DLC films were characterized by a lower I_D/I_G, higher hardness, and improved tribological properties when deposited at a lower accelerating voltage (6 kV). At the CH₄/H₂ ratio of 1:99 and 6 sccm/6 kV, minimum I_D/I_G values of 0.62, relatively low friction coefficient of 0.12 , and a maximum hardness of 4056 HV were attained respectively.

Abstract: Deposited on hot work tool steel substrate coating system composed of AlTiCrN film covered by diamond-like carbon (DLC)-based lubricant, was the subject of the studies. The AlTiCrN and DLC layers were deposited by PVD lateral rotating ARC-cathodes (LARC) and PACVD technology on the X40CrMoV5-1 respectively. This paper provides an analysis of the microstructure, mechanical and tribological properties. Several surface sensitive techniques and methods, i.e. High Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM), Raman spectroscopy and ball-on-disk were used to performed study of the coating. TEM investigation shows an amorphous character of DLC layer. It was found that tested AlTiCrN layer has nanostructural character with fine crystallites. In sliding dry friction conditions the friction coefficient for the investigated elements is set in the range between 0.02-0.04. The investigated coating reveals high wear resistance. The coating demonstrated good adhesion to the substrate.

Abstract: The systems of DLC film/304 stainless steel were separately treated with cryogenic treatment,annealing treatment and composite treatment of cryogenic+annealing to study the effects of different treatments on friction and wear property of DLC film/304 stainless steel,mainly from the film’s hardness,fracture toughness and surface roughness. The results show that the friction and wear property of DLC film/304 stainless steel is improved in different degrees by the three kinds of treatment,single cryogenic treatment performs best. It is because that three kinds of treatment all can improve the fracture toughness of DLC film and reduce DLC film’s surface roughness,but only single cryogenic treatment doesn’t reduce film’s hardness and makes film get the best lubricity and highest hardness-to-elasticity ratio. The residual stress of film/substrate composite system can be effectively adjusted by cryogenic or annealing,but annealing often sacrifices DLC film’s hardness as the price.

Abstract: The tribological properties of DLC(Diamond like carbon) films deposited for different time on mono-crystalline silicon were investigated by using the UMT-2 micro friction and wear tester. The surface topography, composition and hardness of the films were determined by three-dimensional topography instrument, Raman spectrum and nano mechanics tester. The worn surface topography of the films deposited for different time were observed by scanning electron microscopy. The results show that the thickness of the films deposited for different time is nonlinearly increased with the deposition time. The films are the standard nano-films. The surface hardness of the films is low because the films contain hydrogen composition and the deposition temperature is very low. The films deposited for different time have a good anti-friction property, which is improved when the deposition time is prolonged.

Abstract: The friction and wear properties of the DLC coatings were evaluated while being lubricated with pure PAG, PAG containing PN and ZDDP using reciprocating ball-on-disk sliding UMT tester, respectively. The morphologies of the worn surfaces of the DLC coatings were observed using a scanning electron microscope (SEM). The results indicated that the DLC coatings exhibited better tribological properties under the lubrication of PAG containing PN or ZDDP than that of pure PAG. In addition, PN and ZDDP as additives show different tribological properties. The former offers better anti-wear ability, the latter offers better friction-reducing properties.

Abstract: The tribological performance of conventional microcrystalline diamond (MCD) film and diamond-like carbon (DLC) film is investigated comparatively under water lubricating condition. The MCD and DLC film are deposited on cobalt cemented tungsten carbide (WC-Co) substrate using the hot filament chemical vapor deposition (HFCVD) method and the vacuum arc discharge with a graphite cathode respectively. Scanning electron microscopy (SEM), white light interferometer, and Raman spectra are employed to characterize as-deposited MCD and DLC samples. The friction tests are carried out on a ball-on-plate reciprocating friction tester, where the sliding process is conducted under water lubricating condition. Silicon nitride, tungsten carbide, ball-bearing steel and copper are used as counterpart materials. The results indicate that DLC film always exhibits lower friction coefficient than MCD film under water lubricating condition, except the case of sliding against the silicon nitride, in which DLC film is worn out very rapidly and thus leads to the high friction coefficient. The wear resistance of DLC film under water lubricating condition is significantly poorer than that of MCD film. While sliding against silicon nitride, tungsten carbide, ball-bearing steel and copper, its wear rate is calculated as 3.67´10^-7 mm³N^-1m^-1, 9.31´10^-9 mm³N^-1m^-1, 3.54´10^-7 mm³N^-1m^-1, and 4.97´10^-8 mm³N^-1m^-1 respectively. Comparatively, no measurable wear track can be found on the worn surface of MCD films.

Abstract: The mechanical performance of DLC coatings on 316L stainless steel deposited by a saddle field fast atom beam source has been evaluated using the four point bend (FPB) test. Two different deposition parameters, pressure and current were varied when depositing the films. Load-displacement measurements were carried out during the bend test to determine the load corresponding to crack initiation. This load designated as the cohesive strength of the coating which is also called the cracking resistance of coating and provides a measure of the strength of the coating. The cohesive strength of the coating was calculated based on elementary beam theory. Scanning Electron Microscopy (SEM) was used to determine the location of the crack. Finite element analysis was used to predict the stress distribution across the coating thickness. The experimental work on FPB tests has been used to support the numerical (finite element) model for the determination and prediction of film cohesive strength. It was observed that at lower deposition current, the cohesive strength increases with increased deposition pressure whereas, for higher deposition current, these values do not increase with increasing deposition pressure. The model takes into account the film’s Young’s modulus, thickness and deposition pressure and current, and has shown that it is capable of predicting film cohesive strength when combined with a theoretical formulation for brittle fracture. It has been observed that the maximum stress develops at the outer surface of the film and propagates through the film-substrate interface. This result has only been validated for films with higher Young’s modulus compared to that of the substrate material.

Abstract: At atmospheric pressure, Diamond-Like Carbon (DLC) thin films were deposited on the Ti6Al4V alloy surface by a DBD plasma gun at low temperature (<350°C), with CH4 as a precursor and Ar as dilution gas. The structure of the DLC thin film was analyzed by Laser Raman spectroscope and X-ray photoelectron spectroscopy. The surface morphology was observed through scanning electron microscopy. The adhesion between the DLC thin film and the substrate was investigated with the scribe testing. The friction and wear behavior of the DLC thin film under dry sliding against GCr15 steel was evaluated on a ball-on-disc test rig. The results show that it is feasible to prepare a DLC thin film of 1.0μm thickness by plasma gun. The surface roughness Ra is about 13.23nm. The DLC thin film has a good adhesion of critical load 31.0N. It has been found that the DLC thin film has excellent friction and wear-resistant behaviors. The friction coefficient of the Ti6Al4V substrate is about 0.50 under dry sliding against the steel, while the DLC thin film experiences much abated friction coefficient to 0.15 under the same testing condition.

Abstract: The friction and wear properties of AISI 52100 steel and DLC coatings were evaluated while being lubricated with silicone oil, PAO and PAG lubricants by using a reciprocating ball-on-disk sliding UMT tester. The morphologies of original surface and worn surfaces for the DLC and Ti doped DLC coatings were observed by using a scanning electron microscope. The results show that the DLC coatings have better tribological properties than AISI 52100 steel under silicone oil, PAO and PAG lubrication conditions. In addition, the DLC coatings have much better wear resistance than the AISI 52100 steel.

Abstract: Magnetron sputtering metallic or non-metallic materials on epoxy resin coating surface can effectively reduce the friction, improve the wear resistance and inhibit the abrasion, loss and so on. Sputtering Ti/C on the epoxy resin coating can modify the surface, it is proved that the friction can be reduced and wear resistance can be improved on different levels by the experimental results, and in this paper, the mechanism of friction reduction and wear resistance improvement is also investigated and researched comprehensively. By analysis, the layered structure produced by sputtering C can play an important role of lubricating, and the diamond film or diamond-like carbon film can exist on the coating surface, which can play an important role of wear resistance. This study lays the foundation for research on the modification of coating surface.