Boron Composite Structures in Aviation
The purpose of this paper is to discuss, and analyze the development and application of boron composites in airframe structures.
BORON'S HISTORY
Compounds of boron, most notably from unfinished borax ore, known as Tincal, were exported from Tibet in olden times. Historically, boron has been used for refining gold and silver in Arabia, ceramic glazes in China, and embalming in Egypt.
During the 13th Century A.D., "Regular imports of Tincal (name derived from tincana, the Sanskrit word for borax), from the Far East into Europe began along trade routes taken by Marco Polo's caravans. The source of Tincal (Tibet) and its methods of production remained a secret closely guarded by Venetian traders for four centuries."
Boric acid, a mild antiseptic, was isolated in the laboratory by chemistry professor William Homberg in 1720 and was discovered also occurring naturally from steam vents in Tuscany, Italy. Sir Humphrey Davy, a British chemist, and two French chemists, Joseph Gay-Lussac and Baron Louis Thenard, discovered boron in 1808 concurrently. However, it took another 155 years before science turned its focus from borax to boron, and began to reveal the secrets of this mysterious and valuable element.
"The recovery of pure crystalline boron did not succeed until the 1950s…Because of its ability to absorb neutrons the lighter isotope is important as an alloying component of boron steels used in nuclear reactors" (Stark, H.C). The revival of interest in boron in the late fifties and into the sixties was driven by the ability of the U.S. To introduce large quantities into a potentially lucrative global market. The elemental properties of boron were now well-known, and chemical variants began to find application in: grinding materials, lightweight armor, rocket motor propellant, and tools for metalworking.
Aerospace industries constantly seek new or improved hard, lightweight, heat resistant materials that can be introduced cost effectively into the manufacturing process. The introduction of high strength boron filaments and boron composite epoxy in the early 1960s, although expensive, lead to the rise of composites technology in aerospace manufacturing. Ceramic fibers including boron carbide were developed for use in heat-resistant composite materials such as ceramics.
Many components of helicopters, military aircraft, civil aircraft, missiles, and spacecraft, including satellites and space shuttles, are made from these high-strength, lightweight...
Surface irregularities are often seen when using the scanning electron microscope, but these are absent using the AFM. One such analysis is described below: Occasionally, the cartilage surface exhibits local discontinuities where an underlying fibrous network is distinguishable. Digestion of the cartilage surface with chondroitinase AC exposes this fibrous network more systematically so that the individual fibers are visualized with great clarity by AFM. When imaged at higher magnification, these
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