TF5:
Protective and Functional Coatings
Posters
TF5.1.P
TiN/AlN BILAYERS AND MULTILAYERS
GROWN BY MAGNETRON CO-SPUTTERING
M. A. Auger1*, O. Sanchez1, J. M. Albella1, M. Jergel2,3, M. Aguilar-Frutis4, C. Falcony2
1Instituto de Ciencia de Materiales de Madrid (CSIC), Madrid, Spain
2Departamento de Física, CINVESTAV-IPN, México, D.F., México
3Institute of Physics, Slovak Academy of Sciences, Bratislava, Slovakia
4CICATA-IPN, Miguel Hidalgo 11500, México D.F., México
TiN/AlN bilayers and multilayers have been grown on Si(100) substrate by reactive magnetron sputtering using a two cathode system and Ar + N2 as reactive atmosphere. The total nominal 800 nm thickness of three bilayers has been divided between the top AlN and bottom TiN layers in the ratios dAlN/dTiN = 1, 3, 19. Two periodic multilayers have been grown by a repeated deposition of (200nm AlN/ 200nm TiN) and (5nm AlN/ 5nm TiN) basic bilayers (multilayer periods) for 2 and 5 times, respectively. Nitrogen incorporation in the nitrides has been correlated to the argon/nitrogen ratio in the sputtering gas in order to get stoichiometric compounds. The chemical composition of the layers has been studied by ESCA and Auger Electron Spectroscopies. The morphology of the coatings was observed in cross-section by Scanning Electron Microscopy. Columnar growth was found in both TiN and AlN layers, the column density being larger in the latter. The structural information has been obtained by X-ray diffraction in Bragg-Brentano and grazing incidence modes; completed by rocking curves and azimuthal scans, and by X-ray reflectivity. The polycrystalline hexagonal and face-centered cubic structures have been identified in AlN and TiN layers, respectively, with some tendency to texture in accord with the columnar growth observed. The grain size and lattice perfection are affected by the layer thicknesses. The optical properties of the layers have been obtained by spectroscopic ellipsometry in the energy range from 1.5 to 4.75 eV. The obtained coatings have a number of mechanical properties surpassing those of TiN, in particular the wear resistance, making them useful for industrial applications as practical coatings in cutting tools.
*Corresponding author: M.A. Auger, Instituto de Ciencia de Materiales de Madrid - CSIC, Departamento de Física e Ingeniería de Superficies, Cantoblanco 28049, Madrid, Spain, Tel. +34 91 334 90 00; Fax. +34 91 372 06 23; e-mail:
TF5.2.P
DEPOSITION AND SOME PROPERTIES OF NANOCRYSTALLINE WC AND NANOCOMPOSITE WC/a-C:H COATINGS
A. Czyzniewski
Technical University of Koszalin, Department of Materials Engineering,
Raclawicka 15-17, 75-620 Koszalin, Poland
Nanocrystalline WC and nanocomposite WC/a-C:H coatings were deposited using reactive unbalanced magnetron sputtering of tungsten target under argon/acetylene atmosphere on steel substrates held at the temperature below 423K.The effect of carbon content on microstructure and mechanical properties of coatings was investigated. Special attention was given to the deposition of coatings with a carbon content of 30–90at.%. Chemistry of coatings was investigated with energy dispersive X-ray analysis (EDAX) and X-ray photoelectron spectroscopy (XPS). Beside tungsten and carbon, some coatings contain oxygen and argon and as showed elastic recoil detection analysis (ERDA) hydrogen was also present. In the range of carbon content of 30–55at.%, formation of WC chemical bonding and nanocrystalline cubic -WC1-x structure was observed by XPS, X-ray diffraction (XRD) and transmission electron microscopy (TEM) respectively. Coatings containing more than 55at.% of carbon have two phase nanocomposite structure, composed of nanocrystalline -WC1-x grains dispersed in amorphous carbon (a-C:H) matrix. The presence of amorphous carbon phase was detected using XPS and Raman spectroscopy. Mechanical properties such as hardness and Young`s modulus of coatings were measured by nanoindentation. Nanocrystalline WC coatings show hardness in the range of 36-40GPa. The hardness of nanocomposite WC/a-C:H coatings decreases continuously from 32GPa to 20 GPa as the carbon content increases from 60at.% to 90at.%, respectively. The results of scratch investigation show that failure mode and cracking resistance depend strongly on carbon content and microstructure of coatings. WC/a-C:H nanocomposites show higher fracture toughness than nanocrystalline WC coatings of a similar hardness. The first cracks of WC/a-C:H nanocomposites appear at load twice higher than in nanocrystalline WC coatings with a similar hardness, as it was observed using optical microscopy and scanning electron microscopy (SEM). Tribological properties of coatings, including friction and wear were also investigated using ball-on-disc method. The lowest friction coefficient (f0,1) and high wear resistance (k210-7mm3N-1m-1) show WC/a-C:H nanocomposites containing about 90at.% of carbon.
TF5.3.P
Structure and properties of composite coatings from the nitride CrN and TiN
V. Gorban
Institute for Problems of Material Science, National Academy of Sciences of
Ukraine.
The work purpose is research of the structure, phase composition, properties and serviceability of composite coatings on the basis of nitrides CrN and TiN in conditions of high temperatures and contact loading. The coating was obtained by the ion-plasma spraying of Cr and Ti in nitrogen environment. The ratio of thickness of multiple coatings was chosen as 4:1 at thickness of a layer of nitride CrN 0.4 microns. Serviceability of the given coatings was compared with that of gas-thermal and galvanic coatings from the chromium-based alloys. The research of structure of multiple coatings of nitrides CrN + TiN has shown, that the technology allows to ensure the chosen ratio of thicknesses. X-ray structure analysis of the given coatings has revealed a phase of nitrides CrN and firm solution (TiCr) N. Chromium is distributed rather uniformly on layers, and titanium has the precisely expressed concentration dependence. The peak minimum of titanium is on a layer of nitride CrN, and maximum - on nitride TiN. Multiple coatings of nitrides CrN + TiN are characterized by high stability of structure and, as a consequence, of operational properties in the temperatures range up to 1300 Ę (Tables 1).
Tables 1. Researches of influence of annealing temperature on microhardness
of coatings from the nitride CrN and nitride TiN.
Material Nit. comp Annealing temperature, Ę1000 1100 1200 1300
CrN 15,0 15,0 15,0 14,0 14,0
CrN+TiN 24,0 24,0 24,0 23,0 22,0
The hardness of coverings is reduced from 21 up to 16 ĂĎŕ after 1 hour annealing at temperature 1300 K. Similar dependence is characteristic and for coatings from the chromium-base alloys. The stability of the characteristics composition coatings of nitrides CrN + TiN is confirmed with the given dependence's of changes of force of friction on temperature of tests of coatings from the chromium-base alloys (Tables 2).
Table 2. Dependence of force of friction (H) on temperature of tests and method of production of coatings Method of production of coatings Temperature, K
273 473 573 673
Gas-thermal Cr 24.0 23.7 22.1 19.6
Galvanic Cr 22.0 20.0 19.3 18.5
Ion-plasma CrN+TiN 19.0 14.0 11.0 9.0
The conclusion is made, that for composition coatings of nitride CrN mechanisms of structural changes, mass transfer and the oxidation of superficial layers bring in the insignificant contribution in wear resistance of a material.
Gorban Viktor, 3, Krzhizhanovsky Street, 03142, Kiev, Ukraine Institute for Problems of Materials Science, .
TF5.4.P
SYNTHESIS AND CHARACTERIZATION OF AN ANTICORROSIVE COATING BASED ON CERAMIC AND ZrO2 NANOPARTICLES.
S. Jiménez1, G. Canizal1, H. B. Liu1, V. M. Castaño2and J. A. Ascencio1*
1Institito Mexicano del Petróleo, Coor. Inv. y Des. de Ductos. Eje Central LazaroCardenas 152, MexicoD.F. 07730, México. 2 Instituto de Física campus Juriquilla.UNAM.JuriquillaQueretaro, Mexico
The use of nanoparticles has become really popular in the last decades, because of its singular properties, from optical and electronic properties to mechanical properties. Besides, the development of nanocomposites is well known as one of the most important field in this age because of their possibility to improve the properties of a material depending of the matrix and the nanoparticle inclusion that induce important changes over the system.
We are reporting a new obtained film by using the synthesis of a ceramic anticorrosive coating based on metal oxides and addition of ZrO2 nanoparticles, which helps to protect steel pipes and to improve the properties of a common glass. Basically the mechanical properties of the ceramic are improved by the nanoparticles inside it as a nanocomposite.
The obtained material is characterized by different techniques, from the study of its surface by scanning electron microscopy with secondary electrons for a morphology analysis and backscattering electron in order to have contrast from the different composition in the sample. Atomic force microscopy was also used to study the interface by means of the topographical and phase analysis, which allows us to study the way the nanoparticles affect in the matrix in function of the synthesis parameters.
The analysis is also made to the local details by using a transmission electron microscopy which allows to study the nanoparticles and to make a full structural determination. All of these methods help to study the structure and we are also applying compositional techniques as the use of characteristic X-ray in the scanning and transmission electron microscopes.
Besides the analytical data, we used theoretical method to study the stability of these systems and to identify in a better way the structures from the experimental data. To do so we apply molecular simulation and analytical data simulation, since high resolution electron microscopy images to crystalline morphology.
TF5.5.P
Temperature dependence of friction coefficient and wear rate of hard coatings
T. Kubart, R. Novák, T. Polcar
Czech Technical University, Dept. of Physics, Technická 4, 166 07 Praha 6, Czech Republic
Coating temperature rise or drop can cause changes of coating morphology, structure, phase composition or chemical reaction on the coating surface. All these changes can affect some macroscopic coating parameters, among them the tribological properties. Good knowledge of the temperature dependence of tribological parameters is important especially in the case of hard and wear resistant coatings. In operating conditions the coated machine elements or tools are heated up due to the friction between the moving parts or between the tool and the workpiece. The combined effect of the temperature rise and local contact stress accelerate the coating material degradation and in this way they shorten the life-time of the coating.
This paper resumes results of our study of the temperature dependent parameters of TiN, CoCr, CoCrN and MoS2 coatings. All investigated coatings were sputtered by means of a system of unbalanced magentrons with pulsed d.c. supply. The most important deposition parameters ( e.g. total and partial pressures of Ar+N2 mixture, sample bias) were registered. The coatings thickness, determinated by means of Calotest method, was 2 – 3 microns. The adhesion was measured with a scratch tester, for coating structure and internal stress evaluation the XRD and for coatings hardness the Hanemann microhardness were used.
The temperature dependence of tribological parameters was determinated by means of a high temperature tribometer. This instruments was a conventional ball-on-disc system. Apart from the major variables of normal load, contact area, sliding speed and testing time also the temperature was controlled and monitored during all tests. Analysis on wear test tracks was peformed using the ball crater method. Optical measurement and image analysis of a ball crater produced over the wear track helped to reveal the failure mechanism, to determine the presence of brittle interfaces or lack of adhesion. The analysis of determinated temperature dependences could estimate the part of frictionally generated defects and of thermally activated processes on the wear rate or on the total coating failure.
TF5.6.P
properties of Cr(c,n) hard coatings deposited in Ar-C2H2-N2 plasma
Marijan Maček1,2, Miha Čekada1, , Darja Kek1, Peter Panjan1
1) ”Jožef Stefan”” Institute, Jamova 39, 1000 Ljubljana, Slovenia
2)University of Ljubljana, Faculty of Electrical Engineering, Tržaška 25, 1000 Ljubljana, Slovenia
Mechanical properties, microstructure and the average chemical composition of Cr(C,N) hard coatings deposited in Ar-C2H2-N2plasma strongly depends on the partial pressure of the reactive gases (N2, C2H2) and on the type of the deposition equipment. In this study we report on the properties of Cr(C,N) hard coatings deposited by means of the triode ion plating in the BAI 730 apparatus and those prepared by sputter deposition in Balzers Sputron in the pressure range from 0.12 Pa (pure Ar) up to 0.35 Pa with different ratios (0-100%) between C2H2 and N2.
At first mechanical properties (microhardness and adhesion) of coatings were analyzed on the common way. Internal stress was measured by the radius of substrate curvature. Chemical composition of coatings was analyzed by means of AES while the Raman and XPS spectroscopy was used to determined the nature of carbon bonding in the Cr(C,N) films. Microstructure was determined by XRD as well as by means of TEM and TED.
Results have shown that layers from pure Cr to pure CrC and CrN, as well as ternary alloy of different Cr(C,N) have been successfully prepared in both deposition system. Typical layers deposited at partial pressures above 0.05 Pa constitute of about 50% of Cr and the balance was C and N in different concentrations according to the gas mixture used . XRD have revealed two phases of chromium nitride, namely Cr2N and CrN, as well as different carbide and carbo-nitride phases, Cr7C3, Cr(C,N), Cr2(C,N). Contrary to the XRD, TED shows in some samples also the existence of the metastable cubic CrC phase.
Chemical state of various elements in the coating has been studied by XPS. The ratio of the carbide bond (C-Cr) against the C-C and C-H bonds was calculated. The existence of the graphite phase in some Cr(C,N) coatings was confirmed by Raman spectroscopy.
TF5.7.P
Improvement of adhesion of diamond thin films on WC-Co cutting tools
J. Pavlov*, M. Vojs, P. Kúš1, A. KROMKA, V. Dubravcová
Department of Microelectronics, Faculty of Electrical Engineering and Information Technology, Ilkovičova 3, 812 19 BRATISLAVA, Slovak Republic
1Department of Solid State Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská Dolina, 842 48 BRATISLAVA, Slovak Republic
Because of its merits, diamond is one of the most promising materials for the tribological uses. Therefore, it is a significant interest in the diamond film growth on WC-Co cutting tools. Such WC-Co based inserts are commercially used as cutting tools for non-ferrous materials (wood, glass, aluminum, copper, etc.). The main problem remains of poor adhesion of diamond over-coating to cemented carbides due to a cobalt dissolution effect of diamond phase.
In this paper, we present the influence of pre-treatment method on adhesion of diamond films to WC-Co. Prior to deposition, WC-Co substrates were treated in different reactive solutions (Al2(OH)2-COOHdiluted in acetic acid, Murakami, HCl:HNO3) in order to suppress Co diffusion to WC surface. Furthermore, some treated substrates were annealed at 600°C in vacuum conditions. After then, these substrates were once diluted in reactive solution.
Processed substrates were over-coated by polycrystalline diamond films grown by dual plasma HF CVD method. Raman spectra confirmed diamond phase over all samples. Film surface morphology varied with used pre-treatment method. Adhesion strength was evaluated using the scratch test. Combined process of etching and annealing results in improved adhesion due to reducing of cobalt on the substrate surface.
TF5.8.P
Characterization of transparent silica films deposited on polymeric materials
Katsuya Teshima*1,2, Hiroyuki Sugimura1, Yasushi Inoue3, Osamu Takai4
1Department of Materials Processing Engineering, Nagoya University, Nagoya 464-8603, Japan
2Research & Development Center, Dai Nippon Printing Co., Ltd., Kashiwa 277-0871, Japan
3Research Center for Nuclear Materials Recycle, Nagoya University, Nagoya 464-8603, Japan
4Center for Integrated Research in Science & Engineering, Nagoya University, Nagoya 464-8603, Japan
Silica has been applied in a wide variety of industrial fields because of its excellent properties. Recently, silica coatings have attracted particular attention as barrier coatings against gas and vapor permeation. Among many coating methods, plasma-enhanced chemical vapor deposition (PECVD) is one of the preferred methods to deposit silica films on polymeric substrates at low substrate temperature. In the present work we studied film structures of silica deposited by PECVD under various deposition conditions and effects of film structures on their gas barrier properties.
Silica films were synthesized by capacitively coupled RF PECVD using mixtures of organosilane and oxygen as a source. The chemical bonding states and compositions of the films deposited were evaluated with FTIR and XPS. Film surfaces and cross-sections were observed by SEM. Oxygen transmission rates (OTR) of the films coated on polyethylene terephthalate (PET) substrates were measured by an isopiestic method.
The SEM images obtained clearly demonstrated that silica domes formed on the PET substrates only in the early stage of deposition. Silica domes did not form in the vapor phase, but rather, directly onto the polymer surface. The growth of these silica domes depended on the presence of activated oxygen species in the vapor phase. When no oxygen existed in the vapor phase, the domes did not connect well with each other even after long deposition time. In such cases, the siloxane networks in the film were terminated with many functional groups, such as -CHx, -H and -OH. On the contrary, in the presence of active oxygen species, many types of impurities in the film were largely eliminated, with the result that a dense silica film in which the domes fused together well could form on the PET substrate. The densely-packed silica film satisfied the requirements for industrial products in the field of food packaging.
Corresponding author*: Tel. +81-52-789-4639; Fax. +81-52-789-3260; E-mail
Address: Department of Materials Processing Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
TF5.9.P
TiO2 (Fe3+) NANOSTRUCTURED THIN FILMS WITH ANTIBACTERIAL PROPERTIES
C.C. Trapalis1, P. Keivanidis1, G. Kordas1
M. Zaharescu2, M. Crisan2, A. Szatvanyi2, M. Gartner[*]2
1 Instittute of Materials Science, National Center for Scientific Research “Demokritos”, 153 10 , Athens, Greece
2Institute of Physical Chemistry “I.G.Murgulescu”, Romanian Academy,
202 Splaiul Independentei, 77208, Bucharest, Romania
TiO2 based nanostructured Fe3+ doped coatings have been prepared by sol-gel method on glass substrates. The coatings were characterized by X-ray diffraction and spectroellipsometry methods. The influence of Fe3+ dopant concentration, number of coatings, and calcination temperature on the films structure was established.
The antibacterial activity against Escherichia Coli, has been studied appling the so called antibacterial-drop test. The bacteridicidal activity for the above bacteria cells was estimated by relative number of bacteria survived calculated from the number of viable cells which form colonies on the nutrient agar plates. The coatings exhibited a high antibacterial activity, which was enhanced with the increase of the temperature of thermal treatment and formation of anatase crystalline structure. The long time thermal treatment results to rutile crystalline structure formation follwed by the decrease in the antibacterial activity of the coating.