Tungsten Steel Sintering Process

1: Removal of forming agents burn stage, at this stage of the sintered body changes as follows: removal of forming agent, as the initial stage of sintering temperature, forming agent gradual decomposition or vaporization, excluded from the sintered body, at the same time , more or less to the sintered body forming agent by carbon, increasing the amount of carbon forming agent with the type, quantity and sintering process vary. The powder surface oxides are reduced, at the sintering temperature, the hydrogen can be reduced cobalt and tungsten oxides, if the vacuum-forming agent removal and sintering, the oxygen reaction is not strong. Contact stress between the powder particles gradual elimination, bonding metal powder begins to generate recovery and recrystallization, surface diffusion began, briquette strength increased.

2: solid-phase sintering stage (800 ℃ - eutectic temperature) appears before the temperature of the liquid phase, in addition to carry out the last stage of the process that occurs, the solid phase reaction and diffusion increase, reinforced plastic flow of the sintered body appear significant contraction.

3: The liquid phase sintering stage (eutectic temperature - sintering temperature) occurs when the liquid phase sintered body after contraction completed soon, and then produce crystalline transition, the formation of the basic organization and structure of the alloy.

4: cooling stage (sintering temperature - room temperature), at this stage, tungsten steel with the organization and phase composition of the different cooling conditions have some changes that can take advantage of this feature, tungsten steel, heat treated to improve its physical and mechanical performance.


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A plastic and metal powder produced by the method for processing a certain amount of the tungsten oxide of cerium (≤ 4%) of the electrode material . Cerium tungsten electrode material is a non-radioactive electrode material , it is since the 1950s to replace the radioactive thorium tungsten electrode material and gradually developed . This electrode material in an inert gas shielded arc welding and plasma welding , cutting, etc. has been widely applied .

Production began thorium tungsten electrode for the early 1950s , it was added to the tungsten ≤ 3% of thorium oxide . This material has a high electron emission capability , resistance to burning and arcing good performance ; However, because thorium is radioactive elements in the production, storage and use of the process prone to radioactive pollution, endangering human health , and thus from the mid-1950s , people have carried out research work on behalf of thorium materials . In 1956, the United States Lewis (A.Louis) conducted directly in the metal tungsten powder, 0.5 to 3.0% cerium oxide powder of testing, and then compacts melt down , rotary forging of welding electrodes . Two years later he cerium oxide content is reduced to 0.01% to 0.30% , so that the processing performance is improved. U.S. 1965 Herman (J.Hermann) using fine tungsten powder pressed into a pure green , green , or after this billet burn- soaked in a solution of rare earth salt , to achieve doping by imbibition , followed by sintering, according to the conventional method swaged to the desired diameter . 1967 ROMON Ivanov (V.N.Romonov) developed a 1% cerium oxide containing cerium tungsten material , the preparation process is: under 800 ~ 850 ℃ calcined ammonium paratungstate, tungsten trioxide , and the cerium nitrate an aqueous solution of a salt or oxide incorporated in the suspension of tungsten trioxide , tungsten trioxide and then doped with hydrogen good a reduced tungsten powder . Ethanol and glycerol mixture after a pressure of 600MPa into a 9mm × 9mm × 400mm billet bar , after burn-in and vertical melt , the billet of CeO2 content of 0.87% , when the swaging process , the heating temperature for the 1475 ~ 1500 ℃.

China started to develop in the 1970s, cerium tungsten electrode material , after nearly 10 years of production practice , the production process tends to be stable and mature , in the early 1980s , both domestically and internationally cerium tungsten electrode material for the production of patents. In the production process , how to make a tungsten doped ceria -based in vivo distribution and dispersion , the electrode is to improve the electron emission capability , improved arc performance , extend the life of one of the important factors . Therefore, the choice of raw materials , usually by blue tungsten oxide or doped tungsten oxide , and the doping agent is not used directly cerium oxide , instead of using the soluble salts such as cerium chloride or cerium nitrate . This aqueous solution as the mother liquor , add inwards blue tungsten trioxide or tungsten , during the addition , the heating and stirring continuously , and concentrated by evaporation to form a coating powder. Doping can also be an aqueous solution of cerium nitrate, cerium chloride or spray containing tungsten blue oxide powder, tungsten or a special container ( heat while rotating ) . The powder doped must be heated to a certain temperature , the salts decompose to form cerium oxide particles distributed in the tungsten trioxide powder, tungsten or blue on the surface of the particles , and then after hydrogen reduction , to obtain W-CeO2 powder. CeO2 content of 1% to 4%, selected according to requirements . Doped powder after molding, burn , vertical melt , get cerium tungsten billet , see doped tungsten its production process , but its swaged temperature slightly higher for 1500 ~ 1600 ℃.

Electrode performance as an electrode material , the level of electron work function is the amount of material raft electron emission performance is an important indicator of good or bad . Only a low electron work function , in order to meet the arc stability, focus , load current density process performance requirements.

Experiments show that cerium tungsten electrodes with thorium tungsten electrode is lower than the electron work function ( pure tungsten electron work function of 4.55eV, W-2% ThO2 is 2.7eV, W-2% CeO2 is 2.4eV ) , this electrode material than thoriated tungsten electrode has greater advantages . First , cerium tungsten electrodes electron emission capability , easy to get a slim arc , so that the heat is more concentrated , the allowable current density thoriated tungsten electrodes increased by 5 % to 8% . Secondly , cerium tungsten electrodes burning rate, long life , easy to arc initiation and stability are guaranteed . Again , cerium tungsten electrodes radioactive dose is very low, and only about one thousandth of thorium tungsten materials , the equivalent radiation dose earth soil . So instead of using cerium tungsten electrodes thorium tungsten electrode , not only can eliminate the production and use of human cumulative internal radiation hazards, and eliminating radioactive contamination of the environment , but also in technical performance and the results are also able to replace thoriated tungsten electrodes , Some properties even superior than thorium tungsten material .

Cerium tungsten electrode material in addition to the application in welding , plasma arc welding replacing thoriated tungsten electrode areas , but in plasma cutting , plasma spraying , plasma melting the application effect is satisfactory . In addition, as the pump laser light source to cerium tungsten electrodes after replacing thoriated tungsten electrodes , so that the light source efficiency by about 12% , life expectancy increased by 5 to 10 times. In the electric light , for small and medium power xenon lamp has been used cerium tungsten electrodes , the electric vacuum , cerium tungsten material as the sealing member having a good use of effects . Problems and trends Although cerium tungsten electrode material in a small tungsten electrodes for welding specifications had succeeded in replacing thoriated tungsten , but as AC welding electrodes and high-power xenon lamps and other aspects of the cathode gas discharge light source material , cerium tungsten electrodes performance and life compared with thorium tungsten , there are still fluctuated unstable situation . Further, since the cerium has a high vapor pressure , and thus as the cathode material , there are still fast decay , poor stability . Thus in these areas are still using thorium tungsten electrode material .

With the progress and development of modern industry , welding, cutting the base material of the species, size and shape of the increasingly numerous , but in the field of welding is the rise since the resumption shou automatic welding , a series of new high- precision welding technology, the electrode materials and arc features a higher and more demanding requirements. Thorium tungsten , cerium tungsten electrode material , whether in arc starting , stable arc burning resistance or in terms of performance are unable to meet the growing requirements of welding technology . To this end , national science and technology workers are working on a new type of electron-emitting material . Studies have shown that adding tungsten matrix lanthanum or yttrium and other rare earth oxides , can greatly improve the ability of tungsten electron emission , especially lanthanum tungsten electrode material , from small to large current current range , all with excellent arc, arc stability and resistance to burning performance. Japan in the late 1980s has been able to mass production of rare earth tungsten electrode material , shortly thereafter , China has successfully developed . It is anticipated that this new type of electron emission materials will be involved in many industrial fields , use more widely, promising .


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Tungsten carbide rotary burr is an effective way to realize mechanization in hand work operations. In the fields of airplane, ship building, automobile, machinery, chemistry etc., carbide rotary Burr can be widely used in machining iron, steel casting, carbon steel, alloy steel, stainless steel and copper aluminum etc.

1) Machining various kinds of metal.
2) Replacing small emery wheels, without powder pollution.
3) Increasing productivity of several ten times than using hand tools and three to five times than using small emery wheels.
4) Having ten times longer life than high speed steel Burrs and fifty times than small emery wheels.
5) Finish machining various kinds of die cavities.
6) Removing the Burrs of the castings, forgings and the welding spatter on the weld assemblies.
7) Chamfering angle, circular bead or flute on the mechanical components.
8) Chamfering or Burring the pipes.
9) Polishing the impeller channel.
10) Grinding the hole to an accurate shape.


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Tungsten carbide tips and blanks are four times harder than titanium, twice as hard as steel, is virtually unscratchable, and has been widely used for decades in industrial applications such as cutting tools, mining machinery, and rocket engine nozzles. The extreme hardness of tungsten carbide tips and blanks makes them useful in the manufacture of cutting tools, abrasives and bearings, as a cheaper and more heat-resistant alternative to diamond. Tungsten carbide tips and blanks are also used as scratch-resistant material for jewelry including watch bands and wedding rings.


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Brazing tungsten carbide is a very easy and reliable process if a few simple steps are taken but the steps are not necessarily obvious or widely known.   There are many additional articles on How to Braze in our Brazing index.

The carbide must be wettable, it must want to chemically and physically bond with the brazing alloy.   Clean tungsten carbide brazes well.   Tungsten carbide with any sort of oil, grease, oxide or free carbon on it will not braze.   You can clean carbide by grinding the surface with a sander or a bench grinder.  The simplest is just to specify that the carbide be wettable when you order it.   There are also companies that will treat the carbide and pretin it with brazing alloy so that it is ready to use when you get it.  

Test carbide parts for wetting or Brazeability.  Above are parts for a farm implement.   The manufacturer couldn’t get the carbide to stick to the steel.  He thought it was the chrome in the steel.  We put a small bit of brazing alloy dipped in Black flux in the middle of one steel part (left) and two carbide parts (right) and heated them with a torch.  You can see that the alloy flowed well over the steel and not at all on the carbide.   

The steel must be clean.  See our article on Cleaning Steel.   It used to be common to use vapor degreasing and very aggressive solvents to clean steal.  Most of the really effective solvents are now illegal so it is now common to use legal solvents that don’t work very well.    

The easiest way to test steel cleanliness is with an eye dropper or similar.  Put a drop of water on the surface and see what shape it forms.   The wider and flatter the puddle, the better.  A high, round shape means trouble brazing.

The best steel cleaner seems to be a strong caustic substance.   There is a wide variety of cleaners that work with varying degrees of success.  We tested about a dozen.   The cheapest and most effective was a barbecue and oven cleaner from the local janitorial supply.  For small parts we use a can of spray oven cleaner from the supermarket.

There are several brazing alloys used for carbide.  The classic is BAG-3, 50% silver with Cadmium.  This is an excellent product but does have Cadmium.  Commonly used is BAG-7, 56% silver with Tin, because it wets out readily however it is a very weak brazing alloy and joint failure is common with this alloy.  The strongest non-Cadmium alloy is BAG- 22, 49% silver with manganese, but it is a bit gummy in the flow.  BAG-24, 50% Silver, is Cadmium free and is a compromise.  It flows well but is about 40% weaker than BAG-3 and BAG-22.

We strongly prefer Black Flux although many braze successfully with White Flux.   In both cases they are clearly high temperature fluxes.    In addition we find that purified Black Flux gives better flow and stronger joints than ordinary Black Flux.  

The final area where mistakes are common is in joint design.   Trained welders commonly want to assemble the parts and then run a bead.  When they braze they want to assemble the parts and then wick the brazing alloy into the joint.

When brazing carbide it is often much more effective to flux the sides and bottom of the notch then put pieces of fluxed alloy wire under the carbide.  All you do then is to heat until the carbide settles in place.   

The standard should be that the carbide ruptures or the steel rips before the joint fails.  


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Emitting Principle

All incandescent light principle is the use of the object emitting heat and thermal radiation theory and principles to achieve the most simple to the filament incandescent lamp is turned on enough current, filament heating to incandescence, we will send light, but this incandescent lamp life will be quite considerable shorter.

We saw the reason for using the following incandescent technology, its purpose is to make incandescent lamps have a longer life and more convenient to use: Vacuum tube (to reduce the degree of oxidation filament), light foot (easy you will Bulbs inserted in the lamp holder), filled with an inert gas (reducing filament degree of oxidation at high temperatures), etc.

Working Principe

Halogen incandescent bulbs with the biggest difference is that the point is that the halogen lamp glass envelope is filled with some of the halogen element gas (usually iodine or bromine), which works as follows:

When the filament heats up, the tungsten atoms are evaporated to a glass wall direction, when close to the glass wall, the tungsten vapor is cooled to about 800 ℃ and halogen atoms combine to form a tungsten halide (iodide, bromide, tungsten or tungsten). Tungsten halide continues to move to the central tube, and oxidized back to the filament, as a tungsten halide is a very unstable compound and then re-heated steam into the halogen and tungsten, and the filament so that the tungsten deposited on, make up for being part evaporated.

By this recycling process, the filaments are not only greatly extend the service life (almost 4 times the incandescent lamp), and because the filament can operate at higher temperatures, resulting in a higher brightness, higher color temperature and higher luminous efficiency.


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Halogen is late eighties successfully developed a new type of light source. It has a high luminous efficiency, small size, light weight, long life and other characteristics.

To make this small volume, high luminous efficiency light source is effectively a new application, the researchers turn into one kind of small halogen bulb made ​​of quartz glass with cold cup. The shape shown in Figure 2-8-2. The quartz glass halogen bulb cold cup and a combination of light called "quartz cold spot" (commonly known as cold light source, or cold light). It has a cold. Light into a beam angle of cold cup can
choose according to need, with a range of functions. Ordinary incandescent match.

Therefore, this light spotlights widely used in store mall counters. Windows for illumination and lighting effects.
Recent years due to the improvement of people's living standards, living conditions continue to improve. EL lighting decoration in the home has become increasingly popular. To enable people to live and work life, EL lighting is also widely used security products.

As cold working voltage spotlights are low voltage, 6V, 12V, power 20W, 50W, so in actual use step-down transformer must be used, generally 50W, 12V inductive transformer its large size and weight too, should not be in the mall lot of use. For this reason, scientists have launched an electronic transformer, which is characterized by: small size, light weight, low cost, easy to use and so on. Disadvantages are: electromagnetic interference (can increase its interference absorption circuit absorption). Electronic transformer circuit diagram: (12 * 8cm)
Working principle is basically the same, and electronic ballasts that the output voltage is reduced by the ferrite transformer isolation to the point of contingent Designed 12V.


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Halogen is thermal radiation source, the working principle is basically the same as with ordinary incandescent lamp, the structure has a larger difference. The most prominent difference is within the halogen bulb containing part of the gas filled halogen element or halides.

Halogen light efficiency higher (about 18 ~ 21lm / W), the lower the color temperature is generally 2700 ~ 3300K, CRI high color rendering index Ra 99 to 100.

Halogen Structure

Is a tungsten filament halogen, halogen-filled glass bulb and the lamp, and the like. Halogen lamp with double-ended, single-ended and double blister of the points;

Halogen Free

1 Press the charge into different halogen bulb for tungsten and bromine tungsten lamp;

2 Press the bulb housing material can be divided into hard glass halogen lamps, halogen quartz glass;

3 halogen at work can be divided into high and low voltage halogen mains (220V) and low voltage-halogen (6V, 12V, 24V);

4 halogen lamp according to the different structure can be divided into double-ended, single-ended halogen;

Halogen Works

When filled with halogen bulb powered substances when working out of the tungsten evaporates from the filament, and halogen compounds, forming a volatile halogen compounds. Halogen compound diffusion in the lamp, when spread to the area around a hot filament, a halogen compound into a halogen and tungsten, tungsten deposited on the release of the filament, and then continue to diffuse into the halogen lower temperature bulb wall region and tungsten compounds, forming halogen cycle.

Halogen Applications

Should pay attention to the following questions:

Halogen does not apply to low-temperature applications. Double ended halogen work, the lamp should be installed horizontally, tilted at an angle not more than 40, otherwise it will shorten its life; addition, since the halogen filament thin and crisp, halogen used, to avoid vibration and impact, and it is not as mobile lighting fixtures.


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HIP (hot isostatic pressing)

1, HIP Treatment Summary

Powder metallurgy method is easier than the melting alloy is formed within the pores, although with advances in manufacturing technology, has been able to produce almost no pores, but at high pressure processing conditions of use, although the internal micropores is small, can make carbide tools damaged. In addition, for users that require extremely high reliability requirements, can be found in the existing material based on the increase HIP treatment, especially for the semiconductor industry uses progressive die, pin punch, encapsulation molds blanks, require a high material stability. Daijie the company 20 years ago to eliminate the use of the most advanced internal micropores HIP equipment to produce no internal defects of high quality carbide.

2, HIP Treatment Principle

HIP treatment is the principle of high temperature and pressure carbide placed in an argon atmosphere, so that destruction of the internal micropores, by changing the working conditions, HIP can significantly improve the bonding strength of carbides in the less binding agent timber species HIP better show results.


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Carbide, chemical formula WC, by its own physical properties, hardness comparable to diamond, is widely used to produce cutting tools and wear-resistant member.

Production of tungsten carbide mixed into materials, carbonation, milling, screening, testing, and several other steps.

1, the Material Mix: the tungsten powder was mixed with carbon black. Depends on the quality of tungsten carbide powder tungsten powder mixed with carbon black uniform extent that if uneven mixing of materials, tungsten carbide powder will appear sinister and stratification. Cemented carbide manufacturing process, in general, the tungsten powder and carbon black were mixed in a ball mill (ball to powder ratio of 1:1, the ball diameter is 35 ~ 50mm), milling time is 2 ~ 4h, no material with the naked eye stratification that is considered mixed.

2, Carbonized Material: tungsten carbide powder, usually in the graphite tube furnace, carbonization process according to the granularity of tungsten powder and tungsten carbide particle size requirements to select, in general, fine tungsten powder carbonization temperature of 1300 ~ 1350 ℃, coarse tungsten powder carbonization temperature of 1600 ℃, carbonization time is 1 ~ 2h.

3, Ball: in a ball mill for milling. Ball to powder ratio of 1:1, the ball diameter is 10 ~ 45mm, milling time according to process requirements, usually 2h.

4, the Screening: In order to prevent the powder from flying, sieved to be carried in a closed case, the fine particles of tungsten carbide through 200 mesh sieve, the particles through a 250 mesh tungsten carbide, tungsten carbide coarse particles through a 60 mesh sieve.

5, After passing inspection derived products.


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