A highly accurate multi-point pressure measurement system based on MEMS pressure sensors spliced into a fiber optic cable and suitable for downhole deployment in a CO2 sequestration well was designed, developed and tested in the laboratory. An interrogator system based on a pulsed laser excitation was shown to be capable of multiple (potentially 60+) point sensor measurements on a single fiber. The interrogator was interfaced with the GE PredixTM industrial internet to demonstrate a remote monitoring system. Sensor packages were fabricated and tested at high temperatures and pressures in supercritical CO2. Environmental and stress testing of the sensor components and package indicated areas in which the design of the package should be further improved.

Operation of single crystalline Ca3TaGa3Si2O14 (CTGS) and La3Ga5SiO14 (LGS) bulk acoustic wave resonators is demonstrated up to 1270 °C and 1470 °C, respectively. The mass sensitivity of such devices is about 35 cm2 Hz/μg at 800 °C. Therefore, they are sensitive transducers suited to monitoring, for example, mass deposition processes at high temperatures. The electromechanical loss in CTGS is found to be significantly lower than that in LGS. Platinum coated CTGS samples show a remarkable long-term stability at 1000 °C in air. After an initial period of 300 h, the conductivity is found to remain nearly constant for at least 2400 h. Measurements of resonance frequency of CTGS for 1000 h show a qualitatively similar sequence, with an initial systematic increase followed by nearly constant values. In contrast, measurements on platinum-coated LGS plates show a conductivity decreasing by 15 % over a period of 5000 h.

Flexible SAW devices based on ZnO piezoelectric thin film deposited on ultra-thin flexible glass were fabricated and their performances as a strain sensor have been investigated. The XRD and AFM characterizations showed that the ZnO layers have good crystal quality and smooth surface. The flexible SAW devices show excellent strain sensitivity which increases from ∼87 to ∼137 Hz/με with the increasing ZnO thickness, and the sensors can withstand strains up to ∼3000 με, 4∼6 times larger than those of SAW strain sensors on rigid substrates. The sensors exhibited remarkable stability up to hundreds of times bending under large strains. The effects of environmental variables (temperature, humidity, UV light) on the sensor performance have been investigated. The temperature has a significant effect on the performance of the SAW strain sensor, while humidity and light have limited effect.

A number of electrical components and devices work in extreme environment such as high temperature, high pressure, strong vibration, corrosive chemicals, etc. A common practice to protect them is to shield them in materials that are mechanically and chemically resistant to these harsh conditions. In this scenario, epoxy bonding is preferred and it is crucial to have high bonding strength. One example is the acoustic transducers used in oil drilling. The temperature can reach 200 °C and the pressure can reach 140 MPa. The piezoelectric ceramic parts cannot withstand these conditions so different packaging materials are used such as polyether ether ketone (PEEK).

Here an epoxy bonding apparatus is presented that has demonstrated ultrahigh bonding strength. Though epoxy resin is degassed before applying, which gets rid of air bubbles generated in the mixing process, there is trapped air when two surfaces are closed together. This trapped air has minuscule effect for applications in ambient environment, but under extreme environment, it compromises the bonding strength majorly. We devised a vacuum system that contains a motorized stage with the bonding parts attached. After the epoxy is applied and the system is pumped to 1% vacuum, a computer controls the motor to move the bonding parts into contact. Since the entire operation is in vacuum, it leaves no trapped air and results in increased bonding strength. This apparatus confirmed the importance of surface preparation, including removal of air by starting the cure in vacuum (5 mm Hg) and subsequently releasing the vacuum [1].

Another technique to improve the bonding strength utilizes the finding that a uniform epoxy resin layer between 50 µm and 150 µm [2] results in the optimal bonding strength. Here we applied spacers such as optic fiber (125 µm in diameter) or glass fiber fabric (150 µm in thickness) in between the bonding surfaces. These spacers ensure that the epoxy resin layer is of uniform thickness. It also utilizes the principle of glass-epoxy compositing to increase mechanical strength by fiber reinforcement and load distribution [3, 4].

The above bonding apparatus has been proven to increase the bonding strength by experiments. Acoustic transducers bonded with this technique passed the high pressure, high temperature tests resembling the oil drilling conditions.

With the recent terrorist attacks in Paris and the continued use of IED’s employing TATP for delivering these threats, there is a real need for explosives detection at trace levels. This work describes the fabrication and characterization of metal oxide nanowires used as catalysts for the detection of energetic materials at trace levels. Recently, several oxide nanowires, based on zinc oxide and copper oxide, have been incorporated into our solid-state gas sensors as catalysts. These nanowire catalysts produced a dramatic increase in sensor response with improved selectivity for threat molecules of interest. The improved responses were attributed to a large increase in surface area available for catalyst/analyte interaction. Zinc oxide and copper oxide nanowires were grown by hydrothermal and controlled oxidation reactions, and were characterized using XRD, XPS and SEM to determine extent of crystallinity, oxidation state and morphology. Results indicated that energetic materials such as TATP and 2-6 DNT could be detected at the part per billion level using these nanowire catalysts. Other oxide nanowires are being considered as catalysts for the detection of explosives and are discussed as well.

Two different methods were used to synthesize 200 nm thick single-phase, orthorhombic-PtSi films: (i) e-beam co-evaporation (EBC) of Pt and Si onto r-sapphire substrates and (ii) solid-state reaction (SSR) of sputtered Pt films on Si (100) wafers. Morphology, electrical conductivity, and crystalline structure were characterized for as-grown films and for films annealed in air at 1000 °C via scanning electron microscopy (SEM), 4-pt conductivity measurements, and in situ X-ray diffraction (XRD). As-grown EBC films exhibit columnar grain morphology and slight (101) crystalline texture, while SSR films exhibit granular morphology with many voids and a strong (002) texture. Above 600 °C, EBC PtSi films rapidly oxidize to form crystalline Pt3Si and amorphous SiO2 phases. Around 1000 °C, the Pt3Si phase melts and c-Pt grains nucleate. After air annealing for 6 h at 1000 °C, room-temperature XRD shows that the oxidized EBC films consist of Pt3Si and Pt phases within a SiO2 matrix and become electrically insulating. SSR films initially form with a (002) o-PtSi orientation and above 900 °C they recrystallize to preferred (101) texture and exhibit an unchanged electrical conductivity and a stable film morphology during 48 h of air annealing at 1000 °C. Separate oxidation mechanisms are proposed for the two film types.

Mesoporous zinc oxide nanopowders were synthesized by the homogenous precipitation method. Zinc acetate dissolved in water, at different molar concentrations, was used as Zn precursor, whereas ammonium carbonate ((NH4)2CO3) and ammonium hydroxide (NH4OH) were used to prepare the precipitant solutions. The precipitated powders were dried in a conventional drying chamber at 100°C for 1 h, and then calcined at 400°C during 2 h. Crystal structure of powders was determined by X-ray Diffraction (XRD), and the crystallite sizes were calculated from Scherrer’s formula. Morphological characteristics (size and shape) were analyzed from Scanning Electron Microscopy (SEM). The surface area and the pore volume were obtained from BET analysis. The hexagonal wurtzite phase was corroborated in all synthesized powders, irrespective of the synthesis conditions. From SEM micrographs different structures, depending on the experimental routes, were observed. In order to test the sensing properties of the ZnO nanopowders, 10 mm diameter pellets were manufactured and then measured in a propane (C3H8) atmosphere at different gas concentrations and temperatures. Pellets processed from ZnO powders at 0.05, 0.35, and 0.5 M presented the highest sensitivity, 413, 532, at 300°C and 500 ppm of C3H8.

Aluminum alloy 6082 (AA6082) should be a suitable material for use as casings in offshore based sensors due to its mechanical strength and corrosion resistance. However, there is concern with this materials remaining strength after a fire. This paper will discuss the room temperature creep behavior of AA6082 samples after thermal aging at various temperatures. Samples were aged at a constant temperature in the range 373 K to 423 K and for durations ranging from 4 hr to 24 hr. The creep behavior was investigated using loads slightly exceeding the yield strength of aged samples. We propose an empirical model to relate steady state creep rate at room temperature with aging temperature and time. Such empirical relationship can potentially be used in deciding whether AA6082 casings can still be used to carry loads after exposure to elevated temperatures such as platform fires.

In this work polypyrrole (PPy) and its respective composite with functionalized multiwalled carbon nanotubes (PPy-MWCNT) was obtained by the chemical polymerization of the monomer pyrrole (PPy) in aqueous solution by the dropwise addition of a solution of ammonium persulfate (PSA). The obtained PPy as well as its composite (PPy-MWCNT) were used to prepare two self-assembled films (SA) by the immersion of ITO blades (Inidium Tin Oxide) into PPy and PPy-MWCNT dispersions with alternated immersions into Polystyrene sulfonate (PSS) dispersion, thus resulting in a bilayer. The SA films were produced with ten bilayers (alternated layers of PPy or its composite). The obtained films were characterized by Fourrier Transformed Infrared Spectroscopy (FTIR), UV-Visible analysis, voltammetric analyses (square wave and cyclic voltammetry) and Scanning Electron Microscopy (SEM). The SA films were evaluated to determine the chlorothalonil pesticide which is commonly used as anti-fouling agent in marine environments. The SWV results showed a reduction peak at around -0.8 to 1.2 V (according to pH). It was also observed a synergic effect of the composite film (PPy-MWCNT/PSS) to determine the chlorothalonil by increase of the peak currents.

It has been reported that the addition of liquid rubbers, like poly(dimethylsiloxane) (PDMS), to epoxy resins alter the final morphology, increase the toughness and influence the curing kinetics. Due to immiscibility, there is phase separation of the elastomeric phase during curing giving rise to microdomains embedded in the epoxic matrix. The resultant heterogeneous morphology obtained after the reaction controls to an important extent the properties of the epoxy composite. Here we report a method to obtain well-dispersed rubber nanodomains of silyl-diglycidyl ether terminated polydimethyl siloxane (PDMS-DGE) in diglycidyl ether of bisphenol-A (DGEBA) epoxy by using a prepolymerization step. Light scattering and optical microscopy showed that initial mixing of pre-polymerized rubber produced phase separation with micron-scale droplet formation. However, as the curing reaction proceeded, the rubber domains decreased below optical resolution, light scattering intensity reached a maximum and then decreased. Finally, rubber nanodomains of about 100 nm size were formed at the end of curing reaction, as revealed by transmission electron microscopy (TEM). The pre-polymerization step induced a two-fold increase in gel time, tgel, due to lesser active groups available for reaction. Strikingly, tensile modulus and toughness increased, suggesting rubber-epoxy interaction. The final nanocomposite also exhibited higher thermal stability and char formation.

Organic-inorganic hybrid nanocomposites are considered a new generation of high performance materials because they combine both the advantages of inorganic materials (stiffness, high thermal stability, barrier properties, optical, catalytic, electrical and thermal conductivity among others) and organic polymers (flexibility, dielectric, toughness, lightweight, processing). Each part of a nanocomposite has a synergistic function in its performance and has much better combination properties than a single material. We report on the thermo-mechanical properties and morphology of polyacrylic-nanosilica (SiO2) composites prepared in-situ via emulsion polymerization, using a semi-continuous mode. The latex emulsion thus obtained was stable for at least six months. Moreover, this process produced controlled molecular weight in the final latex and low formation of agglomerates. Films drawn from the latex exhibited excellent optical transparency, suggesting good dispersion of the nanosilica, and confirmed by scanning electron microscopy (SEM). There was an increase in glass transition temperature, Tg, suggesting a modification of molecular dynamics; hydrophobic behavior, as probed by water contact angle, was also promoted. Moreover, the Young’s modulus of the nanostructured latex films increased up to 57% with only 3 wt% nanosilica, therefore denoting a reinforcing effect of the nanoparticles.