A series of microstructural phenomena within a thickness of material (tribolayer) below the worn surface, have been developed during dry sliding wear of a high-chromium cast iron. The overall wear behavior of the alloy is determined by the properties of this tribolayer. From the present work, a transmission electron microscopy analysis has been undertaken on the different features developing at different distances below the worn surface following wear sliding tests of a 17%Cr white cast iron alloy, whose microstructure is composed by 25% eutectic M7C3 carbides within an austenitic matrix. The observed phenomena is an increase in the dislocation density, plastic deformation by twinning followed by severe shear banding along with carbides fracture, a mechanical mixture formed by iron oxide and carbide particles produced from large carbides comminution, and finally a flat iron oxide layer. Wear debris was apparently created from the oxide film detaching from the outermost surface where equivalent strain is maximum. No evidence of strain induced martensite was observed from the present work, which has been reported in some austenitic materials. The implications of the microstructural evolution are discussed in terms of the wear theories and behavior of metals at high strains levels.

Interface coatings on fibers are important in ceramic matrix composites. In addition to providing toughness, the interface coating must also protect the reinforcing ceramic fibers from corrosive degradation. A double interface coating has been applied onto silicon carbide fibers. The double interface coating is comprised of a combination of nitride and oxide coatings. Among the nitrides, boron nitride and titanium nitride were utilized. These nitrides were deposited by CVD. The metal oxides of choice were aluminum oxide and zirconium oxide which were applied onto the nitride coatings by MOCVD. The phases on the coated fibers were determined by XRD. The surface coating microstructures were observed by SEM. The effect of the coatings on the tensile strengths was determined by Instron tensile strength measurements.

Nitride thin films have potential applications in different areas of silicon device technology, namely as diffusion barrier in metallization schemes, rectifying and ohmic contacts, and gate electrodes in field effect transistors. In the present investigation, TiN and CrN films have been deposited by reactive pulsed laser deposition technique using Ti and Cr targets at 10mTorr background pressure of N2. Si (100) and AISI 440C steel substrates were used for the present study. Films were deposited at different temperatures in the range of 200°C to 600°C. The deposited films exhibited densely packed grain, with smooth and uniform structures. X-ray Photoelectron Spectroscopy (XPS) analysis of the films showed and 50% Ti and 40% of N in TiN films, 45% of Cr and 45% of N in CrN films deposited on Si (111), with the balance mostly oxygen, indicating near stoichiometric composition of the deposited nitride thin films. Hardness of the films changed from 22 GPa at 200°C to 30 GPa at 600°C for TiN, whereas for CrN we obtained 26 GPa at 200°C to 31 GPa at 600°C. The residual stress in the films showed a change from compressive stress at 200°C to tensile stress at 600°C in both the cases. Friction coefficient of the films were measured by pin-on-disk technique for all films, up to the tested limit of 10, 000 cycles at 1 N load and found to be very high (≥ 1) in both cases.

Composite Ag-SiO2 thin films were deposited to examine the stability of materials with high resistivity above 5000 μΩ-cm. We found that the resistivity increases exponentially with SiO2 volume fractions larger than 0.50 which is consistent with a tunneling conductivity mechanism. In order to obtain a broad composition range, these films were deposited on a stationary substrate placed above Ag and SiO2 sputtering sources. This configuration allowed compositions ranging from 0.8 to 56.3% SiO2 to be deposited on the same sample. Resistance measurements were made using a four-point probe and a profilometer was used to measure thickness. Predicted values of thickness and composition were obtained by calibrating deposition rates from the separate sources, and were verified using Rutherford Backscattering Spectroscopy. Electron microscopy analysis revealed Ag agglomerating on the surface of the film. Because of the high mobility of Ag, the films should be capped to prevent Ag agglomeration. The results of this research demonstrate that high-resistivity thin films can be grown using Ag-SiO2 composites.

Relationships of indentation hardness numbers to to other physical properties are demonstrated. They differ depending on the type of chemical bonding; metals, alloys ionic, covalent, and metal-metalloid. The properties are: shear modulus; ionic charge; band-gap density; polarizability; and formation energy, respectively. In each case the rationale is provided. The concept of a “bonding Modulus” is introduced. It is concluded that the conventional wisdom that hardness is a purely empirical property does not hold. Phase transformations and indentation hardness are connected broadly.

Polymer-based Micro/Nano Electro Mechanical Systems (MEMS/NEMS) have attracted a great deal of interest from industries and academia. The common polymer processing methods involve either organic solvents or temperatures above the glass transition temperature (Tg), which is undesirable, particularly for biomedical applications. On the basis of different properties near polymer surfaces from those in the bulk, we introduce subcritical fluids (particularly carbon dioxide, CO2) into polymer surfaces to manipulate the polymer properties at the nanoscale so that we can achieve low temperature surface engineering. In this study, polymer surface dynamics under CO2 were addressed using atomic force microscopy (AFM) and neutron reflectivity (NR). Monodispersed nanoparticles were deposited onto the smooth polymer surface and then embedded into the surface by annealing the sample at the pre-specified temperatures and CO2 pressures. The embedding of nanoparticles in the proximity of the surface was measured using AFM, and thus the surface Tg profile could be determined. It was revealed that there is a rubbery layer of up to a hundred nanometers thick at the surface where the Tg is lower than that in the bulk and CO2 dramatically reduced the surface Tg. NR studies also show that CO2 can enhance chain mobility at the polymer surfaces below the polymer bulk Tg. These results indicated that even low concentrated CO2 greatly could enhance polymer chain mobility below the Tg of the CO2–plasticized polymers. The thickness of the rubbery layer can be controlled by tuning either temperatures, or CO2 pressures, or both, which makes it possible to engineer polymer surfaces at low temperatures. Guided by the CO2 enhanced polymer surface dynamics, we developed a novel CO2 bonding technique to succeed in low temperature bonding of polymers at the micro/nanoscales. This CO2 bonding technique has been applied to seal polymeric nanofluidic biochips and construct well-defined three-dimensional (3D) biodegradable polymeric tissue scaffolds.

The optical system that is pervious to ultraviolet light of 200nm and under in the wavelength has been developed by putting one silica glass to another with the silicone oil photo-oxidized in oxygen atmosphere.

Quartz has siloxane bonds, while silicone oil (dimethyl siloxane) is composed of siloxane bonds of the main chain and methyl groups of the side chain. Therefore, the organic silicone oil has been photo-oxidized by irradiating UV rays in oxygen atmosphere to change into inorganic glass. That is, the silicone oil was poured into the thin gap between the two pieces of silica glass in oxygen atmosphere and was irradiated with the Xe2 excimer lamp while heating at temperature above 150°C. Consequently, the siloxane of the silicone oil was linked with the O atoms that had been absorbed on the glass surface to form SiO2.

The UV and IR spectrum analysis was conducted on the silicone oil before and after lamp irradiation. The results revealed that as the time of lamp irradiation increased, the absorption peak of the CH3 group in the region of 2960 cm−1 decreased but the transmittance of the light in the 190nm wavelength conversely became high. The UV transmittance of the silicone oil was 50% before the lamp irradiation; which improved to 87% after the irradiation for 60 minutes. Furthermore, the tensile strength of the bonded sample was measured. It confirmed that the adhesive strength of the silicone oil was enhanced from 0 kgf/cm2 of before-irradiation to 180 kgf/cm2 of after- irradiation.

The machinability of austenitic stainless steels is, in general, considered to be a difficult process. This is due in great part to the high plasticity and tendency to work-harden of the workpiece, which normally results in extreme conditions imposed on cutting edges. Additionally, austenitic stainless steels have much lower thermal conductivities in comparison to plain carbon and tool steels; this inflicts high thermal loads within the chip-tool contact zone, which can significantly increase the wear rate. The complex machining of austenitic stainless steels can be, in part, relieved by use of a hard coating with low thermal conductivity and an adequate coating surface quality. This can lead to a low friction coefficient between the parts and an improved chip evacuation process. In this study, stainless steel plates were machined using a high speed finishing process and cemented carbide tools coated with four high aluminum containing coatings namely, AlCrN, AlCrNbN, fine grained (fg) AlTiN, and nanocrystalline (nc) AlTiN. Both AlTiN and AlCrN-based coatings are known for their high oxidation resistances and the formation of aluminum oxide surface layers during oxidation [1]. The coating surface textures before and after post-deposition treatment were analyzed by means of the Abbot-Firestone ratio curves in order to study the influence of surface configurations leading to reduced tool wear. A maximum tool life of 150 m was observed for the tool coated with the nc-AlTiN coating.

Hydrogen plasma (H-plasma) treatments applied on (100)-oriented standard Czochralski (Cz) silicon wafers cause a structuring of the surface regions in the sub-100 nm scale. The reconstruction of the ‘nano-structured’ surface layers by high temperature vacuum annealing induces strong tensile stress (∼ GPa) at the surface and in the subsurface regions of the wafers, as can be verified by depth resolved μ-Raman spectroscopy (μRS). Although the H-plasma caused ‘nano-structured’ surface layer is very thin (100 – 200 nm), the stressed subsurface regions of the annealed samples are quite extended, i.e. up to ∼ 10 μm depth. The impacts of several process parameters including 1) the doping type of the wafer substrate, 2) the frequency of the H-plasma, 3) the power and duration of the H-plasma, 4) the temperature and duration of the vacuum annealing on the stress are investigated. It is found that the stressed region in the surface engineered silicon wafer can be controlled by the process parameters. The presented results might be important for various applications in semiconductor technology. For example, the H-plasma exposure could be done in local areas near the electrically active regions on the forefront of the wafer. After appropriate annealing, stressed local regions for external getter purposes can be created. Such a method might especially be useful for the formation of getter regions on SOI substrates.

Ion bombardment during deposition may simultaneously affect thin film topography, composition and crystallographic texture. Ion etching can produce periodic ripples that depend on the angle of ion incidence and surface temperature. When applied during deposition, ion bombardment can produce in-plane crystallographic orientation in polycrystalline materials for specific angles of incidence. In addition, ion bombardment changes the composition of multicomponent thin films according to the local angles of ion incidence and ion/atom ratios. Therefore, these three mechanisms may be linked under certain deposition conditions to generate novel topographically patterned materials with locally controlled composition and texture. Examples include metal alloys, oxides and nitrides, and recommendations for specific nanoscale structures are given.

The surface nitridation of GaAs substrate under various conditions were performed and its surface morphology was studied by using atomic force microscope. The RMS roughness of the surfaces was closely related to formation of the particles which was formed by As evaporation and subsequent Ga migration, which was enhanced by higher substrate temperature.

Silver and platinum were incorporated within diamondlike carbon (DLC) thin films using a multicomponent target pulsed laser deposition process. Transmission electron microscopy of the DLC-silver and DLC-platinum composite films reveals that these films self-assemble into particulate nanocomposite structures that possess a high fraction of sp3-hybridized carbon atoms. DLC-silver-platinum films demonstrated exceptional antimicrobial properties against Staphylococcus and Pseudomonas aeruginosa bacteria.

A mullite coating process has been conducted to form an electrically insulating layer on the surface of the silicon carbide whiskers for whisker reinforcement application by a chemical deposition and hydrolysis. The phase, structure, morphology and electrically insulating property of the coated silicon carbide whiskers have been investigated by using x-ray diffraction, scanning electron microscopy, transmission electron microscopy and electrical measurement. The study indicates that a crystalline mullite coating layer is formed after heat-treating the precursor coating at elevated temperature. The formed mullite coating significantly increases the electrical resistance of the silicon carbide whiskers.

This contribution deals with fundamental and applied concepts in nano-structured coatings, in particular focusing on the characterization with high-resolution (transmission) electron microscopy. Both unbalanced and balanced magnetron sputtering systems were used to deposit nc-TiC/a-C nanocomposite coatings with hydrogenated or hydrogen-free amorphous carbon (a-C) matrix, respectively. The contents of Ti and C in the coatings have been varied over a wide range (7∼45 at.% Ti) by changing the flow rate of acetylene gas or the locations of substrates relative to the center of C/TiC targets. Different levels of bias voltage and deposition pressure were used to control the nanostructure. The nanocomposite coatings exhibit hardness of 5∼35 GPa, hardness/E-modulus ratio up to 0.15, wear rate of 4.8×10−17 m3/Nm, coefficient of friction of 0.04 under dry sliding and strong self-lubrication effects. The nanostructure and elemental distribution in the coatings have been characterized with cross-sectional and planar high-resolution transmission electron microscopy (HRTEM) and energy filtered TEM. The influences of the volume fraction and size distribution of nano-crystallites TiC (nc-TiC) on the coating properties were examined.

In order to improve the performance of WC-Co cutting tools, high quality microcrystalline diamond coatings were produced using microwave plasma enhanced chemical vapor deposition (MPECVD) method. The adhesion of the diamond film deposited on the substrate has been considered to play an important role in the performance of the cutting tools in machining applications. A thin layer of Cr was coated on the WC-Co substrate before the diamond deposition; 75 μm diamond powders were sandblasted on the surface at 40 Psi to increase the nucleation density. Diamond film has been successfully deposited on the substrate at temperature around 750°C with 1.5 % CH4 in Hydrogen plasma. Scanning electron microscopy (SEM) has been used to study the surface morphology and Raman spectroscopy has been performed to characterize the quality of the diamond films and measure the residual stress. The adhesion of the diamond film has been evaluated by Rockwell indentation test. The results indicated that film grown on the Cr interlayer with diamond powder sandblasting has much better adhesion strength.

UV Raman scattering is employed as a nondestructive structure sensitive probe to investigate the vibrational properties of the wide bandgap, machined and indented surfaces of 6H-SiC and β-Si3N4. In these materials, the short absorption depth of UV light allows for accurate probing of the surface, and the transparency to visible light allows for analysis of the bulk material. The study on 6H-SiC (0001) included measurements of indentations, and of machined circular (0001) wafer edges. The indentation analysis indicates the response of the material to localized pressures. Machined 6H-SiC wafer edges and machined β-Si3N4 surfaces indicate a ductile response and ductile material removal for machining at cutting depths on a nm and μm scale. Raman scattering measurements of the ductile surfaces and ductile material removed indicate residual structure changes. The residual surface structures could indicate that a high-pressure phase transformation is the origin of a ductile response on machined brittle materials.

Energetic nitrogen implantation into austenitic stainless steel or nickel alloys leads to the formation of a very hard and wear resistant surface layer with an expanded lattice, while similar results are reported for selected martensitic steels. A comparison of the phase formation under identical process conditions at 380 °C using an austenitic (304) and a martensitic (420) steel grade (in an annealed ferrite/cementite condition) shows that the initial microstructure is retained in both of them. As the formation of dislocations and stacking faults cannot account for the dramatic hardness increase, the build-up of compressive stress is proffered as an explanation covering these two steel types. Furthermore the energetic nitrogen implantation apparently stabilizes the expanded lattice with suppressing the chemical transition to iron nitrides and, for steel 420, the metallurgical transition towards austenite at high nitrogen contents.

We have reported the synthesis of carbon nitride thin films with evidence of formation of carbon nanodomes over a range of substrate temperature from 50 °C to 550 °C. An RF magnetron sputtering system was used for depositing carbon nitride films. The size of the nanodomes can be controlled by deposition temperature and increases from 40–80 nm at room temperature to 200–400 nm at high temperature (550 °C). Microstructural characterization was performed by AFM. Electrical characterization shows that these films have conductive behaviour with a resistivity depending on the size of the nanodomes. Resistivity values of 20 mΩ-cm were found for nanodomes of size 40–80 nm falling to 6 m?-cm for nanodomes of size 200–400 nm. Nanoindentation results show that the hardness and Young's modulus of these films are in the range from 9–22 GPa and 100–168 GPa respectively and these values decrease as the size of the nanodomes increases. GXRD results confirm that a crystalline graphitic carbon nitride structure has formed.

The photochemical reaction process steps in substituting the functional groups on the surface of fluorocarbon [FEP] by irradiating an Xe2 excimer lamp on water or formic acid and FEP placed on the attenuated total reflectance [ATR] prism, has been measured in real time. These steps include, water photo-dissociation, the defluorination of the FEP and the hydrophilic group substitution.

In case of formic acid, the absorption peaks of the -CHO in the region of 2940 cm−1 and the -COOH in the region of 1710 cm−1 decreased respectively by photo dissociation, but that of the -OH in the region of 3300cm−1 increased. The results indicated that the -CHO and -COOH have turned to -OH.

Furthermore, the contact angle with water was measured. When compared to the untreated sample, whose contact angle was 110 degrees, the contact angle of the sample treated with water and the Xe2 lamp irradiation for 25 minutes became 31 degrees, and that of the sample modified with formic acid and the lamp irradiated for 25 minutes further improved to 17 degrees. This implies that the hydrophilic groups were produced more in formic acid than in water.

Hafnium oxide is the leading high-κ candidate for next generation CMOS devices, however, it is plagued by problems such as a propensity to react with the Si(100) substrate, to crystallize, and to have fixed and trapped charges and low transistor mobilities. A remote N2/He plasma was used as a reactant during MOCVD with Hf (IV) t-butoxide which incorporates 6 at.% nitrogen located at the film-substrate interface and reduces the interdiffusion problem upon anneal [1]. A new process for pretreating the silicon wafer with a N2/He plasma was developed to improve nitrogen concentrations at the interface and reduce interdiffusion further. Films deposited with N2/He plasma and the pretreatment method were compared to O2/He plasma deposited films and N2/He plasma deposited films without the nitridation step. It is shown that a 16Å interface SiNx layer is sufficient to prevent reaction during a 1000°C Ar/O2 anneal at atmosphere and an intermediate annealing step is crucial for desired reduction in interdiffion. Thick films show some crystalline peaks by XRD which are suppressed using the N2 process. Electrical measurements on thick films show the pretreatment process results in the lowest leakage current density and the highest dielectric constant of 21.5.