The Technology

Polymer composites have become an integral part of modern life due to their light weight, ease of processing, and exceptional combination of properties. They are now found in aerospace, aviation, and even defense industries. In this context, the use of polymer composites for radar absorption applications has been discussed.

Radar is a detection system that uses electromagnetic waves to determine information such as the distance, altitude, direction, or speed of objects. It can detect both moving objects such as aircraft, ships, and vehicles, and stationary ones such as terrain. Radar can also be used to gather meteorological data. This technology, which revolutionized air and naval warfare, is one of the most important technological developments of World War II. In fact, the term RADAR was coined in 1940 by the U.S. Navy as an acronym for RAdio Detection And Ranging. Since then, it has gained importance not only for military and police use but also for flight navigation and weather observation.

At first glance, radar operation seems simple: a signal is emitted, it bounces off an object, and the reflected signal is received. This is similar to how an echo works—but instead of sound, radar uses microwaves. The degree of reflection and refraction depends on the properties and surface of the material hit by the signal. When a radar signal strikes a perfectly flat surface, it is reflected in one direction. When it hits an uneven surface, it is scattered in multiple directions, and only a small portion of the original signal returns to the receiver. Another way to reduce the reflected signal is through absorption of the radar waves by the material itself.

Radar-absorbing materials (RAM) have a mechanism that traps incoming radar waves within the material, preventing them from being reflected. The earliest forms of such materials were developed by the Germans during World War II.

Barium hexaferrite and ultrafine copper powder were used to produce radar-absorbing composite coatings. The barium hexaferrite powders were synthesized using the sol-gel method. After synthesis, mixtures were prepared by adding barium hexaferrite and ultrafine copper powder in various amounts to a polyurethane resin (to determine the dependence on concentration). These mixtures were then applied to glass and metal substrates, producing coatings about 3 mm thick, which were dried at room temperature in air.

The morphology of barium hexaferrite shows smooth-edged, plate-like particles with an average particle size of about 5 μm. The copper particles are relatively large, between 7–10 μm.

The radar absorption of the sample containing 5% barium hexaferrite and 10% copper powder reached a maximum of 11.38%, while increasing the copper content further boosted absorption beyond 12%. Theoretically, maximum absorption could exceed 80%.

As for the mechanism of copper, copper itself does not absorb electromagnetic waves. The radar absorption mechanism in copper differs slightly from that in barium hexaferrite. When electromagnetic waves strike the copper surface, the electric field drives free electrons, generating an alternating current. These oscillating electrons create a magnetic alternating field in and around the conductor. This generates an electromagnetic counterforce that confines the charge carriers to the surface of the conductor. Thus, the electromagnetic waves are either absorbed by the electrons or reflected in the same direction, with some of the electromagnetic energy dissipated as heat.

Analysis of the results shows that coatings reinforced with barium ferrite and copper powder exhibit higher magnetic saturation values than single-component coatings. As the amounts of barium hexaferrite and copper increase, radar absorption also increases. The addition of barium hexaferrite and copper therefore creates a synergistic effect, enhancing absorption performance. This synergy arises because the additives contribute independently through their magnetic and electrical properties—each activating different mechanisms that together improve radar absorption.

The Copper Powder Market

Copper powder is primarily produced in Russia, Canada, and Chile. In Canada and Chile, mostly biologically derived, nearly spherical copper powder is made, often used in pharmaceutical applications. In Russia, nearly all copper powder production is for technological uses.

With the (hot) war Russia began against Ukraine in 2022, global trade patterns changed dramatically. Western banks now rarely process payments related to Russian goods. As a result, thousands of Russian companies restructured—relocating operations, moving machinery abroad, or restarting under new names in neighboring countries. Consequently, we now see copper powder producers operating along the Russian border, from Estonia to Kazakhstan.

Because most producers of ultrafine metallic powders are our clients, we are in a good position to monitor the market for ultrafine copper powder. We have seen increasingly large volumes traded. In 2018, global trade was estimated at around 20 tonnes. By 2023, we alone observed over 60 tonnes changing hands, suggesting a current annual market volume of roughly 100 tonnes.

Since demand in other known application areas of copper powder has not grown nearly as much in the past five years, we suspect the emergence of a new player — the military. Known applications for copper powder include: electronics, semiconductors, antibacterial coatings, 3D printing, pharmaceuticals, and paint production.

For the military, the potential applications are virtually limitless. From satellites to armored vehicles, anything could be made invisible to modern radar systems. Such a tactical advantage could be worth billions of U.S. dollars to the world’s militaries.

We will continue to monitor this market and report again.

HF • Atomic Number 72

• History

  Hafnium was discovered in 1923 by Dutch physicist Dirk Coster and Hungarian-Swedish chemist George Charles von Hevesy. They identified it in zirconium minerals from Norway and Greenland by analyzing their X-ray spectra. The element was named after the Neo-Latin name for Copenhagen, Hafnia, the city where it was discovered.

  The discovery history of hafnium involved a long search. Dmitri Mendeleev had predicted in 1869 an element with properties similar to titanium and zirconium. Many scientists searched unsuccessfully, including Georges Urbain and Henry Moseley. Misinterpretations led to false claims of discovery, such as “Celtium” in 1911, which was later identified as lutetium.

  In the 1940s, the U.S. nuclear industry began using hafnium for control rods in nuclear reactors because, unlike zirconium, hafnium strongly absorbs neutrons.

• Application

  The largest application area for hafnium is the aerospace industry. It is used in superalloys for components such as engines and in the form of hafnium-containing coatings for high-temperature components.

  Another significant consumer of hafnium is the nuclear power industry. Due to its high neutron absorption cross-section and excellent mechanical properties, hafnium is used in control rods in nuclear reactors.

  Hafnium also plays a role in microelectronics and the semiconductor industry. In capacitors, hafnium is used as a high-k dielectric. It can replace silicon dioxide, enabling thinner insulating layers, which improves the performance and miniaturization of semiconductor devices.

  New findings regarding the properties of hafnium oxide suggest that these materials could play a key role in the development of new memory technologies. Due to the ferroelectricity of hafnium oxide, data can be stored for extended periods without power. These memory applications could pave the way for larger and faster computer systems by reducing the heat generated through continuous data transfer to volatile memory.

• Occurence, Mining and Extraction

  The most important minerals for the commercial extraction of hafnium are zircon and baddeleyite, which occur as by-products during the extraction of titanium minerals. In nature, hafnium is always bound to zirconium compounds and is difficult to separate.

  Due to the strong chemical similarity between hafnium and zirconium, separating the two elements from each other is very complex and expensive. The preferred methods for separating hafnium and zirconium are ion exchange and solvent extraction techniques. However, for some applications, separation of the two elements is not necessary.

  The main producing countries for hafnium-containing zirconium minerals are Australia and South Africa, where they are obtained from mineral sands and river gravels. By far the largest reserves are located in Australia.

  The Australian mining company Iluka Resources is the world's largest producer of zirconium ores, followed by the US company Tronox and the British-Australian mining corporation Rio Tinto.

  Framatome, a subsidiary of the French electricity company EDF, dominates the market for nuclear-grade hafnium. Allegheny Technologies Incorporated is the leading US manufacturer of hafnium for the aerospace and nuclear industries, producing highly pure hafnium for turbine blades.

  China National Nuclear Corporation is China's largest producer of hafnium.

  Chepetsky Mechanical Plant, a subsidiary of the state-owned corporation Rosatom, is an important Russian manufacturer supplying hafnium for the domestic nuclear and defense industries.

  In 2024, the global sales volume of hafnium (Hf) is estimated at around 80 tons; however, the exact quantity cannot be determined with certainty due to secrecy in the nuclear and military sectors.

  Developments in the electronics industry, increased investments in the defense sector, and the expansion of nuclear power plants are driving the growing demand for hafnium.

• Substitution

  In alloys, hafnium can be replaced by magnesium, cobalt, chromium, niobium, and tantalum. In certain superalloys, hafnium is interchangeable with zirconium.
  In control rods of nuclear reactors, boron or cadmium-silver-indium alloys can be used instead of metallic hafnium.

   

Conflict in Central Africa: The Dark Side of Global Electronics

For more than three decades, a devastating conflict has raged in Central Africa — one that, since the 1994 Rwandan genocide, has rarely made global headlines. In recent months, the situation in the Democratic Republic of the Congo (DRC) has become increasingly tense. UN observers fear the region is on the brink of a regional war. Yet anyone using an electronic device is likely holding a small piece of the Congo in their hands — and, unknowingly, a link to this conflict.

The DRC is exceptionally rich in the very materials that power modern technology. It is one of the world’s leading producers of tantalum, tin, tungsten, and gold — collectively known as the 3TG conflict minerals, as defined by the U.S. Dodd-Frank Act and the EU Conflict Minerals Regulation. Both laws were enacted in response to the decades-long Central African conflict. Since 2021, EU companies importing these minerals have been required to ensure due diligence in their supply chains, while U.S. companies have had similar obligations since 2010.

The World’s Largest Neglected Refugee Crisis

Eastern Congo is plagued by violence involving over 100 armed groups. Civilians face massacres and extreme sexual violence. The number of displaced people in the northeast alone has reached 5.5 million, making it the world’s largest neglected refugee crisis.

The provinces of North and South Kivu, bordering Uganda, Burundi, and Rwanda, are home to rich coltan deposits— the ore from which tantalum is extracted.

Tantalum is extremely rare and highly valued for its stability and heat resistance. Its primary use is in the electronics industry, particularly in capacitors, which store electrical charge on circuit boards — a key component in virtually every electronic device. About 60% of global tantalum production is used in electronics.

Tantalum is also essential for semiconductor manufacturing — a crucial factor as the U.S. tightens export restrictions on semiconductor products amid its technology war with China. The metal is further used in jet engines, where its heat resistance improves fuel efficiency, and in smartphones, where it’s found in RF filters in antennas.

Rising Demand for Tantalum

Market analysts expect growing demand for tantalum, both as an alloying element and due to 5G technology expansion. It may also gain importance as an anode coating in electric vehicle batteries. Because of its biocompatibility, tantalum is increasingly used in medical implants.

In 2023, the DRC produced about 980 tons of tantalum, mostly from North and South Kivu. The Congolese government, however, has lost control of vast areas in these provinces and blames Rwandan President Paul Kagame for supporting the March 23 Movement (M23) — a Tutsi-led rebel group that broke away from the Congolese army in 2012.

A UN expert report (December 2023) provides serious evidence supporting Kinshasa’s claims, alleging that Rwanda’s government supplies M23 with weapons, materials, and even regular army troops.

The DRC remains the world’s leading tantalum producer, with about 35% of the global market share in 2023. However, some reports suggest Rwanda may have surpassed its much larger neighbor that same year.

Rwanda Accused of Resource Plundering

The Congolese government has long accused Rwanda of plundering mineral resources in eastern Congo through the M23 rebels and smuggling them across the borders into Rwanda and Uganda — while the international community turns a blind eye.

According to Congolese Finance Minister Nicolas Kazadi, the country loses nearly $1 billion annually due to mineral looting. “Since Rwanda has few deposits of its own, it is obvious that everything comes from the DRC,” Kazadi told the Financial Times.

Rwanda denies all allegations. The U.S. and France have called on Rwanda in the UN Security Council to withdraw from Congo and end support for M23. Kinshasa, in turn, was urged to cease collaboration with militias that also commit atrocities against civilians. There is also evidence suggesting that rival groups cooperate in smuggling minerals.

Congo’s Legal Battle Against Apple

Congo’s President Félix Tshisekedi has been striving to draw international attention to the crisis. In late 2023, he hired an international legal team to explore a potential lawsuit against Apple, accusing the tech giant of using smuggled minerals from Congo in its products.

The lawyers sent a letter to Apple CEO Tim Cook in April 2024, to which the company has not yet responded — a silence the legal team interprets as a sign that Apple is reluctant to give precise answers.

Breakdown of Responsible Sourcing Verification

Apple’s compliance reports claim there is no evidence that its refiners of tin, tungsten, or tantalum directly or indirectly finance armed groups in Congo or its neighboring countries.

However, UN experts warn that coltan ores from Rubaya, a mining area in North Kivu, are being traded under ITSCI traceability tags — a system run by the International Tin Association meant to ensure that minerals are responsibly sourced.

According to the UN report, ores from Rubaya are also being smuggled into Rwanda. The ITSCI program suspended operations in North Kivu on April 30, 2024, after M23 rebels took control of the region.

While ITSCI tags are designed to ensure that mineral extraction in unstable regions does not fund armed groups, violate human rights, involve child labor, or encourage corruption, observers say the system is failing.

Mining in eastern Congo is largely artisanal, taking place in remote, unregulated areas with rudimentary tools. According to a 2022 EU-funded report, illegally mined coltan is often brought at night into “legal” mines to be tagged. Official ITSCI tags are also sold on the black market.

“Consumers cannot be certain about the origin of the tantalum in their electronic devices,” the report concludes.

Industry insiders have also criticized ITSCI for publishing data with a one-year delay and aggregating ore weights for the entire region rather than by country — making it impossible to verify whether Rwanda’s production truly comes from domestic mines or from smuggled Congolese material.

Tantalum Chart 2011 bis heute – Quelle: Screenshot: WWW.ISE-AG.COM

Bloody Conflict and Tantalum Mining Are Not Mutually Exclusive

Despite the renewed outbreak of violence in eastern Congo since late 2021, no significant disruption of global tantalum supplies or prices has occurred. In fact, history suggests the opposite: the conflict in eastern Congo has persisted almost continuously since 1994, yet tantalum production began to accelerate around the turn of the millennium. This coincided with the rise of Silicon Valley, the boom of the electronics industry, and the spread of mobile phones.

At the same time, Australia — previously the world’s main tantalum producer — withdrew from the market, as the metal was primarily obtained as a byproduct of lithium mining. This caused a sixfold surge in tantalum prices, sparking a small-scale mining boom in eastern Congo and establishing Central Africa’s central role in the global tantalum supply chain.[xxi]

By 2009, the coltan trade and mining sector in the DRC employed around 300,000 people. Other major producers include Brazil, Nigeria, and China, while Australia and Brazil together hold about 60% of the world’s known tantalum reserves.[xxii]

EU Support for Rwanda with Weapons and Money

How is it possible that, despite Western companies’ due diligence obligations, conflict minerals continue to find their way into everyday consumer goods?

One reason is that EU regulations only apply directly to importers of raw ores — i.e., refiners and smelters. Companies that process or manufacture intermediate or finished products containing these metals are only indirectly affected by the regulation.

Another issue, from an African perspective, is the financial and military support that Western countries provide to Rwanda. While Western governments publicly urge Rwanda to withdraw from Congo, they simultaneously supply the country with money and weapons.

For example, Poland sold weapons worth nearly €5 million to Rwanda in 2022. In return, Rwanda exported mainly tungsten and tin to Poland.[xxiii]

Currently, the European Union plans to provide Rwanda with €40 million in support. The funds are intended for non-lethal military equipment and air transport for Rwandan troops deployed in Mozambique’s Cabo Delgado province since 2021. There, Rwanda is helping to suppress the local branch of the Islamic State, which has disrupted the operations of French energy giant TotalEnergies.

TotalEnergies has been trying to develop a €20-billion liquefied natural gas (LNG) project in the region — a project that has faced repeated delays due to insecurity.[xxiv]

Rwanda had already received €20 million from the EU’s Peace Facility in 2022 for its military involvement in Mozambique.[xxv]