Search Results for surface reactivity

The application potential of magnesium alloys as lightweight structural materials in aerospace and especially inside the aircraft cabin are hindered by their high surface reactivity at increased temperatures with particular concerns of ignition and flammability during a potential contact with a flame or other heat source. This article describes global efforts to develop ignition-resistant and nonflammable magnesium alloys. A widely explored avenue involves microalloying magnesium with rare earth metals and other elements having a high affinity to oxygen. As demonstrated by experimental alloys, this approach allows shifting the ignition temperature well above the liquidus, not only easing requirements on protective atmospheres during liquid-state processing, but also increasing the safety margin for possible aerospace applications.

Active screen plasma nitriding and nitrocarburizing are relatively new processes in which a plasma discharge is applied to a metal screen surrounding the workload, generating highly reactive gas species that flow to the component surface. The active screen also radiates heat, resulting in a uniform temperature throughout the load. This article provides an overview of the two processes and presents examples of their use on stainless steel piston rings (nitriding) and 4142 and 1045 steels (nitrocarburizing).

An advanced, patented probe sensor provides early detection of water infrastructure problems caused by corrosion and harsh atmospheric conditions. Designed to detect graphitization in active pipelines, it identifies areas at risk of major failures early on. By using indirect methods like GIS mapping, in-situ soil resistivity testing, and structure-to-soil potential measurements, high-risk zones can be pinpointed. Once these areas are identified, the probe assesses the severity and depth of graphitization, providing a comprehensive evaluation of the pipeline’s condition. This allows for the implementation of effective corrosion management strategies, including cathodic protection systems, to prevent critical failures. This article describes the sensor system and provides a case study of its use. The technology received the 2024 Engineering Materials Achievement Award from ASM International.

New electrical, mechanical, and chemical testing capabilities give scanning electron microscopes the feel of a self-contained “nano-laboratory.” Several developments in SEM technology allow new and more flexible approaches to the analysis of novel systems, such as Li battery-related materials, nanostructured and nanoporous materials, and novel approaches to 3D analysis.

Metal additive manufacturing has steadily progressed over the past decade, with today’s directed energy deposition processes enabling rapid builds of large structures in near-net shape—and with minimal machining required to achieve final dimensions.

Given the demonstrated antimicrobial properties of copper, it is incumbent upon materials scientists to design potent antimicrobial copper-containing stainless steels as an economical option.

Radio frequency inductively coupled plasma (RF-ICP) spraying is shown to be a promising method for producing oxidation-resistant W and W-Cr coatings on plasma-facing surfaces in fission and fusion reactors.

Enhanced antiviral performance is associated with antipathogenic copper material consolidations obtained using cold spray processing.

Many broken parts look similar at a glance, but examination of the failed part using advanced equipment and methods such as scanning electron microscopy (SEM) reveals much more about the origins of the failure. This article presents a case history involving SEM analysis of a trailer hitch fatigue failure.

New thermal and cold spray technologies are being developed to extend the lifespan of thermal barrier coating (TBC) systems at elevated temperatures. This article describes the relevant attributes of coating technologies such as high velocity air fuel, high velocity air plasma spray, and high pressure cold spray for use in TBC systems.

This article is the second in a two-part series on cost-saving methods for the production of titanium components. Part 1, published in the September 2012 issue of AM&P , covered a number of powder metallurgy techniques, including press-and-sinter and both cold and hot isostatic pressing. Other near-net shape processes are described here, including additive layer manufacturing (ALM), metal injection molding (MIM), and spray deposition (SD). Examples are also given showing how titanium PM parts compare with cast and wrought components.

Corrosion under insulation (CUI) exacts a heavy toll on petrochemical processing equipment, particularly piping, where leaks and safety risks associated with CUI drive maintenance costs. This article assesses the high cost of CUI and explains how the petrochemical industry is working to reduce those costs by protecting components with thermal spray aluminum (TSA) coatings and by employing complementary pipe welding procedures.

Laser surface modification (LSM) techniques provide new pathways to improving the performance of engineered structures and components, either by altering surface metallurgy or chemistry or by adding a functional surface layer.

Conventional manufacturing from wrought bar stock typically involves extensive machining, creates significant material waste (scrap metal), and requires numerous steps to obtain the final part geometry. As a more efficient alternative, powder metallurgical (PM) processes are now available to cost effectively fabricate both simple and complex shapes with minimal material waste. Combustion driven higher pressure powder compaction (CDC) for near-net or net shape manufacturing was recently developed. It offers a unique way of forming near-net or net shape high-density powder metal components both cost effectively and at relatively higher compaction pressures than other PM processes.

Using a physical vapor deposition process to manufacture medical device components reduces post-processing time and improves materials properties. This article addresses metallic sputter deposition technologies for Nitinol medical devices.

As the engineering systems of the world adapt and change due to the effects of the pandemic on global health and worldwide economies, engineers and scientists provide paths of preservation to ensure safe and reliable operations.

Plasma nitriding is very effective in removing the passive layer of chromium oxide formed naturally on the surface of stainless steel, but controlling the kinetics is key for optimal results.

Among the structural materials developed in the 20th century, titanium and its alloys have played a leading role in improving component performance. This article provides background on the extraction and primary processing of titanium.

New FDA guidance for Nitinol used in medical devices includes clarification on the determination of safety factors, the requirements for corrosion testing, and proper labeling of potentially harmful elements.

Field assisted sintering is a breakthrough technique for producing aluminum matrix composites that could replace high-density materials in a variety of applications.