One of the important parts of examine the microstructure is analyzing the defect of tungsten points. to You can check the quality of products on the basis of the standards and its material microstructure of tungsten points. The determination of its defect type and size could be available according to the distribution of its microstructure and check whether they satisfy the requirements of tungsten points’ specification.

The defect types of tungsten points are listing as follows: pores, inclusions, porous holes, bubbling, squeezing cracks, and unevenly distributed organization, purity of tungsten points’ material, delaminating cracks or the particle size and morphology of tungsten powder... There are problems of the process, because the reason is complicated, you should comprehensively analyze and resolve them.

One way to test the quality of metal materials is microstructure analysis; it adopts the principle of quantitative metallography.

Defect types and sizes of tungsten points’ materials may also be relevant to production processes and other causes; therefore, the analysis of the causes of the defect phenomenon can be as a reference to improve product quality.



 

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Tungsten and molybdenum possess wear resistance, high boiling point, high hardness, anti-welding resistance, high melting point and other excellent properties. Silver and copper posses good electrical conductivity and good thermal conductivity and other properties. Tungsten carbide can improve the arc-erosion resistance and anti-welding properties of tungsten points’ material and others. So the performance of tungsten points can be improves greatly by adding an appropriate amount of copper, silver or tungsten carbide and other elements.
The copper tungsten points, silver tungsten points and silver tungsten carbide points can usually be prepared by infiltration sintering process. The processes can be seen as bellow:
press tungsten or tungsten carbide powder, and then mold it, then sinter it, therefore, a porous skeleton of tungsten or tungsten carbide can be formed. And then immerse molten silver or copper in porous skeleton, so due to the capillary action of tungsten or tungsten carbide, they will soak in skeleton pores. After that copper tungsten, silver tungsten or silver tungsten carbide points materials which own high density can be available. For copper tungsten, silver tungsten or silver tungsten carbide points material which own less tungsten or tungsten carbide content can use mixing and sintering process.

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
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The elements of silver tungsten carbide points’ material are silver and tungsten carbide. Silver owns good oxidation resistance, good electrical conductivity, nice thermal conductivity and good processing performance, etc., and tungsten carbide having the advantages of improving their anti-welding resistance and arc erosion resistance performance and so on.

After galvanic corrosion, the surfaces of silver tungsten carbide points will have cracks, its composition is not evenly distributed, you can see the loose structure of their melt layer surface, and compared to the previous experiment, the silver content is significantly reduced, contact surfaces also did not find holes and gas eruptions pits, what suggesting that silver drip splash does not occur in the high-temperature smelting process, among which is the reason for the cracks that the lack of silver result in the loose structure. Certainly, this does not explain that the higher of the silver content can prevent cracks. Studies have shown that if the silver content is too high, it is more easily lead to large silver shedding phenomenon. Therefore, the silver content should be controlled in a certain proportion, which can reduce drip splashes and prevent cracks.



 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
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Mechanical alloying method is a method which is applied to alloy fine crystalline alloy powder material. For example, titanium-aluminum-based alloys should adopt this method to form crystals, whose most significant property is that it is easier to obtain nano-crystalline organization whereas is with bad compactness and difficult form shape. What is more, the rapid cooling method is not available to titanium-aluminum-based alloy products.

Tungsten points prepared by mechanical alloying possess the following properties:
1. Possess uniform microstructure and dispersed strengthening phase and fine;
2. Own simpler production process and cost-effective advantages;
3. The mechanical and electrical properties of tungsten points can be improved;
4. Supersaturated solid solution can be prepared, and alloying system of immiscible tungsten contact material can be prepared;
5. Nano contact materials with good properties also can be prepared;
6. Metal oxide-based, refractory metal and other series of contact materials can be prepared as well.



 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn

 Tel.: 86 592 5129696; Fax: 86 592 5129797
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Defect analysis of tungsten contacts is an important part to examine the microstructure. According to the standards and regulations related to tungsten contacts, and the material microstructure to check the quality of products is good or bad, that is, according to the distribution of its microstructure to largely determine the defect type and its size finally check whether they meet the requirements of the relevant standards of the product specification.

The defect types of tungsten contacts including unevenly distributed organization, porous holes, pores, bubbling, delaminating cracks, squeezing cracks, inclusions, purity of tungsten contacts material or the particle size and morphology of tungsten powder, etc.. There may be a problem of the production process, the reason is complex, and it should be comprehensively analyzed and resolved.

Microstructure analysis is one way to test the quality of metal materials, which adopt the principle of quantitative metallography.

Defect types and sizes of products materials is related to production processes and others, so, analyze the cause of the defect phenomenon can provide reference for improving product quality.



 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
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Refractory metals tungsten and molybdenum own high hardness, high boiling point, high melting point, wear resistance, anti-welding resistance and other excellent properties, silver and copper own a good thermal conductivity and good electrical conductivity and other excellent performance, tungsten carbide can improve the anti-welding properties of tungsten contacts material and arc erosion resistance properties. Therefore, adding an appropriate amount of silver, copper or tungsten carbide, etc. can greatly improve the performance of the tungsten contacts.

Normally, the preparation process of silver tungsten contacts, copper tungsten contacts and silver tungsten carbide contacts is that: infiltration sintering process. The steps of process is shown as follows: First, pressing tungsten powder and tungsten carbide powder, molding it, and then sintering them, so that tungsten or tungsten carbide can form a porous skeleton, and then immersing molten copper or silver in porous skeleton, copper or silver will soak in skeleton pores due to the capillary action of tungsten or tungsten carbide, thus silver tungsten, copper tungsten or silver tungsten carbide contacts material with high density are available, and for silver tungsten, copper tungsten or silver tungsten carbide contacts with less content of tungsten or tungsten carbide can adopt mixing powder and sintering method.



 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
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 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Silver tungsten carbide contacts material, in which the silver having good thermal conductivity and electrical conductivity, good oxidation resistance and good processing performance, etc., and tungsten carbide having the advantages of improving their anti-welding resistance and arc erosion resistance performance and so on.

After galvanic corrosion, the surfaces of silver tungsten carbide contacts will have cracks, its composition is not evenly distributed, you can see the loose structure of their melt layer surface, and compared to the previous experiment, the silver content is significantly reduced, contacts surfaces also did not find holes and gas eruptions pits, what suggesting that silver drip splash does not occur in the high-temperature smelting process, among which is the reason for the cracks that the lack of silver result in the loose structure. Certainly, this does not explain that the higher of the silver content can prevent cracks. Studies have shown that if the silver content is too high, it is more easily lead to large silver shedding phenomenon. Therefore, the silver content should be controlled in a certain proportion, which can reduce drip splashes and prevent cracks.



 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Mechanical alloying method is an effective method to compound fine crystalline alloy powder material. For example, titanium aluminum alloys was required to use this method to form crystals, its most important feature is easier to obtain nano-crystalline organization, but its compactness is not good and its forming is more difficult, besides, the rapid cooling method can not get titanium aluminum alloy products.

Tungsten contacts prepared by mechanical alloying method have the following features:

1. With dispersion strengthening phase and fine, uniform microstructure;
2. The production process is simpler and more economical;
3. Improve the electrical and mechanical properties of tungsten contacts;
4. Prepare supersaturated solid solution, so immiscible tungsten contact material can be an alloying system;
5. Prepare nano contact materials with good performance;
6. Prepare refractory metal, metal oxide-based and other series of contact materials.



 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
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The interest in CaWO₄ and CaMoO₄ has been driven by the fact that these compounds have especially attractive properties for a variety of optical applications (phosphors, laser hosts, scintillators). Recently, CaWO₄ was implemented in the CRESST dark matter search, enabling discrimination between electron and nuclei recoils. Different types of interaction events can be identified by simultaneously measuring a combination of phonon and scintillation signals from cryogenic phonon-scintillation detectors (CPSD) operating at milli-kelvin temperatures. This technique offers high sensitivity and the unique advantage of background identification, which is crucially important for experimental searches for rare events.

 

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For their approved use in scintillating applications, solid-state optoelectronic devices, lasers and optical fibers-like components, scheelite-type photonic crystals have attracted much interest and materials like scheelite CaWO4 have been synthesized in the last years by a diversity of methods including Pechini, polymeric precursor, co-precipitation, solvothermal, Czochralski, and microemulsion-mediated hydrothermal. However, scheelites obtained by these routes show serious problems like off-stoichiometry in any case and undesirable optical quality and scintillating properties in single crystals.

In this work, powders and single crystal minirods of scheelite CaWO4 were obtained by the methods of solid state reaction and laser heated pedestal growth, respectively, and an investigation has been made of their composition, scintillating and optical properties as revealed by X-ray diffraction (XRD), radioluminescence (RL) and optical absorption (OA) measurements.

We have found single phase CaWO4 in both as-obtained powders and single crystals, and wellbehaved optical and scintillating properties. Enhanced scintillating properties in single crystal samples were evidenced, with single or double RL peaks between 400 nm and 500 nm, with sources of β-ray or X-ray, respectively. Also, a decrease of the RL light yield with the temperature increase was observed in all the samples. A shift of the RL peak was also observed with the temperature increase.

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