Microstructural stability

Some researchers explored Ni-YSZ cermets that used both fine (average size of 0.6 pm) and coarse (average size of 27.0 pm) YSZ as the starting materials. It was hoped that the coarse YSZ particles would form a frame that keeps the total volume unchanged while the fine YSZ particles would sustain the network of Ni and pore, providing good electrical conductivity and microstructural stability [14]. However, it is not clear how such an anode compares with conventional anodes made from both fine NiO and YSZ in terms of strength, electrical conductivity, and electrochemical activity. 

Kiescheke, R.R., Warwick, C.M. and Clyne T.W. (1991b). Sputter deposited barrier coatings on SiC monofilaments for use in reactive metallic matrices - part III. Microstructural stability in composites based on magnesium and titanium. Acta Mctaii. Mater. 39, 445-452. 

The need to develop fibers with better microstructural stability at elevated temperatures and ability to retain their properties between 1000-2000°C. The requirements of fiber properties for strong and tough ceramic composites have been discussed by DiCarlo.83 A small diameter, stoichiometric SiC fiber fabricated by either CVD or polymer pyrolysis, and a microstructur-ally stable, creep-resistant oxide fiber appear to be the most promising reinforcements. 

The stability of emulsion and foam films have also been found dependent upon the micellar microstructure within the film. Electrolyte concentration, and surfactant type and concentration have been shown to directly influence this microstructure stabilizing mechanism. The effect of oil solubilization has also been discussed. The preceding stabilizing/destabilizing mechanisms for three phase foam systems have been shown to predict the effectiveness of aqueous foam systems for displacing oil in enhanced oil recovery experiments in Berea Sandstone cores. 

Badwal, S.P.S., Zirconia-based solid electrolytes Microstructure, stability and ionic conductivity. Solid State Ionics 52 (1992) 23-32. 

Key words nanostructured metallic systems/microstructural stability/structure-property relationships/metallic nanostructures/nanostructured multilayers... 

Following these considerations the Al3Zr intermetallic compounds are used as dispersoids or precipitates in the Al-Al3Zr composite system, rather than the monolithic ones [7, 8], Many previous works have been concentrated on the microstructural stability, mechanical properties and thermomechanical processing of these kind of systems. Some authors have studied the hot formability of the same alloy by demonstrating the microstructural stability of Zr-stabilized aluminum alloy from 300 and 500 °C [7],... 

Microstructure stabilization. Before complete removal of the sacrificial oxide, small cavities are etched around and under the mechanical polysilicon and down to the ground-plane polysilicon below the sacrificial oxide layer. These cavities are then backfilled with photoresist, resulting in pillars that support the polysilicon. In a subsequent masking operation, strips of photoresist are placed across the micromachined elements. This results in a web of photoresist material that holds the polysilicon elements in place after complete removal of the sacrificial oxide layer. Subsequent etching of the sacrificial oxide with a buffered... 

Aluminum is a low melting point metal, therefore microstructural stability (and consequently creep) is an important issue even for near ambient temperature. Many common structural aluminum alloys are precipitation strengthened at heat treatment temperatures on the order of 423 K, implying that the service temperature must be considerably lower. There are a few aluminum alloys designed for high-temperature applications however, creep makes them unacceptable as materials of construction for contaimnent of pressurized gas at elevated temperature. On the other hand, aluminum alloys are commonly employed at cryogenic temperatures. 

A certain body of recent research has focused on the microstructural stability of protein stabilized oil-in-water emulsions that are structurally similar to recently developed foodstuffs (e.g., dairy alternative or fresh cheese type products, etc.). - The image of such an emulsion has been visualized by the use of Confocal Laser Scanning Microscopy (CSLM). However, not much research has been done yet on the oxidative destabilization of these emulsion systems. A better understanding of the factors monitoring the oxidative deterioration of emulsions would offer antioxidant strategies to improve the organoleptic and nutritional value of the related products. 

Microstructural stability change of microstructure with temperature is not accepted. 

Because most development work has been done on non-oxide materials, particularly SiC fiber-reinforced SiC CMCs (SiC/SiC) with fiber interfacial coatings of either carbon or boron nitride, non-oxide CMCs are more advanced than oxide CMCs. Non-oxide CMCs have attractive high temperature properties, sueh as creep resistance and microstructural stability. They also have high thermal conductivity and low thermal expansion, leading to good thermal stress resistance. Therefore, non-oxide CMCs are attractive for thermally loaded components, such as combustor liners (see Figure 1-4), vanes, blades, and heat exchangers. 

Assessing the state of the art in ceramic fibers requires a thoughtful definition of performance requirements and comparisons of these requirements to current capabilities. Defining the state of the art also requires the rigorous characterization of available materials, particularly the properties that are relevant to CMC applications. Microstructural stability, stiffness (elastie modulus), and creep behavior, as a function of temperature and time at temperature in actual service environments, are the most eritieal fiber properties. Therefore, research should focus on determining these properties, including understanding mierostruetural and compositional relationships to these properties. 

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