This work is an update of the original reference compilation by Charles F. Burns, Jr., Copyright 1997. The current booklet contains revisions to the original work as well as numerous additions. This booklet should serve as a handy reference for people that work in the metals industry.
Electrochemical capacitors, also called supercapacitors, store energy in two closely spaced layers with opposing charges, and are used to power hybrid electric vehicles, portable electronic equipment and other devices. By offering fast charging and discharging rates, and the ability to sustain millions of cycles2–5, electrochemical capacitors bridge the gap between batteries, which offer high energy densities but are slow, and conventional electrolytic capacitors, which are fast but have low energy densities. Here, we demonstrate microsupercapacitors with powers per volume that are comparable to electrolytic capacitors, capacitances that are four orders of magnitude higher, and energies per volume that are an order of magnitude higher. We also measured discharge rates of up to 200 V s21, which is three orders of magnitude higher than conventional supercapacitors. The microsupercapacitors are produced by the electrophoretic deposition of a several-micrometre-thick layer of nanostructured carbon onions6,7 with diameters of 6–7 nm. Integration of these nanoparticles in a microdevice with a high surface-to-volume ratio, without the use of organic binders and polymer separators, improves performance because of the ease with which ions can access the active material. Increasing the energy density and discharge rates of supercapacitors will enable them to compete with batteries and conventional electrolytic capacitors in a number of applications.
Aeronautical engineers are consistently searching for new and optimal materials to achieve specific applications throughout an airframe. There are a multitude of considerations affecting the structural design of an aircraft such as the complexity of the load distribution through a redundant structure, the large number of intricate systems required in an airplane and the operating environment of that airframe. All of the above criteria is governed primarily by weight savings. Thus, the optimal materials selected today and for the future of airframes are composite material and titanium.
Despite the widespread commercial use of hydrogen, not all of the flammability limits of the gas are known. Experiments were performed to determine hydrogen reaction limits in a partial pressure vacuum to allow the design of a vacuum furnace system having the necessary safeguar
Heat treatment standards are stricter in the aerospace industry than in the medical industry where lives are on the line. This doesn’t make sense and something is being done about it. Recently, I was asked to give a vacuum heat treating presentation to a group of design engineers at a large medical device company. The lead engineer asked if I would help educate his team on this subject primarily because they had just experienced a major failure caused by improper heat treatment. After learning more about the failure, it became evident that the medical device engineers in that room could learn a great deal from the aerospace industry, especially regarding knowledge of aerospace materials and secondary aerospace processes. It also became apparent that an industry-managed oversight program addressing the technical competency required in special processing was necessary in order for medical device companies to improve design and manufacturer of future medical devices.
Increased usage of refractory metals, titanium and their alloys in the aerospace and electronics industries has led to the use of the hydride/dehydride (HDH) heat treating process for recovery of spent materials. The HDH process has been known for many years in the manufacturing of transition-metal powders.
The fuzzy definitions of “raw material” and “parts” in specifications create variable and debatable heat treating quality standards.
Heat treating is the unsung hero of the commercial and military aviation industries. Much like the support staff behind any good play or movie, and the mom behind the Olympic athlete, heat treating of critical aerospace parts is relegated to the background, to the fine print of the credits…if at all. But if it weren’t for heat treating, planes wouldn’t fly, ships wouldn’t sail, submarines wouldn’t dive, and cars wouldn’t drive. This article introduces you to the technical world of vacuum heat treating and why vacuum thermal processing is vital to the aerospace and defense industries. First, let’s nail down what we mean by “heat treating.” In simple terms, heat treating is cooking metal much like you would cook food – with a predetermined recipe and desired outcome in mind. Metal is placed into an oven, or more accurately a furnace (ovens typically don’t handle temperatures over 1,000°F), and precisely held at a specified temperature for a pre-determined period of time. The metal is then cooled either slowly or quickly depending on what properties are desired. Thermal processing can make the metal harder, softer, stronger, more flexible, more rigid, more wear resistant, chemically altered, or a host of other desirable properties.