Materials & Coatings

An advanced technique of deep reactive-ion etching (DRIE) has been developed for fabricating smooth vertical walls in silicon wafers. These walls are suitable for use as bounding surfaces of optical waveguides in photonic and optoelectronic devices. The roughness of a typical 8-µm-high...

An improved method of plasma chemical-vapor deposition (CVD) of a thin film of boron carbide has been devised. Boron carbide is useful because it is hard, is electrically insulating, withstands high temperature, and resists chemical attack. Plasma CVD of boron carbide involves the thermal...

A report discusses a proposed nesting-hoop solar sail that would be used to propel a spacecraft on a deep-space mission. The nesting-hoop design concept was chosen as one that would afford a desired combination of small mass and compact stowage during launch. The sail would include multiple disks, each comprising a thin...

Scientists have developed a derivative of the lithium-ion cell that could prove useful in spaceflight and commercial applications in which it is planned to use oxygen batteries based on solid polymer electrolytes. This derivative cell, which contains a solid polymer electrolyte and an oxygen gas...

NASA scientists, who are very concerned with the increasing hazard of impacts of orbital debris impact on spacecraft, have designed the "stuffed Whipple" shield — a lightweight, relatively inexpensive alternative to simple aluminum meteoroid/orbital-debris (M/OD) shield. The stuffed Whipple...

Lightweight, inflatable tubular structural components containing tape-spring reinforcements are undergoing development. The basic (without tape-spring reinforcement) tubular components are made, variously, of aluminum laminates or composite materials and are under consideration for use in...

A report presents additional information on the GENOA-PFA computer program, which was described in "Software for Simulating Progressive Fracture in Braided PMCs" (LEW-16845), NASA Tech Briefs, Vol. 24, No. 3 (March 2000), page 52. On the basis of material-property data, finite-element...

Carbon nanotubes (also known as "bucky tubes") have shown promise for use as anode materials in rechargeable lithium-ion power cells. In comparison with graphite and other forms of carbon used under identical conditions, bucky tubes exhibit greater specific discharge capacity and greater...

Aerogels with gradients in density have been produced in experiments, as part of an effort to develop materials that will be used in outer space to capture particles traveling at high speeds for the STARDUST mission.

An improved method of manufacturing high-temperature superconductors of general composition YBa2Cu3O7— x and various grain structures has been devised. This method involves mixing, pressing, and heating of Y2O3, CuO, and Ba(NO3)2 powders. This method is easier than an older method that...

An improved process for waterproofing ceramic materials — especially lightweight ceramic insulation materials in both rigid (tile) and flexible (blanket) form — has been invented. In this process, traditional waterproofing agents are used, but before the waterproofing agents are applied, the...

Two reports present additional details about the method described in "Reaction-Forming Method for Joining SiC-Based Ceramic Parts" (LEW-16661), NASA Tech Briefs, Vol. 23, No. 3 (March 1999), page 50. To recapitulate: A carbonaceous mixture (typically a paste) is applied to a joint between parts....

LIPS (LIFE PREDICTION SOFTWARE) is a computer program for predicting the life of an object that is made of a unidirectional-fiber/metal-matrix composite (MMC) material and that is subjected to mechanical loading along the fiber direction. The program is derived from a theory formulated to be...

The term "Molecular-Sieve Type 3Å" denotes a clay-based, zeolite material that revolutionizes a fluid-purification process by removing trace water and iron from nitrogen tetroxide/nitric oxide (MON-3) mixtures used as oxidizer components of spacecraft propellants. Older processes of this type removed only water or iron...

Scientists have developed a type of composite graphite anode that will benefit the U.S. space program and private industry by increasing the rechargeability of lithium-ion batteries. Rechargeable lithium-ion batteries, which are used on the space shuttle and Space Station, are also used in...

Experiments have shown that electrically conductive polymers with water-soluble fractions can be synthesized by polymerization of pyrrole or aniline in the presence of lignosulfonic acid, which is a polymeric acid that can be derived relatively easily from the spent sulfite liquor byproducts...

Reports labeled as chapters 2, 3, 4, 7, 8, 9, and 10 of a NASA technical memorandum that addresses topics in tribology have been compiled into a document that emphasizes those aspects of the subject matter that pertain to chemical-vapor-deposited (CVD) diamond and diamond-like films. The...

White Sands Test Facility (WSTF) scientists have developed an energy-absorbing laminated shell that is a prototype of lightweight, inexpensive, and removable covers to shield and otherwise protect carbon-composite overwrapped pressure vessels (COPVs). Although COPVs are superior to metal...