It is known that zirconia has excellent thermal and chemical stability, and oxide ion conduction. Therefore, YSZ is expected to be used as oxide ion conducting materials, optical mirror materials, catalytic materials and heat-resistant materials. Zirconia films have been fabricated by PVD (ex. sputtering and laser-ablation), chemical vapor deposition (CVD) and sol-gel methods. CVD is capable to prepare high quality zirconia films with excellent conformal coverage; however, deposition temperature of conventional CVD was usually high than PVD. On the other hand, an electron cyclotron resonance (ECR) plasma is high-activity plasma and high quality crystalline films can be obtained at low temperature by using ECR plasma. In the present study, zirconia thin films were prepared at low temperatures on quartz, polycarbonate and polyimide substrates by ECR plasma MOCVD.

Zr-hexafluoroacetylacetonato solution was used as a precursor. The source, which was placed in a glass bubbler, was carried into a reactor by Ar gas. A microwave (2.45 GHz, 500 W) was introduced into the ion chamber through a rectangular wave guide. A magnetic field (875 Gauss) was applied to the ion chamber to satisfy the ECR condition. A mirror-type magnetic field (450 Gauss at the substrate stage) was applied in order to raise a plasma density, which results in an increase of the deposition rates of films. Substrate temperature (Ts) was from 30 to 700 C by water-cooling holder and infrared lamp heater. Microwave power was changed from 0 to 900 W. The deposition time was from 30 to 120 minutes.

Cubic, monoclinic and tetragonal zirconia films were obtained over Ts=400 C, and cubic and monoclinic zirconia films were obtained below Ts= C. Cubic and monoclinic zirconia films were also obtained at no heating. The deposition rate increased from 10 to 20 nm/min with increasing Ts from no heating to 600 C. Crystallized zirconia films were obtained on polycarbonate and polyimide substrates at no heating. The ECR plasma was significantly effective to prepare crystallized zirconia films at low temperatures.

The continuous advances in the aircraft and nuclear industry demand the development of new materials that among other properties offer a good resistance at elevated temperatures. For this reason, Ni super alloys were developed from a simple Ni-Cr matrix to multi-element, multi-phase systems. These new super alloys are specially favored for their exceptional thermal resistance and ability to retain mechanical properties at elevated temperatures. They are classified as difficult-to-machine materials due to their high shear strength, work hardening tendency, content of abrasive carbide particles within the microstructure, strong tendency to weld and to form built-up edges. Their low thermal conductivity leads to elevated temperatures during machining. Consequently, their tendency to maintain a high strength at elevated temperatures leads to elevated cutting forces. On this account, the development of an adequate coating for machining Ni alloys is today an important challenge. Nowadays, TiAlN is well known because of its excellent overall cutting performance. However, Al2O3 possesses better chemical and thermal properties than TiAlN, especially regarding hot hardness, oxidation resistance, diffusion resistance. Motivated by the advantages offered by PVD-Technology, γ-Al2O3 was synthesized by reactive bipolar pulsed magnetron sputtering in previous works. PVD-Processes allow the deposition of insulating coatings such as alumina at reduced temperatures, which implies a lower substrate thermal load. At the same time using PVD-Technology it is possible to produce high compressive stresses in the coatings (high alternating thermal stress resistance), keep sharp cutting edges, synthesize pure structures and deposit various coating combinations such as multilayer multilayer TiAlN + γ-Al2O3. Therefore, a PVD-multilayer coating TiAlN + γ-Al2O3 is very promising for machining of Ni alloys such as Inconel 718. However, due to the very different characteristics of the nitrides and oxides, particularly the good coating cohesion of this coating concept constitutes a challenge. In this work different multilayer combinations were deposited on cemented carbide cutting inserts. In order to improve the adhesion between the nitride and oxide layers and consequently the coating cohesion, a special gradation was developed. The reactive gas flows (N2 and O2) was gradually changed during the coating deposition. The result was a soft gradation consisting of different nitrides and oxides species synthesized in very thin layers. Tribological tests demonstrated that the developed soft gradation offers an important improvement of the coating cohesion and fatigue resistance. For the evaluation of the coating adhesion and cohesion calo-, Rockwell- and scratch-tests were carried out. Mechanical properties were investigated by impact.

A highly hydrophilic surface, with a water contact angle smaller than 20 degrees, was rendered to a poly-methylmethacrylate [PMMA] by Xe2 excimer lamplight and plasma treatment. In result, the implant material that was highly biocompatible and adhesive to soft tissue was developed. The PMMA surface, which had been pretreated by ammonia plasma, was irradiated with Xe2 excimer lamplight in the presence of hydrazine as a reaction solution. In order to evaluate the wettability of the modified sample, the contact angle with water was measured. The contact angle was decreased from 83 degrees for untreated PMMA to 60 degrees when irradiated the Xe2 lamplight for 30 minutes. With the ammonia plasma pretreatment, the contact angle of the treated sample became to 7 degrees at the 1 minute Xe2 lamp irradiation.

Increasing the efficiency and the relative ease of creating ordered nanostructures is essential to the advancement of nanotechnology. The practical benefits from ambient processing of nanostructures, like reduced complexity and increased efficiency, makes it an important avenue for investigation as nanomanufacturing processes. We have recently shown that pulsed laser melting of ultrathin metal films in vacuum leads to nanostructure ordering presumably due to metal dewetting. Here we show that UV pulsed laser irradiation (10 ns pulse width) of ultrathin Co films on SiO2 substrates under ambient conditions with a two-beam laser interference pattern generates Co nanoparticles with both long- and short-range order (LRO and SRO) and are qualitatively comparable to those created in vacuum. Furthermore, preferential etching of the metal shows that there is minimal interaction of the Co with the substrate. These results show that the presence of oxygen in the ambient does not substantially influence the resulting nanostructure formation. Therefore, ns pulsed laser processing under ambient conditions may be a practical way to realize ordered metal nanostructures.

With the focus on bio terrorism and environmental sensing, there is need for development of smart integrated bio-chemical sensors. We investigate Whispering Gallery Mode (WGM) based High Q micro cavity as a biosensor. We integrate the lab-on-a-chip approach with High Q technology to develop highly selective and smart sensors for in-situ detection of aqueous media based agents. We have investigated the ring based micro-cavity structure as a sensor. We identify the detection of agent through the changes observed in the wavelength shift and Q factor as a result of enzyme-substrate interactions. We report an experimental demonstration of a compact micro-cavity based biochemical sensor based on the micro ring structure. The micro-cavity, fabricated on a silica-on-silicon substrate, is designed to have a resonant wavelength (l) near 1.34 μm. The transmission spectrum of the sensor is measured with different ambient refractive indices ranging from n =1.0 to 1.5. Chemical detection was achieved by measuring the shift in resonant wavelength, and variation to the quality factor

In this research, a 1∼2 um NiCo film coated by electroplating technique as protection film in high temperature environment was studied. The improvements of hydrophilic property and high temperature stability by coating NiCo film upon pure Cu plate have been characterized through experiments. In thermal stability characterization, the specimens were put into a temperature-controlled oven and applied a thermal load at 100°C, 200°C and 300°C for annealing. After thermal annealing, the hydrophilic property was characterized to confirm that NiCo film was stable in high temperature environment. The hydrophilic property was represented by the contact angle between the DI water and the surface of NiCo film. The outgasing effect of contaminated polymer was also study. The electroplated NiCo film has advantages of good hydrophilic property, high temperature stability and easy fabrication. Therefore, the NiCo film could help the development of thermal related products.

The in-plane electrical conductivity and the apparent density of air plasma sprayed (APS) molybdenum coatings having thicknesses in the range 30 um to 450 um were measured as a function of coating thickness. Both conductivity and the apparent density were found to increase with thickness until a saturation density (∼ 80% of the bulk density of molybdenum metal) was achieved. Attributing this increase in the apparent density to the increased volume fraction of the metallic component (or decreased porosity volume) in the coatings allows for the treatment of the problem in a framework of percolation theories. In order to eliminate the contribution of surface roughness the results were further analyzed using a two-layer parallel resistor model of the coating. In this model the top layer, which was composed of coating roughness, was assumed to have fixed thickness and conductivity whereas the conductivity of the bottom layer was assumed to vary with thickness (density). A fit to the data obtained from the above model showed that the conductivity of the bottom layer obeys a power law relationship of the type σ α (V –Vc)n throughout the composition range (with n=1.72 and Vc=0.09). These results show that that the coatings behave as a three-dimensional percolation system [1] and also indicate the asymmetric shape of the metallic and insulator regions in the coatings [2].

Green manufacturing technology has become a significant innovative keyword to reduce the environmental burden and CO2 emission at the stage of manufacturing and production. In daily operations by machining, huge amount of lubricating oils and cleansing agents is wasted so that dry machining technology provides us a way to completely reduce these wastes. Among several candidates, self-lubrication via in-situ formation of lubricious oxide films is accommodated to protective coatings in order to attain low friction and wear state even at higher cutting speed range. Materials science of in-situ formed lubricious oxide tribofilms is stated with consideration of accommodation mechanism via the chlorine implantation. Mechanical characterization is made for evaluation on elasto-plastic deformation of lubricious oxides. Turning test is employed to evaluate dry machinability of various tools for wide range of cutting speed. Self-lubrication in dry machining is described both for bare WC and TiCN-coated WC tools with and without chlorine implantation. Precise microstructure analyses are made by using the laser microscope, EDS and XPS. In-situ formation of lubricous oxides proves that self-lubrication process takes place even in dry machining to reduce the flank wear and friction coefficient.

Previously, we reported that the viscosity of a polymer film can be measured in situ by observing the liquid-liquid dewetting of polymer bilayer films. In this study, we use the technique to investigate the effect of film thickness and surface interactions on the effective viscosity of polymer thin films. We found that the effective viscosity increases dramatically with decreasing the film thickness. We attribute this to the pinning of the polymer chains at the strongly interacting polymer/Silicon interface.

Selective laser melting has been used to build high aspect ratio, three-dimensional NiTi components for the first time. The influence of laser dwell time and raster pitch on the density of NiTi shape memory alloy parts and their resolvable feature sizes are reported. The properties of shape memory springs produced by this method are reported and the application of selective laser melted NiTi components in microelectromechanical devices is discussed.

In this paper an attempt was made to impose different degrees of rapid solidification by spraying on diverse substrates of varying thermal properties. Substrates such as Copper, Aluminum, Stainless steel, Low alloy steel substrates were used to alter the imposed cooling rate and thereby the amount of residual α phase. A start powder of 3 wt % Alumina-titania powder was used for spraying to a thickness of 250 μm on the different substrates specified. In all cases the rapidly solidified phases show nanocrystalline sizes with the most rapidly solidified metastable γ phase showing finer grain size of less than 25 nm. The surface roughness of the substrate and the coating were characterized by Atomic force microscopy. In contrary to the Alumina-13 wt % titania, coupons of Alumina-3 wt % titania had shown poor indentation fracture toughness with increased amount of residual α phase. Coupons of stainless steel and low alloy steel had shown the lowest fracture toughness when tested by Vickers type indentation at loads of 3 N and 5 N. In contrast to these results the interfacial toughness when measured by Rockwell indentation technique at loads of 150 N was found to be dependent on the elastic modulus of the substrate more than the coating hardness. The interfacial toughness was found to be lower for softer material such as aluminum and copper than stainless steel and low alloy steel.

For the better understanding of anti-wear properties of hard coating films, the effects of preferred orientation, surface roughness, and surface hardness on the tribological property of TiN and CrN films have been studied. TiN and CrN films were deposited by cathodic AIP (CAIP) with working temperatures of 350∼450°C, working pressures of 1∼5Pa, arc currents of 50∼90 A, and bias voltages of 30∼150V. The characteristics of microstructure and its effect on the friction coefficient were investigated with working conditions. The preferred orientation of the film was examined by XRD. The friction coefficient was determined using ball on disk tribometer. The preferred orientation of films was changed from (200) to (111) with decreasing working pressure and increasing bias voltage. It is reported that TiN coating with strong (111) orientation have better tribological property, but, in this study, although similar tendency was also found in TiN, the tribological property was increased with diminishing (111) orientation in CrN films. It is concluded in this study that the tribological property is not affected only by the orientation of the film, but it depends on the combined properties of surface roughness, surface hardness, and orientation of the film. The friction coefficients of TiN and CrN were 0.48∼0.52 and 0.49∼0.53, respectively.

The thermal stability of Cr1−xAlxN and Cr1−xAlxSiyN nanocomposite coatings with different composition x, Si content, and phase structure has been investigated. The coatings were deposited in an industrial unit by the cathodic arc evaporation method, using rotating cylindrical cathodes. Further sets of coated WC/Co plates were subjected to an annealing step in a forming gas (92% N2 / 8% H2) atmosphere for several hours at a constant temperature (maximum 1000°C). Chemical composition, microstructure and mechanical properties of the coatings were investigated by the RBS, XRD, TEM, SEM, XPS and nanoindentation techniques.

As-deposited Cr1−xAlxSiyN coatings with Al contents x in the range of 0.4 ≤ x ≤ 0.6 showed a single-phase cubic CrAlN structure and a maximum hardness of 38 GPa. With increasing the Al content to x = 0.95 – 0.96, two-phase films consisting of hexagonal AlN and cubic CrAlN structure with hardness of about 31 GPa were obtained. The hardness of Cr1−xAlxSiyN coatings increases during annealing at temperatures in the range of 800 – 1000°C by about 1 – 4 GPa, even though the residual compressive stress in the coatings was found to relax considerably during this procedure. The addition of Si into Cr1−xAlxN delays the appearance of hcp-AlN and thereby improves the thermal stability of the coatings.

Traditional indentation models relating the toughness to applied load and the length of well-developed radial cracks were initially developed for monolithic bulk brittle materials. Their application can also be extended to coated systems if sufficiently thick, however, the use of such models to thin coatings will be influenced by other factors such as substrate deformation and it is difficult to use traditional approaches to assess sub-threshold cracking. The method of extrapolating the load-displacement curve has been widely used to assess the toughness of a coating when a step in the load-displacement curve is observed which is clearly associated with chipping. This approach completely ignores the change of other mechanical behaviour associated with the fracture event and it cannot be applied to displacement control experiments. The plot of the irreversible work vs. load for a range of applied loads can be used in this case but is time consuming. Also this method does not work well for sub-threshold cracking. Therefore, it is necessary to find a method to solve such problems if the fracture properties of very thin coatings (≤1μm) are to be assessed. In this paper, a method which is based on extrapolating the total work vs. displacement curve at a load where cracking occurs is presented to estimate the fracture toughness of the coated system.

Si-based ceramics such as SiC require environmental barrier coatings to protect against hot-corrosion and recession in gas turbine applications. Dense, crystalline mullite coatings of uniform thickness have been deposited by hot-wall chemical vapor deposition (CVD) on SiC substrates, using the AlCl3-SiCl4-CO2-H2 system. The effects of the CVD deposition parameters such as temperature, total reactor pressure, and metal-chloride partial pressure on the coating microstructure and growth kinetics have been investigated, and are discussed in this paper.

High quality well-adhered microcrystalline diamond coatings have been produced by the microwave plasma enhanced chemical vapor deposition (MPECVD) technique on cemented carbide substrates. A multi-interlayer system Cr/CrN/Cr was deposited on the WC-Co substrate before diamond deposition to work as a diffusion barrier. The coated substrate was peened with friable diamond powder to roughen the surface resulting in high nucleation density. Adherent diamond film has been successfully deposited on the substrate at temperature around 700°C with 1.0 % CH4 in Hydrogen plasma. The surface morphology and film structure has been studied by Scanning Electron Microscopy (SEM) and X-Ray diffraction technique. The adhesion of the diamond film has been evaluated by Rockwell indentation tests.

This report demonstrates the effects of IR and UV laser energy on common semiconductor layer stack materials used for DRAM laser fuses. By moving from IR to UV wavelengths it is possible to significantly shrink the laser spot diameter from ∼1.6 μm to 0.8 μm. Effects and concerns for the absorption of UV energy by Si, SiO2, nitrides, and oxynitrides are also presented.

The hydrogen microwave remote plasma CVD was introduced to fabricate carbon nanotubes(CNTs). C2H2 or CH4, used as source gas react with hydrogen radicals introduced from the cavity. In this experiment, hydrogen radical etching effect on the substrate surface could be controlled independently. We confirmed CNTs growth at 400°C under adequate hydrogen radical etching effect on the substrate surface. The result directly suggests that the etching effect of hydrogen radicals on the reaction surface contribute to the low temperature growth of CNTs. The CNT thickness did not depend on the hydrogen radical etching effect but the catalyst layer thickness.

We control the stiffnesses of two dual double cantelevers placed in series to control penetration into a perflurooctyltrichlorosilane monolayer self assembled on aluminium and silicon substrates. The top cantilever which carries the probe is displaced with respect to the bottom cantilever which carries the substrate, the difference in displacement recorded using capacitors gives penetration. We further modulate the input displacement sinusoidally to deconvolute the viscoelastic properties of the monolayer. When the intervention is limited to the terminal end of the molecule there is a strong viscous response in consonance with the ability of the molecule to dissipate energy by the generation of gauche defects freely. When the intervention reaches the backbone, at a contact mean pressure of 0.2GPa the damping disappears abruptly and the molecule registers a steep rise in elastic modulus and relaxation time constant, with increasing contact pressure. We offer a physical explanation of the process and describe this change as due to a phase transition from a liquid like to a solid like state.

AlN/TiN multilayered thin films with layer thickness ranging from 1 nm to 50 nm were synthesized using rf magnetron sputtering at 400°C. Two series of samples were prepared at the substrate bias of Vb = −25 V and −100 V to modify growth texture of individual layers and verify its influence on the formation of coherent structures. XRD and TEM observations showed that in large period films (tc ≥ 30 nm) each constituent grows under its own kinetic, leading to the formation of nano-crysatlline film randomly oriented with no pronounced texture. Decreasing progressively the layer thickness favours the alignment of (0002) basal plane of w-AlN on (111) plane of TiN, and results in development of strong (111) texture, prerequisite for stabilisation of c-AlN and the formation of epitaxial coherent structures. The degree of crystallographic coherence was found to be higher in TiN(111) oriented films than for TiN(002) textured films. The increase of hardness coincides with the structure transition from a randomly oriented nanocrystalline films to a highly (111) textured multilayers, and the maximum hardness was obtained for epitaxially coherent nanolayers.