Apatite films were deposited onto titanium (Ti) metal substrates by an electrodeposition method under a pulse current. Metastable calcium phosphate solution was used as the electrolyte. The ion concentration of the solution was 1.5 times that of human body fluid, but the solution did not contain magnesium ions at 36.5 °C. We used an average current density of 0.01 A/cm2 and current-on time (TON) equal to current-off time (TOFF) of 10 ms, 100 ms, 1 s, and 15 s. The adhesive strength between apatite and Ti substrates were relatively high at TON = TOFF = 10 ms. It is considered that small calcium phosphate (C–P) crystals with low crystallinity were deposited on the Ti surface without reacting with other C–P crystals, H2O, and HCO3− in the surrounding environment. This resulted in relaxation of the lattice mismatch and enhancement of the adhesive strength between the apatite crystals and Ti substrates.

Two kinds of composites (i.e., conductive and strong Cu–Ti3AlC2 composites) were prepared at 850 °C, while high-strength in situ Cu–TiCx composites were prepared by consolidation at 850 °C and then hot pressing at 1000 °C. In both kinds of composites, the reinforcements were uniformly distributed within the Cu matrix. In Cu–Ti3AlC2 composites, strengthening was achieved by the load transfer through a strong interfacial layer consisting of TiCx and Cu(Al), which was formed by the partial deintercalation of Al from Ti3AlC2. For the in situ Cu–TiCx composites, the higher modulus of TiCx as well as the highly twinned structure formed during processing contributed to the enhancement of strength. It was demonstrated that the deintercalation of Al from Ti3AlC2 formed substoichiometric Ti3AlxC2 (with x < 1), and no detrimental effect on the electrical conductivity was observed.

Fully dense and net-shaped silicon carbide monoliths were produced by liquid silicon infiltration of carbon preforms with engineered bulk density, median pore diameter, and chemical reactivity derived from carbonization of crystalline cellulose and phenolic resin blends. The ideal carbon bulk density and minimum median pore diameter for successful formation of fully dense silicon carbide by liquid silicon infiltration are 0.964 g cm−3 and approximately 1 μm. By blending crystalline cellulose and phenolic resin in various mass ratios as carbon precursors, we were able to adjust the bulk density, median pore diameter, and overall chemical reactivity of the carbon preforms produced. The liquid silicon infiltration reactions were performed in a graphite element furnace at temperatures between 1414 and 1900 °C and under argon pressures of 1550, 760, and 0.5 Torr for periods of 10, 15, 30, 60, 120, and 300 min. Examination of the results indicated that the ideal carbon preform was produced from the crystalline cellulose and phenolic resin blend of 6:4 mass ratio. This carbon preform has a bulk density of 0.7910 g cm−3, an actual density of 2.1911 g cm−3, median pore diameter of 1.45 μm, and specific surface area of 644.75 m2 g−1. The ideal liquid silicon infiltration reaction conditions were identified as 1800 °C, 0.5 Torr, and 120 min. The optimum reaction product has a bulk density of 2.9566 g cm−3, greater than 91% of that of pure β–SiC, with a β–SiC volume fraction of approximately 82.5%.

Nitrogen-doped titanium dioxide (TiO2) thin films were synthesized on glass substrates by reactive pulsed laser deposition technique (PLD). A frequency quadrupled Nd:YAG (λ = 266 nm, τFWHM ≅ 5 ns, ν = 10 Hz) laser source was used for the irradiations of TiO2 targets. The experiments were performed in controlled reactive atmosphere consisting of mixtures of oxygen and nitrogen gases. We demonstrated that there exists the possibility for the accurate control of the nitrogen incorporation through the growth parameters, i.e., the nitrogen partial pressure in the reaction enclosure. The substitutional nitrogen doping of the anatase phase TiO2 thin films allows for the continuous shift of the optical absorption edge towards the visible spectral range. When a threshold value of the nitrogen dopant level is surpassed the crystallization structure of the TiO2 anatase phase thin films changes, and the onset of a stable titanium-oxinitride phase formation takes place.

Zr60Ni21Al19 metallic glass rod, with a diameter of 8 mm, is manufactured by copper mold casting. The as-cast bulk metallic glass (BMG) exhibits nearly zero plastic strain, but a high strength of 1.88 GPa. The compression behavior of this new zirconium-base ternary BMG under high pressure at ambient temperature in a diamond-anvil cell instrument has been unraveled using energy dispersive x-ray diffraction with a synchrotron radiation source. The investigation shows that the amorphous structure of Zr60Ni21Al19 is stable under pressures up to 24.5 GPa at room temperature. According to the Bridgman equation of state, the bulk modulus B0 = 96 GPa has been obtained.

Starting from Cu60Zr30Ti10, the compositional dependence of bulk metallic glass (BMG) formation was revisited in the Cu−Zr−Ti ternary system. It was revealed that the optimal BMG-forming composition is located at Cu60Zr33Ti7, for which a monolithic BMG rod 4 mm in diameter can be fabricated using copper mold casting. This composition is along, although slightly off, the univariant eutectic groove for the reaction (L → Cu8Zr3 + Cu10Zr7). With respect to the corresponding Cu−Zr binary alloys, Ti has a significant effect on further stabilizing the liquid, thus increasing the glass-forming ability. For the Cu60Zr40−yTiy (3 ⩽ y ⩽ 10) series BMGs, the glass transition temperature Tg decreased with increasing Ti content, at a rate of about 2.8 K/at.%. Among these BMGs, significant compositional dependence of compressive plasticity is not observed, irrespective of the Tg change. Cu60Zr33Ti7 glass exhibits maximum fracture strength around 2160 MPa.

Dental enamel forms through a protein-controlled mineralization and enzymatic degradation process with a nanoscale precision that new engineering technologies may be able to mimic. Recombinant full-length human amelogenin (rH174) and a matrix-metalloprotease (MMP-20) were used in a pH-stat titration system that enabled a continuous supply of calcium and phosphate ions over several days, mimicking the initial stages of matrix processing and crystallization in enamel in vitro. Effects on the self-assembly and crystal growth from a saturated aqueous solution containing 0.4 mg/mL rH174 and MMP-20 with the weight ratio of 1:1000 with respect to rH174 were investigated. A transition from nanospheres to fibrous amelogenin assemblies was facilitated under conditions that involved interaction between rH174 and its proteolytic cleavage products. Despite continuous titration, the levels of calcium exhibited a consistent trend of decreasing, thereby indicating a possible role in protein self-assembly. This study suggests that mimicking enamel formation in vitro requires the synergy between the aspects of matrix self-assembly, proteolysis, and crystallization.

The strain rate dependence of freestanding, nanocrystalline gold films was evaluated by a microtensile technique with applied strain rates on the order of 10−4 to 10−6 s−1. Film thickness ranged from 0.25 to 1.00 μm with corresponding grain sizes of 40 to 100 nm. The plastic properties were found to be particularly sensitive to strain rate, film thickness, and grain size, while the elastic property remained relatively unchanged. The thinner films exhibited significant strain rate sensitivity, while the thicker film exhibited only marginal changes. Hall–Petch boundary hardening was observed and dominated plastic flow at larger strain rates, while diffusion-controlled deformation mechanisms appeared to be activated with increasing influence as strain rate decreased. Analysis of dislocation-based and grain-boundary diffusion-related creep suggested that the films were likely experiencing power-law creep as the dominant deformation mechanism in this grain size regime at lower strain rates.

NiCrAlY coatings with and without CrN or CrON interlayer as diffusion barrier were deposited on superalloy DSM11 by arc ion plating (AIP). The oxidation performance of the coating systems was evaluated by isothermal oxidation tests at 1100 °C for 100 h. The element interdiffusion and oxidation behavior of the coating systems were described. It was found that the NiCrAlY coatings provided protective effect for the DSM11 substrate. However, serious interdiffusion between the coatings and substrate resulted in rapid degradation of the coatings. The addition of CrN or CrON interlayer between the coatings and substrate markedly decreased the interdiffusion. CrON interlayer performed better than CrN interlayer, which was attributed to the excellent diffusion barrier ability of Al2O3 layer formed in the interlayer at high temperature. Also, the NiCrAlY/CrON coating system exhibited more effective protection for DSM11 than the NiCrAlY/CrN coating system.

Cyclic stress–strain response of an equal channel angularly pressed Sn-3.8Ag-0.7Cu alloy was investigated to seek a mechanistic understanding of cyclic softening in Sn-rich alloys. The equal channel angular pressing (ECAP) was applied to modify the microstructure of the solder alloy by breaking up the needlelike Ag3Sn intermetallic phase into fine granules and by reducing the large β-Sn dendrites into smaller and equiaxed grains. The extruded alloys were subjected to strain-controlled fatigue test at various strain amplitudes. It was found that the extruded alloy exhibited a sharp decrease of the stress amplitude within the initial few cycles compared with the as-cast alloy. After only a few cycles, the alloy suffered from noticeable surface damage. In situ scanning electron microscopy observations of the cyclic bending specimens revealed an approximately logarithmic relationship between crack density and the number of cycles. A theoretical model of microcrack accumulation was constructed to explain the rapid cyclic softening behavior. The predicted results, based on the model, agreed well with the experimental data and indicated that the rapid softening had resulted from an increased tendency for grain boundary cracking in the ECAPed microstructure due to the increase in the grain boundary area per unit volume and the reduced resistance of Ag3Sn to grain boundary sliding.

A viscoelastic solid was contacted by a pointed indenter using low-frequency large-amplitude sinusoidal load functions to determine its contact stiffness in a manner similar to that of the continuous stiffness measurement (CSM) technique but in a quasi-static condition. The contact stiffness of a viscoelastic solid determined by the CSM technique, or the dynamic stiffness, is known, from previous CSM-based studies, to overestimate the quasi-static contact stiffness. The contact stiffness of a viscoelastic solid determined in a quasi-static manner is thus hypothesized to help predict the contact depth more accurately. A new analysis procedure based on truncated Fourier series fitting was developed specifically to process the large amplitude sinusoidal indentation data. The elastic modulus of the material characterized in this work was in agreement with that determined by dynamic mechanical analysis, thereby providing evidence for the validity of the present method in characterizing other viscoelastic materials.

We have studied the lattice structure of variously oriented lead iron niobate (PFN) thin films with thicknesses of 50 < t < 500 nm that were deposited by pulsed laser deposition (PLD). We have identified that (001)-, (110)-, and (111)-oriented PFN thin films have tetragonal, orthorhombic, and rhombohedral phases at room temperature, respectively. The change in phase stability, when deposited on substrates of different orientations, is discussed with respect to the influence of epitaxial stress.

Microstructural evolution occurred in 5Sn–95Pb/63Sn–37Pb composite flip-chip solder bump during electromigration. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) observations for 5Sn–95Pb/63Sn–37Pb composite flip-chip solder joints subjected to 5 kA/cm2 current stressing at 150 °C revealed a gradual orientation transformation of Pb grains from random textures toward (101) grains. We proposed that the combination of reducing the surface energy of Pb grain boundaries and resistance of the entire polycrystalline system are the driving force for the orientation transformation of Pb grains during an electromigration test.

On the basis of the CALPHAD (Calculation of Phase Diagrams) method, the compositional range of stable miscibility gap and volume fractions of the two liquid phases in the Cu–Fe–Cr–Ni system were predicted, which can provide the guidance for design of self-formed composite materials. Based on such information, the self-formed pencil-like bulk composite materials consisting of copper alloy and two kinds of stainless steels were prepared by controlling the compositions of Cu-rich and Fe-rich phases in immiscible liquid system by the conventional casting process. The experimental results are in good agreement with the ones predicted by calculation. This study indicates that it is possible to develop the pencil-like bulk composite materials consisting of copper alloy and stainless steels by the conventional casting process.

In this paper, we systematically demonstrate the corrosion behavior and surface characteristics of a newly developed Cu36Zr48Ag8Al8 bulk metallic glass (BMG). The Cu36Zr48Ag8Al8 BMG exhibits excellent corrosion resistance in acidic and alkaline solutions without Cl− ions. The alloy is spontaneously passivated with a markedly low current density in 1 N H2SO4 solution. The formation of the bilayered passive film of the present alloy immersed in 1 N H2SO4 solution, which is composed mostly of Zr4+ cations in the exterior part and Zr4+- and Al3+-enriched cations in the inner part, could be responsible for the high corrosion resistance.

Three sets of original dynamics model parameters for MgO–Al2O3–SiO2 (MAS) system were reported for the first time in this paper; moreover, a new parameter optimization standard was put forward to study three different molecular dynamic models of MAS glass-ceramics. The limitations of the conventional parameter optimization methods were also studied. The results indicate: (i) Born-Mayer-Huggins (BMH) model can be only used to simulate amorphous MAS systems. Furthermore, both static optimization and a dynamics test are necessary; (ii) for structure optimization or macroproperties calculation, high accuracy has been achieved relative to the experimental results by using the core-shell (CS) model; (iii) partialQ model computes at a high speed, about twelve times that of the CS model; (iv) for a bulk system, the partialQ model can be first used to obtain an initial structure rapidly, followed by the CS model for high accuracy calculation. In this way, both accuracy and efficiency are achieved. When the model was used to simulate the cordierite crystal and the amorphous in the cordierite glass-ceramic, the results were consistent with the experiments and the structure data from the ab initio calculation. Simulations on amorphous structures in the cordierite glass-ceramic with various compositions displayed that the bond length or coordination numbers (CN) of Si–O and Al–O remained the same with increasing content of MgO, suggesting no change in the tetrahedral configuration of short-range structure. Although the bond length of Mg–O stays almost the same with the increasing content of MgO, the coordination number increases to a certain extent, and the content of O-bridge in SiO2 glass drops from 100%–60% in pyrope glass.

A new type of composite metal–nanoparticle coating that significantly reduces the friction force of various surfaces, particularly archwires in orthodontic applications, is demonstrated. The coating is based on electrodeposited Ni film impregnated with inorganic fullerene-like nanospheres of tungsten disulphide. The first encouraging tests have shown reduction of up to 60% of the friction force between coated rectangular archwires and self-ligating brackets in comparison with uncoated archwires. The coating not only significantly reduces friction of commercial archwires but also maintains this low value of friction for the duration of the tests in comparison to archwires coated with nickel film without the nanoparticles. The coated surfaces of the wires were examined by scanning electron microscopy equipped with energy dispersive analyzer and by x-ray powder diffraction methods before and after the friction tests. Using these analyses, it was possible to qualitatively estimate the state of the Ni+IF-WS2 coating before and after the friction test compared to Ni coated wires without IF-WS2.

The presence of low-molecular-weight by-products is a major problem in poly[2-hydroxethyl methacrylate (HEMA)-silica] hybrids prepared using sol-gel synthesis. Low-molecular-weight by-products have a detrimental effect on the optical transparency, and mechanical and storage properties of poly(HEMA-silica) hybrids. To solve this problem, a new sol-gel synthesis procedure was developed to prepare organic–inorganic hybrids. Glycidyl methacrylate (GMA) was used as a comonomer to form poly(HEMA-GMA-silica) (PHGS) hybrids. In addition to forming a copolymer, GMA has two more functions. It facilitates the removal of almost all of the low-molecular-weight by-product molecules formed during sol-gel synthesis and also prevents further condensation of free silanol groups during the polymerization, storage, and use. The mechanical properties of PHGS hybrids were evaluated by using compression testing. The mechanical properties of PHGS hybrids were higher compared to Plexiglas G poly(methyl methacrylate), and the hybrids can be synthesized with reproducible mechanical properties.

Oxygen diffusivities in mullite/zirconia composites were measured by 18O/16O isotope exchange and secondary ion mass spectrometry. They exhibited a wide range of values from 10−21 to 10−10 m2/s at temperatures between 1000 and 1350 °C in the composites with 0 to 80 vol% zirconia. At a fixed temperature, oxygen diffusivities in high-zirconia composites were larger by at least eight orders of magnitude than those in low-zirconia composites. The percolation threshold occurred between 30 and 40 vol% zirconia, where oxygen diffusivities dramatically changed. There was a clear tendency of the activation energies of oxygen diffusion in composites to decrease with increasing zirconia contents. The large oxygen diffusivities in the high-zirconia composites were attributed to the interconnected channels of zirconia from the microstructural aspect.

Experimental studies were conducted to investigate the microwave (MW) heating behavior of soda-lime glass beads with added iron powder. These studies were intended to obtain fundamental knowledge for vitrification solidification and for the fabrication of metal-reinforced glass-matrix composites. The glass beads (0.2 mm diameter) did not heat very well by themselves at temperatures greater than 200 °C within 600 s in a multimode applicator at a power of 0.67 W. The addition of iron powder (average 70 μm, volume fraction 18%) made it possible to heat the glass beads above 700 °C within 60 s. At lower fractions of 3–11 vol%, however, a sudden temperature rise [thermal runaway (TRW)] occurred after the incubation time period. A single-mode MW applicator was used for clarifying the electric (E)-field and magnetic (H)-field contributions to the heating of each material and their mixtures. The results of this study demonstrated that the H-field contributed to the heating of the iron and then triggered the heating of the glass. The E-field component is necessary for heating the glass to a temperature higher than 800 °C. The factors determining the threshold values of the volume fraction causing TRW are discussed.