Basics 4 min read
Space Science echnology
In this chapter, we will discuss what is Space Science and how technology influences Space Science. We will focus more…
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Material Science 3 min read
Fabrication and processing of ceramics
Ceramic Synthesis Our expertise and capabilities in synthesizing ceramics are based onchemical solution techniques. Chemical solution or sol-gel approaches have beendeveloped to fabricate powders, films, and porous bodies. Materials of interest range from silica to complex, multicomponent electronic ceramics. The complexity inherent in fabricating materials with structured nanoporosity or complex chemistries requires a fundamental understanding of these chemical solution approaches. Fabrication of unique precursors for complex oxides is being done with novel metal alkoxide chemistry to produce powders and thin-film materials with carefully controlled properties. Our ability to synthesize materials with complex structures, chemistries, or both, is at the heart of numerous research and development efforts at Sandia. Ceramic Processing Sandia’s fabrication of ceramic components and devices is based on a strong ceramic-processing capability. We recently have demonstrated the ability to characterize and model the powder- compaction process in detail, and to address and control density gradients in powder compacts that cause shape distortion and differential shrinkage. Proprietary 3D, finite-element code packing and compaction models, and process-control tools are now available to improve the production of ceramic components. Sandia has capabilities in the areas of hydrostatic and triaxial compaction testing to characterize materials properties, and x-ray radiography, ultrasound, and computed tomography for density characterization. In addition, expertise in slurry processing has enabled the…
Basics 3 min read
Communication Technology
Communication is the exchange of information through different mediums. It is an activity that started even before the civilization of…
Material Science 3 min read
Portland Cement
Portland cement is a closely controlled chemical combination of calcium, silicon, aluminum, iron and small amounts of other compounds, to which gypsum is added in the final grinding process to regulate the setting time of the concrete. Some of the raw materials used to manufacture cement are limestone, shells, and chalk or marl, combined with shale, clay, slate or blast furnace slag, silica sand, and iron ore. Lime and silica make up approximately 85 percent of the mass The term “Portland” in Portland cement originated in 1824 when an English mason obtained a patent for his product, which he named Portland Cement. This was because his cement blend produced concrete that resembled the color of the natural limestone quarried on the Isle of Portland in the English Channel. Different types of Portland cement are manufactured to meet different physical and chemical requirements for specific purposes. Common Examples Structural clay products Brick, sewer pipe, roofing tile, clay floor and wall tile (i.e., quarry…
Basics 2 min read
Artificial Intelligence
Artificial Intelligence or simply AI is an experimental science being developed with the purpose to understand the nature of intelligent…
Material Science 11 min read
Types and applications of ceramics
Ceramics offer a high temperature range. However, ceramics are not very strong. To compensate for their lack of strength ceramics are usually combined with some other material to form a ceramic composite. 1) Glasses and glass ceramics- The glasses are a familiar group of ceramics; containers, windows, lenses and fiberglass represent typical applications. The properties of standard vitrified products are insufficient for architectural applications and structural building components, insulation or other specialized applications. Yet there is an effective way to improve these properties without major alterations to the process itself – the introduction of a controlled crystallization process through a subsequent heat treatment, i.e. by forming a glass-ceramic. Production of Glass-Ceramics Glass-ceramic articles may be produced by three routes: • The heat treatment of solid glass (the traditional route) • The controlled cooling of a molten glass, known as the petrurgic method • The sintering and crystallisation of glass powders. In the latter case, the powders are densified at relatively low temperatures by exploiting a viscous flow sintering mechanism. After densification, the material is subjected to a crystallisation heat- treatment to obtain the required glass-ceramic microstructure. Alternatively, both densification and crystallisation may take place during a single sintering step. Along with the economic advantage of using relatively low processing temperatures, the powder technology route is…
Material Science 3 min read
Ceramics (Applications and Processing)
Ceramics encompass such a vast array of materials that a concise definition is almost impossible. However, one workable definition is: Ceramics can be defined as inorganic, nonmetallic materials. They are typically crystalline in nature and are compounds formed between metallic and nonmetallic elements such as aluminum and oxygen (alumina-Al2O3), calcium and oxygen (calcia – CaO), and silicon and nitrogen (silicon nitride-Si3N4). Ceramics is a refractory, inorganic, and nonmetallic material. Ceramics can be divided into two classes: traditional and advanced. Traditional ceramics include clay products, silicate glass and cement; while advanced ceramics consist of carbides (SiC), pure oxides (Al2O3), nitrides (Si3N4), non-silicate glasses and many others. Ceramics offer many advantages compared to other materials. They are harder and stiffer than steel; more heat and corrosion resistant than metals or polymers; less dense than most metals and their alloys; and their raw materials are both plentiful and inexpensive. Ceramic materials display a wide range of properties which facilitate their use in many different product areas. In general, most ceramics are: – hard, – wear-resistant, – brittle, – refractory, – thermal insulators, – electrical insulators,…
Basics 3 min read
E-Infrastructure in India
In today’s world, e-infrastructure is the key element for the development of a society. E-infrastructure facilitates competent equipment and favorable…
Basics 2 min read
Meissner Effect & Superconductor Types
The Meissner effect is an expulsion of a magnetic field from a superconductor during its transition to the superconducting state. T he German physicists Walther Meissner and Robert Ochsenfeld discovered the phenomenon in 1933 by measuring the magnetic field distribution outsidesuperconducting tin and lead samples. The interior of a bulk superconductor cannot be penetrated by a weak magnetic field, a phenomenon known as the Meissner effect. When the applied magnetic field becomes too large, superconductivity breaks down. Superconductors can be divided into two types according to how thisbreakdown occurs. In type-I superconductors, superconductivity is abruptly destroyed via a first order phase transition when the strength of the applied field rises above a critical value Hc. Type-II superconductor is characterized by the formation of magnetic vortices in an applied magnetic field. This occurs above a certain critical field strength Hc1. The vortex density increases with increasing field strength. At a higher critical field Hc2, superconductivity is completely destroyed.
Basics 3 min read
Cyber Crime Cyber Security
The crime that involves and uses computer devices and Internet, is known as cybercrime. Cybercrime can be committed against an…
