Multi-pass Scratch Research Articles

Experimental and numerical evaluation of multi-pass scratch on borided ARMCO iron

Thermochemical treatments are used for increasing the surface mechanical properties of iron and steels. The wear on mechanical components caused by sliding contact is an important parameter in the field of tribology. In this study, the wear resistance of ARMCO pure iron hardened by the powder-pack boriding process was evaluated using unidirectional dry sliding. The thermochemical treatment of boriding was carried out at temperatures of 850 °C for 1, 2 and 3 h of exposure time. Surface properties such as hardness and Young's modulus were obtained using the nanoindentation technique. The wear testing was performed by multi-pass scratch using an Al2O3 sphere as counterpart, constant loads of 20 and 30 N and 50, 100 and 150 passes (with a sliding distance of 5 mm for each pass). The Archard's model was used to obtain the wear coefficient for each treatment condition. The finite element method applying mesh nonlinear adaptivity was used to evaluate the stress field in the borided samples under sliding contact. Results showed that borided ARMCO pure iron under unidirectional sliding loading caused both adhesive and abrasive wear. Furthermore, for the boriding conditions established in this work, the wear behavior at loads ≥30 N was governed by both the mechanical properties of the boride layer and its thickness, whereas at lower loads only the mechanical properties of the boride layer influenced the wear resistance.

Enhanced Interfacial Adhesion of TiO2 Nanotubes Decorated With Ag Silver Nanoparticles Prepared by Photo-Reduction Process

Abstract In the present study, the adhesion of TiO2 nanotubes (TiO2-NTs) to thicker substrates was improved by decorating them with metallic Ag nanoparticles (NPs) using the photo-reduction process. The obtained coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy, and transmission electron microscope (TEM). The XRD confirmed that all TiO2-NTs crystallized in anatase after annealing at 400 °C regardless of the anodization potential. The SEM indicated that the TiO2-NTs were uniformly distributed on the substrate with an ordered and vertically aligned morphology. It also revealed that the diameter of the TiO2-NTs reached ∼100 nm. The decoration of TiO2-NTs surface with silver nanoparticles was assessed by the TEM. Moreover, a new scratch test mode called “wear mode” was performed to evaluate the wear resistance of the coatings. Results obtained by the scratch tests proved that the decorated coating with Ag nanoparticles improved the interfacial adhesion. The friction coefficient decreased from 0.65 to 0.45 when pure TiO2 was decorated with 10 min-Ag-NPs. The wear behavior was studied using a multi-pass scratch test. It was found that the wear volume reduced with the incorporation of Ag nanoparticles. The study of the damage mechanisms showed visco-elastic plastic deformation in the pure TiO2 coating.

Scratch and multi-pass scratch behavior of poly (methyl methacrylate) (PMMA)

Polymer materials with high specific strength properties are widely used in engineering applications. Poly (methyl methacrylate) (PMMA) is a rigid and brittle thermoplastic with a high glass transition temperature. It is used in many engineering applications due to its low density, lightweight, high transparency, chemical resistance, and high toughness properties. Intense research efforts have been carried out in recent years regarding the scratching behavior of polymers. The scratch test is performed by moving a hard abrasive indenter across the surface of relatively soft material and is used to determine the mechanical resistance of the surfaces of materials. Scratches on the surfaces of amorphous polymeric materials such as PMMA cause optical and mechanical performance loss. For this reason, it is important to determine the scratching behavior of materials under different operating conditions. Within the scope of the study, the scratching behavior and multi-pass scratch behavior of PMMA were investigated. Experimental studies were carried out with Rockwell and Vickers abrasive indenters at different scratch force and velocity values. Scratch and wear marks were examined by means of an optical microscope, optical profilometer and Scanning Electron Microscope (SEM), and scratch hardness, volumes removed, surface topographies and surface morphologies are presented. It has been observed that these results vary remarkably depending on the type of abrasive indenter, scratch force and velocity.

Investigation of friction and wear resistance of carbonitrided AISI 4130 steels using single and multi-pass scratch technique

The present paper investigates the friction and wear resistance of carbonitrided AISI 4130 steels using single and multi-pass scratch techniques. The influence of carbon concentration in high-temperature gas carbonitriding on friction, wear, and corrosion behavior was studied. The microstructure and morphological properties of carbonitrided layers were investigated employing optical microscope and XRD. The corrosion performance of carbonitrided layers was also evaluated using potentiodynamic polarization in 3.5 wt.% aqueous solution of NaCl. The results of microstructure showed the formation of an arrangement of carbonitrides, chromium nitride, retained austenite, and [Formula: see text] carbides phases in the carbonitrided layers. The carbonitrided layer microhardness increased as a function of increasing carbon concentration to attain a maximum value of about 980 HV0.1 at a carbon content between 1 and 1.2%. The microhardness value was more than 3 times than those of the untreated AISI 4130 steels. Moreover, carbon content has a significant influence on the scratch resistance. For single pass, a critical load (LC1) of about 3.5 N was found. The use of multi-pass scratching allowed to examine friction coefficient, wear volume, and damage mechanism. Carbonitrided layers revealed a low friction coefficient (0.06) and a low wear volume that does not exceed [Formula: see text]. Moreover, the multi-pass scratch technique can extract valuable information about the wear behavior of the carbonitrided layers. The results of corrosion test showed that the formation of [Formula: see text], [Formula: see text] and chromium nitride phases in carbonitrided layers were at the origin of high electrochemical resistance.

Scratch testing of plasma nitrided and nitrocarburized AISI 321 steel: Influence of the treatment temperature

This work studies the effect of treatment temperature on plasma nitrided and nitrocarburized AISI 321 stainless steel by scratch test in two modes: progressive and multipass. The treatments were conducted at 400 and 500 °C for 6 h. Progressive scratch revealed a detrimental influence of increasing the temperature in both layers, failure mechanisms worsened with the 500 °C treatments, besides a higher residual depth and a more fluctuating coefficient of friction (COF) were observed. In multipass scratch, a higher and scattered COF was found after 100 passes in the 500 °C layers. The lowest volume loss and COF were registered for nitriding at 400 °C, although nitrocarburizing at 400 °C showed the best integrity with milder failures and low and stable friction.

Coatings strength evaluation of cutting inserts using advanced multi-pass scratch method

The strength of the cutting inserts coating significantly determines the tool wear and the quality of the machined surface. To determine the inserts coating strength, a new method of micromechanical evaluation was developed and tested. The method is based on multi-pass progressive sclerometry with a stepwise maximum indenter load increasing with each subsequent pass. On the first pass, the indenter load increased from zero to 300 mN in the middle of the scratch distance and decreased to zero at the end of the scratch distance. On each subsequent pass, the maximum load on the indenter was increased by a further 100 mN. The indenter loading and unloading rate were 13.4 mN/s. Coating failure criterion is defined as a significant change in the correlation tightness between successive scratches profilograms. The accuracy of determining the load at which coatings starts to fail depends on the step of increasing the indenter load. The developed method has been tested on various PVD coatings of inserts. Surface topography measurements of formed scratches confirms the coatings failure in area of maximum loads on the indenter.

Fluorinated Ethylene Propylene Coatings Deposited by a Spray Process: Mechanical Properties, Scratch and Wear Behavior

To increase the lifetime of metallic molds and protect their surface from wear, a fluorinated ethylene propylene (FEP) polymer was coated onto a stainless-steel (SS304) substrate, using an air spray process followed by a heat treatment. The microstructural properties of the coating were studied using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) as well as X-ray diffraction. The mechanical properties and adhesion behavior were analyzed via a nanoindentation test and progressive scratching. According to the results, the FEP coating had a smooth and dense microstructure. The mechanical properties of the coatings, i.e., the hardness and Young’s modulus, were 57 ± 2.35 and 1.56 ± 0.07 GPa, respectively. During scratching, successive delamination stages (initiation, expansion, and propagation) were noticed, and the measured critical loads LC1 (3.36 N), LC2 (6.2 N), and LC3 (7.6 N) indicated a high adhesion of the FEP coating to SS304. The detailed wear behavior and related damage mechanisms of the FEP coating were investigated employing a multi-pass scratch test and SEM in various sliding conditions. It was found that the wear volume increased with an increase in applied load and sliding velocity. Moreover, the FEP coating revealed a low friction coefficient (around 0.13) and a low wear coefficient (3.1 × 10−4 mm3 N m−1). The investigation of the damage mechanisms of the FEP coating showed a viscoelastic plastic deformation related to FEP ductility. Finally, the coating’s resistance to corrosion was examined using electrochemical measurements in a 3.5 wt% NaCl solution. The coating was found to provide satisfactory corrosion protection to the SS304 substrate, as no corrosion was observed after 60 days of immersion.

Scratch resistance of cobalt boride layer subjected to a diffusion annealing process

This work studies the effect of a diffusion annealing process in cobalt boride layers by progressive load scratch (PLST) and multipass scratch (MPST) tests. First, a double-phase CoB/Co2B layer was formed on CoCrMo alloy at 1000 °C for 6 h. Next, a single-phase Co2B layer was obtained through a diffusion annealing process. The scratch tests were conducted with a progressive load from 5 to 150 N in PLST, whereas in MPST, up to 400 passes were applied with a subcritical load of 38 N. Conducting the diffusion annealing process significantly improved the scratch resistance; in PLST, the achieved layer avoided severe failure mechanisms and decreased residual depth by 60%. In MPST, friction was reduced and the volume loss decreased around 50%.

Evaluation of microstructural, mechanical, and tribological characteristics of Ni-B-W-SiC electroless composite coatings involving multi-pass scratch test

A comprehensive study on the fabrication and characteristics of electroless Ni-B-W-SiC composite coating is presented. The role of tungsten in NiB matrix in improving mechanical and tribological performances is well-known. Here, the composite is formed with the incorporation of silicon carbide in Ni-B-W alloy matrix and is systematically investigated in reference to two electroless binary (NiB) and ternary (Ni-B-W) alloy coatings and Ni-B-SiC composite deposited in similar route. All coated specimens are characterized with SEM, EDS, XRD, ICP-AES, and HRTEM analyses in order to draw conclusions in comparative studies concerning morphological features, compositions, and phase structures. These coatings are also subjected to heat treatment at 450 °C for further observations. Raman spectroscopy is used to confirm the presence of SiC particles in coatings' matrix. Tribological evaluations based on results obtained from multi-pass scratch tests provided insights into characteristics evolved in the developed electroless coatings. Silicon carbide reinforcements in electroless alloy matrices (NiB, and Ni-B-W) show noticeable enhancements in microhardness, fracture toughness, and scratch resistance and those further improve on heat treatment due to the formation of harder nickel boride (Ni3B, and Ni2B) phases within crystalline coatings' matrices. Heat-treated Ni-B-W-SiC coating evolved as characteristically superior in terms of average microhardness (1141 HV0.1) and is closely followed by heat-treated Ni-B-SiC, Ni-B-W, and NiB coatings. Under different load values, heat-treated Ni-B-W-SiC composite coating exhibits higher values of scratch hardness and fracture toughness lying within a range of 10.59–10.92GPa and 4.60–4.99 MPam0.5, respectively. These values are significantly higher than all as-plated alloy and composite coatings studied here. Frictional characteristics of all developed coatings are evaluated through both progressive and multi-pass scratch tests by observing failure mechanisms observed on scratch tracks. In this study, heat-treated Ni-B-W-SiC composite coating evolved as superior in terms of mechanical and tribological characteristics.

Friction and Wear Behavior of a Physical Vapor Deposition Coating Studied Using a Micro-Scratch Technique

Abstract CrSiN coating was deposited by physical vapor deposition (PVD) magnetron sputtering on XC100 steel substrate. Microstructural and morphological properties were studied using scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and atomic force microscopy (AFM). Nanoindentation and scratching experiments were conducted to study the mechanical and adhesion behavior. Multi-pass scratch tests were conducted under different sliding conditions. Results showed that CrSiN coating has a dense and compact nanocomposite microstructure consisting of CrN nanocrystallites and SiN amorphous matrix. The CrSiN thin film exhibit hardness and Young's modulus of 30.52 ± 1.85 GPa and 338.32 ± 13.5 GPa, respectively. The H/E, H3/E2, and 1/HE2 ratios were also calculated (H/E ≈ 0.09, H3/E2 ≈ 0.024, and 1/HE2 ≈ 2.86 × 10−07) and used to predict and assess the elastic/plastic and wear resistance. Critical loads LC1, LC2, and LC3 obtained with scratch test, were, respectively, 11.5 ± 0.12, 16.6 ± 0.23, and 20 ± 0.35 N. Multi-pass scratch were analyzed and the friction coefficient (COF), the damage mechanism, and wear volume were determined. The use of an energetic approach allowed to determine the energetic wear coefficient. CrSiN coating revealed a low friction coefficient (around 0.1) and a low energetic wear coefficient (6.3 × 10−7 mm3/N.m). In addition, it was found that multi-pass scratch method has the potential to extract relevant information about wear behavior.

Comparative investigation of scratch resistance and tribological performance of Ni–B–TiO2 composite coatings prepared by conventional and novel processing methods

Ni–B–TiO2 composite coatings were elaborated by conventional and novel methods. While the first one was designed using TiO2 powder, the second was prepared by adding TiO2 sol in the bath solution. A comparative study between both coatings was performed in terms of microstructure, adhesion strength and wear resistance. To achieve a systematic study, various characterization tests were carried out, including Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), microhardness test, progressive load scratch test, reciprocating sliding test and multi-pass scratch test. The results showed that the TiO2 structure (crystalline or amorphous) has extensively changed the microstructure of Ni–B matrix. Furthermore, it was proven that the novel process provided superior scratch response and better wear resistance of the Ni–B deposit since it offers a compact structure. Nevertheless, the traditional method yielded to porous one, thus leading to mediocre mechanical properties of the same coating.

Multi-pass scratch test on pearlitic steel: Phase identification and crystallographic orientation analysis of the sub-surface layers

In this study, the abrasive wear of pearlitic steel was investigated, including the corresponding microstructural changes at the sub-surface. Multi-pass scratch tests were conducted under different conditions of normal load (4 and 18 N) and number of sliding cycles (from 1 to 12). Scanning electron microscopy (SEM) was employed to characterize the worn surface following the scratch tests. The microstructure after the tests was analyzed via focused ion beam/SEM, and electron backscattered diffraction (EBSD). A geometrically necessary dislocation (GND) analysis was utilized to evaluate the dislocation density from the EBSD data. The results facilitated the establishment of a relationship between the coefficient of friction (COF) and the test parameters. It was found that a decrease in COF was associated with an increase in the number of indenter passes while the COF was independent (statistically) of the normal load. During the multi-pass tests, the work-hardening behavior of the material controls the evolution of the microstructures beneath the scratch. The density of dislocations did not show any significant difference across the test conditions. The nano-hardness analysis showed the presence of a multi-layer with some microstructural transformation. The values of hardness obtained suggested the formation of nanocrystalline martensite in the topmost layer known as the white etching layer (WEL). The microstructure of the layer below the hard WEL is compatible with nanocrystalline martensite and saturated ferrite (based on the high hardness values). The third layer is characterized by nanocrystalline ferrite and partially dissolved cementite. No correlation was found between the crystallographic orientations prior to the tests and work hardening. The plastically affected region did not show any predominant crystallographic orientation.

Structure and adhesion properties of TiNi/MoS2 coatings

One of the most important features expected from protective coatings is good adhesion to the substrate. In this paper, TiNi/MoS2 functional solid lubricant coatings were deposited by closed field unbalanced magnetron sputtering system on 52100 and D2 steels. The adhesion and multipass scratch characterization of the coatings were investigated. The obtained results were analyzed in terms of deposition parameters, as well as structural and mechanical properties of the coatings. Adhesion properties of the coatings were determined by scratch tests with a progressive load. The fatigue-like behaviors of the coatings were obtained by the bidirectional multipass scratch test with a constant load. The results showed that the TiNi/MoS2 has high adhesion and multipass scratch resistance than the literature results. The coatings deposited on the 52100 steel yielded better performance.

CAE-PVD synthesis and characterization of titanium-based biocompatible coatings deposited on titanium alloy for biomedical application

• A compact and uniform layers (TiO 2 and TiN) was obtained on the TiAl6V4 substrate with CAE-PV Deposition. • Multi-pass scratch test was applied study wear resistance of coatings. • The methodology well reveals the various damage mechanisms under loading conditions. • With multi-pass scratch, TiN coating exhibited an ability to hardening process under high sliding conditions. • Multi-pass scratch provides an approach to fast investigation of friction and wear resistance of TiN coating. Cathodic arc evaporation vacuum deposition (CAE-PVD) presents an efficient process for the synthesis of coatings with controlled properties. In this work, we have developed TiN biocompatible layer on the TiAl 6 V 4 titanium alloy by CAE-PVD. The choice of these coatings is based on the excellent resistance to corrosion and erosion, non-toxicity and excellent bioactivity. We focused our study on a characterization of the coating through microstructural observations, indentation tests, scratch and multi-scratch-tests. The results showed a dense and uniform morphology coupled with important mechanical and interfacial properties. The hardness of coating TiN was 15.04 GPa. Measuring adhesion by scratch-test showed that both coatings had a slightly different adhesion quality. The worked-out coating presented critical cohesion load of 3.8 N with a critical adhesion load that exceeds 13.7 N. Tribological properties have also been greatly improved, achieving very low coefficients of friction and wear rates compared to materials commonly used for medical implants.

The effects of TiO2 sol concentration on single- and multiple-scratch damage in electroplated Ni–B-TiO2 sol composite coating

The electrodeposited sol-enhanced Ni–B–TiO2 composite coatings were elaborated using a novel electroplating process. This coating was assessed in terms of tribological behavior and corrosion resistance. However, the adhesion strength of this coating has not been discussed so far. The aim of this study is to evaluate the adhesion behavior of this coating, considering different TiO2 sol concentration in the plating solution in order to predict its effectiveness and its sustainability when used in mineral crushing process. A progressive load scratch test and multi-pass scratch test were performed on coatings. The morphology of scratched surfaces was analyzed to identify the scratch failure mechanism. The results indicate that the addition of TiO2 sol significantly enhanced the deposit adhesion to the substrate compared to pure Ni–B coating. No spallation failure was observed on the sol-enhanced coatings after progressive load scratch test, contrary to Ni–B coating. Moreover, the multi-pass scratch test demonstrated that the improvement in adhesion strength depends strongly on the quantity of the TiO2 sol added to the plating solution. For the optimal concentration of TiO2 sol (25 ml/L), the sol-enhanced Ni–B–TiO2sol composite coating boasts the best adhesion strength. However, further increase in TiO2 sol concentration results in a deterioration of coating adhesion.

Friction and Damage Evolution of the Borided CoCrMo Alloy

Abstract In this study, friction and evolution of cohesive failures (cracks and spallations) in CoB/Co2B layers were analyzed. Thermochemical treatment was carried out at 950, 975, and 1000 °C during 6, 8, and 10 h of exposure time, respectively. The characterization techniques include scanning electron microscopy (SEM) for morphology inspection of layers and thickness measurement, X-ray diffraction for the investigation of phases formed, and instrumented indention to obtain hardness, Young’s modulus, and residual stresses. The practical adhesion of the boride layers was evaluated by a progressive load scratch test (PLST), and the critical loads of cracking, chipping, and spallation were calculated. Later, unidirectional multipass scratch tests (MPSTs) were performed by applying subcritical loads selected from the lower spallation load (54 N); these tests were conducted for a different number of scratch passes. The results show that the coefficient of friction (COF) and coating damage depend on the applied load, the number of passes, and coating thickness. In multipass scratch, the mechanical properties, residual stress state, and thickness play a significant role in the evolution of the coating damage that manifests in the form of cracks and cohesive spallations. Considering the scratch and multipass scratch results, it was found that the sample with 10 h of exposure time presents a better performance among the samples.

Scratch test of pearlitic steels: Influence of normal load and number of passes on the sub-superficial layer formation

Abstract The formation of sub-superficial deformed layer in pearlitic steels under dry sliding conditions has been widely researched, especially for the rail/wheel system. The RCF defects are considerate the most important feature to be analyze on the rail service life determination, being common practices, the employ of rail grinding procedure to remove the surface defects. In this work, the multi-pass scratch was used as the laboratory test simulating the material removal mechanism under wear-controlled conditions, observed in maintenance procedures on heavy railways (which correspond to multi-pass abrasive wear events). It was analyzed the microstructural transformation beneath the scratched surface as a function of the numbers of passes (i.e. one-pass to five-passes) and the constant normal load (i.e. 4 N and 8 N). The material of interest consisted in samples of pearlitic steel without prior work hardening. The features of the grooves were characterized by Coherence Correlation Interferometry (CCI) and Scanning Electron Microscopy (SEM). The White Etching layer (WEL) formation was characterized by Focused Ion Beam (FIB-SEM) and the crystallographic orientation was determined by Electron Backscatter Diffraction (EBSD). The characterization of the grooves features shows a small difference in the friction coefficient between test conditions not correlated by the geometrical aspects (variation up to 30% in depth and width). The SEM and FIB-SEM micrographs revels the WEL formation, consisted in a sub-superficial and transitional layer, characterized by ultra-fine grains and mixture of deformed pearlite colonies with undeformed colonies, respectively. Crystallographic texture can be found in samples tested with the lower normal load (4 N) and its relationship with the number of passes was determined as a function of the reference plane selected. The crystallographic texture to scratch direction (RD) was found in the less severe condition of passes, while in the transversal direction (TD) as a reference plane, a high concentration of pearlite colonies oriented at {111} was determined.

Multipass Scratch Behavior of Borided and Nitrided H13 Steel

AISI H13 steel was subjected to boriding and nitriding; its performance was evaluated by the progressive load scratch test, and then by the multipass scratch test (MPST), to evaluate the accumulated damage. Boriding and nitriding were carried out at a temperature of 800 and 580 °C, respectively, both treatments for 1 and 5 h of exposure time. In scratch test, a load range of 3-90 N was used for borides; a higher range (3-180 N) was chosen for nitrides. Critical loads (Lc) were estimated based on optical microscope observations of the scratch tracks. Failure mechanisms and residual depths were examined by scanning electronic microscope and optical profilometry. Finally, using fractions of Lc, MPST was applied on uncoated and coated samples, for 25, 50, 75 and 100 unidirectional scratch cycles. The coefficient of friction (COF) evolution was recorded and analyzed. A decrease in COF was observed as cycles go through; it was initially higher in uncoated sample; moreover, it was observed that normal load was determinant in its behavior, regardless of the treatment time. Nitrided samples exhibited less catastrophic failures over borided ones, also showed a better volume loss/load ratio performance, from 6 to 8 times better compared to borided samples.

Investigation of Adhesion and Multi-pass Scratch Test Behaviour of Magnetron Sputtered Diamond-Like Carbon Films

Elmas benzeri karbon (DLC) ince filmler sahip oldukları düşük sürtünme katsayısı, yüksek sertlik, yüksekaşınma dayanımı ve kimyasal inaktiflik özelliklerinden dolayı günümüzde çok yaygın olarak çok çeşitli tabanmalzemeler üzerine kaplanmaktadır. Bu tür kaplamalarda önemli olan bir husus ise kaplamanın taban malzemeyeolan adezyonu/yapışkanlığıdır. Bu çalışmada DLC filmler inconel taban malzeme üzerine adezyonu artırmak vedaha yüksek dayanım elde etmek için TiN ve TiCN aratabakalar kullanılarak magnetron sıçratma yöntemi ilekaplanmıştır. Fimlerin yapısal, mekanik, adezyon ve yorulma benzeri davranışları karakterize edildi. Bu çalışmadafilmlerin yapısal ve kimyasal analizleri için X-ray difraktometre (XRD) ve taramalı elektron mikroskopu (SEM)kullanıldı. Mekanik özellikler için mikro-sertlik, adezyon ve yorulma benzeri özellikleri için ise artan yüklü çiziktest ve 100, 250 ve 500 çevrimlik çoklu-çizik testleri filmlere uygulandı. Filmin mikrosertlik değeri 39.8 GPaolarak tespit edildi. Adezyon testlerine göre DLC filmde kritik yük değeri 22 N olarak belirlendi ve 25N yükekadar film taban malzeme üzerinde dayanımını sürdürdü. Çoklu çizik test sonuçlarına göre TiN/TiCN aratabaka ilebüyütülen DLC filmlerin 250 çevrim sonuna kadar çok iyi dayanım gösterdiği gözlenmiştir.

Adhesion and multipass scratch characterization of Ti:Ta-DLC composite coatings

DLC (diamond like carbon) is one of the most studied coatings due to its excellent mechanical and tribological properties, desirable chemical inertness and high corrosion resistance hence it has been widely used in industrial applications for a long time. However, low adhesion and low fatigue resistance are disadvantages of this coating. In this study, we deposited Ti:Ta doped DLC graded-composite coatings on Ti6Al4V and M2 substrates and adhesion and multipass scratch behaviors were characterized. SEM, EDAX and XRD were used to determine the structural properties. Adhesion and fatigue-like behaviors were obtained by scratch tests. The results showed that the critical loads and fatigue resistance of the coatings were affected by the target currents and the hardness of the coatings and substrate.