ICMCTF2003 Session FP-2: Symposium F Poster Session

Thursday, May 1, 2003 5:00 PM in Town & Country

Thursday Afternoon

Time Period ThP Sessions | Topic F Sessions | Time Periods | Topics | ICMCTF2003 Schedule

FP-2-1 Adhesion Scratch Testing on Various TiN Coatings
I. Efeoglu (Ataturk University, Turkey); R. D. Arnell (Salford University, United Kingdom); F. Bulbul (Ataturk University, Turkey)
The critical loads (Lc) of TiN coating deposited by closed-field unbalanced magnetron sputtering (CFUBMS) have been detennined using a conventional scratch test. Tests were carried out using loading rates (dL/dt) of 50,60,70,80,90 and 100 N/min and a table speed (scratching speed dx/dt) of 15 mm/min, with a total scratch length of 22 mm. Friction monitoring was used to detect to point out coating failure, and the failure region was then examined by optical microscopy and SEM. In general, the type of deformation was characterised by thinning within the scratch track. The failure which occurred within the track is cohesive while it is mainly of no adhesive nature at the sides of the track. The typical results obtained here yielded a clear relationship between the critical load and the microhardness values obtained. With increasing negative substrate bias, dramatic increases in the Knoop microhardness, but decreases in the critical load decreased. It was observed that one of the factors having the greatest effect on the measured critical load is the condition of the diamond tip, and this condition can change significantly from one scratch to the next.
FP-2-2 The Tribological Properties of Co-deposited Aluminium-Titanium Alloy Coatings
J. Hampshire, P.J. Kelly (University of Salford, United Kingdom); D.G. Teer (Teer Coatings Ltd, United Kingdom)
Materials with the structures of ordered inter-metallic phases have been studied for many different applications. Aluminium-titanium alloys are attractive for these types of applications owing to their low density and high temperature strength. This is dependant on the alloy deposited and its corresponding properties. @paragraph@ Thin films have been prepared by physical vapour deposition using two closed field unbalanced magnetrons with a biased substrate. Sputtering targets of aluminium and titanium have been used for the co-deposition of aluminium-titanium coatings with different compositions. This process allows the deposition of the full binary range of alloys from pure aluminium to pure titanium in a single process. @paragraph@ Tribological testing was performed on the thin films both before and after a high temperature annealing process designed to produced stable inter-metallic phases. The results of Vickers hardness testing, SEM analysis, composition by EDX and friction and wear testing are reported here.
FP-2-3 Porosity and Corrosion of TiN-coated Stainless Steel
G.P. Yu (National Tsing Hua University, ROC); Y.M. Chen (Materials Research Laboratories Industry Technology Research Institute); J.-H. Huang (Department of Engineering and System Science)
Porosity is virtually unavoidable in coatings such as TiN films deposited by modern vacuum deposition techniques on metal surface. Localized corrosion can occur at these sites, possibly causing significant undercutting of the coating and reducing the coating's service life. This investigation thoroughly examined the porosity and corrosion of TiN-coated stainless steel. The TiN coatings were deposited by a HCD ion plating system. The porosity of TiN coatings was affected by the combined effects of deposition time, deposition temperature and the process parameters related to the ion bombardment during deposition, such as bias voltage and deposition power. Prolonged deposition time, high temperature, high degree of ion bombardment can reduce the porosity of TiN films. Generally, TiN-coated stainless steels with lower porosity are more corrosion resistant. However, the variation of corrosion extent may be more than one order of magnitude for TiN coatings with the same level of porosity, especially at low level of porosity.
FP-2-4 The Modified Critical Passivation Current Density Method for Porosity Measurement of TiN Coatings Deposited on Stainless Steel
Y.M. Chen (Materials Research Laboratories, ITRI, Taiwan); G.P. Yu, J.-H. Huang (National Tsin Hua University, Taiwan)
Porosity is virtually unavoidable in coatings deposited on metal surface. The critical passivation current density (CPCD) method utilized the potentiodynamic test in sulfuric acid solution containing potassium thiocyanate to measure the porosity of TiN coatings deposited on stainless steel. This work proposes a methodology, which is based on reducing the corrosivity of CPCD method, to measure the porosity. By decreasing the corrosivity of CPCD method the problem of pinhole enlargement during porosity test can be avoided and accurate measurement can be achieved.
FP-2-5 Effect of Bias on the Structure and Properties of ZrN Thin Film by Unbalanced Magnetron Sputtering
Y.W. Lin, J.-H. Huang, G.P. Yu (National Tsing Hua University, ROC)
ZrN films were deposited using a Mirrored-field Type-II Unbalance magnetron sputtering system (STS-400). The optimum coating conditions were first determined using Taguchi experimental method. Based on the optimum condition, the single-variable experiment on the effect of bias was conducted. A negative bias voltage ranging from 20 V to 130 V was applied to the substrate. The effect of bias on the microstructure and properties of zirconium nitride (ZrN) film was investigated. The cross-sectional microstructure observed by SEM revealed that the columnar structure of the ZrN film became denser with increasing bias. The results of X-ray diffraction show that all the coating samples exhibited (111) preferred orientation. Hardness of the deposited film was determined by nanoidentation, and the hardness values of ZrN films were ranged from 20 to 40 GPa. The composition depth profiles of ZrN films were obtained using the Auger electron spectroscopy. The N/Zr ratios all close to 1 were measured by Rutherford backscattering spectrometry, and the packing factors of ZrN films can also be obtained by the results of RBS. The resistivity measured by a four-point probe decreased from -20V to -90V and then increases from -90V to -130 V. The resistivity of ZrN films was related to the packing factor. The residual stress determined by the XRD sin2Ψ method was ranged from 2 to -13 GPa. The maximum of residual stress was located at -50V.
FP-2-6 Interfacial Analysis on Superhard TiAlN/Mo Multilayers
L. Rebouta, C.J. Tavares (Universidade do Minho, Portugal); J.P. Rivière, J. Pacaud, M.F. Denanot (Université de Poitiers, France)
On this work we focus on study of multiple interfaces from nanocomposite TiAlN/Mo multilayers that were fabricated by reactive magnetron sputtering, with modulation periods below 6 nm. The structural disorder at the interfaces was probed by X-ray diffraction (XRD), both in the low and high angle regions, while the interface morphology was studied by high-resolution transmission electron microscopy (HRTEM). Particular attention has been directed to the evolution of the interfacial disorder with the bias voltage. For particular conditions, these structures can be prepared with relatively planar interfaces, revealing layer-by-layer growth and withholding hardness values up to 60 GPa. For modulation periods below 3 nm the interdiffusion acts a major role in the chemical modulation degradation and subsequent hardness decrease. A correlation between the evolution of roughness and hardness will be given, based on the calculations and fits of experimental XRD patterns.
FP-2-7 Finite Element Analysis of Substrate Effects on Indentation Behaviour of Thin Films
Zhihui Xu, D. Rowcliffe (Royal Institute of Technology, Sweden)
The substrate effects on indenation behaviour of thin films are analysed using finite element method. It is found that there is no universal critical penetration depth beyond which the substrate effects come in. The critical penetration depth is dependent on the combination of the film and the substrate and more sensitive to the difference in the elastic properties rather than the plastic properties of the film/substrate system. The finite element simultation results of the substrate effects on the elastic modulus and the hardness of the film/substrate system have also been compared with the empirical models of Doerner's and Bhattacharya's respectively.
FP-2-8 On the Behaviour of Indentation Fracture in the TiAlSiN Hard Thin Films
O. Nakonechna, A. Karimi (Swiss Federal Institute of Technology (EPFL), Switzerland)
Nanoindentation, as a widely used technique for characterizing mechanical properties at the micron and submicron scales, was used to determine hardness and elastic modulus of thin TiAlSiN films. The films of 1-3 microns thiknesses were deposited on WC-Co substrates and engeneired as nanocomposite, multilayer and single layer materials. To examine the effects of the substrate on the determination of elastic modulus and hardness different theoretical models (for example, King's, Nix, Korsunsky approaches) were applied to fit experimental results. During indentation process cracks of different type were formed radial (in single layer sample), circular or through thickness cracks (in nanocomposite). Multilayer TiAlN film exhibits different crack morphology - irregular cracks were observed.. The mechanics of crack propagation in these materials is described, taking into account that the driving force for fracture has its origin in the residual component of the elastic/plastic field, which becomes dominant when indenter is unloaded. A theory for describing the evolution of cracks in bulk brittle materials is well established. To estimate thin film fracture toughness, we modified the equations proposed for bulk brittle materials. Our inputs are the thin film elastic properties, thikness, interfacial crack area and maximum thin film deflection during the test. Closed form analytical solutions, obtaining from three limiting cases are consistent with a numerical approach. The obtained values for stress intensity factor KI vary from 1.86 (for nanocomposites) to 2.49 MPa m1/2 (for monolayer).
FP-2-9 Effect of Bi@sub 4@Ti@sub 3@O@sub 12@ Seeding Layer on the Structural and Ferroelectric Properties of Bi @sub 3.25@La @sub 0.75@Ti@sub 3@O@sub 12@ Thin Films Fabricated by a Metalorganic Decomposition Method
C.I. Kim, K.T. Kim, D.H. Kang, I.W. Shim (Chungang University, South Korea)
Ferroelectric Bi@sub 3.25@La@sub 0.75@Ti@sub 3@O@sub 12@ (BLT) thin films have been prepared by depositing a very thin layer of Bi@sub 4@Ti@sub 3@O@sub 12@ on the substrate as a seeding layer, which was expected to enhance crystal growth during heat treatment. From the XRD analysis, the peak in the XRD pattern of BLT thin films with thin layer of Bi@sub 4@Ti@sub 3@O@sub 12@ higher than that without a seeding layer. SEM analysis data indicate that bigger grains were obtained for films coated with a seeding layer compared with films without a seeding layer. A BLT film with seeding layer has better fatigue properties. The leakage current properties of the BLT thin film with seeding layer consisting of large grain are higher leakage current density than small grains. The remanent polarization of BLT thin film with seeding layer increases with the increasing in seeding layer thickness. A BLT film with seeding layer has better fatigue properties compared with BLT films without a seeding layer. The BLT thin films with seeding layer were a remanent polarization of 32.56 µmC/cm@super 2@, and a coercive field of 74.75 kV/cm. The BLT thin films showed little polarization fatigue test up to 3.5 x 10@super 9@ bipolar cycling at a 5 V and 50 kHz.
FP-2-10 Morphology, Mechanical and Tribological Properties of Thin Gold Coatings Deposited by PVD and Electroplating
A. Toppo, F. Jolliet, E. Bergmann (Geneva School of Engineering, Switzerland)
150 nm thin gold coatings were deposited on TiN sublayers with various plasma assisted PVD technologies and compared with layers of similar thickness deposited by electroplating. We analyse the relation between deposition condiions, morphology, mechanical properties and tribological properties. Morphology was analysed by AFM, Mechanical properties are determined from Nanoindentation. Erosion resistance measured with a microeosimeter was used as tribological test. The coating morphology of he PVD and electroplated coatings is similar and can be explained by the classical nucleation models. They contradict the recent models of growth kinetics based on energy of the arriving atoms. The mechanical properties of some coatings show a first phase of irreversibe compaction prior to plastic deformation. The erosion rate was determined quantitatively.
FP-2-11 The Structure of Co-deposited Aluminium-Titanium Alloy Coatings
J. Hampshire, P.J. Kelly (University of Salford, United Kingdom); D.G. Teer (Teer Coatings Ltd, United Kingdom)
Aluminium-titanium alloy coatings are attractive materials for a wide range of applications from aerospace and high performance engine applications to solar absorbers, depending on the alloy deposited and its corresponding properties. Consequently, a detailed study of the Al/Ti alloy system has been carried out, and the results to date are presented here. @paragraph@ In this study Al/Ti thin films have been prepared by physical vapour deposition using two planar unbalanced magnetrons in a closed field configuration, with a biased substrate. Pure aluminium and pure titanium sputtering targets were used for the co-deposition of coatings with compositions varying throughout the full binary range from pure aluminium to pure titanium. The coatings were deposited onto 316 stainless steel and glass substrates. @paragraph@ The deposited films were analysed by EDX, XRD, SEM and TEM processes in the as-deposited state and after high temperature annealing, to investigate changes in structure and phase composition. The as-deposited coatings contained only aluminium and titanium phases but after the annealing process, stable inter-metallic phases were formed. Attemps have been made to relate these changes to specific process and geometrical factors within the deposition system used.
FP-2-12 Waveguide-resonator for the Element Composition Analysis of Surface Layers and Hyperfine Films
V. Egorov, E.V. Egorov, T.V. Bil'chik (Russian Academy of Science, Russia)
Element concentration analysis of solid state hyperfine surface layers is usually carried out by X-ray fluorescence analysis at total reflection of the beam excited the testing target (TXRF). The X-ray beam must have the line form with low width and divergence and characterize by a high radiation density. Such X-ray beam is formed indeed by planar X-ray waveguide-resonator (PXWR) [1]. This device is the narrow extent slit (clearance) between two plane polished dielectric plates (reflectors). The waveguide-resonance mechanism of an X-ray beam propagation characterized by low flow attenuation can be realized in the small slit size area, only [2]. This area is 15-36 nm for quartz reflections and MoK@alpha@ radiation. The density radiation in the beam created by PXWR exceeds one in beams formed by conventional slit-cut systems by factor 10@super 2@-10@super 3@ at the same power of X-ray source. So, TXRF spectrometers equipped by PXWR are characterized by reduced magnitudes of element detection limits. @paragraph@ This work is devoted to description of TXRF spectrometer completed by PXWR and standard X-ray tube with an immobile Mo-anode. It's design and construction peculiarities are discussed, in details. The procedure of hyperfine film targets analysis is described in details too. TXRF spectra of epitaxial and nonepitaxial thin film targets with complete element interpretation are presented. It is shown that TXRF spectrometry with PXWR application has beautiful perspectives for hyperfine film composition analysis. @paragraph@ [1] V.K. Egorov, E.V. Egorov, Thin Solid Film, v398-399, 2001, pp. 405-412. @paragraph@ [2] V.K. Egorov, E.V. Egorov, T.V. Bil'chik, Investigation in Russia, v3, 2002, pp. 423-441. htp://zhurnal.ape.relarn.ru/articles/2002/040e.pdf.
FP-2-13 The Effect of Annealed Chromium Nitride Films with and without an MEVVA Cr-Implanted Interlayer
S. Han (National Taichung Institute of Technology); Hong-Ying Chen (National Chung Hsing University, Taiwan, ROC); K.L. Chang (National Tsing Hua University, Taiwan, ROC); F.-H. Lu (National Chung Hsing University, Taiwan, ROC); Han. C. Shih (National Tsing Hua University, Taiwan, ROC)
The effect of metal vapor vacuum arc implanted chromium interlayer on the microstructure of CrN coatings on a silicon wafer was investigated. Two types of CrN-coated specimens (CrN/Si and CrN/Cr/Si) were prepared with and without the MEVVA Cr-implanted interlayer by cathodic arc plasma deposition. Both specimens were annealed at 500°C for 2 h in N@sub 2@/H@sub 2@=9 at the same batch to examine the thermal stability of CrN films. The columnar structure of CrN/Cr/Si was observed by cross-sectional TEM. The XRD patterns of the coated specimens (as-deposited and annealed) indicated the presence of CrN, and the (220) preferred orientation for both CrN/Si and CrN/Cr/Si assemblies. CrN/Si revealed that the phase transformation from CrN to Cr@sub 2@N during the annealing is due to the large stress relaxation occurring in the films. A MEVVA Cr interlayer, i.e. CrN/Cr/Si, can effectively decrease the residual stress in the growing of the CrN films and then the phenomenon of the phase transformation doesn't occur in the CrN/Cr/Si assembly during the annealing.
FP-2-14 A Study of Growth Properties of SiC Whiskers in Various Temperatures and Input Gas Ratio on Different Si Substrate.
D.C. Lim, D.J. Choi (Yonsei University, South Korea)
In this study, we successfully grew the SiC whiskers and films on Si substrate with the carbon buffer layer. And we did not use any metallic catalyst that may act as the impurity or barrier on the tip of the whisker. The deposition temperature was varied from 1000@super o@C to 1100@super o@C. And input gas ratio @alpha@ [H@sub 2@/MTS] was 30, 40, and 50. We used the bare Si and surface polished Si by SiC abrasive paper as the substrates which have different surface conditions. And we examined the growth properties all of them according to the temperature and input gas ratio variation by SEM and TEM.
FP-2-15 Influence of Nitrogen Flow Rate in the Physical Properties of ZrOXN@sub 1-x@ Coatings Produced by Reactive Magnetron Sputtering
A. Portinha, V. Teixeira (University of Minho, Portugal)
In this work we produce ZrOXN@sub 1-X@ thin coatings and ZrYOXN@sub 1-X@ by DC reactive magnetron sputtering. In order to study the effect of nitrogen flow rates in physical and mechanical properties the N@sub 2@/O@sub 2@ relation was changed between 0.025 and 0.2. The addition of nitrogen to the ZrO@sub 2@ and ZrO@sub 2@Y2O@sub 3@ system was performed to study the influence in the stabilization of the high temperature tetragonal or cubic phases of ZrO@sub 2@. X-Ray diffraction (XRD) measurements were used to characterize the coatings structures and to study the influence of nitrogen addition in the high temperature stabilized phases. The residual stresses were also determined by measuring the radius of curvature of the thin-coated substrates. The surface microtopography was analyzed by atomic force microscopy (AFM) and the roughness was evaluated. Energy Dispersive X-ray Spectroscopy (EDX) was used to assess the thin film composition. Scanning Electron Microscopy (SEM) was used to measure the film thickness, to observe microstructure of the film cross-section and to analyze the surface morphology. The adhesion of the coatings was determined by scratch test.
FP-2-16 Characterization of the Aluminum Nitride Thin Films Prepared by Unbalanced Magnetron Sputtering
C.-C. Wang, M.-C. Chiu, F.-S. Shieu (National Chung Hsing University, Taiwan, ROC)
Aluminum nitride thin films were deposited by an unbalanced magnetron (UBM) sputtering system equipped with a pulse dc power supply on silicon wafers and glass substrates. The microstructure and chemistry of the nitride-coated silicon were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Optical transmission property of the nitride-coated glass was investigated by an UV/VIS spectrophotometer. It was obtained that the thin films are polycrystalline having hexagonal wurtzite structure with (002) preferred orientation demonstrated by XRD and TEM. AFM analysis indicates that the surface of the thin films is rather smooth with Ra=6.464 nm, and the films are suitable for the surface acoustic wave (SAW) device application. XPS spectra show the presence of Al, N, and O elements in the thin films, and their peak positions are consistent with the existence of the AlN phase. In addition, the aluminum nitride thin films are transparent in the visible region with an average transmittance of 60%. Keywords:AlN, Unbalanced magnetron sputtering, Characterization.
FP-2-17 Electrical Properties and Microstructure of Ba@sub 1-x@Sr@sub x@TiO@sub 3@ Thin Films Deposited by RF Unbalanced Magnetron Sputtering
M.-C. Chiu, C.-C. Wang, F.-S. Shieu (National Chung Hsing University, Taiwan, ROC)
Ba@sub 1-x@Sr@sub x@TiO@sub 3@ (BST) ceramic is of interest for applications in bypass capacitors and dynamic random access memories (DRAM) because of its high dielectric constant. In this study, BST thin films with platinum (Pt) electrodes were prepared by a RF unbalanced magnetron sputtering (UBM) system. Electrical properties such as the leakage current as a function of applied voltage were characterized by a Keithley 590 1MHz CV analyzer and a HP 4284A electrometer. It was obtained that the dielectric constant of the films was closely related to the surface morphology, grain size, composition and film thickness. The existence of an interfacial layer between the BST film and the Pt electrode was revealed by analytical electron microscopy (AEM). Morphology of the BST films was investigated using a scanning electron microscope (SEM). The phase and crystallinity of the BST films were determined by X-ray diffraction (XRD) with Cu K@alpha@ radiation. Grain size of the BST films was estimated using atomic force microscopy (AFM).
FP-2-18 Growth Behavior of Crystalline TiO@sub 2@ Films Deposited by Reactive RF Magnetron Sputtering Method
T. Asanuma, T. Matsutani, C. Liu, T. Mihara, K. Murai, M. Kiuchi (National Institute of Advanced Industrial Science and Technology, Japan)
Thin films of crystalline TiO@sub 2@ were deposited on SiO@sub 2@ substrates by reactive rf magnetron sputtering method. Amorphous, anatase and rutile films can be obtained depending on the deposition parameters (RF power, substrate temperature (T@sub s@), O@sub 2@ concentration (f@sub O2@) and total pressure (p@sub total@)). In the case of RF = 120 W, f@sub O2@ = 30 % and p@sub total@ = 5x10@super -2@ Torr, the substrate-temperature dependence of the deposition rates changed between 136 and 298 °C, although XRD patterns of the films showed no obvious peak due to the crystalline films. When f@sub O2@ increased to 100 % at T@sub s@ = 140@super o@C, very small peaks were observed due to the anatase and rutile films. At RF = 140 W and f@sub O2@ = 100 %, the crystalline TiO@sub 2@ films were found to grow over the narrow p@sub total@ range between 3x10@super -2@ and 5x10@super -2@ Torr. The emission spectroscopic analysis showed the existence of O@sub 2@@super +@ and atomic O in a 100 % O@sub 2@ atmosphere. Those lines decreased drastically as the p@sub total@ increased from 1x10@super -2@ to 3x10@super -2@ Torr. These results suggested the film properties were determined by the substrate temperature and the energy of the particles incident on the surface. It is considered that the energy of the particles as well as the oxidation rate of the Ti target is affected by the density of oxygen, resulting in the growth of the crystalline films.
FP-2-19 Deposition of TiO@sub 2@ Thin Films using Grid-assisting Magnetron Sputtering
M.J. Jung, Y.M. Chung, J.G. Han (SungKyunKwan University, South Korea); K.Y. Bang (Hanyang University, South Korea)
It is well known that thin film growth and surface morphology can be substantially modified by ion-bombardment during the deposition. This is particularly important in case of thin-film deposition at low temperatures where the film growth occurs under highly nonequilibrium conditions. An attractive way to promote crystalline growth and surface morphology is deposition of additional energy in to the surface of the growing film by bombardment with hyperthermal particles. We were deposited crystalline Ti and TiO@sub 2@ thin films on Si substrate by magnetron sputtering method with grid. Its thin films were highly smoothed and dense as increasing grid bias. In order explore the benefits of a bombardment of the growing film with high energetic particles, Ti and TiO@sub 2@ films were deposited on Si substrates by an unbalanced magnetron sputter source with attached grid assembly for energetic ion extraction. Also, we have studied the variation of the plasma states for the feed back control of nucleation and growth behavior by Langmuir probe and Optical Emission Spectroscopy (OES). The epitaxial orientation, microstructual, optical characteristics and surface properties of the films were analyzed by XRD, SEM, Elipsometry and AFM.
FP-2-20 Effect of Substrate Bias Voltage on Amorphous Si-C-N Thin Films Produced by PVD Techniques
L. Cunha, C. Moura, J. Leme, H. Órfão, G. Andrês (Universidade do Minho, Portugal); K. Pischow (Savcor Coatings Oy, Finland)
Si@sub x@C@sub y@N@sub z@ thin films were deposited by reactive magnetron sputtering in glass, silicon and steel substrates. The films were grown in a rotation mode over a carbon and a silicon targets in a mixed Ar/N@sub 2@ atmosphere. The substrates were held at a substrate temperature of 573 K. The argon flow was kept constant (100 sccm) and the nitrogen flow was 20 sccm or 25 sccm, in each one of the two series of produced films, resulting in a working pressure around 0.5 Pa. The substrate bias varied between grounded and -100 V. Ternary composition of the films were obtained. The films were analysed with respect to composition, microstructure, state of chemical bonding and optical properties by energy dispersive spectroscopy (EDS), X-Ray Diffraction (XRD), Raman Spectroscopy (RS), optical reflectance and transmittance. Raman spectroscopy was used as a probe of microstructural modifications induced by deposition conditions. The main features observed in RS spectra are the well-known D- and G-bands characteristic of amorphous carbon materials. The presence of other features in the low frequency region characteristic of Si-C and Si-N vibrations are correlated with the deposition conditions. The position, widths and intensity ratio of these bands are found to be dependent on the films composition. The refractive index, absorption coefficient and also the thickness were calculated from transmittance spectra obtained between 200 nm and 2500 nm.@paragraph@ The residual stress of the coatings depends on deposition conditions and was calculated by measuring the substrate curvature before and after films deposition. The curvature of the samples was measured by laser triangulation in two series of two orthogonal directions.@paragraph@ The hardness of each coating was measured by nano-indentation and the average values was 21 GPa. The nano-hardness of the grounded produced samples presented values about 30% lower.
FP-2-21 Influence of Nitrogen Gas Flow and Substrate Bias Voltage on Reactive Magnetron Co-sputtered Si-C-N Films
C. Moura, L. Cunha, J. Leme, G. Andrês (Universidade do Minho, Portugal); K. Pischow (Savcor Coatings Oy, Finland)
Si@sub x@C@sub y@N@sub z@ thin films were deposited by reactive magnetron sputtering in glass and steel substrates. The films were grown by magnetron co-sputtering of silicon and carbon targets in a mixed Ar/N@sub 2@ atmosphere using a fixed silicon fraction in the magnetron erosion track area. The substrates were held at a negative bias from 0 to -125 V and a substrate temperature of 573 K. The argon flow was kept constant (100 sccm) and the nitrogen flow varied between 0 and 25 sccm, resulting in a working pressure of 0.5 Pa. @paragraph@The films were analysed with respect to composition, microstructure, state of chemical bonding and optical properties by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy (RS), optical reflectance and transmittance. @paragraph@Raman spectroscopy was used as a probe of microstructural modifications induced by deposition conditions. The main features observed in these spectra are the well-known D- and G-bands characteristic of amorphous carbon materials. The position, widths and intensity ratio of these bands are found to be dependent on the films composition. Refractive index, absorption and extinction coefficients were calculated from transmittance and reflectance spectra obtained in the wavelength range from 200 nm to 2500 nm. @paragraph@The residual stress of the coatings depends on deposition conditions and was calculated by measuring the substrate curvature before and after films deposition. The curvature of the samples was measured by laser triangulation in two series of two orthogonal directions. @paragraph@The hardness and elastic modulus of each coating was measured by nano-indentation.
FP-2-22 Micro-structural Analyses of Titanium Silicon Nitride Films by HRTEM and EELS
J.H. Suh, C.-G. Park (Pohang University of Science and Technology (POSTECH), South Korea); I.-W. Park, K.H. Kim (Pusan National University, South Korea)
The nanocomposite Ti-Si-N films prepared by a DC magnetron co-sputtering technique using separate Ti and Si targets were analyzed by a high resolution transmission electron microscopy (HRTEM), electron energy loss spectrometry (EELS), X-ray diffraction (XRD), electron probe micro-analysis (EPMA) and X-ray photoelectron spectroscopy (XPS). Our research has focused to show the percolation phenomena of an amorphous Si@sub3@N@sub4@ phase in TiN crystallites with various Si contents from ~4.6 to ~28.0 at. % in series by means of high resolution electron microscopy (HREM), selected area electron diffraction (SAED), and dark field (DF) images. The EELS spectra were observed to reveal and identify the structure and phase composition of nanostructured multiphase films throughout the atomic concentration of Ti, Si and N with a high resolution quantification. The Ti- L@sub2,3@ spectra of TiN and TiSi@subx@ and Si-L@sub2,3@ EELS spectra of Si@sub3@N@sub4@, free Si, and TiSi@subx@, for the Ti-Si-N film with Si content of 17 at.%, also have been investigated as a function of input N@sub2@/Ar gas ratio of 0.2, 0.4, and 0.6.
FP-2-23 Synthesis and Mechanical Properties of Superhard Ti-Al-Si-N Coating Layers Deposited by a Hybrid System of Arc Ion Plating and Sputtering Techniques
I.-W. Park, S.R. Choi (Pusan National University, South Korea)
Quaternary Ti-Al-Si-N coating layers were deposited on WC-Co substrates by a hybrid system of arc ion plating (AIP) and sputtering techniques using Ti@sub3@Al and Si targets, in an Ar/N@sub2@ gas mixture. The microstructure and mechanical properties for the coating layers were investigated as a function of deposition variables such as Si content and substrate bias voltage. The Si content was increased with increasing d.c. sputter current from zero to 2 A at a constant arc current of 60 A and temperature of 300°C. The crystallinity, thickness, chemical composition, bonding status, and microstructure of the coating layers were measured by X-ray diffractometer (XRD), scanning electron microscope (SEM), electron probe micro-analyser (EPMA), X-ray photoelectron spectroscope (XPS), high-resolution transmission electron microscope (HRTEM), respectively. The micro-hardness of the coating layers was carried out by ultra micro-indentation. As the Si was incorporated into Ti-Al-N coating layers, the microstructure of Ti-Al-Si-N coating layers were changed from a columnar structure with coarse grains to a glass-like structure with fine grains, and the micro-hardness of the Ti-Al-Si-N coating layers showed higher hardness values compared with Ti-Al-N coating layer. Besides, the variation of substrate bias voltage to the coating layers resulted in the changes of mechanical properties such as micro-hardness, Young's modulus, and residual stress.
FP-2-24 Structural Optical and Mechanical Properties of Coloured TiN@sub x@O@sub y@ Thin Films
F. Vaz, L. Rebouta, J.A. Mendes (Universidade do Minho, Portugal); E. Alves (ITN, Portugal); Ph. Goudeau, J.P. Riviiere (Universitat de Poitiers, France); K. Pischow, J. Rijk (Savcor Coatings Oy, Finland)
Microstructure is one of the most important aspects to be considered in materials possessing for most varied applications, such as those related with decorative purposes. Changes at the microstructural level are frequent: crystalline size, phase evolution and, in a more dramatically perspective, the full loss of the coating. Mechanical properties such as adhesion, hardness and stress also play an essential role, especially when dealing with these decorative films. In order to contribute to the existing knowledge, two sets of coloured films based on single layered titanium oxynitride (TiN@sub x@O@sub y@) compounds were prepared. The presence of oxygen in the films gives the possibility to tailor the film properties between those of pure covalent titanium nitride and those of the correspondent ionic oxide. Thus, varying the oxide/nitride ratio will allow tuning the band-gap, bandwidth, and crystallographic order between oxide and nitride and consequently the electronic, mechanical and optical properties of the material, including here the coating colour. Films were deposited by r.f. magnetron sputtering under variation of process parameters such as bias voltage and flow rate of reactive gases. Colour varied from shiny golden type for low oxygen contents (characteristic of TiN films) to dark blue for higher oxygen contents. X-ray diffraction results revealed the development of a face-centred cubic phase with <111> orientation (TiN type; lattice parameter of about 0.429 nm) and traces of oxide phases. Nanoindentation experiments revealed values of hardness between 20 and 40 GPa, strongly dependent on the composition and microstructure. Composition was determined by RBS. Compressive stresses between - 0.5 and - 6 GPa were determined. Electrical resistivity varied from about 120 µ@Omega@cm for samples with very low oxygen contents to 470 µ@Omega@cm, at the highest oxygen contents. Scanning electron microscopy (SEM) revealed a mixture of very dense and columnar type structures.
FP-2-25 Influence of Sputtering Deposition Conditions on the Morphology and Surface Roughness of Decorative Ni and NiCr PVD Coatings
V. Teixeira, N. Lima, A. Santos, A. Portinha, F. Guimaraes (University of Minho, Portugal)
Ni, NiCr and Cr thin films were produced by DC magnetron sputtering technique. These thin coatings are interesting for optical, decorative and corrosion resistant layers. The influence of the sputtering gas pressure, the applied bias and substrate temperature during the deposition process on the microstructure and surface roughness were studied. We present a phenomenological model of energetic bombardment of the growing film that explains the changes in the film microstructure and surface micro-roughness. AFM coating micro-roughness measurements were performed to get a more physical basis understanding of influence on the physical properties of the conditions of sputtering, energetic bombardment and surface mobility. The coating optical properties were also measured to correlate the changes of surface optical reflectivity of the layers with the observed changes of roughness. The topics discussed should provide some insights regarding the development of a methodology for mesoscopic modelling of the surface roughness evolution in sputtered coating systems where optical quality and surface characteristics such as wear resistant and corrosion resistant are a concern for technological applications.
FP-2-26 Laser-acoustic Quality Control of Wear Coatings on Cutting Tools
M.K. Yaran, M. Becker, T. Schuelke (Fraunhofer USA)
Fraunhofer's laser-acoustic tester LAWave has been applied for non-destructive quality control of TiN coatings on WC-Co substrates. Cutting inserts out of each coating batch have been tested before and after the coating process. The data show the variation of the obtained signals within batches and from batch to batch. It is possible to establish control limits based on the measured dispersion curve. The paper will also discuss film thickness related issues such as the dependence on the chamber load and the position of the individual substrates.
FP-2-27 Optical Profiler for Surface Characterization and Film Thickness Measurement
J. Schmit (Veeco Instruments Inc); P. Unruh (Veeco Instruments Inc.)
The optical profiler's main use is shape and surface characterization measurements. The profiler, which operates on interferometric principles, allows for the measurement of both smooth and rough surfaces over the field of view up to about a few millimeters by a few millimeters. In addition, the profiler can be used to measure the thickness of optical films and coatings. Depending on the thickness of film to be measured and the structure of the film, a few different measurement methods are used. For transparent coatings with thicknesses above 3 microns, the instrument looks for the positions of maxima of white light interference fringes created at two interfaces of the coating. The effective group index of refraction of the coating needs to be determined experimentally for each of the profiler's objectives. For thinner coatings, down to 100 or 50 nm, the reflectance phase is analyzed; the index of refraction across the wavelengths must be first determined. The interference of monochromatic light can be used to measure thin and thick films with a known index of refraction (film needs to create a step to a bare substrate), but the approximate thickness of the film needs to be known to avoid the ambiguity introduced by the monochromatic illumination; however, performing additional measurements for illumination with different wavelengths can significantly reduce this ambiguity. Special software allows for the independent analysis of areas with different coatings or substrates within the field of view. The thickness of film measurements with the optical profiler significantly expands the capability of the surface profiling instrument making the optical profiler a great tool for whole field characterization of film thickness as well as surface and interface characterization.
FP-2-28 Performance and Characterisation of CVD Diamond Coated, Sintered Diamond and WC-Co Cutting Tools for Dental and Micromachining Applications
H. Sein, W. Ahmed (Manchester Metropolitan University, United Kingdom)
Diamond coatings are attractive for cutting processes due to their high hardness, low friction coefficient, excellent wear resistance and chemical inertness. The application of diamond coatings on cemented tungsten carbide (WC-Co) tools has the subject of much attention in recent years in order to improve cutting performance and tool life. WC-Co tools contain 6% Co and 94% WC substrate with grain size 1-3 micron is desirable for diamond coatings. In order to improve the adhesion between diamond and WC substrates it is necessary to etch away the surface Co and prepare the surface for subsequent diamond growth. Hot filament chemical vapour deposition (HFCVD) with a modified vertical filament arrangement has been employed for the deposition of diamond films. Diamond film quality and purity have been characterised using scanning electron microscopy (SEM) and micro Raman spectroscopy. Diamond coated WC-Co bur, uncoated WC-Co bur, and diamond embedded (sintered) bur have been compared by drilling a series of holes in the various materials such as human teeth, borosilicate glass and porcelain teeth. Flank wear has been used to assess the wear rates of the tools. The materials subjected to cutting processes have been examined to assess the quality of the finish. Diamond coated WC-Co micro drills and uncoated micro drills were also tested on aluminium alloys. Results show that the there was a 300% improvement when the drills were coated with diamond compared to uncoated tools.
FP-2-30 Study of Corrosion Resistance of AISI 420 Stainless Steel after High Temperature N and Si Ion implantation
D.L. Tang, R.K.Y. Fu, P.K. Chu (City University of Hong Kong)
The effects of high temperature nitrogen and silicon ion implantation on the corrosion resistance of martensitic stainless steel 420 are investigated. Silicon implantation is used to achieve a Si-rich region near the stainless steel surface to improve the localized corrosion resistance, and plasma nitriding and high-temperature ion implantation are used to further improve the surface microhardness and corrosion resistance. The effects of different substrate temperature, implantation dose and implantation energy on the surface properties are assessed. The corrosion measurements are carried out in a NaCl solution using electrochemical impedance spectroscopy. The surface microhardness, crystal structure and microstructure are measured by microhardness measurement, XRD, SEM and AES. The process is applied to industrial injection molds in the production line, and the results are reported in this paper.
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