Tungsten Infiltrated

Tungsten base infiltrated metals with either copper or silver as infiltrates have been widely used in industry for many years. The major uses include missile vector control vanes, nozzle and throat materials, missile plume deflector shields, electrical contacts, resistance welding contacts, and porous emitters.

Recently, the aerospace industry has opened up an entirely new field for both tungsten-silver and tungsten-copper composites. These, with approximately 90 weight % tungsten have proven highly advantageous because of their excellent mach inability. Complicated forms of nozzles and inserts can now be machined from a powder metallurgy product. Excellent thermal shock resistance, especially during firings, ablative cooling by silver vapor or copper vapor, and approximately 10% less weight than pure tungsten, with much easier handling, are additional benefits of infiltrated compounds.

Infiltrated tungsten powder is extensively used as matrix support material in diamond rock drilling bits. Its main function is to hold the diamond grit in place and the purpose of infiltrating the tungsten powder is to form a strong chemical bond between the diamond and the matrix.

It has been estimated that only 1/10 of the diamond grit is actually consumed in the intended cutting application. The remainder of the grit is wasted either by being left over when the tool’s useful life has expired or by being pulled-out or broken during use due to poor attachment and inadequate support.

The ideal support for the cutting particles is to have a matrix hard enough so that it will gradually of delaminating, plowing, cracking, cutting and fatigue fracture. The displacement of the abrasive particle on the surface of the matrix and the subsequent passes of other abrasive particle cause the detachment of small chips, usually by a fatigue-controlled mechanism. If the matrix is more brittle in nature, with a propensity for cracking during plowing, then fracture is the primary material removal mechanism. The ability of the infiltrate alloy to hold the tungsten particles together, measured by the amount of ductility of the composite, has been shown to have a major effect on the amount of plastic deformation of the composite prior to the formation of micro cracks due to wear. Most of the diamond drill manufacturers and the geological exploration companies agree that the performance of the bit is greatly affected by the type of infiltrate alloy, even when the percentage of the infiltrate alloy does not exceed 30% by weight.

In addition, the use of secondary abrasive particles has been found to be a very effective method to improve the wear resistance of the MMC. Harder particles such as TiB2, TiC and TiN added to Ti powder caused a significant the samples infiltrated with 60Cu–40Ag and 65–70wt% tungsten in the samples infiltrated with 56Cu–43Zn–1Sn. The green compact and the graphite mold were placed in a box furnace under a partially protected atmosphere generated by adding activated carbon on top of the infiltrate alloy. The type of infiltration can be described as infiltration by capillary forces aided by gravity. That is, the infiltrate alloy was placed on top of the green compact. The temperature of the box furnace was kept 100C over the fusion temperature of the infiltrate.

In some of the 60Cu–40Ag and 56Cu–43Zn–1Sn samples, single additions of 3% by volume of SiO2, SiC and WC were made to the tungsten powder before infiltration. The material infiltrated was disk-shaped, 38 mm diameter and 6 mm thick.

Tungsten Copper Mounts

Copper Tungsten Mounts Keep Diode Lasers Cool
In addition to traditional heat sinking in packaging of microelectronic dies, more demanding applications are emerging for copper/tungsten (WCu) metal-matrix composites (MMCs) as mounts and submounts for semiconductor laser diodes. Currently, the majority of semiconductor laser diodes are mounted on a mount or submount made out of WCu. Improved thermal expansion match between the heat sink and the die, coupled with the current trend of increasing die size and power-dissipation requirements, has made WCu the material of choice for packaging laser diodes. This is particularly true for die larger than 1000 µm in any direction. Copper/tungsten provides the needed thermal dissipation and good thermal expansion match. Some laser diodes are mounted directly on oxygen free high purity copper, on a beryllia or aluminum nitride ceramic substrate, or even on a diamond substrate.
The majority of power semiconductor laser diodes manufactured for wavelengths in the 800 to 1550 nm range have benefited from the improved performance of the new WCu heat sink bases. Applications include medical, scientific, and fiberoptic-based communication networks, among others.

Copper Tungsten Mounts Changing Conventions
Conventional copper tungsten heat sink bases provide thermal conductivity between 170 and 220 W/mK and a reduced coefficient of thermal expansion that matches the semiconductor dies for diode manufacturing (5.6-9.0 ppm/°C). Laser dies are typically built on gallium arsenide (GaAs) substrates using processes such as molecular-beam epitaxy or metal-organic chemical-vapor deposition. The final chemical composition may include indium gallium arsenide (InGaAs), indium aluminum gallium arsenide (InAlGaAs), aluminum gallium arsenide (AlGaAs), indium gallium arsenide phosphide (InGaAsP), or indium gallium phosphide (InGaP). Recently, indium gallium nitride (InGaN) lasers have been manufactured on a sapphire substrate using a layer of epitaxially laterally overgrown GaN to match the lattice energy between the sapphire and the semiconductor.

Different tungsten copper mounts were modeled using the finite boundary value solution technique. Performance was compared using 160-W/mK WCu material as the baseline and high-purity copper (thermal conductivity = 398 W/mK) for top-end performance. Based on thermal-resistance reduction, an improvement of 19.1% was obtained for the 200-W/mK material. The functionally graded 320-W/mK material was about 47.54% better, with the top-end material providing a 56.88% improvement over the standard. Corresponding reduction in junction temperature is also shown.

Technical developments using functionally graded materials (FGMs) push the performance envelope of copper/tungsten to thermal conductivity levels around 320 W/mK. This performance level is comparable to the thermal performance provided by copper. These thermal-management solutions are pursued using common, readily available materials such as copper and tungsten.

Tungsten Copper Electrical Contacts

The high Electrical & thermal conductivity of copper are combined with the arc-resistant & non-welding properties of tungsten or their carbides to form an extensive series of compositions each designed to give the best performance for your particular application. These materials are used for such heavy duty contact applications as:

Circuit breakers, air & oil immersed
Arcing tips or arc runners
Make & break contacts
Heavy duty conductors, relays & switches.

The high electrical and thermal conductivity of tungsten copper alloy allows a cool, effective transfer of power, while the excellent arc-resistance properties of tungsten copper minimize arc erosion and transfer problems. These characteristics can be varied by composition more silver or copper yields higher electrical and thermal conductivity, while a higher refractory metal content results in superior arc erosion properties. We offer a variety of composites to meet your demands. Regardless of the environment (oil-filled devices, air and gas circuit breakers, contactors, high voltage switch gear) or the application (arcing contacts and plates, arc runners, current carrying members and blade facings), you won't be disappointed in electrical contacts made from our copper tungsten composites.

We will analyze your application & recommend sintered materials to suit your requirements. We can often suggest design revisions that may improve the performance of the product & reduce your costs.From simple to complex geometry, Chinatungsten produces custom electrical contacts that meet the demands of customer applications. A variety of shapes and sizes for contact requirements are possible because of powder metal technology.

Tungsten Copper for Low Voltage Electrode Contact Application

Low Voltage Electrode Contact Application-1
Automotive electrical contacts
Car electrical contacts are typically pure tungsten rod cutting, brazed tungsten the surface oxide layer, if long-term placement will produce automotive electrical failure phenomenon tungsten copper alloy rod to ensure that the contact has good electrical conductivity, resistance to arc erosion and oxidation-resistant performance.

Low Voltage Electrode Contact Application-2
Medical equipment with discharge board
The human crusher, pulse ray generator equipment in high-voltage, high-current discharge electrodes, tungsten copper alloy with copper one way of making, not only to ensure good electrical conductivity of the electrode, arc erosion resistance, and solve the electrodes connectivity issues.

Low Voltage Electrode Contact Application-3
The Overall Electrical Contacts
The arc current 380V contactors, switches, etc. used finger brazing copper and contacts connections occurred often in the process of using high temperatures lead to melting of the brazing layer to produce U-turn phenomenon. Tungsten copper produced by the method of the overall sintered integrally arc contact means to solve the above problems, and to reduce the production processes.

Low Voltage Electrode Contact Application-4
Other applications
Tungsten-copper alloy has a high melting point, high electrical conductivity and good ablation resistance; it can be used in many electrical fields.

Tungsten Copper for Switch

Tungsten Copper for Switch
The circuit breaker is one of the systems the most important of the high-pressure equipment. When systems failure, to trip the circuit breaker protection devices excision of failure to maintain system stability. The circuit breaker in accordance with its interrupter media sub-divided into the oil circuit breakers, compressed air circuit breakers, vacuum circuit breakers and SF6 circuit breakers. Oil circuit breaker is divided into two types of oil and less oil. Products are eliminated more oil has basically not used; less oil circuit breaker is not to say that in our country there is a certain range of applications, but this performance is very good, but relative to the same voltage level of vacuum its cheaper price and s breaker can basically meet the requirements, the specific use down. Oil circuit breaker has a fatal flaw, it is in the long-running the insulating oil prone carbonation phenomenon, especially in the case of a short time repeated resection failure are more likely to insulating oil carbonization, which will greatly reduce its ability to interrupter. The second is the maintenance workload, maintenance interval shorter in the new project is not recommended to use.

Compressed air circuit breaker must be equipped with a compressed air device, relying on compressed gas interrupter larger area and greater wear contacts, and therefore a very small range of applications. The vacuum circuit breaker is a vacuum (pressure of l0 ~ l0-6 Pa) to the interrupter of a circuit breaker, the contact is mounted in the vacuum interrupter chamber. Since there is almost no free gas in the vacuum, therefore, when such contacts of the circuit breaker in the disconnected only emitted because of the high electric field, and the thermoelectric emission produces little vacuum arc so that it can in the first current zero crossing off, so that both ensures that the interrupter can be within a very short time, but not so in the system to produce a high pressure changes due to the Shaanxi speed current. Vacuum circuit breaker has small size, light weight, fast action, long service life, high security and reliability, and eases of maintenance overhaul many advantages, but the price is more expensive than oil circuit breaker. SF6 Circuit Breaker is the use of a circuit breaker of the SF6 gas as the insulating and arc extinguishing medium, s is a colorless, odorless, non-toxic and flammable gases, its chemical properties are fairly stable below 150 ℃, although at a high temperature will break down to produce toxic gas interrupter state, and will produce a small amount of the active substance, but through the use of the adsorbent and the contact has a self-cleaning function, equipment and personal will not cause harm.

Tungsten Copper Alloy for Military

Feds mull looser regs on armor-piercing bullets as Obama calls for end to gun violence
While President Barack Obama is calling for a high-level study to come up with ways to end the nation's "epidemic of gun violence" in the wake of last week's schoolhouse massacre, the Bureau of Alcohol, Tobacco, Firearms and Explosives is seeking comments on the possible easing of regulation on armor piercing bullets.
On Dec. 6 - eight days before the tragic shootings at Sandy Hook Elementary school in Newtown, Conn. -  the National Rifle Association's Institute for Legislative Action sent out an alert to members urging them to weigh in on the request, which the ATF made after receiving requests from unnamed sources to review its policies. The comments period closes at the end of the month.
Meanwhile, the president has tasked Vice President Joe Biden, pictured right, to lead an interagency group to explore responses to last week's shootings.
Here's the notice, published on the ATF's website:
"ATF is seeking public comments on specific projectiles or projectile cores which  may be used in a handgun and which are constructed entirely from one or a combination of tungsten, alloys, steel, iron, brass, bronze, beryllium, copper or depleted uranium, and whether these projectiles or projectile cores pose a threat to public safety and law enforcement, or are, "primarily intended to be used for sporting purposes" and therefore may be exempted from classification as "armor piercing ammunition."
The request for comments - which is not yet part of a formal rulemaking process and therefore is not available on regulations.gov - is in addition to a series of meetings that the ATF held in late November with law enforcement officials, gun control groups, representatives of the firearms industry, and gun rights groups according to this document posted on the ATF website.
At issue: ammunition that is banned for handguns under a 1986 law because it can pierce body armor. The purpose of the law, says the ATF, was "to protect law enforcement officers by regulating the ammunition that could be loaded into a handgun and would penetrate an officer's bullet resistant vest."
However, law provides for an exemption from the definition for any projectile "which the Attorney General finds is primarily intended to be used for sporting purposes."
With large caliber handguns now being manfactured that take rifle-caliber bullets, there are requests for an exemption so that certain ammunition that can be used in both rifles and handguns remain legal.
The ATF says it is caught between two problems--protecting police officers versus the rights of hunters. "In developing ATF's criteria, we recognize that a broad exemption will necessarily encompass many projectiles that may pose a danger to law enforcement officers," says the agency. "However, in developing a narrow sporting purposes test, ammunition in traditional hunting calibers will become regulated."
Kristen Rand, legislative director for the Violence Policy Center, a nonprofit group that works to reduce violence, says any change in the rule would be a mistake. "There is no rationale that would justify allowing the sale of any handgun ammunition that can pierce body armor and endanger first responders," she told Sunlight.
Comments are due by Dec. 31. A call to the ATF was not returned by the time of this posting. Sunlight has filed a Freedom of Information Act request for the comments submitted to the ATF, as well as records of the meetings the agency held with stakeholders.

Tungsten Copper Age Returns

How much thought have you given to copper recently? My guess is that the answer is “not much” or “none at all.” I’d probably have said the same myself until recently, when I read Bill Carter’s fascinating new book, Boom, Bust, Boom. Its central theme is the author’s ongoing struggle with his conscience: how is he to reconcile his disgust with the ugliness of the copper-mining industry -- the yawning pits, the sulfuric acid dripping through mountains of crushed rock, the acid mine drainage -- with his dependence on copper for every aspect of his everyday life? And that includes his dreams of a future economy powered by renewable energy.

I was forcefully reminded of Carter’s dilemma last week by a news item from newly democratic Myanmar, once known as Burma. It concerned a copper mine called Letpadaung. This began life as a 50-50 joint venture between a Canadian company, Ivanhoe Mines, and the military government of Myanmar. Two years ago, Ivanhoe’s share was bought out by a subsidiary of the giant state-owned Chinese company NORINCO -- the China North Industries Corporation. NORINCO is best known as a manufacturer of weapons systems for the People’s Liberation Army, though its tentacles also reach into engineering and infrastructure projects such as highways, dams, power plants, and subway systems; precision optics; retail vehicle sales; and microelectronics; as well as mining. Think of it as Halliburton, IBM, and Lockheed Martin all rolled into one.

Last Thursday, riot police used water cannons, tear gas, and incendiary devices to attack a peaceful encampment of protesters at the Letpadaung mine site -- an assortment of Buddhist monks, peasants complaining of illegal land seizures, and activists taking advantage of the country’s recent democratic opening -- who had been protesting for months against a proposed billion-dollar expansion. When the raid was over, dozens were injured; videos from a local hospital showed saffron-robed monks disfigured by burns.

This was just the latest in a string of similar events around the world. Five protesters against a new gold and copper mine were killed in Peru while I was there earlier this year (a story I tell in the current issue of OnEarth); a few weeks earlier, two more Peruvians had died during protests against another copper mine; and just days before the Myanmar attack, the Democratic Republic of Congo saw a new warlord and accused war criminal, Bosco "The Terminator" Ntaganda, seize control of the province of North Kivu. The endless bloodletting in North Kivu is explained by the fact that it contains some of the richest mineral deposits on the planet -- including copper, gold, cobalt, tungsten, and 70 percent of the world’s supply of tantalum, a mineral critical to our cell phones, tablets, and computers.