UHMWPE (Ultrahighmolecular Weight Polyethylene) was attached to silica using a two step process, in which the first step involves silanating the silica surface with a 0.5–1.2 mole % vinyltrimethoxysilane-ethylene copolymer (PE-silane), and in which the UHMWPE (Mw = 3–6 × 106) is solution coated onto the silanated silica in the second step. Glass beads (3.6 μm diameter) were cleaned using distilled water or refluxed with 5% aqueous Na2S2O8, to remove metallic surface contaminants, were used for UHMWPE attachments. SEM and optical microscopy showed individual particles. TGA (thermogravimetric analysis) studies confirmed the attachments as well as their stability after attachment. The integrity of the coatings was examined by SEM following treatment with HF, which left thin “skins” of polymer remaining. Both washing methodologies for the glass beads provided similar UHMWPE coatings. Bend bars (10) prepared using UHMWPE coated beads show no adverse drop in moduli and strength.

As the trend for miniaturisation in the microelectronics field continues, metallisation connecting components has smaller and smaller dimensions, especially width and thickness. The mechanical properties of the deposited metal are very different from those of the bulk material and it is important to evaluate them accurately if the reliability of the metallisation is to be optimised. The assessment of the mechanical properties of thin aluminium metallisation is possible by nanoindentation but to extract properties useful for lifetime prediction such as yield stress or creep relaxation behaviour additional modelling is necessary using finite elements analysis (FEA). In this study evaporated aluminium layers from 50nm to 600nm thick on (100) silicon were indented to various depths. Proportional loading was used to minimise the effect of creep. The loading curves were then simulated by FEA and the results compared to identify the yield properties of the coating. Modelling data for thicker samples closely follows experimental data but for thinner coatings there is a considerable gradient in properties through the film thickness.

Measurements of the hardness and Young's modulus of superhard coatings (HV≥40 GPa) by means of automated load-depth-sensing indentation technique can be subject to a number of errors that are discussed and exemplified here. Only load-independent values of hardness for loads larger than 30–50 mN can be considered reliable when the technique of Doerner and Nix (linear extrapolation of the unloading curve) is used to determine the corrected indentation depth. The results are compared with values of Vickers hardness calculated from the contact area of the remaining plastic deformation which was measured by means of calibrated scanning electron microscope. The values of Young's modulus obtained from the indentation are close to the zero-pressure shear modulus of the coatings as measured by means of Vibrating Reed and surface Brillouin scattering techniques.

The present study concerns the deposition of α–Al2O3 for diffusion barrier applications on superalloy substrates. The growth of α–Al2O3 has been achieved by chemical vapor deposition (CVD) using an AlCl3/CO2/H2 gas mixture at 1080 °C. Among several growth-controlling parameters with potential importance for the whisker growth process, the reactor pressure during deposition seems to be highly influential on the resulting film structure. Deposited films at low pressure presented solely a fine whisker structure. This non-closed structure is not suitable as diffusion barrier; however, the observed high porosity makes the deposit a potential candidate as a catalysis support. An increase of the deposition pressure led to a competitive growth of whiskers and grains. A suitable microstructure was attained at relatively high pressure (100 mbar) where the surface was fully covered by 2 μm large alumina crystals that formed a closed structure. Further increase of the pressure led to an irregular and rough surface microstructure.

Carbon nitride (CNx) thin films have been prepared by hot carbon filament chemical vapor deposition, and the nitrogen content in the films is approximately 0.05. The CNx films have been irradiated by 0.1 keV nitrogen ions to increase the nitrogen content after deposition. The nitrogen content in the CNx films was obtained with X-ray photoelectron spectroscopy. Scanning electron microscopy was employed to study microstructures of the films. The experimental results show that nitrogen ions are chemically combined with the CNx films and as a result the nitrogen content increases up to approximately 0.30. Furthermore, it is found that nitrogen ions change the film microstructures and sputter the surfaces of CNx films.

Based on the identification of the residual stress-free state using electronic speckle pattern interferometry (ESPI), we modeled the relaxed stress in annealing, the thermal strain/stress and the residual stress field in case of both single and film/substrate systems by using the thermo-elastic theory and the relationship between relaxed stresses and displacements. Thus we mapped the surface residual stress fields on the indented bulk Cu and the 0.5μm Au film by ESPI. In indented Cu, the normal and shear residual stress are distributed over -800 MPa to 700 MPa and -600 MPa to 600 MPa respectively around the indented point and in deposited Au film on Si wafer, the tensile residual stress is uniformly distributed on the Au film from 500 MPa to 800 MPa. Also we measured the residual stress by the x-ray diffractometer (XRD) for the verification of above residual stress results by ESPI.

Size-controllable nanostructure fabrication has drawn much of research attention lately, because it may allow the tuning of optical, magnetic, catalytic and electric transport properties of materials. To achieve this goal, we need to investigate the size dependent behavior of materials. The most popular method for size-controlled nanostructure fabrication is e-beam lithography. However, e-beam lithography is not an efficient process for large area fabrication. We report here a novel method to produce large area, well-ordered, size-controlled nanopillar arrays. Nanopillar arrays are among the most studied nanostructures because of their potential applications in photonic crystals, data storage, and sensors. To fabricate nanopillar arrays, we have employed both single layer and double layer nanosphere lithography. Nanosphere lithography, which uses the close packed structure formed by monodispersed colloidal particles as template, is known to produce large area, well-ordered nanostructures on substrate surfaces. These nanostructures have been utilized as the masks in the reactive ion etching process. By carefully controlling the gas composition and etching time, various sizes of nanopillar arrays have been produced. To characterize the optical properties of these nanopillar arrays, surface nonlinear spectroscopy has been used to investigate the size dependent response of nanopillar arrays.

Microtribology of Silicon single crystals is one of the important factors for the practical use of MEMS. In this study, the effect of crystal orientation on microwear of Silicon single crystal and the wear structure were mainly investigated. Microfriction experiments using atomic force / friction force microscope (AFM / FFM) were carried out to investigate the effect of crystal orientation on the microwear depth of Silicon single crystals. In these experiments, the scanning-scratching directions of a tip of AFM / FFM were <100> and <110> on Si(100) surface and <112> on Si(111) surface. As a result, it was found that the depth of the wear marks generated on Silicon surfaces increased in the following order: <112>, <100>, <100>. Cross-sectional TEM observations of the microwear marks were carried out. As a result, it was found that the small dislocation loops were generated in the surface region at the first stage of the microwear, and the size and the number of dislocations increased with the progress of the microwear.

In the present work we have studied efficacy of ion beam induced epitaxial crystallization (IBIEC) to recover amorphous layers (300 – 350 nm) produced by MeV Kr ions in Si(100) and studied the associated changes occurring on surface and interface of the recrystallized region. IBIEC experiments were carried out at sample temperatures in the range of 200 − 400°C using 1 MeV N+ ion beam. Rutherford backscattering-Channeling technique showed planar and gradual recovery of the amorphous layer as a function of temperature. Transmission electron microscopy measurements show good crystalline structure of the recovered region at 400°C while at lower temperatures nano-crystalline Si formation embedded in the amorphous structure is evident. The surface topography studied by atomic force microscopy shows development of islands after IBIEC. The rms roughness is around 0.5 nm and average height of the islands is found to be 1.8 nm. The observed epitaxial growth and the surface topographical features have been correlated.

Aluminum nitride (AlN) thin films with different thickness were synthesized by ion-beam assisted deposition on various substrates, Corning 7059 glass, fused silica, Si single crystal, and sapphire, which show the hardness ranging from 7 to 37 GPa. Effects of substrate materials on indentation-hardness of AlN films were studied by using a nanoindentation system equipped with a diamond Berkovich indenter. The maximum force applied to the films was kept at 3 mN. For the films on the Corning 7059 glass substrate, when the normalized penetration depth to the film thickness is 0.98, the film hardness is found to be about 7 GPa, which is close to the hardness of the substrate. While the normalized penetration depth is reduced to 0.11, the film hardness becomes to be about 16 GPa. On the other hand, for the films on the sapphire substrate, when the normalized penetration depth is 0.83, the film hardness is observed to be about 25 GPa, while the normalized penetration depth is reduced to 0.10, the film hardness is found to be about 15 GPa. These results reveal that when the normalized penetration depth to the film thickness is about 0.1, the hardness of the AlN film can be evaluated to be about 15 GPa without being affected by substrate materials.

High temperature materials such as nickel superalloys require the development of corrosion resistant coatings. These coatings must be thermally stable and chemically inert in order to protect the substrate material. Aluminum oxide is one such candidate. Aluminum acetylacetonate was used as the precursor for metal-organic chemical vapor deposition at atmospheric pressure. Uniform, amorphous, and multi-colored protective coatings were deposited onto nickel substrates at 400 to 500°C and dark gray, and powdery coatings were obtained at higher temperatures of 550 to 600°C. The coating was free from cracks when higher carrier gas flow rate were used.

Au nanowires and sequential metal nanostripes were prepared by AC pulse electrodeposition in anodic alumina membrane (AAM). Due to the high toxicity of cyanide-based electrolytes, which commonly used for electrodeposition of noble metals, new types of Au electroplating solution has been introduced. Electroplating solutions of noble metals Au, Ag and Pt were alternately used for nanostripes fabrication. The AAM was prepared by a two-step electrochemical anodization process in oxalic acid. The pore size was controlled by varying anodizing voltage and current density. The AAM was investigated by SEM and AFM. The results show hexagonally ordered channels with a pore diameter 50 nm. The morphology and composition of nanowires and nanostripes were examined by TEM and optical microscopes, which show uniformly, ordered Au nanowires with a length about 250 nm and a diameter about 50 nm. Au-Ag-Au-Pt-Au sequential nanostripes have a length about 3.5 μm and diameter 50 nm has been successfully prepared.

Different laser beam techniques were applied to AISI M3 steel samples in order to produce well-defined surface microtextures consisting of pores, which can act as lubricant pockets (reservoir) as well as traps for wear debris. Both effects contribute to improve the tribological performance of textured functional surfaces. The tribological performance of lasertetxures was studied as function of the pore depth and diameter in unidirectional sliding tests under starved lubrication. The lasertetxured surfaces tested under those conditions were produced by a well-established ns laser technique using a Q switched Nd:YAG laser. The topographical microstructures of these laser-induced textures were characterized by optical and scanning electron microscopy as well as replica technique. A significant change in friction behavior as compared to untextured tool surfaces was observed when using microtextured surfaces.

In another part of the study, the influence of new-developed fs laser technique of the tool steel was investigated. The fs laser texturing of the steel results in a change of the metallographic structure of the laser-affected zone, which is clearly detectable in cross-section samples. The structure of the material and chemical composition of the laser-affected, pore-near region was analyzed by transmission electron microscopy with combined EDX analysis. It could be shown that the laser-affected zone seems to consist of an amorphous or nanocrystalline material in opposite to the ‘macrocrystalline’ steel substrate. Nanoindentations revealed a two times higher hardness of the laser-affected zone than the steel bulk phase.

Differently stressed films of tungsten on silicon dioxide have been studied to determine the interfacial fracture toughness and the Mode I fracture energy release rate of tungsten on glass. Tungsten films with a low compressive stress (less than 1GPa) had nanoindentation tests performed on them to induce buckling. Using mechanics based models and the dimensions of the buckles the fracture energy release rate and the phase angle of loading (Ψ) were calculated to be between 3.8 and 13 J/m2. By varying the residual stress in the film it was possible to examine regions of pure shear (Mode II) interfacial fracture as well as mixed mode interfacial fracture toughness of this system. A similar tungsten film was then used as stressed overlayer on sputtered Pt films on silicon dioxide to determine the fracture energy release rate. Nanoindentation was required to induce buckling, as the overlayer alone did not cause spontaneous buckling. The stressed overlayer method and nanoindentation were used to determine the interfacial toughness of the Pt/silica system to be 1.4 J/m2.

An efficient way to reduce energy consumption and costs of machines is to reduce the friction in tribological systems such as gear wheels, spindle bearings and regular ball bearings. Tribological PVD (Physical Vapour Deposition)-coatings have thus been developed at the Materials Science Institute in the context of the special research project SFB 442 named “Environmentally Compatible Tribosystems”. The main challenge facing PVD applications is the complex geometry of machine parts as well as the low deposition temperature. Therefore, the use of Magnetron Sputtering Ion Plating (MSIP-PVD) offers the advantage of producing coatings with a much wider range of properties. A superstoichiometric coating with an over saturated amount of carbon is adjusted by PVD parameters. This creates a shear-weak top coating with a low friction coefficient and a self smoothing surface. The coatings were analysed in standard tests such as the calo-test, scratch-test and HRC-test. Furthermore, the nanoindentation and SEM observations proved a clear correlation between chemical composition and physical properties.

The paper reports the syntheses of c-BN films by the reaction of B2H6 and NH3 in the hydrogen and argon mixture using microwave plasma-assisted chemical vapor deposition (MPCVD). The effects of NH3/B2H6 ratios, hydrogen addition, pulsed-DC substrate-bias voltage and diamond as bufferlayer on the formation of c-BN were investigated. As-grown films are characterized by FTIR, grazing-incidence XRD, and SEM. The NH3/ B2H6 = 3 was selected to obtain a better crystallized BN films with moderate deposition rate. When the hydrogen content was at 85 vol.% in the gas mixture and the substrate bias at −200 V, the maximum c-BN content about 65 % was obtained. However, the film was easily cracked in a few hours. The film deposited at lower substrate biasing of −100 V could preserve for a few days without peeling off, although it had lower c-BN content about 40 %. Nanocrystalline diamond film, deposited from 1 vol.% CH4/Ar plasma, as bufferlayer can promote the heteroepitaxial growth of c-BN, resulting in 80 % c-BN content. The c-BN/diamond bilayer were adherent with a total thickness of 1.2 μm.

Composite coatings consisting of hard compounds and soft solid lubricant phases have been actively investigated as tribological coatings for reducing friction while improving wear resistance. In most cases structural modifications in these coatings have been achieved by either natural phase separation or sequential layer deposition. In this study, we explore the concept of creating a three-dimensional structure in a tribological composite coating by using well-established semiconductor patterning methods. Using photolithography, we have patterned the substrate surface with a regular array of micron-size islands. The substrate was then coated with various metal and carbide coatings, including Cr and TiC, using sputter deposition. The substrates were sonicated in a solvent to remove the photoresist islands leaving an array of holes. MoS2 was then deposited onto the substrates. A pin-on-disk friction and wear test was conducted on a TiC/MoS2 sample to examine the effects of these islands on wear morphology. The results showed that the MoS2-filled holes can act as lubricant reservoirs, and the areas of the sample coated with TiC/MoS2 provided better wear protection than areas coated with only MoS2.

In this study the stress and morphology of Ta coatings sputtered on Si (100) substrates were monitored in situ and in real-time during thermal testing to allow interruptions at critical events in the coatings' stress evolution. These observations were carried out using white beam Laue transmission diffraction topography/radiography and a high-temperature sample stage at the Stanford Synchrotron Radiation Laboratory (SSRL). The structure of specimens from interrupted thermal tests was then analyzed using x-ray diffraction θ-2θ scans. The structure and phases present in the film at different stages of the thermal test were correlated with specific mechanical responses in the coating such as stress generation. This information was employed to elucidate the role of phase evolution in the respective stress responses of films deposited in high and low-pressure regimes.

A soft thin coating on top of a hard substrate is a highly effective way to reduce friction of sliding mechanical components. However, soft coatings often have high wear and short lifetimes, and the restoring of solid lubricants can be remarkably uneconomical. In our recent work, composite TiC-Ag films were successfully deposited by the magnetron-sputtering pulsed laser deposition technique (MSPLD). Secondary electron (SE) images from the wear tracks revealed that silver migrates to the surface and smears along the sliding direction providing low friction, while the carbide phase provides adequate support and storage for the solid lubricant phase, all resulting in lower wear and longer lifetime. One proposed mechanism for lubrication is the friction-induced thermally activated migration of silver to the surface due to the insolubility of the carbide and silver phases which was corroborated by X-ray diffraction (XRD) analysis. The formation of incoherent interfaces between the two phases, observed by transmission electron microscopy (TEM), may influence the adhesive friction behavior of the soft metal. In this study, we investigate the structural properties and vacuum tribological behavior of SiC-Ag and HfC-Ag films.

Mechanical and tribological properties of thin films draw special attention and differ from those of bulk materials due to the effects of interfaces, microstructure and thick underlying substrates. In this study hard wear resistant nitride coatings (TiN, ZrN, TiAlN, TiCN and CrN) were coated on high speed steel substrates using cathodic arc deposition method. Mechanical properties of the films were evaluated using nanoindentation technique. Continuous stiffness method was employed to evaluate the depth sensing hardness and modulus values. Studies of tribological properties were performed using ball-on-disk friction and wear test. We have also investigated the wear track using optical microscopy. Variation of coefficient of friction with time has been analyzed and coating endpoint was estimated. Nanoindentation evaluation of mechanical properties along with the measurement of tribological properties is very useful in order to use them as wear resistant hard coatings.