Composite Ceramic Based on Silicon Carbide

Refractories and Industrial Ceramics - An effective method for preparing dense granular ceramic from SiC with a residual porosity of less than 5.0% is the use of additives of oxide system eutectic...     

Comparison of the Free Volume of LiCl-Added SPPO Membrane and SPPO-PES Blend Membrane by Positron Annihilation Method

Positron annihilation lifetime spectroscopy （PALS） is a powerful technique for the study of free volume in polymers. The lifetime of ortho-positronium （o-Ps）, a bound state of an electron and a positron, can be used to assess the pore size, while the intensity can be used to characterize the number of pores. Based on the values of the long-lived o-Ps components in the lifetime spectra, the radii and fractional free volumes of sulfonated poly （2,6-dimethyl-1,4- phenyleneoxide） （SPPO） membranes with added LiCl and SPPO-PES （Polyethersulfone） blend were compared. Free volume radii in both kinds of membranes are discussed.     

High Microwave-Noise Performance of AlGaN/GaN MISHEMTs on Silicon With Gate Insulator Grown by ALD

High microwave-noise performance is realized in AlGaN/GaN metal–insulator semiconductor high-electron mobility transistors (MISHEMTs) on high-resistivity silicon substrate using atomic-layer-deposited (ALD) $hbox{Al}_{2}hbox{O}_{3}$ as gate insulator. The ALD $hbox{Al}_{2}hbox{O}_{3}/hbox{AlGaN/GaN}$ MISHEMT with a 0.25- $muhbox{m}$ gate length shows excellent microwave small signal and noise performance. A high current-gain cutoff frequency $f_{T}$ of 40 GHz and maximum oscillation frequency $f_{max}$ of 76 GHz were achieved. At 10 GHz, the device exhibits low minimum-noise figure $(hbox{NF}_{min})$ of 1.0 dB together with high associate gain $(G_{a})$ of 10.5 dB and low equivalent noise resistance $(R_{n})$ of 29.2 $Omega$. This is believed to be the first report of a 0.25-$muhbox{m}$ gate-length GaN MISHEMT on silicon with such microwave-noise performance. These results indicate that the AlGaN/GaN MISHEMT with ALD $hbox{Al}_{2}hbox{O}_{3}$ gate insulator on high-resistivity Si substrate is suitable for microwave low-noise applications.      

Fault isolation in semiconductor product,process, physical and package failure analysis: Importance and overview

Failure analysis plays a major role in all areas of the semiconductor company especially during product development cycle, 1st silicon stage, or in wafer processes and fabrication as well as assembly and package development. Different companies have different FA flows but all FA steps will need to start with fault isolation. Fault isolation is the step to narrow down the focus area of a failing component or product to a manageable area that will allow us to (a) improve success of finding the defect that is causing the failure and, (b) significant speed up turn-around time for analysis.This paper provides an overview of all the available failure analysis on fault isolation methodologies and tools, for device/product level and expanding to package/assembly and PFA level isolation. The aim of the paper is to provide sufficient depth to each topic including some case studies to emphasize the key points related to each methodology. The tutorial will also cover some future directions/roadmaps.     

Compression of polymer bound alumina agglomerates at the micro deformation scale

In this paper, the mechanical properties of alumina particle based agglomerates, prepared in a tumble mixer by using a poly (vinyl alcohol) (PVA) binder (ca. 5% by volume) in conjunction with water solvent, are described at a micro deformation level. Uniaxial compressive deformation profiles of these alumina agglomerates, typically 180–200 μm in diameter, are reported and their diverse behaviour during compression have been observed, which vary from a clear brittle rupture to progressive ductile deformation. However, certain common patterns of the agglomerate reaction force response, as a function of the compressive displacement, are identified, such as the similarities in the reloading response after each discrete fracture event. The Hertz Theory and a slope and peak force analysis are applied to establish the common patterns and trends, and generalize the intrinsic deformation characteristics of these agglomerates.     

Use of tortuosity for discriminating electro-facies to interpret the electrical parameters of carbonate reservoir rocks

The electrical parameters of 80 various carbonate rock plugs from a Saudi Arabian reservoir were measured. The results were first analyzed without considering the lithology, and then subsequently lithology was considered. Tortuosity distribution and correlations with other petrophysical parameters were used in differentiating samples of similar electrical properties, called “electro-facies”. Tortuosity distribution indicated two populations of data points one of which corresponded to the oolitic and skeletal-intraclastic lithofacies, referred to as “granular electro-facies”; and the other to the muddy and the dolomitic lithofacies, named “dolomitic-muddy electro-facies”.Three methods were applied to interpret the cementation factor: (1) the Archie; (2) the best fit; and (3) the cementation factor as a function of porosity. Error analysis showed that the Archie cementation factor was not an appropriate method for the studied reservoir rocks. The best fit and the cementation factor as a function of porosity methods yielded more reasonable results and they are recommended over the Archie method.A comparison of the water saturations obtained using the electrical parameters of the overall samples with the water saturations obtained using the parameters of each electro-facies showed significant errors especially in low water saturation zones. This indicates the importance of litho- or electro-facies discrimination in heterogeneous reservoirs.     

Influences of extrusion parameters on physicochemical properties of textured vegetable proteins and its meatless burger patty

Isolated soy protein, wheat gluten, and starch at ratio 5:4:1 were texturized under different moisture contents (40 and 50%) and die temperature (130 and 150 °C) by the twin-screw extruder. Physicochemical properties were firstly studied. These textured vegetable proteins (TVPs) were used to form 100% plant-based burger patties. Cooking and textural features were secondly investigated. TVP at 50% moisture content and 130 °C die temperature represented the highest water absorption capacity and integrity index but the lowest solubility among TVPs. Cooking loss and shrinkage in diameter and thickness, cohesiveness, chewiness, hardness, and cutting strength of TVP meatless burger patties were significantly lower than that commercial meat patty, while moisture retention and springiness of TVP meatless burger patties were higher (p < 0.05). Our results found that the texture of patty made with TVP at 50% moisture content and 130 °C die temperature was the most similarity to commercial meat patty.     

Evaluation of fermentation and aerobic stability of wet brewers' grains ensiled alone or in combination with various feeds as a total mixed ration

Wet brewer's grains (BG; 200 g kg^?1 dry matter(DM)) were ensiled alone or in combination with various dry feeds as a total mixed ration (TMR; 540 g kg^?1 DM) in laboratory silos. Ensilage was stopped at 40 days (experiment 1) or at 5, 20, 40 and 60 days (experiment 2) after storage. The composition of soluble sugars and the profiles of fermentation products were determined. The 60 day silages were subjected to aerobic deterioration and changes in silage temperature were recorded for 7 days. A rapid pH fall coupled with accelerated lactic acid production was observed in BG silage; soluble sugars, mainly composed of maltose and raffinose, completely disappeared within 5 days of ensiling. Prolonged storage, however, decreased lactic acid concentration and increased acetic acid greatly. Appreciable amounts of propionic acid and 1‐propanol were also produced in BG silage in the late stages of fermentation. When TMR silage was made, the decline in pH and the increase in lactic acid were delayed due to the low moisture content. Acetic acid production was enhanced from the beginning of storage, and mannitol accumulated in TMR silage. Yeast numbers were lower in TMR than in BG silage, but the changes were limited in the late stages of fermentation. When exposed to air, the temperature of BG silage increased after 3 days, whereas that of TMR silage appeared stable during the 7 days test. The results indicate that BG is a suitable by‐product for ensiling and, when ensiled with various feeds as a TMR, improved stability against aerobic deterioration can be expected. Copyright © 2003 Society of Chemical Industry     

Temperature profile in the combustion wave of low calorific value propellants

Combustion wave temperature profiles are determined for two low calorific value propellants (Q _c = 2189 and 2518 kJ/kg). It is shown that the structure and parameters of the combustion wave differ significantly from those for previously studied propellants of medium (propellant N) and high (propellant NB) calorific values. At a relatively short distance from the burning surface, the temperature is significantly (180–270 K) higher than the calculated value due to fact the combustion products contain carbon black from the decomposition of heat-resistant dibutyl dinitrotoluene and dibutyl phthalate. Then, part of carbon black reacts endothermically with CO₂ and H₂O, leading to a decrease in temperature, which for the first sample is nevertheless 100–140 K higher than the thermodynamic value. For the investigated propellants, the activation energy of the leading reaction is the same as for the previously studied propellants, suggesting a common decomposition kinetics of the condensed phase regardless of the propellant composition. However, a uniform dependence of the burning rate on surface temperature is not observed. For low calorific value propellants, the surface temperatures are close to those for propellant N although their burning rate is significantly (2–2.2 times) lower. The causes of this fact are considered.