Tech Downloads
The Vacuum Heat Treatment of Titanium Alloys for Commercial Airframes
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.
Critical Melting Points Booklet
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.
Nature Nano: Ultrahigh-power micrometre-sized supercapacitors based on onion-like carbon
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.
Controlling Compound (White) Layer Formation During Vacuum Gas Nitriding
Solar Atmospheres has established a method of controlling the amount and depth of White layer resulting from Gas Nitriding. This procedure was accomplished following extensive testing using AISI 4140 Steel in a Solar Atmospheres Gas Nitriding Vacuum furnace. Various applications requiring Nitriding often require specific White layer limits which can now be provided by this process. Following an initial rapid pump down to produce an Oxygen free, vacuum environment, the Nitriding cycle consisted of a pre-heat at a partial pressure of Nitrogen followed by Nitriding at a slightly positive pressure using an Ammonia/Nitrogen mixture. Many cycles were performed varying the time and gas flow parameters at temperature and the resulting White layer composition and thickness determined. The key to controlling the White layer formation was the introduction of a Boost-Diffusion technique during the Nitriding phase. Surface hardness and depth of nitride zone were then recorded from microhardness measurements and metallography. All this data was compiled to establish Nitriding procedures that provide the final desired structure in the minimum cycle time. This includes processes that produce the minimum depth or complete absence of White layer as dictated by the final application of the parts.
Optimizing Procedures For Temperature Uniformity Surveying For Vacuum Furnaces
A Temperature Uniformity Survey ( TUS ) for a vacuum furnace to satisfy AMS 2750D must be performed using established procedures and methods that fully meet the requirements of the specification and allows for consistent and more accurate results of actual furnace capabilities. Solar Atmospheres and Solar Manufacturing, with their extensive vacuum furnace experience and processing knowledge, have combined to create a standard procedure for TUS for all newly manufactured and current in-production vacuum furnaces. This procedure considers the many critical aspects of AMS 2750D that must be fully satisfied to produce acceptable processing results and the following outline could be applied to any vacuum furnace user to satisfy their TUS requirements.
Vacuum Gas Nitriding Furnace Produces Precision Nitrided Parts
Currently, nitriding is carried out predominantly in pit type vertical furnaces with metal alloy retorts to hold the work load during the nitriding cycle. The large thermal mass of these furnaces requires long heat-up and cool-down times. Another factor is that the ammonia nitriding gas cracks not only on the work load but on the metal retort too. In time, this leads to non-uniform nitriding of the work, and the retort has to be conditioned before uniform nitriding can be restored. In contrast, the much smaller thermal mass inherent in vacuum furnaces (as well as other features) offers an opportunity of designing a more desirable vacuum furnace for providing efficient uniform nitriding. Such a furnace was designed and developed over several years to replace traditional retort gas nitriding.
No Hydrogen Embrittlement with Low Pressure Gas Carburizing
Results of study of steel carburized at low pressure using a vacuum furnace show no evidence of hydrogen embrittlement, which should relieve any concern of the possibility of such an occurrence in low pressure gas carburizing.
Explosive Nature of Hydrogen in Partial-Pressure Vacuum
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
Reconditioning Ceramic Insulators
Furnace insulators are designed to electrically and thermally insulate. When they become coated with metals and carbon from high-temperature processing, their electrical resistance is compromised. This article discusses a technique to restore the insulator to its original purpose.