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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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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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 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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