A presentation by Solar's Don Jordan given at the ASM's Heat Treat 2015 trade show about reducing alpha case on titanium parts when heat treating in a vacuum furnace.
A recent process development test relating to carburizing illustrated the need to better understand the effect of surface emissivity and the proper use of dummy thermocouple test blocks. The testing involved carburizing areas of a partially copper plated alloy steel part. The copper plating covered areas of the part that were not to be carburized. Since the configuration of the part made it impossible to place a thermocouple within the part, a dummy test block made of carbon steel with the approximate same cross-section was used for the process thermocouple without proper consideration of the surface condition of the test block. Using the test block as the control, carburizing was initiated at the proper temperature based on the test block having reached that temperature. At the completion of the test, the part was examined for carburizing results and found in the non-copper plated areas, the depth of the carburized case to be shallow. This indicated that the cycle performed did not initially hold the part long enough at the correct temperature prior to carburizing. This resulted in the conclusion that when using dummy test blocks for controlling process times and temperatures, many factors must be considered including surface emissivity.
Advanced material solutions for fixtures, grids and internal furnace components are available today. They are designed to allow for higher processing temperatures, larger loads, increased production rates, energy savings, and lower overall cycle costs.
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