electromagnetic processing of sintered powder metal parts
“Spark Plasma Sintering” by the Idaho National Laboratory via Flickr is licensed under CC BY 2.0

Sintering is the process of compacting a material, usually in powdered form, into a solid mass using heat or pressure, but without melting the material. It is a manufacturing technology that dates back to at least 3000 B.C. and was used to make ceramic objects that were hard to cast. Modern sintering of metallic and cemented carbides started in the 20th century. Today, nearly 20% of automotive parts are now produced by the powder metal (PM) sintering process.

The advantages of PM is the ability to produce net-shape parts that require minimal or even no machining. However, PM parts have pores, and this porosity has its advantages and disadvantages. The main advantage is that porous metals can be used to make oil-impregnated bearings that are, therefore, self-lubricating. The main disadvantage is that pores are actually defects in materials. The PM industry is, therefore, trying to make parts that have a high density (less porosity) for improved properties and performance. To make parts that approach the full density of the material being used is the “Holy Grail” of the PM industry.

One method for enhancing the density of sintered metal parts is to treat the parts with high magnetic fields. Many of us have seen demos where coins are shrunk in magnetic fields. The coins become smaller (a nickel becomes the size of a dime), but thicker, because the compressed material must go somewhere. With a sintered part, the same kind of magnetic treatment should simply push material into the existing pores, thus increasing the density of the part and decreasing its porosity. In addition, this magnetic compression will affect other properties of the part.

In this study, a small sample is placed inside a coil at the National High Magnetic Field Laboratory in Tallahassee, Fl. The sample had a radius of 0.375 (or 3/8) inches and a thickness of 0.3 inches. It was compacted to these dimensions with a pressure of 30 tons per square inch by Atlas Pressed Metals of DuBois, PA. The coil is connected to a capacitor charged to 7 kV. When the switch is closed, a large pulse of electric current (maximum value, one hundred thousand amps) runs through the coil for a little longer than a microsecond. The large current creates a large magnetic field in the coil of the order of 40 Tesla, or about eight hundred thousand times the strength of the earth’s magnetic field (magnetic fields in MRI machines are typically about 1 to 3 T). This magnetic field creates a maximum pressure on the sample of almost 60 tons per square inch.

The dimensional and property changes of the processed part depend on the electrical conductivity of the material. For steel, even with this large pressure, the volume of the sample doesn’t change much, but the small compression increases the density by about 2% when compared with a similar sample that is not subject to the magnetic field. In addition, the hardness of the sample is increased by the treatment. The texture of the em-processed specimen is also different, along with its response to heating and cooling cycles: the em-treated specimen shrank less when cooled and expanded less when heated. This means that it was less sensitive to temperature changes, a property that is highly desirable in many applications.

This initial study suggests that electromagnetic treatment of sintered parts can provide some advantages over sintering only. This process is also environmentally friendly, with few emissions.

These findings are described in the article entitled, Application of electromagnetic processing for development of high-performance sintered powder metal parts, recently published in the journal Current Applied Physics. This work was conducted by Daudi R.Waryoba from Penn State University and Winston Roberts from Florida State University.

TECH NEWS RELATED

National scientific-technological development and innovation strategy approved

Science, technology and innovation will play important roles in developing key industries in Vietnam. – Illustrative image (Photo: VNA)  Hanoi (VNA) – Deputy Prime Minister Vu Duc Dam has signed a decision to issue a strategy for scientific-technological development and innovation until 2030.Accordingly, science, technology and innovation will play important ...

View more: National scientific-technological development and innovation strategy approved

NASA JPL Says Voyager 1 Spacecraft Seem to Be Mysteriously Confused With Data

NASA experts are investigating a mystery with Voyager 1 spacecraft’s telemetry data. In a statement, the space agency said that the Voyager 1 probe, which is presently 14.5 billion miles beyond Earth, is receiving and executing orders from a NASA team on Earth and transmitting back science data. However, data from ...

View more: NASA JPL Says Voyager 1 Spacecraft Seem to Be Mysteriously Confused With Data

China will soon launch a huge space telescope with a 2.5 billion-pixel camera

China’s first large space telescope could launch as soon as 2023. The new telescope will be called the Chinese Space Station Telescope. It will be roughly comparable to NASA’s long-standing Hubble Space Telescope, though its field of view will be somewhat larger. China’s first large space telescope could launch ...

View more: China will soon launch a huge space telescope with a 2.5 billion-pixel camera

Physicists Control Reactions With Laser Light at the Nanoscale

A nanoparticle in the field of a femtosecond laser pulse with tailored waveform and polarization. The controlled enhancement of the field in specific nanoscopic regions of the nanoparticle (yellow spots) induces site-selective photochemical reactions of the molecules adsorbed on the surface. Imaging of the molecular fragments emitted from these ...

View more: Physicists Control Reactions With Laser Light at the Nanoscale

Solar Orbiter Captures New Before Seen Footage of the Sun

The new videos that were captured by the ESA and NASA’s Solar Orbiter show the Sun in a brand-new light. The said videos were captured during the probe’s first close perihelion passages. This is the first time that the space probe will zoom in on the Sun’s details. New ...

View more: Solar Orbiter Captures New Before Seen Footage of the Sun

What Is Monkeypox? A Microbiologist Explains What’s Known About This Disease

The first human case of monkeypox was recorded in 1970 in the Democratic Republic of the Congo (DRC) during a period of intensified effort to eliminate smallpox. Credit: CDC On May 18, 2022, Massachusetts health officials and the Centers for Disease Control and Prevention (CDC) confirmed a single case ...

View more: What Is Monkeypox? A Microbiologist Explains What’s Known About This Disease

Novel Preclinical Drug Could Have Potential to Combat Depression, Brain Injury, and Cognitive Disorders

Summary: A preclinical drug that inhibits the kinase enzyme Cdk5 may have the potential to treat depression, brain injuries, and disorders associated with cognitive impairment. Source: University of Alabama Birmingham James Bibb, Ph.D., and colleagues have described a novel preclinical drug that could have the potential to combat depression, brain ...

View more: Novel Preclinical Drug Could Have Potential to Combat Depression, Brain Injury, and Cognitive Disorders

Ruminating on Our Ruminations Causes More Depression

Summary: Negative metacognitions and rumination can exacerbate symptoms of depression, researchers say. Source: NTNU Once you have depressive symptoms, it’s easy to fall into a pattern where you aggravate the disorder by ruminative thinking. One of the key issues is what is called negative metacognitions, a phrase that needs an ...

View more: Ruminating on Our Ruminations Causes More Depression

Sixth child in US dies of unexplained hepatitis as global cases top 600

Serious spacesuit problem forces NASA to pause ISS spacewalks

Analysis of prehistoric feces shows Stonehenge people had parasites

Climate Crisis Is Driving Cousins of Zazu, From the Lion King, to Local Extinction

Brain Mechanism Tied to Age-Related Memory Loss Discovered

In Defense of Bread – The “Staff of Life” Throughout History

Unique quantum material could enable ultra-powerful, compact computers

Unraveling a perplexing explosive process that occurs throughout the universe

Geothermal drilling successes offer potential gain for petroleum industry

Where do "Hawaiian box jellies" come from?

All-optical phase recovery and quantitative phase imaging performed instantly without a computer

Researchers demonstrate organic crystals can serve as energy converters for emerging technologies

OTHER TECH NEWS

Top Car News Car News