Adhesion Behavior Research Articles

Adhesion Behavior of Underground Coal Dust with Fused Silica: Effects of Relative Humidity and Particle Size

Coal dust particles adhering to a camera lens reduce its light transmittance, which deteriorates the performance of the camera and may lead to serious problems with mining equipment that requires visual ability. Aiming at improving coal dust removal and cleaning technologies, the adhesion behavior of coal dust with fused silica is studied here. Experiments were conducted from microscopic and statistical points of view. The adhesion force between a single coal dust particle and fused silica is tested using atomic force microscopy (AFM), and the number and size distribution of large amounts of coal dust particles on fused silica are tested using a home-made adhesion experimental platform and image processing method. The results show that the adhesion force increases at high relative humidity (RH); it is dominated by van der Waals forces at low RH and capillary forces at high RH. The fused silica glass surface is predominantly covered by small-sized coal dust particles, and the total number of particles as well as the proportion of large-sized particles increases with RH. The theoretical values of van der Waals and capillary forces are significantly larger than the experimental values, owing to the irregular shape and roughness of the surface of the coal dust.

Pressure‐dependent adhesion between solid‐supported PC‐lipid bilayers and vesicles under electric fields

AbstractFusion of lipid bilayers in membranes is important in processes from vesicle‐cell interactions (as in drug delivery) to exosome‐cell signaling, while transient transmembrane electric fields are known to occur spontaneously. Two contacting phosphatidylcholine (PC) lipid membranes are known to fuse into one under external electric fields, suggesting that the interaction between them is modified by the field as they approach, prior to the fusion event. Here we measure directly the adhesion energy between dimyristoylphosphatidylcholine (DMPC) and between distearoylphosphatidylcholine (DSPC) surface layers attached to solid substrates both without and with a transmembrane electric field. We find a marked pressure‐dependent adhesion behavior in the electric field, which we attribute to fusion intermediates that are formed, shedding new light on membrane electro‐fusion.

Microplastic accumulation and ecological impacts on benthic invertebrates: Insights from a microcosm experiment

Microplastic (MP) pollution poses a global concern, especially for benthic invertebrates. This one-month study investigated the accumulation of small MP polymers (polypropylene and polyester resin, 3–500 μm, 250 μg L−1) in benthic invertebrates and on one alga species. Results revealed species-specific preferences for MP size and type, driven by ingestion, adhesion, or avoidance behaviours. Polyester resin accumulated in Mytilus galloprovincialis, Chamelea gallina, Hexaplex trunculus, and Paranemonia cinerea, while polypropylene accumulated on Ulva rigida. Over time, MP accumulation decreased in count but not size, averaging 6.2 ± 5.0 particles per individual after a month. MP were mainly found inside of the organisms, especially in the gut, gills, and gonads and externally adherent MP ranged from 11 to 35 % of the total. Biochemical energy assessments after two weeks of MP exposure indicated energy gains for water column species but energy loss for sediment-associated species, highlighting the susceptibility of infaunal benthic communities to MP contamination.

Anti-freezing hydrogel regulated by ice-structuring proteins/cellulose nanofibers system as flexible sensor for winter sports

Conductive hydrogels are widely used as sensors in wearable devices. However, hydrogels cannot endure harsh low-temperature environments. Herein, a new regulatory system based on natural ice-structuring proteins (ISPs) and cellulose nanofibers (CNFs) is introduced into hydrogel network consisting of chemically crosslinked network of copolymerized acrylamide and 2-acrylamide-2-methylpropanesulfonic acid, and physically crosslinked polyvinyl alcohol chains, affording an anti-freezing hydrogel with high conductivity (2.63 S/m). These hydrogels show excellent adhesion behavior to various matrices (including aluminum, glass, pigskin, and plastic). Their mechanical properties are significantly improved with the increase in CNF content (tensile strength of 106.4 kPa, elastic modulus of 133.8 kPa). In addition, ISPs inhibit the growth of ice. This endows the hydrogels with anti-freezing property and allows them to maintain satisfactory mechanical properties, conductivity and sensing properties below zero degrees. Moreover, this hydrogel shows high sensitivity to tensile and compressive deformation (GF = 5.07 at 600–800 % strain). Therefore, it can be utilized to develop strain-type pressure sensors that can be attached directly to human skin for detecting various body motions accurately, reliably, and stably. This study proposes a simple strategy to improve the anti-freezing property of hydrogels, which provides new insights for developing flexible hydrogel electronic devices for application in winter sports.

Effect of the experimental parameters on the ice-asphalt adhesion strength and corresponding theoretical model based on the energy-balanced principle

Ice adhesion behavior plays a crucial role in assessing ice-phobic materials. However, the variation of ice-adhesion strength across different laboratories is attributed to the neglect of ice/substrate characteristics. In this work, ice-adhesion strength under different geometric parameters of ice/substrate on asphalt surfaces was examined through an optimized methodology. Additionally, a theoretical model was developed based on the energy balance principle to analyze the influence of various parameters on ice-adhesion strength and to make predictions. The results suggested that the ice-adhesion strength was positively correlated with the substrate thickness and negatively correlated with both the asphalt thickness and the ice diameter. The detachment process of the ice-asphalt interface was divided into two regions, the non-linear mechanical response region, and the linear damage region. The slope of the linear damage region can be defined as the interfacial stiffness of the ice-asphalt system, which was the main reason leading to the change in ice adhesion strength. The increase in ice-adhesion strength was observed as the interfacial stiffness increased. Moreover, the theoretical model of ice-adhesion strength illustrated the effect of ice/substrate geometric characteristics on ice-adhesion strength and was verified by the experiments. This study may provide some new references and a theoretical basis for further research on ice adhesion behavior in different laboratories.

A Molecular Dynamics Analysis of the Thickness and Adhesion Characteristics of the Quasi-Liquid Layer at the Asphalt-Ice Interface.

The quasi-liquid layer (QLL), a microstructure located between ice and an adhering substrate, is critical in generating capillary pressure, which in turn influences ice adhesion behavior. This study employed molecular dynamics (MD) methods to obtain QLL thickness and utilized these measurements to estimate the adhesive strength between ice and asphalt. The research involved constructing an ice-QLL-asphalt MD model, encompassing four asphalt types and five temperature ranges from 250 K to 270 K. The QLL thickness was determined for various asphalts and temperatures using the tetrahedral order parameter gradient. Additionally, capillary pressure was calculated based on the QLL thickness and other geometric parameters obtained from the MD analysis. These findings were then compared with ice adhesion strength data acquired from pull-off tests. The results indicate that QLL thickness varies with different asphalt types and increases with temperature. At a constant temperature, the QLL thickness decreases in the order of the basal plane, primary prism plane, and secondary prism plane. Furthermore, the adhesion strength of the QLL diminishes as the temperature rises, attributed to the disruption of hydrogen bonds at lower temperatures. The greater the polarity of the asphalt's interface molecules, the stronger the adhesion strength and binding free energy. The MD simulations of the asphalt-ice interface offer insights into the atomic-scale adhesive properties of this interface, contributing to the enhancement in QLL property prediction and calibration at larger scales.

Low fouling and pH-responsive poly(N-vinyl imidazole)/poly(ethylene glycol) methacrylate copolymer gels for colon targeted diclofenac sodium delivery

Protein and cell adhesion onto drug delivery matrices interferes with the predesigned drug delivery profile to the targeted site. Antifouling surfaces are needed to overcome this problem and improve the effectiveness and efficiency of drug delivery systems. Copolymers of N-vinyl imidazole (NVI) with poly(ethylene glycol methacrylate) (PEGMA) were synthesized via free radical polymerization under cryogenic conditions as potential pH-responsive drug delivery systems resistant to protein and cell adhesion. FTIR spectroscopy, elemental analysis, thermal analysis (DSC), mechanical tests, contact angle, surface energy, and SEM analysis provide the physicochemical properties of the samples. Static adsorption/adhesion experiments show that the copolymer cryogels resist BSA adhesion. Furthermore, the copolymer cryogels demonstrate anti-cell adhesion behavior against colon colorectal carcinoma (HCT-116) cells. They are non-cytotoxic toward HDFa fibroblasts. Diclofenac sodium (DS) - loaded copolymer cryogels show pH-dependent sustained drug delivery. The release studies show a limited release in stomach pH (2.0). On the other hand, enhanced release is observed in pH 5.0 and pH 7.4 within 15 h. The quantities of diclofenac sodium released from the copolymer cryogels are sufficient to show anti-inflammatory activity.

Using vibration to attenuate the adhesive friction behavior between screw conveyor blades and wet coal particles

Screw conveyors are widely used in the transportation of materials in the mining field. The characteristics of material the water content and material shape differences make it different from other powdery and other uniform particle adhesion and friction phenomena, which affects the conveying performance. In order to improve the capability of conveying particles, this paper adds the consideration of vibration factors on the basis of the existing particle lifting test, aiming to study the adhesion and friction mechanism of multi-shaped wet particles under the influence of vibration, and to determine the work parameter that can help improve the conveying performance. The trajectory of microscopic particles under radial and axial vibration conditions, the wear amount of particles on blades and the statistics of particle adhesion and friction intensity are analyzed by discrete element method. The test results show that the adhesion strength of wet coal particles will increase with the increase of water content, and vibration can reduce its adhesion and friction characteristics, and the impact of amplitude and frequency changes is different. The improvement of the amplitude and frequency of the axial vibration of the screw blade can improve the wet coal conveying rate and reduce the wear of the blade. In radial vibration, the transportation rate of wet coal first increases and then decreases with the increase of the amplitude, but the wear amount gradually increases and causes adhesion phenomenon. The transportation rate increases with the increase of frequency, but the wear amount first decreases after increasing. The direction of the radial vibration has an effect on the wear and has little effect on the transportation rate. These results can provide guidance for reducing the adhesion of wet particles and improving the conveying rate in screw conveying.

Repeated Hyposalinity Pulses Immediately and Persistently Impair the Sea Urchin Adhesive System.

Climate change will increase the frequency and intensity of extreme climatic events (e.g., storms) that result in repeated pulses of hyposalinity in nearshore ecosystems. Sea urchins inhabit these ecosystems and are stenohaline (restricted to salinity levels ∼32‰), thus are particularly susceptible to hyposalinity events. As key benthic omnivores, sea urchins use hydrostatic adhesive tube feet for numerous functions, including attachment to and locomotion on the substratum as they graze for food. Hyposalinity severely impacts sea urchin locomotor and adhesive performance but several ecologically relevant and climate change-related questions remain. First, do sea urchin locomotion and adhesion acclimate to repeated pulses of hyposalinity? Second, how do tube feet respond to tensile forces during single and repeated hyposalinity events? Third, do the negative effects of hyposalinity exposure persist following a return to normal salinity levels? To answer these questions, we repeatedly exposed green sea urchins (Strongylocentrotus droebachiensis) to pulses of three different salinities (control: 32‰, moderate hyposalinity: 22‰, severe hyposalinity: 16‰) over the course of two months and measured locomotor performance, adhesive performance, and tube foot tensile behavior. We also measured these parameters 20 h after sea urchins returned to normal salinity levels. We found no evidence that tube feet performance and properties acclimate to repeated pulses of hyposalinity, at least over the timescale examined in this study. In contrast, hyposalinity has severe consequences on locomotion, adhesion, and tube foot tensile behavior, and these impacts are not limited to the hyposalinity exposure. Our results suggest both moderate and severe hyposalinity events have the potential to increase sea urchin dislodgment and reduce movement, which may impact sea urchin distribution and their role in marine communities.

A Theoretical Model of Enhanced Adhesion of Bioinspired Micropillar Arrayed Surfaces

To achieve better adhesion, micropillar arrayed surfaces inspired by the gecko adhesion system have gained significant attention. However, debate continues on whether micropillar arrayed surfaces actually enhance interfacial adhesion compared to smooth surfaces. To clearly understand the factors influencing the adhesion force of micropillar arrayed surfaces and provide a criterion for achieving enhanced adhesion of such the surfaces, a theoretical model of a micropillar arrayed surface containing an elastic backing layer is established. Under a vertically uniform displacement load, the micropillars will detach from the rigid substrate. The adhesion behavior of each micropillar and the variation pattern of the entire adhesion force influenced by the geometry of the micropillars, materials of the micropillars and backing layer during the detaching process are analyzed. A load sharing efficiency is defined, and is found to increase with an increase in the micropillar aspect ratio, Young's modulus ratio of the backing layer to the micropillars, and separation distance between neighboring micropillars, but decrease with an increase in sample size. The entire adhesion force of a micropillar arrayed surface can be quantified, which is larger than that of a smooth surface if the micropillar aspect ratio, Young's modulus ratio of the backing layer to the micropillars and separation distance between neighboring micropillars are appropriate. Detailed diagrams are respectively provided for the load sharing efficiency of all the micropillars and the comparison of the adhesion forces between micropillar arrayed and smooth surfaces with different geometric and material parameters, from which the design strategies of approaching equal load sharing regime and stronger adhesion force of the micropillar arrayed surface than that of the smooth one can be clearly found. The obtained results can not only deepen the understanding of the adhesion behavior of fibrillar surfaces but also provide theoretical guidance for achieving robust adhesion of the micropillar arrayed surfaces.

Differential Effect of Novel Plant Cystatins on the Adhesive Behaviour of Normal and Cancer Breast Cells

In the present work, we have investigated a novel recombinant cystatin dgECP1 and its mutant form, dgECP1m1, focused on their impact on the adhesive behaviour of two breast cell lines: the cancerous, MDA-MB-231, and the normal, MCF-10A. DgECP1 cystatin is intriguing with its RGD motif, responsible for cell adhesion and typical for mammalian extracellular matrix proteins but uncommon for plant cystatins. The presence of the RGD sequence suggests the potential of the dgECP1 to influence the adhesion of cancer cells and, respectively, cancer metastasis. A mutant form of the dgECP1cystatin, dgECP1m1, where RGD is replaced with HGD tripeptide, was also investigated. We found that both phytocystatins exerted differential effects on the adhesion behaviour of normal and cancer cells. In the case of dgECP1 cystatins, the effect on cancer cell adhesion also depends on the mode of administration of the cystatin to cells. When dgECP1 is pre-adsorbed on a substrate, it improves the attachment of breast cancer cells and induces cell aggregation, which is more typical for normal breast cells, and oppositely suppressed adhesion of cancer cells when added to the medium. The mutant form, dgECP1m1, inhibited cancer cell adhesion independently on the way of administration. On the other hand, both plant cystatins only slightly reduced the adhesion of normal mammary cells pointing to the higher sensitivity of cancer cells to both cystatins. These preliminary results open the possibility of considering the plant cystatin dgECP1 for anti-cancer strategies.

Chitosan-Caffeic Acid Antibacterial Coating for PDMS Surfaces: A Sustained Moxifloxacin Release and Prolonged Coating Adhesion

Central venous catheters (CVCs) are largely used to administer chemotherapy, hemodialysis, and other treatments. Mostly made of polydimethylsiloxane (PDMS), these medical devices present an intrinsic risk of infection due to the possible formation of biofilm, thus increasing the risk of complications. Drug-releasing polymer coatings are a well-recognized strategy for combating biofilm formation. However, adhesion of the coating to the substrate over time is a major challenge. Therefore, this work aimed to design a chitosan-based coating designed to have maximum adhesion and stability to guarantee sustained drug release and antibacterial properties for at least 14 days. A coating composed of chitosan (CS) as a drug carrier, caffeic acid (CA) and copper sulphate (Cu) as crosslinkers, and moxifloxacin (Mox) as an antibiotic, was deposited through a controlled casting process onto functionalized PDMS surface. PDMS surface modification was investigated by X-ray photoelectron spectroscopy (XPS), and Fourier-transfer infrared (FTIR). Antibiotic release over time was measured in pseudo-physiological conditions (pH 7.4 and at 37 °C). Indirect cytotoxicity assays were performed on human dermal fibroblasts (HDF). The adhesion of the as-designed coating was evaluated by a specially designed pull-off test, before and after aging for 14 days in PBS. XPS and FTIR analyses confirmed the successful PDMS surface modification. The CS-CA-Cu-Mox coating resulted in being non-cytotoxic towards HDF and exhibited sustained moxifloxacin release for up to 49 days. Furthermore, the CS-CA and CS-CA-Cu coatings presented antibacterial activity for 21 days against E. coli, and for 14 days against S. aureus. Importantly, the coating maintained stable adhesion after 14 days in pseudo-physiological conditions. This study provides new insights into the adhesion behavior of polymeric coatings for medical devices, which is rarely reported in the literature.

Preparation and characterization of carboxymethyl cellulose/polyethylene glycol films containing bromelain/curcumin: In vitro evaluation of wound healing activity

AbstractIn this study, a wound‐healing membrane was fabricated based on carboxymethyl cellulose (CMC) and polyethylene glycol (PEG) containing curcumin (Cur) and bromelain (Br). Citric acid (CA) was used as a cross‐linking agent. This membrane showed an ideal degree of swelling, which was significantly dependent on the concentration and duration of cross‐linked CA. The chemical characterization showed the CA cross‐linker mechanism was more associated with chemical reactions with CMC carboxyl groups, and PEG hydroxyl groups played an important role in forming a hybrid polymer network. It greatly enhanced mechanical and adhesive properties, so the stress strength was improved from 29.4 to 38.52 Mpa. The hydrophilicity of the membrane surface according to the water contact angle assay showed the membrane surface is suitable for adhesion, growth, migration, and proliferation of skin cells. The drug delivery assay demonstrated that the Br and Cur were released during 48 h, but the Br followed the burst release in comparison with Cur. Antibacterial properties showed that CMC/PEG‐Cur/Br have ideal antibacterial properties for preventing the growth of bacteria. In summary, the engineered CMC/PEG containing Cur/Br films with desired cell viability properties and antibacterial activity can potentially improve and accelerate skin regeneration for chronic wound healing.Highlights Hydrogel film was prepared based on carboxymethyl cellulose (CMC), polyethylene glycol (PEG), and citric acid as cross‐linking agent. CMC/PEG film were induced controlling curcumin (Cur) and bromelain (Br) release for wound healing process. CMC/PEG film revealed a wide range of physiochemical, mechanical, adhesion, and biological properties behavior. Incorporation of Cur and Br promoted in vitro biocompatibility, L‐929 cells attachments, and cell migration.

Transmittance of PDMS film on the fluorescent performance and synergistic antifouling effect of SWLAP/PDMS composite coatings

The film-forming substances in waterborne silicone coatings play a crucial role in the properties of coatings. A novel waterborne fluorescent antifouling coating inspired by fluorescent coral was reported in this paper. A series of sky-blue waterproof long afterglow phosphor (SWLAP)/polydimethylsiloxane (PDMS) composite coatings were prepared with different properties of hydroxy‑terminated silicone oil emulsion (HT-SOE). SWLAP is irradiated by sunlight during the day and emits fluorescence at night to interfere with the normal physiological activities of marine organisms. The high transmittance of PDMS films formed by HT-SOE contributes to the high fluorescence intensity of coatings. The adhesion behavior of marine bacteria and Navicula sp. on the coatings was studied under simulated alternative day-night, continuous light, and constant dark conditions. The results showed that the bacterial adhesion rate (BAR) and diatom removal rate (DRR) under simulated alternative day-night conditions of coatings was significantly decreased and increased, respectively. C-S20/5011 had the best static and dynamic antifouling performance. The BAR was only 2.46 % after 24 h and DRR reached 39.9 % after 48 h. Under continuous light or dark conditions, the antifouling abilities of coatings mainly depend on their surface performance and mechanical properties. The fluorescence effect played an important role in the synergistic antifouling mechanism. This study provides a new idea for environmentally friendly antifouling coatings and becomes an important step in the development of green and long-acting marine antifouling coatings.

The effect of photooxidation aging on the cohesion and interfacial adhesion behavior of epoxy asphalt with a composite acidic curing system based on molecular simulation

AbstractThis paper investigated the cross‐linking network structure of epoxy asphalt (EA) with the different ratio of composite curing agents, and further determined the effect of photooxidation aging on the tensile and interfacial adhesion behavior of EA with different cross‐linking network structures through molecular simulation. Based on the molecular models of EA and the interface model between EA and aggregate, the crosslinking network structural characteristics and tensile mechanical behavior were determined. The interfacial adhesion behavior and the mechanization were further studied. The results indicate that 20‐EA and 6‐EA have an epoxy resin cross‐linked network with uniform pore structure and phase distribution. 2‐EA showed a denser cross‐linking network and uneven aggregation phenomenon. Photooxidative aging alleviated the aggregation phenomenon. A dense cross‐linking network improved the tensile strength and the ability of tensile performance to resist photooxidation aging. The interface of EA‐quartz exhibited higher adhesion strength than EA‐calcite due to the closer distance and stronger nonbonding interactions between EA and quartz. The low anhydride content and photooxidation aging made EA approach to the aggregate interface, increasing nonbonding interaction and interfacial adhesion strength. In addition, quartz aggregates were more suitable for application in EA mixtures due to the higher interfacial adhesion strength and lower water sensitivity.

The effect of crystallographic orientation of α-Al2O3 on the wetting behavior and adhesion characteristics of aluminum droplets

To solve the problem of adhesion of aluminum fluid to the inner wall of the vacuum ladle in the aluminum electrolysis industry, molecular dynamics simulation is performed to research the wetting behavior of Al droplets on the surfaces of the α-Al2O3 substrates C (0001), M ( 11ˉ00 ), and R ( 11ˉ02 ) at 1073 K. Meanwhile, the adhesion characteristics of the Al droplet are evaluated by the potential of the mean force (PMF) for the separation of the Al droplets from different surfaces of the α-Al2O3 substrate. The results show that the wetting behavior of Al droplets on the α-Al2O3 substrate is influenced by the different crystallographic orientations. The diffusion of Al droplets in the x-o-y plane of the substrate exhibits isotropic. The PMF and the interfacial potential energy reveal that the magnitude of the adhesion work in the solid-liquid separation of Al droplets from α-Al2O3 substrates follows the order C (0001) > R ( 11ˉ02 ) > M ( 11ˉ00 ). These findings characterize the wetting properties and adhesion behavior of Al droplets on an atomic scale and provide a theoretical basis for the selection of materials for the inner wall of the vacuum ladle.

The influence of oral cavity physiological parameters: temperature, pH, and swelling on the performance of denture adhesives - in vitro study

BackgroundThe various physical and chemical conditions within the oral cavity are hypothesized to have a significant influence on the behavior of denture adhesives and therefore the overall comfort of denture wearers. As such, this study aims to understand the influence of oral cavity physiological parameters such as temperature (17 to 52 °C), pH (2, 7, 10), and denture adhesive swelling due to saliva (20–120%) on the behavior of denture adhesives. This study further aims to emphasize the need for a collective approach to modelling the in-situ behavior of denture adhesives.MethodsRheological measurements were carried out using the Super Polygrip Ultra fresh brand denture adhesive cream to evaluate its storage modulus (G´) and loss modulus (G´´) values at a range of physiologically relevant temperatures, pH values, and degrees of swelling, to represent and characterize the wide variety of conditions that occur within the oral cavity.ResultsRheological data was recorded with respect to variation of temperature, pH, and swelling. Overall, it can be seen that the physiological conditions of the oral cavity have an influence on the rheological properties of the denture adhesive cream. Specifically, our data indicates that the adhesive’s mechanical properties are weakly influenced by pH, but do change with respect to the temperature in the oral cavity and the swelling rate of the adhesive.ConclusionsOur results suggest that the collective inter-play of the parameters pH, temperature and swelling ratio have an influence on the behavior of the denture adhesive. The results clearly highlight the need for developing a multi-parameter viscoelastic material model to understand the collective influence of physiological parameters on the performance of denture adhesives. Multi-parameter models can also potentially be utilized in numerically simulating denture adhesives using finite element simulations.

Unraveling the influencing mechanism of water ingress on the adhesion behavior of poly(dimethylsiloxane)-silica interface: a molecular dynamic study

Unraveling the influencing mechanism of water ingress on the adhesion behavior of poly(dimethylsiloxane)-silica interface: a molecular dynamic study

Interaction of silica with polystyrene: mechanical properties, polymer/filler adhesion and failure behavior

Composites of polystyrene with different loading of silica were prepared by melt mixing in a Brabender Plasticorder at a rotor speed of 60 rpm. The mechanical properties of the composites such as tensile behavior, impact strength, and flexural properties were studied as a function of filler loading. The tensile moduli of the composites increased with silica content. To improve adhesion between the filler and the matrix, an amino silane coupling agent was used. The composites with coupling agents showed enhanced mechanical properties. Thermal properties were measured using differential scanning calorimetry (DSC), thermogravimetry (TGA) and flammability tests. Composites with 15 wt.% and 0.5 wt.% coupling agent showed optimum properties. Scanning electron microscopy (SEM) studies of the tensile fractured samples revealed the extent of filler dispersion and filler/matrix interaction. Finally, experimental results were compared with theoretical predictions.

Hardness, adhesion, and wear behavior of magnetron cosputtered Ti:Zr-O-N thin films

Reactive magnetron sputtering was used to deposit Ti:Zr-O-N thin films, by using a single Zr target, with Ti ribbons placed on the erosion track of the Zr sputtering target. Zr-O-N thin films have been also deposited in the same chamber to be used as reference films. The number of Ti ribbons, the applied sputtering current, and the reactive gas flow were the variable parameters. The films were analyzed in terms of structural development and mechanical properties (instrumented indentation, adhesion scratch testing, and wear analysis). The films are either amorphous or composed of a mixture of crystalline phases based on zirconium and titanium oxides or nitrides. Hardness values are situated between ∼10 and 11 GPa for the reference films (deposited without Ti) and up to ∼22 GPa for one of the Ti:Zr-O-N films. The films deposited without Ti behave slightly better in terms of adhesion to the substrate in comparison to the remaining samples in relation to the occurrence of first cracks (Lc1, critical load 1) and for first delamination (Lc2, critical load 2), a phenomenon probably related to the lower hardness of these films, which can accommodate the plastic deformation caused by the diamond indenter, prior to the occurrence of delamination. Adhesion to the substrate is a critical characteristic during wear tests since some of the coatings exhibit severe delamination.