Non-sag tungsten wire working temperature is between 2300 ~ 2800 ℃, and the greater the average light bulb power, the higher the wire temperature.

According to a series of study and analysis conducted by Transmission Electron Microscopy (TEM) and Auger Spectrometer (AES) in 1970s, it shows that non-sag tungsten wire recrystallization structure, unique, with elongated strip whose coarse grains is overlapping each other, its formation is closely related to potassium content. Remaining trace potassium in doping tungsten bars form potassium bubble column which parallel to the axis of the filament during processing, and then hinder the process of lateral recrystallization grain growth, and thus generate long thick overlapping structure. Incandescent wire sagging is not only related to the additive element content and machining technology, but also the treatment process of wire production process. Tungsten retains a large number of internal stresses in finished products when we pulling it into wire, and will produce new internal stress of inhomogeneous deformation in the cross section of tungsten wire when we are winding the wire. The internal stress must eliminate thoroughly before tungsten wire is placing into the glass bulb, otherwise bulb will start twisting, distorting and sagging when it is lit. When the wire is sagging, it can severely reduce the luminous efficiency of the lamp.

 

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Sol-gel method for manufacture tungsten trioxide films has a lot of advantages, such as it can be produce different crystal structure material, different degrees of dense material, and easy to control the product's composition and particle size. The most important it can produce large area and uniform films. Thanks to these advantages, it is used by mostly researchers to study and continue to develop. In 1999, researchers use sodium tungstate as reaction precursor and in the different PH value to produce WO3 films. Then with the increasing of PH value, tungsten oxide hydrate gradually change to octahedral 12- tungstate, and this is conducive to the low valence W atoms formation and photochromic pheromone occurs. After that researchers who prepared the same way, produced several hybrid multi-metal oxide film in which phosphorus tungsten oxide film after exposure to UV light in the visible and near infrared region to have a strong absorptive capacity. The method for the sol - gel method large tungsten trioxide film has taken an important step. By 2002, using tungsten hexachloride and tungsten acid as raw materials, by changing the alcohol, water and the proportion of PH value polyethylene glycol to obtain a stable sol, and made into a film. The hybrid films which are using WCL6 as raw material to produced and it has fast response, strong absorption advantages.

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Tungsten Carbide Rod Hardness Test

Tungsten carbide rod hardness test mainly adopts Rockwell hardness tester to test HRA hardness level. The portable Rockwell hardness tester weighs only 0.7kg which is really convenient both in usage and carry. Through the hardness test, we can figure out the different mechanical property of tungsten carbide rod under different chemical agents, organization structure and heat treatment processing. This is a kind of non-destructive test, and is relatively easy to operate. This kind of detection method has small testing force and little indentation, high measuring speed and high efficiency; therefore, it can be directly used to test finished products.

Hardness test has certain similarities with tensile test, both of which are used to test the resistance capability of metals to plastic deformation. Because tensile test is a kind of destructive test, so hardness test is adopted more frequently than tensile test.


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Tungsten oxide is a good photochromic material, in 1973first reported amorphous tungsten oxide film photochromic phenomenon that has been widespread concern and research. In 1980 Gerard and others based on the previous first used vacuum deposition method, by changing the degree of vacuum to produce HXWO3-Y films. Then after that they switched to a sputtering method, in Ar-O2 (preparation pure sub-stoichiometric film), Ar-O2-H2 and Ar-O2-H2O (changing composition WO3 hydroxide) these three different atmospheres sputtering and prepared HXWO3-Y film. However, due to the vacuum deposition method and sputtering method equipment is expensive and technically complex, and the complex molecular structure of the film and ordered the film can not be prepared, besides it is difficult to control the film thickness and size, and more importantly, they are not easy to produce a large area so it is difficult to be widely used. With the development of technology there are many methods for the producing tungsten oxide, such as electron beam vapor deposition method, electrodeposition., spray pyrolysis, sol - gel method. Where the sol-gel method can produce different crystal structure, different degrees of dense material, easy to control the composition and particle size and easy production large area uniform films and other advantages, so now most researchers have been using and continue to develop.

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Tungsten Carbide Rod Tensile Strength Test

The hardness of tungsten carbide rod is related to other properties. Similar to tungsten carbide rod hardness test, tungsten carbide rod tensile strength test is also used to test the strength and resistance capability of metals to plastic deformation. Strength often refers to the capacity of tungsten carbide rod to resist elastic deformation, plastic deformation and breakage under the external force. Plasticity means the plastic deformation of tungsten carbide rod under certain loading action.

Tensile strength testing, also known as tension testing, is a fundamental materials science test in which a sample is subjected to a controlled tension until failure. The results from the test are commonly used to select a material for an application, for quality control, and to predict how a material will react under other types of forces. Properties that are directly measured via a tensile test are ultimate tensile strength, maximum elongation and reduction in area.
Tungsten carbide rod tensile test requires large testing equipment, the process is very complex, and test efficiency is lower than hardness test. Besides tensile strength test is a kind of destructive test, so hardness test is adopted more frequently than tensile test.

 
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Influence tungsten oxide photochromic has many factors, in addition to the structure and composition of itself, which the atmosphere the tungsten oxide exist will also impact on its chromogenic performance. Considered from the internal structure of tungsten oxide, there are different structures of tungsten oxide there. From relatively stable triclinic, monoclinic to cubic, tetragonal and very unstable hexagonal bronze, pyrochlore phase, but the most studied at the present is amorphous (a-WO₃) or polycrystalline (c-WO₃) film’s photochromic properties. After the study found that a-WO₃ compared with c-WO₃ has a good photochromic property, mainly because c-WO₃ has lattice defects or small surface area or others. The internal factors which mentioned above is the main reasons of determine the material properties, and external also has great impact on tungsten oxide photochromic which can not be underestimated, especially on different atmosphere. From colored aspects, some of the hydrogen or hydroxyl organic vapors is good for matachromatism reaction rate and improve absorption intensity of tungsten oxide. Respect for bleaching aspect，it will affected by the oxidizing gas largely, such as O₃, H₂O₂ and FE₂ (SO₄) ₃ and so on. These factors for improve the tungsten oxide photochromic performance have great help, but also conducive to the production of a more favorable performance photochromic material.

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Tungsten Carbide Rod Surface Roughness

Tungsten carbide rods have high hardness and abrasion resistance and thus its grinding process is quite complicated, which includes: coarse grinding, fine grinding, accurate grinding and polishing. There are two types of polishing: matte polishing and mirror polishing.

Grinding can help tungsten carbide rods get higher machining accuracy and lower surface roughness. Grinding precision usually reaches IT6 ~ IT7 tolerance grade, while surface roughness reaching Ra1.25 ~ 0.16μm. Surface roughness Ra of tungsten carbide rods before accurate grinding should be smaller than 6.3um. If tungsten carbide rods are polished, their surface roughness will be up to Ra0.1 μm, which makes its surface be smooth as that of a mirror. Its dimensional accuracy and shape accuracy can be within 1um, the error of which is equivalent to 1/70 thickness of human hair or even thinner. 


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Tungsten Carbide Rod Inspection Standards

Tungsten carbide rod is in huge demand for its very high strength as well as rigidity. Its comprehensive strength is higher than all existing melted and cast or forged metals and alloys. Its compositions range from two to three times as rigid as steel and four to six times as rigid as cast iron and brass. Tungsten carbide rods maintain all the features of tungsten carbide with availability of different grades.

Manufacturers follow the established standards for all tungsten carbide grades and control checks are performed at each operation. They also check the grain sizes and do chemical analysis to assure that all products conform to the set standards, Test are made to determine physical properties of the products for their hardness, strength and density. They also observe for any fractured and polished surfaces through micrographic test with the test results being recorded before shipping the product to the final customers or users. Some manufactured do provide certification of test results when asked by the customers.


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Nano tungsten oxide has strong organizational ability to grow and in a stable reaction conditions the interactions between molecular are fairly obvious. Molecular can epitaxial growth which is accordance with lattice arrangement strictly and to form the formation ratio complete and single component structure. With the improvement of nano technology, now there have been some special form of tungsten oxide, including arborescent, clitheriform, nanorods, nanowires and other special forms. There are many methods to produce special form nano tungsten oxide which can be divided into three types: high-temperature synthesis, hydrothermal synthesis method, and solution low temperature synthesis method. Although high-temperature synthesis method is most common, but it has high requirements in equipment so this method is difficult wildly be used. The hydrothermal synthesis method is acidification W (CO) ₆ and ammonium tungstate, the reaction is from 2 to 100 hours at 160-200 ℃ range in autoclave for produce different shapes of nanorods. This method is low cost so it can be widely used than high-temperature synthesis method. Solution low temperature synthesis method is a new invention so in produce special morphology tungsten oxide is not mature, but the method has attracted much attention and the prospects are very broad.

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Tungsten Carbide Rod Surface Roughness Affecting Factors

Tungsten carbide rod surface roughness affecting factors including the granularity of grinding wheel, rotating speed of grinding wheel, the concentration of grinding fluid and granularity of tungsten carbide rod.

1.The granularity of grinding wheel. The grinding process of tungsten carbide rod is generally divided into two to three steps. The first few steps are coarse grinding and the last step is fine grinding. The higher the granularity of grinding wheel is, the finer the diamond particle will be. The grain will be more detailed and the product will be brighter.

2.Rotating speed of grinding wheel. If the rotating speed is high, the friction period with tungsten carbide rod will be shorter, so there will be less grain formed on the surface of tungsten carbide rod.

3.The concentration of grinding fluid. Although grinding fluid is just an auxiliary material, the concentration will also affect the surface roughness of tungsten carbide rod.

4.Granularity of tungsten carbide rod. Tungsten carbide rod is made of many particles. The finer the particle is, the gap between particles will be smaller, thus the density will be better. It is easier to polish. 


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