Monday, September 4, 2017

High Performance Materials for Nuclear Applications

High Performance Materials for Nuclear Applications

Today’s nuclear reactors are old.  They require long storage time for spent radioactive reactor fuel.  In addition,  extension of life for an additional twenty years will be expensive.
Generation IV nuclear reactors are in the concept stage of design. These nuclear reactors would have advantage over existing nuclear reactors in many aspects. One concept is the design of a reactor that can be constructed and placed on a flat bed for transport to remote sites or sites requiring less space and less isolation. These lighter weight, more efficient, safer reactors would make it possible to establish the reactor at sites such as a waste water area, where the water could be purified for public consumption, and generate electricity for additional usage. Similarly these transportable reactors could be small enough and safe to power large industrial plants, building complexes and even small cities, if coupled with additional similar reactors to supply the required capacity. In addition, the energy produced is clean, could possibly be used to produce clean fuels, and could reduce or eliminate fossil fuels that currently pollute the atmosphere..
            To render these smaller reactors cost effective and safe; these reactors must operate at higher temperatures . Estimated temperature required for the short term is 8500C and ultimately 10000C..Higher operating temperatures cause problems because current alloys are not capable of resisting corrosion, and approach limits of functional capability at these temperatures. In addition any material selected must comply with ASME Boiler and Pressure Vessel Code Section III Division V.
Inconel 617 is one of the alloys of interest because it can satisfy high temperature mechanical properties and be accepted within the confines of the Code. Actually it could serve as components of pumps used to remove heat generated by the reactor, and also in DRECS that  serve as reservoirs for storage of the salt, if the alloy had improved surface protection against harsh corrosive environments, such as molten salts, which are being considered  as coolants. Therefore a coating resistant to the corrosive liquid salts or coolant specified is a must. Thin coatings are available but are not being considered as a solution to the corrosion problem because they have been found to peel, spall, debind and scratch over the service life of the part. Therefore, coatings greater than 0.635 mm are being considered to provide the required elevated temperature corrosion resistance.
MagnaTech has developed a process that provides protective surfaces that resists abrasion, impact and also provides excellent corrosion resistance from salt water. Surfaces  were produced to protect stainless steel and low alloy steels to combat the conditions required of shoes of hook points of F-35 aircraft. There was no spalling, peeling, or debinding  that resulted from the various impact or abrasion tests administered to the surface modified alloys. This was because the process is one that deposits atoms of carbon and/or nitrogen on the activated surface of the substrate to react with elements alloyed within the surface of the steel to form stable carbides and nitrides that provides surfaces that have no interface with the steel matrix. In addition, surface grain boundaries consist of stable carbides and/or nitrides that prevent grain boundary sensitization, resulting in improved corrosion resistance of the alloy, in this case resistance to salt water. MagnaTech believes that the same mechanisms used for the application intended could be used to provide the required surface resistance from the high temperature corrodants transported in pumps  to cool the reactor and in DRECS used to store the coolant , probably liquid salt solutions.
Markets will not be established until the early 2020 s. If developed a huge market for this clean, transportable energy source will rapidly emerge..

Monday, July 3, 2017

A Smaller Electronic World

Summer and the Holidays are here. It is a time to slow down, just a little. However, at times like this I have the luxury of "what iffing". At such times, I reflect back to what the world seemed to be when I was a young engineer. Steel was the material of choice for good reason:  it was cheap, it was abundant, and it had the properties of strength and ductility.
Slowly but surely I watched as new elements began to fill the periodic table New, more exotic microscopes emerged that permitted us to observe topography, defects, and even determine phases and chemistry of these phases. Eventually we could strip atoms from surfaces and determine the composition and degradation of protective surfaces, atomic layer by atomic layer. Now equipment is available that permits us to even look within the atom itself. Thermodynamics became important, and for early designs such as cars and aircraft, stainless steels and superalloys emerged, permitting jet aircraft and space vehicles to become possible. Coatings were developed that protected vulnerable surfaces from oxidation, wear and shock. Processes and techniques were developed to shape and join components together to make more sturdy structures for sea worthiness, windmills and nuclear reactors for efficient electrical energy.
However, with the good comes the bad. As more and more of the resources available courtesy of Mother Nature were depleted and processes required for reclamation, purification, fabrication and operation increased, resources required to do these operations resulted in increased pollution of our environment. Therefore we found ourselves seeking alternate materials and processes that would reduce weight, improve efficiency, reduce cost and permit increasing opportunities to make things that were currently not possible.Weight became cost saving in material, time and labor. For example, in many applications, such as turbine blades, expensive superalloys, containing more expensive alloying elements. to provide high temperature properties such as creep resistance, and prevent more reactive corrosion from occurring at the higher temperatures of operation, limitation of usage resulted and expense became  burdensome for small gains in material properties.
To alleviate some of these problems, solutions were first pioneered again by the auto and the aircraft industry to further reduce weight by looking for new alloy systems that would have higher strength without sacrifice to ductility. Therefore more interest in titanium, aluminum and magnesium alloys. One way of accomplishing this is through powder metallurgy. It  is well known that different tools are available to improve strength of light alloys made from powders. The problem remains how to do this without limitation of ductility.Methods have been developed to atomize fine powders in atmospheres that protect surfaces from contamination, thereby improving densification when consolidated,  with improved ductility. New alloy systems are being developed to take advantage of the new processing of powders.In addition, there is new interest in producing more ductile composite powders and ceramics that may have high temperature strength with improved ductility. If this happens then space becomes the new world and transportation becomes faster, providing opportunities not realized to date.
Powders are not limited in the size of a part being produced. For instance, already possible are production of orthodontic devices to improve functions of the mouth. These devices are made possible by recently developed metal injection molding processes. Other medical devices, such as small stents, have served to improve human and animal life. These are small  parts. They are expensive, but they cannot be made by  currently developed procesess.
However, not so fast, because now new processing has emerged called advanced manufacturing, because it includes several current technology under development. Not only were processes required to produce new undeveloped powders with undefined properties but instruments, such as lasers and electron beam guns were required to deposit the powders in atomic layers quickly, where they are melted and built layer by layer from the smallest conceivable part to an auto body or even a nuclear reactor structural member. These developments are in progress currently. By use of the computer and robots, these structures can be made, small or large, atomic layer by atomic layer with no restriction of geometry. Therefore, thin parts with complex designs not possible before become reality. I could go on, because there is much more to come that is even more mind boggling.
The other buzz word of the day is modeling. This is a new term but an old concept. Back in the 1980s it was known as regression analysis and it came on because hand held computers became available. These permitted storage and saving of information.Today we have aging equipment and processes that have not been maximized for efficiency and precision. Today's technology requires improved efficiency, and in many cases, precision. Through examination of critical variables that could affect the properties, these known, established processes can be fine tuned to yield higher quality functioning parts. Alloy systems and processes can become more efficient, resulting in significant savings.Therefore many well known processes are undergoing modeling studies today to make improved parts at lower cost. Not a new thought--just made faster through use of the computer.
Therefore, to the young materials engineer just starting his or her career,, hang in there. This is still an exciting world with much still to be accomplished. You are that young engineer as I was in days of yore, watching a steel industry and a transportation industry grow. Hey, it just ain't over til the fat lady sings.

Friday, May 19, 2017

Aging Equipment

Current aircraft are designed to last for 40 years. In some cases,the life of these aircraft have been extended well over this time period, and ways to extend life further are being considered. In the case of landing craft gear on the plane, this equipment encounters the most stressful conditions.  For instance,if the plane is to accomplish its mission, it must take off and land each time. Therefore, it is difficult to truly determine the pressurization cycles sustained.
In the case of landing gears, the plane lands at approximately 180 mi/hr. Depending on the weight of the aircraft, you can understand that the conditions for stress are high for each cycle of landing and take-off sustained. Therefore as the number of landings sustained increase the effect of any defect present in the material becomes the initiation for a fatigue crack. Fatigue starts normally at the surface. The effects increase with stress  associated with repeated landings. As the number of cycles of landing increase, so to does the stress or work hardening increase. If a defect is present, then when the stress increases to a certain level  a small crack, known as a microcrack occurs at the defect. Once micro- fracture relieves the sustained stress, then the microcrack is arrested and the sequence of events begins once more, until the stress level is such that further crack extension occurs. This concept is known as fatigue. Therefore these events will continue until the remaining non-stressed area cannot support the forces or stresses sustained in landing. At this point catastrophic failure occurs, resulting in severe danger to the pilot and the expensive aircraft.
In the present sense the flight crew watches progress. When defects in excess of about 0.040 inch are observed the landing gear components are inspected to determine the extent of the damage. Unfortunately, records can become lost and errors or misinformation can result.
The process used for manufacturing these critical parts begins with the manufacture of the steel selected for the component. All steels have defects called inclusions, porosity and perhaps surface corrosion. These defect can be extremely small and difficult to detect. Currently these defects are not often detected because of their small size. Techniques are currently available to permit detection of inclusions 0.040 in size. However, current efforts are attempting to designate inclusions less than 0.010 inch and as small as 0.001 inch. These would be difficult to accomlish using current maintenance.
Therefore a study and record of the total processing conditions becomes of importance. Once the steel is obtained and certified regarding defect content,  machining of the component begins. Generally this is under control, but often defects can occur from poor machining practice. Once the component is machined, then the part must be heat treated to achieve the proper core properties to sustain the stresses that will occur in service. This process to can result in the formation of microcracks, ultimately resulting in fatigue.Finally there is cause for concern of corrosion resulting from operation in harsh environments. Therefore,the parts are normally chrome plated  after heat treatment. This process is quite often a severe problem because of the different expansion rates between the steel and the chrome plate. Therefore the possibility of defects sustained in processing become the limiting factor in the life cycle of the component. MagnaTech intends to propose solutions to identify causes and minimization of these defects in a proposal currently being prepared. MagnaTech is looking for prospective partners to co-operate in resolution or minimization of the current problem.

Saturday, March 18, 2017

A Changing Materials World

A new President and a change in direction for manufacturing in this country. The outgoing flow of manufacturing  from the country has been stemmed and now there is an influx of manufacturing back into the country. In addition, the direction of attention of available resources, both human and material are now starting to be driven in a different direction, both as an effect of policy change as well as obsolescence of things that should have been maintained properly or that merely have reached the end of their life cycle.At any rate the change bodes new challenges and requires different assets to accomplish the job.
To regress, I entered the materials world as a young engineer in the 1950s. At that time, it was a different world. Most of the periodic table was empty at that point. Steel was the material of choice because of its abundance, its cost, and a foundation of an industry ready to produce it, shape it, heat treat it for desired properties and finish it into shapes required for a growing list of applications. Plastics were used for toys and even then, a now-banned lead was used to cast toys. Aluminum was light and therefore it was ideal for an emerging aircraft industry. Because of cost of producing it, expense of material was too great for anything else. Not many remember that the first aluminum utensils were for the French King on his birthday. The other materials that were used were copper alloys, brasses and bronzes, and that was about it.
However, today all of this has changed. The periodic table is now full. From a few basic steels, an extensive Table, listing steels for many different applications, is available and more steels are constantly being added. These include steels for structural applications, chromium steels for hot working, such as dies for extrusion and forging, tool steels, a growing list of stainless steels for corrosion resistance, specialty steels, and now micro-alloyed steels. In addition, because of need for lightness, aluminum and titanium alloys are now under development. Nickel, cobalt and iron superalloys are available for today's aircraft requiring increased payloads and designed to fly at higher altitudes. Chromium and refractory alloys are now starting to emerge for space applications requiring even higher temperature and corrosion resistance.  Sounds exciting? well yes, but with the loss of manufacturing to outsourcing we have a problem of skilled labor. This includes people that use their hands as well as their brains. In other words, with the influx of returning industry and a change in priorities for manufacture, there is now becoming a shortage of people that were machinists, die makers, welders and other skills requiring hands-on skill. These people were developed in special schools called Trade Schools. However, due to over supply, these schools have largely disappeared and to make matters worse the pool of qualified machinists and welders, etc, is aging at a time where more are needed. Robots are replacements, in some cases, however, we now start limiting available jobs, and that is another problem.
Therefore, where are we going today? Well certainly we need people to man industry returning to the country. In addition, look at the national statistics of our transportation system. In our area, trains ordered by the transit system have faulty welds and they require repair. Track for railroads is old and new technology is required to improve travel by train. Bridges are all aging and are in desperate need of repair or replacement. Newer improved roadways are needed. In addition, our nuclear reactors are also aging and in need of costly repairs or replacement. These reactors provide the cleanest energy that we have to date. They also hold the promise of production of cheap hydrogen to replace environmentally unfriendly hydrocarbon fuels. New energy efficient housing is required. All of this requires laborers with hands on experience. Therefore, we predict that in the near future, more emphasis will be placed on re-establishment of trade schools. These will become alternatives to the complex issues now emerging at our Universities.
Yes, a changing world, some of it back to the basics. However, there is always a need for new technology, with some of the problems that it brings. Except for offshore rigs, the ocean remains largely unexplored and it is three quarters of the earths surface. In addition we are fast approaching the capability of faster travel and even unmanned  space travel. Even colonization of unknown worlds is becoming a possibility. My kids when they were young used to say," are we there yet."? I'm afraid the answer is still no. There are a lot of challenges in the next few years. Change is always with us and as long as brain power and skill of hand power is required, it remains a good and an exciting thing. I look forward to the next few years as we begin building our infrastructure.

Saturday, February 4, 2017

Expansion In Magnetic Technology

MagnaTech has been active in development of soft magnetic alloys since the 1980s. At that time Hoganas Sweden developed a powder metallurgy alloy that contained phosphorus. However, Hoganas did not develop the alloy for magnetic applications, but because it contributed solid solution strengthening to iron.
At this time, in America, General Motors was developing a new motor concept for automotive engines. They therefore approached Hoeganaes, Riverton for assistance in making this part. However, General Motors was familiar with silicon steel,  not powder metallurgy. Therefore we convinced GM  that this new phosphorus iron  I was developing for magnetic relays would do the job for their application. Therefore, the phosphorus irons were developed for magnetic applications and a new market for powder metallurgy technology was born. Later on, powder metallurgy ferritic stainless steels were developed for applications that sacrificed some magnetic performance for improved corrosion resistance.
Since then MagnaTech has become more active in consulting and testing of laminated magnetic alloys, such as molybdenum permalloy and iron cobalt alloys. MagnaTech has used only ASTM Specification BA596 (Equivalent ASTM A773) for testing these materials, and continues to do so. However there is now a demand for determinimg core loss of these materials for AC applications. MagnaTech is considering modifying their test equipment to also accomplish this testing in accordance with ASTM A927.
In addition to the above, the alloys of interest require carefully controlled heat treatment to perform to the level expected of the device.MagnaTech is interested in developing qualified sources to provide this service.
MagnaTech has been active both in research and development of heat treatment of these materials as well as in development of procedures for the testing of these magnetic materials that require properties for critical performance. If your company has need for these services please contact MagnaTech and we will quickly respond to your requirements.