Adhesion Strength Of Coatings Research Articles

Adhesion Strength of Hydroxyapatite Coating on Titanium Materials (Ti-6Al-4V ELI) for Biomedical Application

Implantasi menggunakan material titanium Ti-6Al-4V ELI masih memiliki keterbatasan yaitu osseointegrasi yang rendah karena bersifat kurang bioaktif. Hidroksiapatit digunakan sebagai bahan pelapisn meningkatkan bioaktivitas material dan ikatan material dengan jaringan tulang. Material Ti-6AL-4V ELI (kepingan) dilapisi dengan hidroksiapatit menggunakan metode electrophoretic deposition, dengan variasi voltase (5,8, dan 11 volt) selama 5 menit dan variasi waktu deposisi (5,8, dan 11 menit) dengan voltase 8 volt. Pengujian kekasaran dan kekuatan adhesi lapisan hidroksiapatit pada permukaan material dilakukan secara kualitatif. Hasil penelitian yang diperoleh menunjukkan bahwa metode EPD dapat digunakan untuk melapisi material Ti-6Al-4V ELI dengan hidroksiapatit. Massa partikel penyusun lapisan hidroksiapatit relatif dipengaruhi oleh perlakuan waktu deposisi karena terdapat perubahan ketebalan lapisan. Akan tetapi, susunan partikel relatif dipengaruhi oleh daya yang mengakibatkan migrasi partikel yang akan berpengaruh terhadap ikatan lapisan pada permukaan material. Perlakuan voltase 8 volt selama 5 menit menghasilkan kekasaran pemukaan material dilapisi hidroksiapatit Ra 0,88 dan kerusakan lapisan setelah cross cut tape test adalah 2,25% yang berarti lapisan mengalami adhesi dengan baik pada permukaan material. Dengan masa hidroksiapatit relatif tinggi (0,3 mg), lapisan tersebut menutupi permukaan material titanium dengan baik (surface coverage 82,1%) memiliki ketebalan rata-rata (73,3 μm). Hasil yang diperoleh diharapkan sesuai untuk aplikasi biomedis.

Nano-cerium dioxide synergistic potential on abrasion resistance and surface properties of polyurethane-nanocomposite coatings for esthetic and decorative applications on wood

Development of an antiabrasion and optical shield clearcoat for wooden art and decorative works improves its esthetic durability and lifetime. In this study, the synergistic potentials of cerium dioxide nanoparticles (NPs) were exploited to improve the abrasive, structural, and surface properties of polyurethane (PU)/silica nanocomposite coatings applied on the thermally modified spruce wood. Microhardness, adhesion strength, contact angle, and UV–Vis spectroscopy were used to evaluate the nanocomposite coatings’ surface properties. FE-SEM and EDS techniques were also employed to scrutinize distribution of NPs in the structure of nanocomposite coatings. The results showed that the abrasion resistance significantly improves by increasing the content of silica NPs. However, microhardness and performance of nanocomposite coatings containing a high percentage of silica diminished due to the aggregation of NPs and poor crosslinking of the polymer matrix. The presence of cerium dioxide NPs as a synergistic function in the PU coatings containing nano-silica enhanced the abrasion resistance as well as the glass transition temperature and caused enhanced hardness. Incorporation of cerium dioxide NPs exhibited an incremental effect on the adhesion strength of nanocomposite coatings. However, its presence in high concentration caused an adverse impact on the transparency of the nanocomposite films. In addition, wettability of PU/silica composites remained constant after incorporating high levels of cerium oxide NPs. These findings suggest that use of Ce–Si NPs hybrid/blend in the structure of PU coatings can assure the durability of wood coatings for esthetic applications and interior decoration by strengthening the surface, mechanical, and optical properties.

RESEARCH OF THE INFLUENCE OF THERMAL TREATMENT ON THE STRUCTURE, HARDNESS AND STRENGTH OF COUPLING WITH THE BASIS OF THE COATING OF THE CHROMIUM CARBIDE - TITANIUM SYSTEM

The main quantitative dependencies that relate the parameters of heat treatment of parts clad with hard alloys with their structure and hardness, as well as the adhesion strength of coatings to the substrate, are studied. The theoretical substantiation of the found regularities is proposed.

On the heat-treatment induced evolution of residual stress and remarkable enhancement of adhesion strength of cold sprayed Ti–6Al–4V coatings

Cold spraying is an extremely viable repair technique for high-value aerospace components made of Ti–6Al–4V alloys. However, significant residual stresses are generated in as-sprayed coatings and it is desirable to relieve such stresses as they could impact coating adherence and subsequent performance. We have used a series of post heat treatments to identify the most suitable one for stress-relieving of cold sprayed Ti–6Al–4V coatings on Ti–6Al–4V substrates. The alleviation of macroscopic residual stresses is accompanied by changes in coating microstructures, which has also been discussed. Post heat treatment particularly at 600 and 950 ​°C results in a significant increase in the interfacial bond strength compared to as-sprayed coating. Reduction in coating porosity and increased fraction of adhered powder particles to the substrate are also attributed to the increase in coating adhesion strength.

A sustainable two-layer lignin-anodized composite coating for the corrosion protection of high-strength low-alloy steel

In this study, plasticized kraft lignin was used to prepare anti-corrosive coatings on steel, which was galvanostatically anodized (80 °C, 25 wt.% NaOH) by utilizing three different current density values (24, 50 and 120 mA/cm2). It was shown that the anodization affects not only the properties of anodic coatings but also their interaction with lignin coatings. A combination of pull-off adhesion measurements with linear sweep voltammetry (LSV) demonstrated an enhanced adhesion strength of plasticized lignin coatings (4.32 MPa on anodized surface vs. 2.38 MPa on bare steel) and decreased corrosion current density from 15 μA/cm2 (bare steel) up to ca. 0.5 μA/cm2 for anodized and lignin coated steel.

Thermal spray deposition of aluminum and zinc coatings on thermoplastics

Coatings of aluminum and zinc were applied on two thermoplastic materials, ultra-high molecular weight polyethylene (PE) and polytetrafluoroethylene (PTFE), using twin wire-arc spray spraying. Samples were either smooth (Ra = 0.2 μm) or roughened by grit blasting (Ra = 1.6 μm). Before the start of spraying samples were kept at either room temperature or preheated to 55 °C for PE and 95 °C for PTFE, so that the peak temperature during spraying reached the glass transition temperature of the polymer. Surface temperature was monitored during spraying using thermocouples. Coating adhesion strength was measured using pull tests. Single splats of metal on samples were examined using SEM images. Zinc coatings, about 260 ± 20 μm thick, formed on both polymer samples irrespective of their surface roughness. Adhesion strength was significantly higher on rough surfaces than smooth surfaces. Increasing the initial sample temperature also enhanced adhesion strength. Aluminum adhered only to the PTFE but not the PE. Aluminum droplets have a higher melting point than zinc and melted the sample upon impact, inhibiting mechanical bonding. These results suggest that the metal adhesion to thermoplastics can be significantly improved by pre-heating polymer samples prior to thermal spraying.

Analysis ofin vitrocorrosion behavior and hemocompatibility of electrophoretically deposited bioglass–chitosan–iron oxide coating for biomedical applications

Abstract

Restoration of cylinder liners for automotive tractors engines in modern conditions

One of the most promising technologies for restoring machine parts and cylinder liners is electric spark treatment as the most versatile technology that provides high-quality restoration of worn parts with wear up to 0.5 mm. (Research purpose) The research purpose is in developing a technology for restoring various cylinder liners by means of electric spark processing, selecting optimal modes and electrode materials that allow improving the quality of repair and increasing the post-repair life of the sleeve. (Materials and methods) It was taken into account when conducting research aimed at restoring the geometric parameters of the sleeve, that the coating must have sufficient adhesion strength to the surface of the sleeve under mechanical, thermal loads and long-term operation. Laboratory studies of the adhesion strength of electric spark coatings on the separation (adhesive) and on the cut, as well as tribotechnical studies of interfaces were conducted. Authors have found by analyzing the results of operational tests of restored and new cylinder liners the prospects for using electric spark treatment of worn parts, including diesel engine liners. (Results and discussion) It was shown by laboratory studies of the adhesion strength of electric spark coatings with a 0.2 mm thick BrMKc 3-1 electrode to the working surface of cylinder liners that their separation strength (adhesive) was 20-40 megapascals, and the shear strength (cohesive) was 50-80 megapascals. It was found that this provides the required functional strength of coatings with maximum operational load. The article presents the results of comprehensive research in graphs and tables. (Conclusions) The research conducted in the CCP "Nano-Center" of the FSAC VIM and operational tests in the 2nd bus fleet of Moscow confirmed the principal possibility of effectively restoring cast iron liners (blocks) using the technology of electric spark processing.

Improvement of Oxidation Resistance and Adhesion Strength of Thermal Barrier Coating by Grinding and Grit-Blasting Treatments

The formation of thermally grown oxide (TGO), which is composed of alumina and mixed oxides, leads to the delamination of thermal barrier coating (TBC). In this study, to improve the oxidation resistance and adhesion strength of TBCs, grinding and grit-blasting treatments with alumina grits were applied to the surface of the bond-coat (BC) before deposition of the top-coat (TC). These treatments are expected to pre-form an alumina layer as an oxidation barrier and also optimize the TC/BC interfacial roughness. A high-temperature exposure test of TBC specimens grit-blasted with alumina grits of different sizes (B-TBC) revealed the growth of a continuous alumina layer in the B-TBC specimens in contrast to the formation of a complex TGO with alumina and mixed oxides in non-blasted TBC (S-TBC). Moreover, the area and thickness of TGO in the B-TBC specimens were much lower than those in the S-TBC. An indentation test was conducted to evaluate the TC/BC interfacial fracture toughness KIFC which confirmed a significantly higher KIFC of the B-TBC specimens than that of the S-TBC specimen. These results demonstrated that the grinding and grit-blasting treatments are effective in improving the oxidation resistance and adhesion strength of the TBC system.

Evaluation of adhesion durability of Ni–P coating using repeated Laser Shock Adhesion Test

This study aims to evaluate the adhesion strength and durability of NiP coatings in a non-contact manner using the Laser Shock Adhesion Test (LaSAT). A hard coating of electroless NiP deposited on carbon steel substrate (SKD11) was prepared, and the effect of post heat treatment on adhesion was comprehensively investigated in this study. With the LaSAT, strong elastic waves induced by pulsed YAG laser irradiation applies tensile stress to the coating/substrate interface resulted in interfacial delamination. Computation of the elastic-wave propagation using finite element method (FEM) was carried out to estimate the interfacial tensile stress. In addition, the adhesion durability was investigated by repetitive pulsed-laser irradiation, and the relationship between adhesion strength and the number of laser irradiation cycles until delamination was obtained. Finally, the effects of heat treatment on the adhesion strength and durability of the NiP coating were discussed. Owing to the post-heat treatment, it is found that the hardness of coating, adhesion strength and durability were improved. Indentation test reveals that the coating hardness increases from 792 HV to 1163 HV. LaSAT quantitatively evaluated the adhesion strength with increasing from 84.4 MPa to 143.9 MPa. In addition, repetitive LaSAT reveals that adhesion durability improves twice or more. This result was verified using the tensile adhesion test and microscopic observations of the interface. Therefore, the present LaSAT is a quick measurement for the adhesion durability of hard coating, and it may shed some light on quality control of surface coatings.

ВЛИЯНИЕ СИЛ ИНЕРЦИИ НА СЦЕПЛЕНИЕ ПОКРЫТИЯ С ВНЕШНЕЙ ПОВЕРХНОСТЬЮ ТЕЛ ВРАЩЕНИЯ ПРИ НАНЕСЕНИИ ПОКРЫТИЙ

A paper is dedicated to the investigation of inertia impact upon coating adherence with the outer surface of revolution solids during coating application. The work purpose is a qualitative and qualitative assessment of factors of antifriction coating application affecting the parts of friction units of machines and units. The relevance is substantiated with that the strength increase of coating applied ensures life, reliability and power effectiveness of machines and mechanisms. The work novelty consists in the application of fundamental dependences and laws to actual manufacturing operations. Adhesion is a basic parameter charactering quality of the coating applied. Adhesion, in its turn, is characterized with adhesion strength and porosity of the coating applied. The material presented shows the impact of inertia acting upon particles of the coating applied at their falling on the outer surface of rotation. There are defined theoretical dependences describing the process mentioned. The analysis of these dependences shows that inertia can carry out both the positive and negative action during the application of antifriction coatings. To confirm the theoretical results obtained there were carried out experimental investigations. In the experiment took part some sets of samples upon which PRNH17SR4 antifriction coating was applied. Coating application was carried out with the aid of the Iskra-1 burner with the further fusing. For the qualitative and quantitative strength assessment of adhesion of the coating applied there was used a method for a shear test. The samples prepared were pressed through a matrix on the GMS-50 universal rupture-test machine. As a result of tests carried out there are obtained dependences characterizing adhesion of antifriction coating applied. The dependences obtained show efficient factors impacting the adhesion strength of coatings. By the results of theoretical and experimental investigations there are formulated qualitative and quantitative assessments of factors influencing the process of antifriction coating application on parts.

Study of the Adhesion Strength of the Coating with Different Coating Methods to the Surface of Parts of «Shaft» Type

The article deals with the strength of adhesion of coatings with the parts of type «shaft». In accordance with the above separation, gas-thermal methods of spraying and thermal power sintering have an adhesive interaction of particles and coatings. The use of thermomechanical treatment of preformed coatings (applied by thermal spraying) makes it possible to increase the adhesion strength of coatings with parts of «shaft» type. For a quantitative assessment of the adhesion strength of coatings with the base metal, a shear coating method was used. An experiment to determine the adhesion strength of samples of steel with various applied coatings is considered. It was concluded that the adhesion strength of the coatings obtained using the hydrogen-propane mixture was slightly superior.

Effect of Ti interlayer thickness on mechanical properties and wear resistance of TiZrN coatings on AISI D2 steel

In the tool industry, adding a soft metallic interlayer to enhance the adhesion of hard coatings is a common practice. This study investigated the effect of Ti interlayer thickness on the residual stress, adhesion strength and wear resistance of TiZrN coatings. The feasibility of using stored elastic energy as an index of wear resistance of the coatings was also studied. The effect of Ti interlayer thickness was evaluated by comparing the mechanical properties of TiZrN films with different Ti interlayer thickness, ranging from 50 to 250 nm. The results showed that the increase of interlayer thickness from 50 to 250 nm reduced the stress of the TiZrN coatings from −5.67 to −3.75 GPa. The optimal Ti interlayer thickness to enhance the adhesion strength of the TiZrN coatings with about 2 μm thickness on D2 steel was 150 nm; however, the adhesion was insignificantly improved compared with the specimen without interlayer. Introducing 250 nm Ti interlayer could slightly increase the wear resistance of the TiZrN coating about 16%, but the adhesion strength of the coating decreased about 6%. The insignificant improvement on mechanical properties and wear resistance of the TiZrN coatings by the Ti interlayer were mainly attributed to the high residual stress of TiZrN top layer. For the coatings with high residual stress (>−4.0 GPa), the stress relief by adding a metal interlayer is limited and insufficient to enhance adhesion strength or wear resistance. Other approaches that can directly lower the intrinsic growth stress in hard coatings may be more effective.

Effect of pH of Coating Solution on Adhesion Strength of Hydroxyapatite and Octacalcium Phosphate Coatings on AZ31 Magnesium Alloy

Hydroxyapatite (HAp) and octacalcium phosphate (OCP) coatings were formed on a Mg-3Al-Zn (AZ31) alloy with a chemical solution deposition method using a Ca-EDTA solution at various pH levels. The adhesion strength of the coatings was examined using the pull-off method. The microstructures of HAp and OCP coatings were measured X-ray diffraction (XRD). The morphology and composition of the surface and cross section of the samples before and after the adhesion test were characterized using scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and a 3D profilometer. The results showed that plate-like OCP crystals grew from a continuous OCP layer on the surface of the AZ31 substrate in the case of a pH 6.3 coating solution. At pH values of 7.5 and 8.6, the HAp coating showed a two-layer structure with a HAp rod-like outer layer and a HAp continuous inner layer. Regardless of the pH of the coating solutions, a very thin Mg (OH)2 intermediate layer was formed between OCP or HAp coating and substrate. The highest adhesion strength of the coatings was 6.7±0.5 MPa, achieved at a coating solution pH value of 7.5. A part of Mg (OH)2 layer remained on the substrate, indicating that the delamination occurred in the Mg (OH)2 intermediate layer. The primary particles in the inner layer formed at pH 7.5 was smaller than those at pH 8.6. This result indicates that the initial corrosion of substrate AZ31 at pH 7.5 was more rapidly than that at pH 8.6, presumably leading to the formation of mixed layer of Mg (OH)2 and calcium phosphate. Further investigation is necessary to understand the better adhesion strength at pH 7.5 than that at pH 8.6. This good adhesion could be due to the flawless and rod-like uniform crystal, which had the densest and finest structure on the surface.

Study of the Adhesion Strength of Plasma-Sprayed Coatings Using Statistical Methods

The adhesion strength of plasma-sprayed ceramic coatings was studied. Alumina powder was used for plasma spraying. A titanium oxide Nano powder with a particle size of 40-50 [nm] was used as a modifier. The optimal conditions of plasma spraying of coatings are established. The adhesion strength was used as an optimization criterion. Coating adhesion was determined by tensile adhesion testing. A mathematical model is obtained that allows one to determine the effect of spraying conditions (lens current, arc current, and the position of the solenoid relative to the nozzle) on the adhesion strength.

Experimental and Statistical Study of In-Plane Tensile and Adhesion Strength of Plasma-Sprayed Coatings

. The influence of technological conditions on the strength characteristics of plasma-sprayed coatings of aluminum oxide powder with a fraction of 40–63 [μm], modified with a titanium oxide Nano powder with a particle size of 40–50 [nm], was studied. As independent variables (technological factors), which are the most significant and have the greatest influence on the strength characteristics of the coatings, there was chosen lens current, arc current, and the position of the solenoid relative to the nozzle. The adhesion strength and tensile strength of the coatings were adopted as optimization criteria. Mathematical models of the adhesion strength and the tensile strength of plasma coatings of aluminum oxide was obtained. As a result of multi-criteria optimization using the obtained mathematical models, the optimal combination of the levels of controlled factors was determined.

Quantity and quality assessment of multilayer coating adhesion strength

Development and improvement of modern machinery, increasing its performance efficiency are closely related to operation conditions of its main parts, units and devices becoming rougher. Various aggressive and force factors impact on machines and devices resulted in development of special protection and strengthening coatings including multilayer ones. Shifting from simple coatings to more complicated ones set he task to control their quality parameters.

Correlation of Interface Microstructural Features with the Adhesive Bonding Strength of Galvannealed Interstitial-Free Steel

Flaking of galvannealed steel due to interfacial bond failure during press-forming results in a deterioration in product quality and reduced productivity. To solve this problem, an understanding of bonding at the interface must be gained in terms of the microstructure. In this research, the relationship between coating adhesion strength and the evolution of interface microstructure was investigated using an interstitial free steel sheet. Hat channel drawing with a bead machine and stud pin tests were used to measure the flaking resistance and adhesive bond strength, respectively. A strong relationship was found between flaking resistance and interfacial bond strength. High bond strength samples exhibited two distinctive microstructures, Zn-penetrated grain boundary, and rough, island-like knoll, with the knoll always surrounded by the grain boundaries. The rough knoll, with etch pits on the top, formed underneath a crater, and a deep pit was observed at the grain boundary. After stud pin testing, coating residues remained mostly on the Zn penetrated and rough knoll substrates, indicating strong coating adhesion reinforced by a mechanical interlocking effect that originated from the two distinctive microstructures.

Effect of interlayer design on the mechanical properties of AlTiCrN and multilayered AlTiCrN/TiSiN hard coatings

The adhesion strength and mechanical properties of hard coatings on substrates can be improved by adding an interlayer, which is also known as an adhesion, buffer, or seed layer. Cathodic-arc deposition (CAD) of hard coating often results in residual stresses, and the optimized design of the hard coating interlayer helps to reduce residual stress and improve mechanical properties, which is expected to extend the useful life of high speed precision stamping die applications. AlTiCrN transition metal nitride has been used as a protective hard coating because of its high hardness (~36 GPa) and resistance to high temperature oxidation up to 1100 °C. In this study, multicomponent hard coatings of AlTiCrN and AlTiCrN/TiSiN, which in the form of AlTiCrN/TiSiN multilayers, were deposited by cathodic-arc deposition. During the coating process, gradient TiN and CrN were deposited, respectively, as interlayers with different structures to control the residual stress and adhesion strength between the coatings and substrates. AlTiCr and TiSi alloy targets were used to deposit hard AlTiCrN/TiSiN coatings. The multicomponent AlTiCrN/Ti and AlTiCrN/Cr with Ti and Cr interlayers showed high residual stresses of −8 GPa and −8.4 GPa, respectively. The multilayered AlTiCrN/TiSiN coating with intermediate CrN and transition AlTiN/CrN multilayers under the top AlTiCrN/TiSiN multilayers possessed the lowest residual stress (−3 GPa). The residual stress changed by modifying interlayer configuration before the top AlTiCrN/TiSiN multilayers. The design of AlTiCrN/TiSiN multilayered coatings with interlayers of CrN and AlTiCrN/CrN can decrease residual stress and possessed good impact fatigue performance, which can be effective to reduce damage and cracking of hard coatings during cyclic impact loading.

Pulsed Magnetron Sputtering of Ceramic SHS Targets as a Promising Technique for Deposition of Multifunctional Coatings

The processes of the pulsed magnetron sputtering (PMS) of multicomponent ceramic targets are studied upon deposition of functional coatings of various purposes. The regularities of changes in the structural characteristics, as well as mechanical and tribological properties, under increasing magnetron power frequency are studied. Summarizing the results obtained using the PMS technology upon the deposition of coatings using multicomponent SHS cathodes, the following conclusions can be drawn. a) The structure of coatings. Pulsed sputtering leads to the development of a denser and, at the same time, more defective structure with a high level of internal stresses and roughness. The effect of the pulsed mode on the grain size depends on the sputtering type and configuration of magnetic fields. For reaction sputtering, structural refinement is observed in some cases. The effect of increasing the thickness of reaction coatings due to the commencement of interaction between atoms sputtered from the target and nitrogen atoms at precipitation and minimization of target surface poisoning is found. b) Coating properties. The effect of a pulsed mode on the adhesion strength of coatings is reduced to its decrease. Dependences of hardness and other mechanical properties on the frequency of the pulse power have an extreme character with a maximum at 50 kHz. The use of low frequencies (50–150 kHz) leads to a decrease in the friction factor. At the transition to the pulsed mode, the friction factor stabilizes during the test and, in most cases, wear resistance increases.