ICMCTF2003 Session BP: Symposium B Poster Session

Monday, April 28, 2003 5:00 PM in Town & Country

Monday Afternoon

Time Period MoP Sessions | Topic B Sessions | Time Periods | Topics | ICMCTF2003 Schedule

BP-1 Surface Modification of Cermeted Carbide Using Plasma Nitriding and Metal Ion Implantation
R.K.Y. Fu, D.L. Tang, P. Yang, X.B. Tian, P.K. Chu (City University of Hong Kong)
Cermeted carbide has good miscibility, high hardness and toughness, as well as good resistance to wear, abrasion and infusibility. The surface mechanical properties of the cermets can be improved if nitrogen or heavy metals, such as Mo and W, are embedded into the cermets surface. In our work, the cermets surface was implanted in nitrogen plasma in conjunction with Mo or W as well as Mo and W co-implantation. X-ray photoelectron spectroscopy (XPS) was used to determine the concentration and chemical states of the elements present in the high dose implanted cermets surface. Transmission electron microscopy (TEM) was employed to reveal the surface structure. Our results show that the surface hardness and wear can be enhanced to different degrees according to the treatment processes. The increase in the hardness is partially explained by demixing phenomena, that is, the formation of ternary or quadruple carbides through mixed crystal hardening located within the implanted range. As a result, the hard-phase particles on the cermet surface can withstand the external load and can better absorb impact energy.
BP-2 Effect of Al-PBII on the Composition and Phase Structure of AgMgNi Alloy Surface
L. Xia, Z. Yan, W. Yu (Harbin Institute of Technology, PR China); Z. Zhang (Harbin University Technology, PR China)
Al-PBII into AgMgNi alloy is carried out using the unbalance magnetron sputtering (UBMS) and R. F. stimulating to generate metal plasma. The depth profiles and the chemical states of Al and O are acquired by XPS analysis. And the phase structures of the samples with pre- and post-implantation are determined by XRD analysis. The results show that an Al implantation layer appeares on the surface of AgMgNi alloy substrates. The concentration of Al in the layer decreased with the increasing of the depth gradually. There are two chemical states of Al and O in the implantation layer namely Al, O in the solid solution and in the Al@sub 2@O@sub 3@. The comparison of the surface structure of pre- and post-implantation layer by XRD is made. If the small Da-t (200mm) was chosen, the lattice constant of Ag phase in the implantation layer of AgMgNi alloy substrate(α) decreased, but the intensity of the peak defined as the (311) plane increased. If the large Da-t (300mm) was used, the α value increased, and no obvious changes of the intensities of the peak of all planes could find. With the moderate Ds-t (250mm), no obvious change of the α value can be found, but the intensity of the peak defined as (311) plane increased. The reason of the changes of the surface structure of AgMgNi alloy is the formation of Ag-Al implantation layer and the collision cascades of Ar@super +@ in the surface of the substrate.
BP-3 Structure Chacterization of the Chromium Carbide Films Using a 90@super o@ -Bend Magnetic Filtered Cathodic Arc Plasma
C-.C. Lin, J.-H. Lin, W.-J. Hsieh, U.-S. Chen, Han. C. Shih (National Tsing Hua University, Taiwan, ROC)
In a 90@supero@ - bend magnetic filtered cathodic arc plasma (FCAP) system; filter source is the key to a successful process to reduce macro-particles contamination and to obtain high quality films in the deposition of metal. In this study, we prepared chromium carbide films by using a 90@supero@ - bend magnetic FCAP system, and the chromium carbide films were synthesized from Cr target (99.99%) and C@sub2@H@sub2@ gas. Chromium carbides are known to have three different phases; the Cr@sub3@C@sub2@ phase (Orthorhombic) possesses higher oxidization resistance than both Cr@sub7@C@sub3@ (Orthorhombic) and Cr@sub23@C@sub6@ (cubic) phase. The results showed that chromium carbide films obtained were amorphous at room temperature and a textured crystalline Cr@sub3@C@sub2@ phase appeared at 200°C. The carbon excess of the amorphous phase is about 20% more than of the crystalline Cr@sub3@C@sub2@ phase by AES. The chemical bonding of the elements (C, Cr, and O) were checked by XPS. Using SEM and AFM, the Cr@sub3@C@sub2@thin film shows a thickness of 150 nm and a surface roughness of 2.026 nm (Rms), which is even lower than our wearing glasses (~6nm). Various experimental parameters in the formation of chromium carbides were examined and discussed.
BP-4 Chemical, Optical and Mechanical Properties of Pulsed Laser Deposited SiCx Thin Films
W. Waldhauser, J.M. Lackner (Laser Center Leoben, Austria); R. Ebner (Materials Center Leoben, Austria); W. Lenz (Laser Center Leoben, Austria); M. Beutl, G. Jakopic, G. Leising (Institute of Nanostructered Materials and Photonics, Austria); H. Hutter (Vienna University of Technology, Austrai)
Pulsed Laser Deposition (PLD) is a Physical Vapour Deposition (PVD) coating technique for the production of thin films with complex chemical compositions. One of the main advantages of pulsed laser deposition is that excellent coating properties can be achieved even at low deposition temperatures. However, particulate defects in the growing films resulting from the evaporation process are often mentioned as the most important disadvantages of the PLD process. Unfavourable optical, thermo-physical and mechanical properties of the target material evaporated by laser radiation promote the formation of these particulate defects. This paper presents some results on silicon-based PLD-films with reduced density of particulates. Silicon and silicon carbide (SiC@sub x@) thin films of various stoichiometries were deposited by laser ablation from silicon targets with a high power pulsed Nd:YAG laser of 1064 nm wavelength in argon and C@sub 2@H@sub 2@ containing atmospheres. The substrates were arranged in shaded off-axis geometry in order to minimize the droplet density. The chemical composition and optical behaviour of the films were investigated employing secondary ion mass spectroscopy (SIMS), X-ray photoelectron spectroscopy (XPS) and ellipsometry. Atomic force microscopy (AFM) was applied for surface structure characterizations and nanoindentation measurements supplied informations about the hardness resp. Young's modulus of the thin films. By varying the carbon content in the SiC@sub x@ coatings different mechanical and optical properties of the films were achieved.
BP-5 Effects of N Ion Energy During Ion Assisted Filtered Cathodic Vacuum Arc (IAFCVA) Deposition of Titanium Nitride (TiN) Films
G.Q Yu, B.K. Tay, S.P. Lau, K. Prasad, Z.W. Zhao, P. Zhang, I.K. Pan (Nanyang Technological University, Singapore)
Because of its current application in Al metallization, titanium nitride (TiN) has been intensively investigated as a potential diffusion barrier in a Cu metallization. However, few are reported on TiN film prepared by ion assisted filtered cathodic vacuum arc (IAFCVA) to date. Cathodic vacuum arc provides an ideal method for assisted film deposition where the cathode spot is an intense source of ionized material with intrinsic energies considerably higher in comparison to that of evaporated or sputtered atoms and sufficient for self-densification when condensed onto a substrate surface. Besides, the micro-sized macroparticles originated from the arc sites on the cathode surface can be effectively removed by using a variety of filtering schemes. In this work, TiN films were synthesized at ambient temperature on (100) silicon substrates by a filtered Ti cathodic arc source and simultaneous bombardment from nitrogen ion beam. The effects of N ion energy on the film composition, density, microstructure and properties were systematically investigated by means of X-ray diffraction (XRD), AFM (atomic force microscopy), scanning electron microscope (SEM), secondary ion mass spectroscopy (SIMS), Rutherford backscattering spectroscopy (RBS), four point probe, scratch test and nano-indenter. The relevant explanations were also given. This work will be helpful to future study of barrier performance of TiN films prepared by the same method.
BP-6 Low-energy Ion-beam Induced Chemical Vapor Deposition with Precursors of Organometallics
T. Matsutani, T. Asanuma, C. Liu, M. Kiuchi (National Institute of Advanced Industrial Science and Technology, Japan); T. Takeuchi (Nara Women's University, Japan)
Low-energy ion-beam induced chemical vapor deposition (IBICVD) with organometallic bubbling system has been developed for ceramic coatings. IBICVD technique is well known as a promising low temperature process, because ion impacts promote decomposition or chemical reaction of precursors. IBICVD technique using focused ion beam can allow maskless deposition with submicron resolution. As another advantage, low-energy IBICVD can be prepared film with smooth surface. For example, a topograph of silicon dioxide prepared by low-energy IBICVD with hexamethyldisiloxane (HMDSO) measured by atomic force microscopy (AFM). The film was deposited on silicon (100) substrate at room temperature. HMDSO that was vaporized by the bubbling system with Ar carrier gas, and 150 eV oxygen ions of 10 µA/cm@super 2@ were introduced on the substrate surface. The root mean square of surface roughness and the film thickness was 0.25 nm and 20 nm, respectively. An infrared transmission spectra and x-ray photoelectron spectra of the film indicated formation of silicon dioxide with carbon contamination less than 0.1 at.%.
BP-7 Use of Way Cilt for Hardenings of the Tool
V.A. Zavaleyev (Scientific Physical and Technical Center, Ukraine); A.A. Romanov (Kharkov National University, Ukraine); V.T. Tolok (Scientific Physical and Technical Center, Ukraine)
In mechanical engineering alloys which durability is close to durability of a tool material begin to be used. Existing tool materials and coverings are unsuitable for processing similar materials. The technology of synthesis of very strong coverings (technology CILT - Condensation with ion bombardment low-temperature) is developed. Using opportunities which are given with a way, it was possible to apply coverings there where the effect was absent or to improve already received results.
BP-8 Microstructure of Superhard (Ti,Si,Al)N Nanocomposite Coatings
S. Carvalho, E. Ribeiro, L. Rebouta (Universidade do Minho, Portugal); J. Pacaud, J.P. Riviere (Université de Poitiers, France); E. Alves (ITN, Portugal)
(Ti,Si,Al)N nanocomposite coatings were prepared by a combination of rf and dc reactive magnetron sputtering. The composition of the films was evaluated by Electro Probe Microanalysis (EPMA) and Rutherford Backscattering Spectrometry (RBS). The structure of the films was studied by X-Ray Diffraction (XRD) and by High Resolution Transmission Electron Microscopy (HRTEM). Conventional scanning electron microscopy (SEM) and HRTEM were used for morphological characterization, while Extended X-ray absorption fine structure experiments (EXAFS) were used to characterize the bond structure. XRD experiments showed the development of crystalline phases whose structure is very similar to that of bulk TiN. The peak positions revealed changes of the lattice parameter from 0.418 nm to 0.429 nm when the ion bombardment and the adatom mobility are enhanced. The lowest lattice parameter corresponds to a Ti-Si-Al-N phase where some of the Si and Al atoms are occupying Ti positions in the fcc TiN lattice, while the highest lattice parameter corresponds to a system where at least a partial Si segregation can be enough to nucleate and develop the Si@sub 3@N@sub 4@ phase that forms a layer on the growth surface, covering the (Ti,Al)N nanocrystallites and limiting their growth. This reduction in grain size is also evidenced from the selected area diffraction (SAD) patterns in HRTEM experiments. From cross-sectional TEM images it was observed grains with diameter between 6 and 10 nm for the samples grown under higher adatom mobility and/or ion bombardment, while for the samples grown under low energetic bombardment and limited adatom mobility conditions grains with diameter between 30-50 nm are visible. Furthermore, through the visualization of bright field TEM images it was possible to discern a columnar structure.
BP-9 Conventional and High Resolution TEM Investigation of the Microstructure of Multicomponent Nitrides
M. Parlinska-Wojtan, A. Karimi (Swiss Federal Institute of Technology (EPFL), Switzerland); T. Cselle, M. Morstein (Platit AG, Switzerland)
Conventional and HRTEM, being the best-adapted tools for investigation of nanostructured materials, have been used to systematically study the mictrostructure of multicomponent nitride thin films, based on TiAlN, in order to understand the mechanism of th eir growth. Cross-sectional TEM and HRTEM studies demonstrated that these films, engineered as nanocomposites and multilayers have distinct microstructures. The multicomponent nitride films exhibit columnar growth in form of crystalline columns having pre ferential orientation. The density of columns is less pronounced in multilayered and nanocomposite films, than in single layered ones. By using the electron diffraction and local chemical analysis (EELS and EDS microanalysis) the size of crystallites, their relative orientation and compositional distribution of additional elements as Si or B could be determined. These microstructural observations will be correlated with the mechanical properties of the multicomponent nitride thin films.
BP-10 Simulation of SiC Deposition from SiH@sub 4@/C@sub 3@H@sub 8@/Ar/H@sub 2@ Mixtures in a Cold-Wall CVD Reactor
A. Dollet (CNRS-IMP, France); S. de Persis (CNRS, LCSR-Orleans, France); M. Pons (CNRS, LTPCM-Grenoble, France); M. Matecki (CNRS, IMP, France)
A two-dimensional modeling of 3C-SiC growth from SiH@sub 4@/C@sub 3 @H@sub 8@/Ar/H@sub 2@ mixtures in a cold-wall CVD reactor is presented. Mass transport and energy conservation equations are solved to get the deposition rate profile and the concentration fields of the various c hemical species inside the reactor. A Kinetic Monte Carlo (KMC) simulation model is used in another paper to describe SiC growth dynamics at an atomic scale. A realistic film growth simulation requires the knowledge of the impingement rates of the species incoming at the surface, which can be extracted from a reactor modeling. However, only a restricted number of species (those playing an important role in the deposition process) must be considered in a multiscale approach combining a CVD reactor model an d a KMC growth model, otherwise the problem would not be tractable. For this reason, two simple reaction schemes (a 18 species-27 reactions mechanism and a simpler 10 species-13 chemical reactions mechanism) are selected and compared in the present react or modeling work. The predicted deposition rate profiles obtained using both schemes are compared to the experimental deposition profiles. The species playing a key role in the deposition process are identified, and their relative contribution to the deposition is calculated. The strong influence of thermal diffusion in the deposition process is emphasized.
BP-11 Deposition of Hard Metal Nitride-like Coatings in an Electron Cyclotron Resonance Discharge
Z.G. Xiao, T.D. Mantei (University of Cincinnati)
Hard titanium-, zirconium-, and chromium nitride-like coatings have been grown in a high-density microwave electron cyclotron resonance discharge. The organometallic deposition precursors were titanium (IV) isopropoxide and tetrakis(dimethethlyamino)titanium, zirconium 2-methyl-2-butoxide and zirconium t-butoxide, and bis(ethylbenzene)chromium, with ammonia as the reactive gas. The deposited metal nitride-like coatings have nano-indentation hardness values of 20 to 28 GPa for TiN, 17 to 21 GPa for ZrN, and 25 to 31 GPa for CrN. Growth rates are 10 - 20 nm/min. X-ray photoelectron spectroscopic analyses showed the compositions of titanium nitride-like, zirconium nitride-like, and chromium nitride-like coatings to be TiC@sub x@O@sub y@N@sub z@, ZrC@sub x@O@sub y@N@sub z@, and CrC@sub x@O@sub y@N@sub z@ with significant carbon and oxygen atomic concentrations. The titanium nitride-like and zirconium nitride-like coatings have characteristic gold and white gold coloring, and lasted more than 1000 hours in an ASTM B117 salt-fog corrosion test without color change or visible corrosion.
BP-12 Pulse-modulated Plasma-enhanced Deposition of SiO@sub 2@ Coatings from Octamethylcyclotetrasiloxane
Y. Qi, T.D. Mantei (University of Cincinnati)
SiO@sub 2@ coatings have been grown at low substrate temperatures using a pulse-modulated microwave electron cyclotron resonance (ECR) oxygen plasma with octamethylcyclotetrasiloxane (OMCTS) as the organosilicon precursor. The 2.45 GHz microwave power was pulse-modulated with repetition frequencies of 20 Hz to 20 kHz, duty ratios (pulse on-time divided by pulse period) from 5% to 100% (continuous), and peak microwave power from 800 W to 2400 W. With constant peak pulse input microwave power, pulsed plasma deposition significantly lowers the deposition substrate temperature as the average power decreases. With 1600 W input microwave power, substrate temperatures were 140-150°C after 10 minutes of continuous deposition, decreasing to approximately 90°C with 50% pulse duty ratio and 1600 W peak power. The coating hardness decreased with pulsed operation: With 800-900 W continuous input power, the coating hardnesses were approximately 2 GPa, decreasing to 0.7 GPa with pulsed deposition at 50% du ty ratio and 800 W peak power, and further to 0.2 GPa at 25% duty ratio. Deposition growth rates depended only very weakly on the pulse repetition frequency and duty ratio (except at the lowest power levels, where the rates dropped as the duty ratio decre ased), but increased strongly with peak pulse power. Continuous deposition at 800-900 W input power, for example, gave growth rates of 0.6 - 0.7 µm/min, while pulsed operation at 800 W peak power and 50% duty ratio gave 0.5 - 0.6 µm/min for all frequencies between 20 Hz and 20 kHz, saturating at 0.8 - 0.9 µm/min above 1600 W peak power.
BP-13 Structural Analysis of (Ti,Cr,Al)N Coating with High Al Content and its Relationship to Cutting Performance
K. Yamamoto, T. Sato, K. Takahara, S. Kujime (Kobe Steel Ltd., Japan)
A novel super hard coating system of (Ti,Cr,Al)N was deposited by a cathodic arc ion plating process (CAIP) with a new type of plasma enhanced arc evaporation source. Previously we reported [1] that this coating system was characterized by extreme hardness (up to 3500 HV) and high oxidation resistance (more than 1000 degree C). Ti0.1Cr0.2Al0.7 target was used for the coating deposition. The effect of deposition parameters on the coatings structure was investigated. X-ray diffraction analysis of the coatings, which were deposited under different substrate biases, revealed that the crystal structure of the (Ti,Cr,Al)N coating changed from hexagonal (B4) to cubic (B1) structure as the substrate bias was increased from 0 to 50V. Above 50V of substrate bias, peak width of cubic phase decreased as substrate bias was increased, suggesting a decrease of the mean grain size of the coating. The hardness of the coating increased drastically as the crystal structure changed from hexagonal to cubic. TEM observations of the coatings with cubic and mixture of hexagonal and cubic phase were conducted. The coating with cubic phase showed a columnar structure with 50 to 100 nm of column diameters. Whereas small precipitation of hexagonal phase in the coating resulted in a grain like structure with average grain size a few tens of nanometers. Cutting tests of both coating against tempered carbon steel showed that by controlling the coating's crystal structure to cubic single phase, much improved wear resistance can be obtained. The importance of controlling the crystal structure for the cutting application will be demonstrated. @paragraph@ [1] K. Yamamoto et al. ICMCTF 2002, B1-1-4.
BP-14 Tribological Enhancement of CrN Coatings by Co-implantation of Vanadium and Carbon Ions
K.-W. Wong, D.-Y. Wang (Ming-Dao University, Taiwan, ROC)
The chromium nitride coating has been widely used in precision forming and molding applications for to its excellent tribological and oxidation properties. To further improve the wear performance of CrN coatings, vanadium and carbon ions were introduced into the near surface layer of as-deposited CrN coatings by using a metal-plasma ion implantation (MPII) process. The underlying dense and smooth CrN was deposited by using a filtered arc deposition (FAD) system, which provides fully ionized Cr plasma to the substrate surface. Subsequently, surface bombardment of the as-deposited CrN coating with vanadium and carbon ions resulted in densification and alloy formation at the near surface. The correlation between the implantation parameters and the wear resistance, corrosion resistance, and fracture toughness will be address by tribological and mechanical examination.
BP-15 Corrosion Protection of Magnetron Sputtered Nitride-based Coatings Deposited on High Strength Aluminum Alloys
M. Diesselberg, H.-R. Stock, P. Mayr (Stiftung Institut für Werkstofftechnik, Germany)
In recent years much effort has been made to develop anticorrosive coatings by magnetron sputtering as an alternative to chromate-based conversion coatings which are known to be carcinogenic. Especially high strength aluminum alloys used in aircraft industry like AA7075 exhibit low internal corrosion resistance. In our experiments the influence of initial PVD growth conditions i.e. substrate temperature and slowly grown sublayers on the deposition of subsequent layers like TiN, CrN and ternary materials of different stoichiometry has been investigated. The final coatings were ex-situ characterized by scanning electron microscopy (SEM), potentiodynamic measurements (PDM) and salt spray test (SST) to reveal their capability to protect the aluminum alloys from corrosion. @paragraph@ PDM were strongly dependent on the composition of the coatings but were often inconsistent with the behaviour in the SST performed in 5% sodium chloride solution at 35°C (in accordance with DIN 50021) with an exposure time of above 60 hours. The best results obtained from SST revealed a significant improvement of the corrosion protection by coating the aluminum alloy with a Ti sublayer deposited at low growth rates prior to deposition of TiN with a thickness of about 4µm. A possible explanation for the better protection is the higher density of the layer. As verified by SEM examinations the pores that arise from the columnar growth of sputtered TiN layers are reduced by initially depositing the slowly grown Ti sublayer.
BP-16 Characterisation and Tribological Evaluation of Nitrogen-containing Zirconium/ Yttrium Based Nanocomposite Films.
M. Joseph, C. Tsotsos (University of Hull, United Kingdom); A. Leyland, A. Matthews (The University of Sheffield, United Kingdom); M. Baker (University of Surrey, United Kingdom)
There is increasing interest in the development of super hard coatings, which also have a high elastic modulus. These have been produced by the manipulation of nanostructured coatings based on ceramic/ceramic and ceramic/metal phase compositions. This paper reports on the structural, mechanical and tribological properties of zirconium/ yttrium predominantly metallic films, doped with small amounts of nitrogen to produce coatings which contain either no nitride phase or small amounts of lower nitrides. All films were deposited on Si wafer, AISI M2 and AISI 316 stainless steel by reactive sputtering using a hot filament-enhanced dc unbalanced magnetron system. A systematic approach was adopted to investigate the properties of metal/metal and ceramic/metal phase combinations produced with increasing nitrogen content. Chemical composition and microstructure was determined by GDOES, TEM, XPS and SEM. XRD was used to identify metal/metal nitride phases. Mechanical properties such as hardness and elastic modulus were determined by microindentaion and Knoop microhardness. Reciprocating sliding, microabrasion and high frequency impact wear testing were performed to assess tribological performance.
BP-17 The Study on the Microstructure and Mechanical Properties of Metal Doped Transition Metal Nitride Nanostructured Superhard Coatings
H.S. Myung, H.M. Lee, J.G. Han (SungKyunKwan University, South Korea)
Nanostructured superhard coatings have recently been extensively developed for improving performance of various tools and machinery components under complex operating conditions. In these nanostructured superhard coatings, a few percent doping of alloying elements into conventional hard compounds can promote the superhardness by nanostructure formation. In our previous work, we synthesized Ti-Cu-N and Ti-Ag-N nanocomposite films with various Cu and Ag contents. The hardness of Ti-Cu-N and Ti-Ag-N films could be significantly improved by addition of Cu and Ag, indicating that an appropriate amount of doping element was selected. The maximum hardness of these films reached to about 40GPa and friction coefficient was about 0.3. In this study, we deposited various metal doped transition metal nitride nanocomposite films and investigated the relationship between formation behavior of nanostructured film and amount of doping element. Film structure and chemical composition were analyzed by X-ray diffraction(XRD), High Resolution Transmission Electron Microscopy(HRTEM) and Glow Discharge Optical Emission Spectroscopy(GDOES). The mechanical properties of metal doped transition metal nitride films were evaluated by nano indentation test and wear test.
BP-18 Boron Carbide Coatings by r.f. Magnetron Sputtering on Electrical-Discharge Machined Cemented Carbides
A. Lousa (Universitat de Barcelona, Spain); B. Casas (ETSEIB-Universitat Politècnica de Catalunya, Spain); E. Martínez, J. Romero (Universitat de Barcelona, Spain); L. Llanes (ETSEIB-Universitat Politècnica de Catalunya, Spain); J. Esteve (Universitat de Barcelona, Spain)
Boron Carbide (B@sub 4@C) is a very hard material with high chemical and thermal stability. Boron Carbide coatings were deposited by r.f. magnetron sputtering of a (B@sub 4@C)target onto WC-Co substrates, under controlled substrate bias. The substrate surface finish was that resulting from fine executed electrical discharge machining (EDM). Diamond-polished WC-Co substrates were also used as reference samples. The compositional depth profile of the coatings measured by Glow Discharge Optical Emission Spectroscopy (GDOES) and SIMS, revealed uniform and quasi-stoichiometric (B@sub 4@C) films. Their mechanical properties were measured by dynamical nanoindentation and microscratch methods. Substrate temperature and bias play an important role for optimizing mechanical properties and adhesion. The coated samples show lower surface roughness, higher hardness and improved tribological behavior as compared to bare EDM samples. No significant differences were found between films deposited on polished and non polished EDM substrates. These results open the possibility of using (B@sub 4@C) in order to improve the mechanical and tribological properties of EDM WC-Co hard metal.
BP-19 Preparation of Metal (W, Mo, Nb, Ti) Containing a-C:H Films by Reactive Magnetron Sputtering
C. Corbella, M. Vives, A. Pinyol, E. Bertran, M.C. Polo, J.L. Andújar (Universitat de Barcelona, Spain)
We discuss the preparation of metal containing hydrogenated amorphous carbon (a-C:H) thin films by means of reactive magnetron sputtering with pulsing dc power of a metal target (W, Mo, Nb, Ti) and rf bias using different gas mixtures of methane and argon. The samples obtained comprised a thickness between 100 nm and 600 nm and a low internal stress when little quantities of metal were incorporated. The chemical composition was analysed by XPS and revealed that metal inclusions are not detected at relatively high methane flows. The optical characterization of the films was carried out by means of transmittance measurements in visible range and showed a relationship between Tauc gap and the relative methane flow. Electrical measurements, that were performed with the four-probe method, provided a simple way to quantify the metal reactivity with a-C:H. The mechanical properties of the films (internal stress, friction coefficient and critical load for coating failure) were studied by micro-scratch test. The results are compared with those corresponding to metal-free (pure) a-C:H films.
BP-20 Evaluation of Arc-Deposited Boron as an Abrasion and Corrosion Resistant Coating Material for Aluminum Alloy Substrates
C.C. Klepper, J.M. Williams, R.C. Hazelton, M.D. Keitz (HY-Tech Research Corporation)
The boron (B) films, produced by vacuum cathodic arc deposition from a solid, heated, pure B cathode, hold great promise for a number of hard coating and tribological applications.@footnote 1@ In this study, compatibility with Al alloy substrates was examined.@footnote 2@ Although there was experimental evidence that good mechanical adherence of B on Al could be achieved with the vacuum arc, a calculation (Miedema) predicted B-Al incompatibility, because of a positive enthalpy of mixing. It was therefore of interest to explore the limits of the adherence obtained with this deposition method. A number of alloys and surface preparations were examined. It was found that a good mechanical bond can be formed with most Al alloys and under most substrate surface morphologies. However, this mechanical bonding is insufficient for good adhesion in salt-corrosive environments. Comparing a B coating on 52100 steel to a similar coating on 3004 Al alloy, by immersing both in a brine solution, a very different behavior is found. The steel sample has corrosion (rust) only in the spots where macroparticles have left pores and access to the substrate is possible. Upon subsequent sanding and polishing, the remainder of the coating proved to be quite rugged and adherent. By contrast, the coating on the Al alloy delaminated and eventually floated off the sample. Similar results were obtained upon salt fog testing (ASTM B119). A separate test on elemental B revealed very low dissolution rates of the element itself in brine. Corrosion of the substrates and adhesion were considered the main issues at the outset. @paragraph@@super 1@ C.C. Klepper, et al. JVST A, Volume 20, Issue 3 (May 2002) pp. 725-732@paragraph@ @super 2@ This research was supported by the US Army Soldier and Biological Chemical Command, Natick Soldier Center under Contract Number DAAD16-02-C-0024 (Phase I SBIR)
BP-21 Duplex Surface Treatments Combining PAPVD and Plasma Electrolytic Oxidation
A.L. Yerokhin, A. Pilkington (University of Hull, United Kingdom); A. Leyland, A. Matthews (The University of Sheffield, United Kingdom)
Vapour deposition technologies have so far been considered as an efficient tool in post-treatment of plasma electrolytically oxidised metal surfaces@footnote 1@. In the present work, we address the PVD treatment of a HE30 aluminium alloy prior to plasma electrolytic oxidation (PEO), in order to modify its surface with thin layers of the metals which could provide substantial changes in the oxidation conditions. Thin films of pure Al, Ti, Cr and Y of various thicknesses (within the 1 to 20 µm range) and structure were deposited on to the aluminium alloy using the electron beam PAPVD method. The surface modified substrates were subsequently PEO treated to convert the metal surface into oxide ceramic layers of various thicknesses. The effects of the PVD films on structure, phase composition, mechanical properties and corrosion performance of the oxide ceramic layers were studied using SEM, EDX and XRD analyses, microhardness, scratch and potentiodynamic corrosion testing. Structure-property relationships in the produced ceramic layers were discussed with regard to treatment regime optimisation for both PAPVD and PEO processes as constituents of a commercially-viable duplex processing technology. @FootnoteText@ @footnote 1@ AL Yerokhin, et al, Abstracts of the ICMCTF-2001 Conference, San-Diego, USA, 30 April - 4 May, 2001, 73.
BP-22 Comparison of Diluent Gas effect on the Growth Behavior of Horizontal CVD SiC with Analytical and Experimental Data
Y.J. Lee, D.J. Choi, S.S. Kim, H.L. Lee (Yonsei University, South Korea); H.D. Kim (Korea Institute of Machinery and Materials, South Korea)
Silicon carbide film produced by low pressure CVD process in the horizontal hot wall deposition system. The computational simulation of gas velocity, temperature profile and pressure in reaction chamber were conducted with varying process variables i.e. temperature and dilute gas addition. The simulated results were adapted to the experimental results. The modeling showed the reason of microstructural changes and growth rate variation of SiC film with temperature and diluent gas. All simulation had connection with temperature, which affected the growth atmosphere of system. key words : silicon carbide, simulation, diluent gas, CVD.
BP-23 Growth and Characterization of ZrB@sub 2@ Based Nanolayered Coatings for High Temperature Applications
I.W. Kim, K. Martin, J. Wilson, S.A. Barnett (Functional Coating Technology, LLC); D. Li, A. Madan, Y.-W. Chung (Northwestern University); P. Hedge, A. Inspektor (Kennametal, Inc.)
There is a great need for new tool coating materials with good high-temperature hardness, good oxidation resistance, and with low solubility in the workpiece at elevated temperatures. However, currently-available coating materials do not meet all these property requirements. We are developing nitride/boride nanolayered systems which are expected to provide a unique combination of properties including high hardness, excellent stability at elevated temperatures, low chemical solubility in Fe and good thermal expansion match with cemented carbide tools. ZrN/ZrB@sub 2@ nano-layered coatings were deposited using a dual-cathode magnetron sputtering system. The key properties including hardness, adhesion, and residual stress were evaluated as a function of composition, bilayer period, and substrate bias. The hardness values for as-deposited coatings ranged from 30-38 GPa and increased to 49 GPa after annealing at 1000°C under inert atmosphere. Low and high angle XRD revealed that the superlattice structure was stable at elevated temperatures. Adhesion testing verified that the coatings adhered well on cemented carbide inserts even after annealing at 1000°C under inert atmosphere. The oxidation testing showed that the coatings were oxidized at temperature above 750°C under atmosphere. In order to significantly increase the oxidation resistance, selected nitride compositions with higher oxidation resistance are being studied to replace ZrN in the nanolayered coating. Preliminary results on oxidation behavior, hardness, high temperature stability and wear behavior will be discussed for nanolayered coatings and monolithic coatings.
BP-24 Copper Metallization for Sub-micron Interconnect by 90@super 0@-bend Magnetic Filtered Cathodic Arc Plasma Deposition System
U.-S. Chen, J.-H. Lin, W.-J. Hsieh, P.-S. Shih, C-.C. Lin, Han. C. Shih (National Tsing Hua University, Taiwan, ROC)
The cathodic arc evaporation plasma generated the highest plasma density compared with other PVD systems, but is known to be contaminated with macroparticles. In order to produce high quality defect-free copper films, a 90@super o@-bend magnetic filter is suitable for ULSI interconnects metallization application. Macroparticle contamination has been alleviated by magnetic filter, the copper ions in the fully ionized copper plasma were accelerated and deposited on the wafer with a negative pulsed bias voltage. The fully ionized copper plasma flux was highly directionally deposited on the patterned and blank wafers, the filling of trenches/vias as narrow as 0.18 µm, with an aspect ratio as high as 5, FESEM images showed conformable copper step coverage ability. SEM/EBSD spectra showed that the FCAPD copper film has an obvious Cu(111) preferred orientation. The result of this process as made, by mechanical pull-up tests, showed that higher substrate bias and 50% pulse bias duty cycle can effectively enhance the adhesion strength of copper film on a-Ta:N layer.
BP-25 Characteristics of Neutral Beam Generated by Reflection on Planar-type Reflector and Its Etching Properties
D.H. Lee, M.J. Chung, S.D. Park, G.Y. Yeom (Sungkyunkwan University, South Korea)
Charge-induced damage during the plasma etching is one of the biggest problems that have to be solved for the deep submicron semiconductor devices as well as future nanoscale devices. To avoid the charge-related damage, several low-damage processes have been proposed and one of the techniques to avoid the problem is to use neutral beam etching. One of the techniques fabricating a neutral beam is to use a low angle reflection of the ion beam where ions extracted from the ion source are neutralized by a low angle reflection during the reflection. Previous studies showed that, by the reflection of the ion beam at 5 degree angle of incidence, most all of the ions could be neutralized. The degree of neutralization was similar to the all of the gases used in the experiment such as SF@sub 6@, NF@sub 3@ and CF@sub 4@ which can be used for the etching of SiO@sub 2@ and Si. Also, using radical beams from these gases, nearly vertical SiO@sub 2@ etching could be obtained. In this study, a newly improved low angle forward reflected neutral beam apparatus with a planar-type reflector attached to the ion source as a grid system has been used and its effect on the formation of neutral beam and the characteristics of the neutral beam flux have been investigated. Also, we investigated Si and SiO@sub 2@ etch properties with fluorine-based gases using this system.
BP-26 Effects of Annealing on the Properties of Zr-Y Based Mettalic Nanocomposite Coatings.
C. Tsotsos, M. Joseph (University of Hull, United Kingdom); A. Leyland, A. Matthews (The University of Sheffield, United Kingdom)
Zr-Y metal-metal nanocomposites have a great potential in treating soft steels and light alloys since the respective elastic moduli of coating and substrate can be more closely matched. However the measured surface hardness of the coating depends strongly on the elemental composition and structural characteristics of the films. In such low-miscibility binary alloy systems it is possible to create a nanostructured metallic coating with apparent hardness values in excess of 25GPa, without the addition of nitrogen or other ceramic phase formers. The desired nanostructure, consisting of separate Zr(majority) and Y(minority) phases, with some yttrium retained in substitutional solid solution in the former, can be achieved either during the coating deposition process or, if a low (less than 300@super o@C) coating deposition temperature is chosen, by annealing after deposition. Coatings were deposited on AISI M@sub 2@ tool steel, AISI 316 austenitic stainless steel coupons and Si wafers by reactive magnetron sputtering in a filament-enhanced unbalanced dc magnetron system at ~300Â@super o@C and then annealed under vacuum at temperatures between 400 and 600Â@super o@C. Coating structure is characterised using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and glancing angle X-ray diffraction (XRD) analysis. Surface hardness and elastic moduli of the films are determined by Knoop microhardness and Vickers depth-sensing ultra-microhardness measurements. The influence of coating structure on the mechanical properties is discussed.
BP-27 Effect of the Magnetic Field on the Properties of Ti Films Deposited by Unbalanced Magnetron Sputtering.
M. Flores, S. Muhl (IIM-UNAM, Mexico); E. Andrade (IF-UNAM, Mexico); E Sãnchez (IIM-UNAM, Mexico)
The Ti films were deposited by unbalanced magnetron sputtering with a concentric electromagnet coil around the magnetron to produce a variable unbalance of the magnetic field of the cathode. This magnetic field produces changes in the degree of ion bombardment of the substrate and this in turn affects the films properties, such as density and residual stresses. In this work Ti films on silicon substrates were prepared by magnetron sputtering with a variable magnetic field, with the aim of studying the effect of the field on the ion bombardment, deposition rate, density, roughness, stress and microstructure of the films. The film properties were studied as a function of the additional magnetic field and the radial distance. The roughness, thickness and residual stress in the films were measured with a stylus profilometer. The ion bombardment was studied with an electrostatic planar probe and a Faraday cup ion detector. The microstructure and texture index were studied by XRD analysis. The composition, density and film-substrate interface were determined by ion beam techniques.
BP-28 Mechanical Properties of TiN/CrN Superlattice Coating Deposited on Prenitrided Hot-Working Tool Steel
G.S. Kim, S.Y. Lee (Hankuk Aviation University of Korea, South Korea); J.H. Hahn (Korea Research Institute of Standards and Science, South Korea)
TiN/CrN multilayer coatings with superlattice characteristics were deposited on prenitrided hot-working tool steel(AISI H13 steel) by reactive unbalanced magnetron sputtering. AISI H13 steels were quenched at 1180@super o@C and tempered at 560@super o@C After plasma nitriding, AISI H13 steels were mechanically polished to obtain a nitrided surface without a compound layer and TiN/CrN superlattice films were coated. The TiN/CrN superlattice films were deposited with various modulation periods which were controlled by changing time above the Ti and Cr targets alternatively with rotation monitor and total coating thickness deposited on prenitrided AISI H13 steel was 4-5µmm. Coatings were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), cross-section TEM and glow discharge optical emission spectroscopy (GDOES). Scratch test, hardness, impact wear test and high temperature wear test of the coatings have also been performed. The hardness of coatings were measured to be approximately 35~40Gpa. Result from high temperature wear test showed the duplex treated specimen (TiN/CrN film deposited on prenitrided AISI H13 steel) exhibited good wear resistance property than that of only TiN/CrN film coated specimen. Detailed results will be presented.
BP-29 Thermo-Reactive Diffusion Vanadium Nitride Coatings on AISI 1020 Steel
U. Sen (Sakarya University, Turkey); S. Sen (Metal Education, Turkey)
Thermo-reactive diffusion (N and V) on AISI 1020 steel have been obtained by an initial gas nitriding and followed with V by pack method in the powder mixture consisting of ferro-vanadium, ammonium chloride and alumina at the temperature of 800, 900 and 1000 @super o@C for 1-4 hours. The properties of the diffusion layers, namely microstructure and phase composition, have been studied, and influence of temperature and duration of treatment with V on the nitrided steel on thickness of vanadized layer and its phase composition has been determined. By increasing the temperature and treatment time with V on the steel substrate, the depth of vanadium nitride formed on steel samples are changing between 5.16 µm to 16.77 µm. The micro-hardness value of vanadium nitride layers are 14.68±1.55GPa HV (0.005). X-ray diffraction analysis show that the presence phases formed in the vanadium nitride layers on the steel samples are VN and V@sub 2@N.
BP-30 Evaluating the Nanostructure of PVD CrCu(N) Coatings
M. Baker, P. Kench (University of Surrey, United Kingdom); M. Joseph, C. Tsotsos (University of Hull, United Kingdom); A. Leyland, A. Matthews (The University of Sheffield, United Kingdom)
For certain manufacturing operations (e.g. punching, forming), extending the lifetime of the machine tool requires a coating which has a strong resistance to impact/abrasion and the ability to deform (either elastically, or plastically) without undergoing brittle fracture or adhesive failure. Thus, for metallic substrates, desirable coating mechanical properties are a combination of relatively low modulus and relatively high hardness. This paper presents results on the nanocomposite CrCu(N) system, in which the immiscibility of Cr (with low N concentration) and Cu offers the potential of a predominantly metallic (and therefore tough) nanocomposite, composed of small Cr(N) and/or Cr@sub2@N grains interdispersed in a (minority) Cu matrix. A range of CrCu(N) compositions have been deposited using a hot-filament enhanced unbalanced magnetron sputtering system. Coating stoichiometry and nanostructure have been studied by XPS, TEM, SEM, XRD and scanning probe microscopy. Hardness, wear resistance and impact resistance have been determined by nanoindentation, reciprocating-sliding and ball-on-plate high-frequency impact. Evolution of the nanostructure as a function of composition and correlations of the nanostructure and mechanical properties of the CrCu(N) coatings are discussed.
BP-31 Ion Implantation of Ferritic and Austenitic Steels: Analysis of Dosis and Surface Damage Effect
F.J. Pérez, M.P. Hierro, L. Martinez, C. Gómez, B. Chico (Universidad Complutense de Madrid, Spain)
Ion implantation is very useful technique as surface modification when the dimensions of the pieces must be not modified. There are different number of ions that can be implanted to improve the corrosion resistance of metallic materials such a Cr, Si, N, etc. There are not clear evidences about the effect of the dosis implanted and the effect of surface sputtering during the implantation process. In order to analyse this important aspect for industrial treatments two stainless steels AISI 304 (austenitic) and AISI 430 (ferritic) have been implanted with different dosis of nitrogen from 10@super 14@ up to 10@super 17@ ions/cm@sub 2@ on polish samples. @paragraph@ Electrochemical Impedance spectroscopy (EIS) and Atomic Force microscopy have been applied in order to correlate the surface profile and the corrosion behaviour. The effect of dosis and damage haven analyses, proposing different mechanisms and experimental conditions for industrial applications.
BP-32 Deposition of NbN Thin Films by D.C. Magnetron Sputtering Process
S.K. Kim, J.S. Yoo, B.C. Cha (University of Ulsan, South Korea)
Niobium nitrides play a rather special role among the interstitial compounds of transition metals due to their hexagonal structure. In this work, we optimized process parameters for deposition of niobium nitride thin films and characterized their mechanical properties. The films deposited at 10% nitrogen fraction of inlet gas exhibited maximum hardness. Hardness of films decreased with the increase of nitrogen fraction of inlet gas. XRD analysis showed NbN deposited at room temperature had cubic structures. Hexagonal phases were formed with the increase of deposition temperatures. The hardness of films increased with the increase of bias voltage. Adhesion and wear resistance of films were also determined.
BP-33 Tribological Enhancement of CrN Coatings by Co-Implantation of W and C Ions
Y.-Y. Chang (National Chung-Hsing University, Taiwan, ROC); D.-Y. Wang, K.-W. Wong (Ming-Dao University, Taiwan, ROC); C.-W. Kuo, W.T. Wu (National Chung-Hsing University, Taiwan, ROC)
Metal ion implantation is being successfully developed for improving wear, corrosion, and physical properties of material. In this study, W and C ions were co-implanted into CrN films, which were prepared by using a cathodic-arc evaporation system. The accelerated voltage of the implanted W/C ions was 50 kV, the implanted dose varied in the range of 0.5-3 x 10@super 17@ ions/cm@super 2@. With increasing of the W/C ion implantation dose, the W/C concentration increases over the stoichiometric level. Field- emission SEM, auger electron spectroscope (AES), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM) were used to investigate the microstructure and chemical bonding of implanted samples. Tribological and mechanical analyses were performed by pin-on-disk tests, dry sand/rubber wheel abrasion tests and microhardness measurements. The improvement of wear behavior can be correlated to the carbide formation based on the ion-induced crystallization of the surface layer modified by the ion implantation.
BP-34 Plasma-Enhanced Deposition of Hard Corrosion-Resistant Multilayered Coatings from Organosilicon Precursors
Z.G. Xiao, Y. Qi, T.D. Mantei (University of Cincinnati)
Multilayered silicon-containing functional coatings combining hardness and corrosion resistance have been grown in a high-density microwave electron cyclotron resonance discharge. Elemental compositions and growth rates were first compared for SiO@sub 2@ and silicon nitride-like coatings using three organosilicon precursors: Hexamethyldisiloxane (HMDSO), octamethylcyclotetrasiloxane (OMCTS), and tetramethylcyclotetrasiloxane (TMCTS). Hard, colorless SiO@sub 2@ coatings were grown from each precursor in an O@sub 2@ plasma while silicon nitride-like coatings were grown from HMDSO in ammonia. The silicon dioxide coatings were stoichiometrically close to thermal SiO@sub 2@ with oxygen-to-silicon ratios of approximately 2:1 and carbon percentages of 12% for HM DSO, 3.4% for OMCTS, and 1.4% for TMCTS. Growth rates were 0.5 to 1.1 µm/min and nanoindentation hardnesses were 6 to 9 GPa for SiO@sub 2@ and 12 GPa for silicon nitride layers. Multilayer coatings were then grown and optimized using statistical experiment design methodology. The optimized multilayer structures had a relatively soft polymer-like bottom layer deposited from 100% OMCTS and a hard top layer of either silicon dioxide deposited from OMCTS in oxygen, or silicon nitride-like layers grown from HMDSO in ammonia. The soft underlying polymer-like coatings had hardnesses of 0.6 to 1.5 GPa and very good adherence to metal substrates, lasting more than 3000 hours in ASTM B117 salt-fog corrosion tests. The silicon dioxide and nitride-like top layers were much harder, 8 GPa for SiO@sub 2@ and 12 GPa for SiN. The multilayer structures were colorless and transparent and survived up to 2600 hours in salt-fog corrosion tests.
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