Multi-pass Scratch Tests Research Articles

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.

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.

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.

A comparative study of fatigue properties of TiVN and TiNbN thin films deposited on different substrates

Transition metal nitrides, especially ternary phase films attract attention due to their high mechanical and tribological features. Besides these, fatigue properties play a very important role on the performance in service life of these types of films. TiVN and TiNbN films were deposited on M2 and H13 steel substrates by reactive magnetron sputtering system. Fatigue properties of the films were characterized via multipass scratch tests. 100, 250 and 500cycles with bidirectional multipass scratch tests were conducted at room temperature by applying 20N constant load. Structural properties were determined with X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Mechanical features of the films were observed with nano hardness tests. Fatigue behaviors, deformation types, coefficient of frictions of the films and effect of different substrates were discussed comparatively. According to the results, the TiVN films showed better fatigue resistance than the TiNbN films although critical adhesion load value of the TiNbN films was higher than the TiVN films. The TiVN films generally showed ductile type cracks at the edge of the tracks and the TiNbN films showed more brittle type cracks. Additionally, the films deposited on M2 substrates exhibited better strength than those of H13 substrates.

Multi-pass scratch test behavior of AISI 316L borided steel

Abstract Iron borides formed on AISI 316L steel were evaluated by multi-pass scratch tests. The boriding process was carried out by continuous and interrupted boron diffusion at 900 °C during 2 and 4 h for obtained FeB/Fe 2 B and Fe 2 B systems, with non-thick thicknesses. Residual stresses by X-ray diffraction were determined on the borided surface. A conventional scratch test was carried out to determine damage mechanisms. After, the multi-pass scratch test was employed to evaluate sliding wear behavior at subcritical loads (20, 30 and 40% of chipping critical load). During the interrupted boriding, the total coating thickness and FeB phase were thinner compared with the continuous process. The chipping critical load determine by conventional test was around 53 N. The coefficient of friction (COF) behavior and damage mechanism in the multi-pass scratches were analyzed. The interfacial fracture energy was calculated for chipping mechanism of FeB. According with the results, the wear rate was reduced on AISI 316L borided steel. Hence, the effect of the substrate played an important role when the boride layer was thin avoiding severe damage; the presence of thin thickness of FeB phase was even favorable. The continuous boriding at 2 h showed better performance with total layer thickness around 10 μm.

Fatigue and adhesion properties of martensite and austenite phases of TiNi shape memory thin films deposited by magnetron sputtering

The application area of TiNi shape memory thin film is gradually increasing. Especially MEMS applications of TiNi film, such as micro-mirror, micro-pump and micro-actuator are widely used. Adhesion to the substrate and fatigue resistance of these films is particularly important for these applications. In this study, we investigated adhesion and fatigue properties of martensite and austenite phases of TiNi shape memory thin films. TiNi films were deposited on copper and Si wafers with magnetron sputtering. Structural properties of the films were determined via SEM, XRD and EDS analyses. Adhesion and fatigue properties of the films were investigated through progressive and multi-pass scratch tests. Phase transformation temperatures and hysteresis were observed with differential scanning calorimeter (DSC). Scratch test results showed that adhesion and fatigue resistance of austenite phase of TiNi film is higher than martensite phase.

Mechanical and Tribological Properties of PVD-Coated Cemented Carbide as Evaluated by a New Multipass Scratch-Testing Method

A new test method based on multipass scratch testing has been developed for evaluating the mechanical and tribological properties of thin, hard coatings. The proposed test method uses a pin-on-disc tribometer and during testing a Rockwell C diamond stylus is used as the “pin” and loaded against the rotating coated sample. The influence of normal load on the number of cycles to coating damage is investigated and the resulting coating damage mechanisms are evaluated by posttest scanning electron microscopy. The present study presents the test method by evaluating the performance of Ti0.86Si0.14N, Ti0.34Al0.66N, and (Al0.7Cr0.3)2O3coatings deposited by cathodic arc evaporation on cemented carbide inserts. The results show that the test method is quick, simple, and reproducible and can preferably be used to obtain relevant data concerning the fatigue, wear, chipping, and spalling characteristics of different coating-substrate composites. The test method can be used as a virtually nondestructive test and, for example, be used to evaluate the fatigue and wear resistance as well as the cohesive and adhesive interfacial strength of coated cemented carbide inserts prior to cutting tests.

Multi-scale mechanical analysis of thin titanium layer on UHMWPE substrates for biomedical applications

We present a multi-scale scratch resistance analysis of thin titanium layer with thickness varying between 0.5 and 1μm, deposited on two biomedical polymeric substrates (UHMWPE). Using different experimental set-ups with specific tip radii, we have performed scratch experiments at various testing conditions. First, nano scratch tests have been performed with a spherical indenteur (tip radius R=22μm) with increasing progressively the normal applied load between 1 and 100 mN. Then, macro-scratch tests have been realized with a spherical indenter (tip radius R=200μm) with the same experimental procedure by applying normal load in the range of 0.5 to 15N. Finally, experimental results about multi-pass scratch tests at low average contact pressure are presented. Scratch experiments have been performed using a specific built-in microvisioscratch device that allows in situ observations of the contact area and of the residual groove during tests. About 100 repeated scratch experiments have been realized in the same track with a glass spherical indenter (tip radius R=3.3mm) at a constant normal load of 5N. Friction coefficient evolutions are studied as function of the scratching conditions and some correlations have determined with damage mechanisms observed by SEM and chromatic confocal microscopy.

Multipass scratch test behaviour of TiAlN thin film deposited on 316L stainless steel and Ti6Al4V alloy with dc biased and pulsed magnetron sputtering

In this study, TiAlN thin film was deposited with dc magnetron sputtering on 316L stainless steel and Ti6Al4V alloy which are widely used as hip joint implants. The adhesion behaviour of TiAlN thin films was investigated by multipass scratch tester. Multipass scratching with three progressive loads was performed on each sample. Observations of the scratch tests showed that there were three main failure events which were identified and labelled as Lc1, Lc2 and Lc3. Failure mechanisms were discussed according to SEM examinations of the scratch tracks. The TiAlN films with dense and homogeneous structure preferentially grew on the plane of (200) for 316L stainless steel and (111) for Ti6Al4V alloy. During the multipass scratch test, the friction coefficients were measured between 0·02 and 0·05. The best values for the friction coefficient were obtained from the films preferentially deposited on the plane of (111). After the scratch test, the thin film was damaged by mechanisms of chipping, flaking and spalling.

Evolution of deformation and friction during multimode scratch test on TiN coated D9 steel

Three different scratch modes were used to induce deformation in TiN coating deposited on D9 substrate. The consequent surface damage was analyzed using optical and scanning electron microscopy. Main deformation mechanisms found during Progressive Load Scratch Test and Constant Load Scratch Test were cohesive cracking, coating spallation and adhesive failure. However, ductile fracture was induced during Multi Pass Scratch Tests (MPSTs) performed at three different loads. The trend of evolving coefficient of friction was found to be different for three kinds of scratch modes and the evolution of coefficient of friction has been correlated with coating deformation.