Abstract:
L'invention concerne un procédé d'enduction métallique par voie liquide de fibres en matériau céramique, consistant à maintenir une charge (22) de métal en fusion et lévitation de forme sphérique à l'intérieur d'un creuset (12) et à faire défiler à une vitesse prédéterminée une fibre (24) tendue en matériau céramique entre une poulie supérieure (26) et une poulie inférieure (28) disposées de part et d'autre du creuset de sorte qu'une portion (35) de fibre soit immergée dans la charge pour la recouvrir d'un revêtement métallique. Au cours de l'enduction, la portion de fibre immergée dans la charge est déplacée en fonction du volume restant de la charge de telle manière que la hauteur instantanée (h) de fibre qui est immergée dans la charge reste sensiblement constante tout au long de l'enduction. L'invention concerne également un dispositif de mise en œuvre de ce procédé.
Abstract:
A method of preparing a light weight concrete composition using expanded polymer particles that includes a) replacing from about 10 to about 50 volume percent of the coarse aggregate in the concrete composition with prepuff particles; and b) preparing the concrete composition by combining ingredients comprising 3 - 40 volume percent cement, 1 - 50 volume percent fine aggregate, 0 - 40 volume percent coarse aggregate, 10 - 22 volume percent water, and 5 - 40 volume percent of prepuff particles. The prepuff particles have an average particle diameter of from 0.2 mm to 5 mm, a density of from 0.02 g/cc to 0.56 g/cc, an aspect ratio of from 1 to 3. The concrete composition has a density of from about 90 to about 135 lb./ft3 and after it is set for 28 days, has a compressive strength of at least 1800 psi as tested according to ASTM C39.
Abstract:
A three-dimensional composite reinforcement, a three-dimensionally reinforced multifunctional nanocomposite, and methods of manufacture of each are disclosed. The three dimensional reinforcement compπses a two dimensional fiber cloth upon which carbon nanotubes have been grown, approximately perpendicular to the plane of the fiber cloth. The nanocomposite comprises the three-dimensional reinforcement and a surrounding matrix material. Examples illustrate improvements in the through-thickness mechanical, thermal, and electrical properties of the nanocomposite, in addition to substantial improvements in geometrical stability upon temperature changes and vibrational damping, compared to baseline composites reinforced with the two- dimensional fiber cloth alone. Embodiments of the nanocomposite may also be configured to perform multiple functions simultaneously, such as bearing a thermal or mechanical load simultaneously or bearing a mechanical load while also monitoring the state of damage within the nanocomposite.
Abstract:
A modified alkali silicate composition for forming an inorganic network is made by reacting an alkali silicate (or precursors such as an alkali hydroxide, a SiO2 source and water), an acidic oxoanionic compound such as phosphoric acid, water and optionally one or more multivalent cation(s) selected from Groups 2, 3, 4, 5, 6, 11, 12, 13, 14, 15 or 16 of the periodic table such as an alkaline earth salt, water and optional processing aids. A composite can be prepared by applying the modified aqueous alkali silicate composition to a reinforcing medium and curing the composite at a temperature from 15 DEG C up to 1000 DEG C and a pressure of up to 20,000 psi (137.895 MPa). Composite and neat resin components prepared from the invention can exhibit excellent dimensional stability to 1000 DEG C and higher, and can be prepared at temperatures and pressures typical for organic polymer processing. The composite can be shaped by compression molding as well as other known fabrication methods.
Abstract:
The present invention generally relates to mechanisms for preventing undesirable oxidation (i.e., oxidation protection mechanisms) in composite bodies. The oxidation protection mechanisms include getterer materials which are added to the composite body which gather or scavenge undesirable oxidants which may enter the composite body. The getterer materials may be placed into at least a portion of the composite body such that any undesirable oxidant approaching, for example, a fiber reinforcement, would be scavenged by (e.g., reacted with) the getterer. The getterer material(s) may form at least one compound which acts as a passivation layer, and/or is able to move by bulk transport (e.g., by viscous flow as a glassy material) to a crack, and sealing the crack, thereby further enhancing the oxidation protection of the composite body. One or more ceramic filler materials which serve as reinforcements may have a plurality of superimposed coatings thereon, at least one of which coatings may function as or contain an oxidation protection mechanism. Specifically, a coating comprising boron nitride which has been engineered or modified to contain some silicon exhibits improved corrosion resistance, specifically to oxygen and moisture. The coated materials may be useful as reinforcing materials in high performance composites to provide improved mechanical properties such as fracture toughness. The present invention also relates to improved composites which incorporate these materials, and to their methods of manufacture.
Abstract:
This invention relates to a method of coating fibers by contacting the fibers with an organochlorosilane, drying and heating the fibers at a temperature of about 300° to 500°C, thereby coating the fibers. The choice of organochlorosilane and atmosphere under which the heating takes place will determine the composition of the coating.
Abstract:
There is provided a fiber-reinforced brittle matrix composite. The fiber-reinforced brittle matrix composite comprises a brittle matrix material (for example, a cementitious or ceramics material) and a coated fiber embedded in the brittle matrix material, wherein the coated fiber comprises a fiber (for example, polyethylene fiber, glass fiber, silicon carbide fiber, alumina fiber, mullite fiber) and a coating material (for example, carbon nanofibers, carbon nanotubes), which is non-covalently disposed on the fiber. A method for producing the fiber-reinforced brittle matrix composite is also provided. The method comprises providing a fiber, disposing a coating material on the fiber to form a coated fiber, wherein the coating material is non-covalently disposed on the fiber, and embedding the coated fiber in a brittle matrix material to obtain the fiber-reinforced brittle matrix composite.
Abstract:
High-temperature fabrics with a coatings to provide oxidation protection at high temperatures, and capable of being formed into a variety of softgoods parts, and methods for their manufacture are disclosed.
Abstract:
A lightweight concrete composition containing from 10 to 90 volume percent of a cement composition, from 10 to 90 volume percent of particles having an average particle diameter of from 0.2 mm to 8 mm, a bulk density of from 0.03 g/cc to 0.64 g/cc, an aspect ratio of from 1 to 3, and from 0 to 50 volume percent of aggregate; where the sum of components used does not exceed 100 volume percent, and where after the lightweight concrete composition is set it has a compressive strength of at least 1700 psi as tested according to ASTM C39 after seven days. The concrete composition can be used to make concrete masonry units, construction panels, road beds and other articles.