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At least 1,405 records · Page 78

Physical interpretation and development of ultrasonic nondestructive evaluation techniques applied to the quantitative characterization of textile composite materials

In this Progress Report, we describe our continuing research activities concerning the development and implementation of advanced ultrasonic nondestructive evaluation methods applied to the inspection and characterization of complex composite structures. We explore the feasibility of implementing medical linear array imaging technology as a viable ultrasonic-based nondestructive evaluation method to inspect and characterize complex materials. As an initial step toward the application of linear array imaging technology to the interrogation of a wide range of complex composite structures, we present images obtained using an unmodified medical ultrasonic imaging system of two epoxy-bonded aluminum plate specimens, each with intentionally disbonded regions. These images are compared with corresponding conventional ultrasonic contact transducer measurements in order to assess whether these images can detect disbonded regions and provide information regarding the nature of the disbonded region. We present a description of a standoff/delay fixture which has been designed, constructed, and implemented on a Hewlett-Packard SONOS 1500 medical imaging system. This standoff/delay fixture, when attached to a 7.5 MHz linear array probe, greatly enhances our ability to interrogate flat plate specimens. The final section of this Progress Report describes a woven composite plate specimen that has been specially machined to include intentional flaws. This woven composite specimen will allow us to assess the feasibility of applying linear array imaging technology to the inspection and characterization of complex textile composite materials. We anticipate the results of this on-going investigation may provide a step toward the development of a rapid, real-time, and portable method of ultrasonic inspection and characterization based on linear array technology.

Miller, James G.↗

Materials for Advanced Ultrasupercritical Steam Turbines Task 3: Materials for Non-Welded Rotors, Buckets, and BoltingMaterials for Advanced Ultrasupercritical Steam Turbines

The primary objective of the task was to characterize the materials suitable for mechanically coupled rotor, buckets and bolting operating with an inlet temperature of 760°C (1400°F). A previous study DOE-FC26-05NT42442, identified alloys such as Haynes®282®, Nimonic 105, Inconel 740, Waspaloy, Nimonic 263, and Inconel 617 as potential alloys that met the requirements for the necessary operating conditions. Of all the identified materials, Waspaloy has been widely utilized in the aviation industry in the form of disk and other smaller forgings, and sufficient material properties and vendor experience exist, for the design and manufacture of large components. The European program characterizing materials for A-USC conditions are evaluating Nimonic 263 and Inconel 617 for large components. Inconel 740 has been studied extensively as a part of the boiler consortium and is code approved. Therefore, the consortium focused efforts in the development of material properties for Haynes®282® and Nimonic 105 to avoid replicative efforts and provide material choices/trade off during the detailed design of large components. Commercially available Nimonic 105 and Haynes®282® were evaluated for microstructural stability by long term thermal exposure studies. Material properties requisite for design such as tensile, creep / rupture, low cycle fatigue, high cycle fatigue, fatigue crack growth rate, hold-time fatigue, fracture toughness, and stress relaxation are documented in this report. A key requisite for the success of the program was a need demonstrate the successful scale up of the down-selected alloys, to large components. All property evaluations in the past were performed on commercially available bar/billet forms. Components in power plant equipment such as rotors and castings are several orders in magnitude larger and there is a real need to resolve the scalability issue. Nimonic 105 contains high volume fraction y’ [>50%], and hence the alloy is best suited for smaller forging and valve internals, bolts, smaller blades. Larger Nimonic 105 forgings, would precipitate y’ during the surface cooling during forging, leading to surface cracks. The associate costs in forging Nimonic 105 to larger sizes [hotter dies, press requirements], were beyond the scope of this task and not investigated further. Haynes®282® has 20 - 25% volume fraction y’ was a choice for large components, albeit untested. A larger ingot diameter is pre-requisite for a larger diameter forging and achieves the “typically” accepted working ratio of 2.5-3:1. However, Haynes®282® is manufactured via a double melt process [VIM-ESR] limited by size [<18-16” diameter], which limited the maximum size of the final forging. The report documents the development of a 24” diameter triple melt ingot, surpassing the current available technology. A second triple melt ingot was manufactured and successfully forged into a 44” diameter disk. The successful developments in triple melting process and the large diameter forging of Haynes®282® resolved the scalability issues and involved the first of its kind attempt in the world for this alloy. The complete characterization of Haynes®282® forging was performed and documented in this report. The dataset from the commercially available Haynes®282® [grain size ASTM 3-4] and the finer grain size disk forging [ASTM 8-9] offer an additional design tradeoff to balance creep and fatigue during the future design process.

Saha, Deepak↗

Characterization of Multi-Material Interfaces Within Fibrous Structures (CRADA Final Report)

This project aimed to characterize the electrical, ionic, and thermal material properties of printed materials onto various textile and leather substrates. Furthermore, the material interfaces were investigated as well via characterization techniques such as SEM, TEM, and FTIR for example. Results from these studies will be utilized to properly formulate and tune process variables for enhancing the durability of devices and mitigate risks during commercial scale manufacturing studies of interest to Funxion’s product development.

36 MATERIALS SCIENCE↗

Synthesis and characterization of a new photoluminescent material, tris-[1-10 phenanthroline] aluminium

A new photoluminescent material namely tris-[1-10 Phenanthroline] Aluminium Al(Phen){sub 3} has been synthesized and characterized. This material was characterized by fourier transform infrared spectroscopy (FTIR),nuclear magnetic resonance (NMR),mass spectroscopy, thermal gravimetric analysis (TGA),ultraviolet-visible spectroscopy(UV) and photoluminescence (PL). This material shows thermal stability up to 300°C. This material showed absorption maxima at 352nm which may be attributed to the moderate energy (π–π{sup *}) transition. Photoluminescence spectra for this material showed the most intense peak at 423 nm and the time resolved photoluminescence spectra showed two life time components. The decay times of the first and second component were 1.4ns and 4.8 ns respectively.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Comprehensive End-to-End Design of Novel High Energy Density Materials: I. Synthesis and Characterization of Oxadiazole Based Heterocycles

A methodology to design novel energetic materials by means of a holistic approach that links synthesis, experimental characterization, quantum-chemical modeling, and statistical empirical evaluation is proposed. An analysis of the revealed structure–property–function correlations in the LLM compound series (oxadiazole-based heterocyclic energetics), BNFF, BNFF-1, LLM-172, LLM-191, and LLM-192, led us to predict, obtain, and characterize a new member in the materials family, LLM-200, which exhibits attractive energetic characteristics compared to known conventional high energy density materials. Finally, while the applied strategy convincingly demonstrated feasibility of the end-to-end design of high energy density materials, there are certain limitations in parallel improvements of sensitivity and performance within a single compound.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Tribological evaluation and analysis of coating materials

A physical characterization of coating materials by analytical techniques such as XPS, AES, ellipsometry, and nuclear reaction analysis can contribute to the understanding of adhesion and friction of the coatings and can partially predict the tribological properties of the coatings. This two-part paper describes the tribological properties and physical characteristics of (1) diamondlike carbon (DLC) films and (2) silicon nitride (SiN(x)) films. Emphasis is to relate plasma deposition conditions to the film chemistry and composition and to the adhesion and friction of the films. With the DLC films, the higher the plasma deposition power, the less the hydrogen concentration and the greater the film density and the hardness. The friction behavior of DLC films deposited at higher deposition powers (200 to 300 W) is similar to that of bulk diamond. Even in a vacuum, the DLC films effectively lubricate ceramic surfaces (Si3N4) at temperatures to 500 C. With SiN(x) films, the silicon to nitrogen ratios and the amount of amorphous silicon depend on deposition frequency. The presence of rich amorphous silicon in the high-frequency plasma-deposited SiN(x) films increases their adhesion and friction above 500 C in vacuum.

Miyoshi, Kazuhisa↗

Characterizing Disorders Within Cathode Materials of Lithium‐Ion Batteries

The demand for developing high-energy density cathode materials has been increasing. The energy densities of cathode materials have been improved by adapting structural deviation from the ideal fully ordered α-NaFeO2 type, but that led to limitations in terms of structural stability and safety. Although disorders in cathode materials are closely related to their electrochemical properties, unfortunately, characterizing the disorder itself in cathode materials has been challenging due to its complex parasitic reaction and strong correlation with other disorders occurring during charge/discharge. In this review, we categorize various disorders by their scales of ordering from short-range to long-range. We addressed the principles of various characterization tools to figure out how they can help to identify the structural disorder in cathode materials. Specifically, we focused on the underlying principles of each characterization technique to correlate different disorder-driven phenomena through several case studies. It underscores the substantial importance of disorder-property relationships and the corresponding characterization methods, which can provide novel research strategies for developing high-energy density cathode materials with decent structural stability.

Lee, Hakwoo↗