Nanosized Tungsten Powder Prepared from Ammonium Paratungstate

2024.03.18 Monday 18:30
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    Tungsten is used in the production of numerous end use items. It is widely used for high temperature applications such as filaments in light bulbs, cathodes in high power lamps, and rocket nozzles in space crafts. Tungsten is also used in the manufacture of superalloys and catalysts. In addition, its considerable applications in industry as a refractory metal owing to its outstanding Carbide Threading Inserts hardness and wear resistance in the form of tungsten carbide are well known.

    As the powder properties significantly affect the subsequent operations, such as pressing and sintering. Nanoscaled Tungsten Carbide Inserts promises to yield very hard, strong, and wear resistant materials via the press-sinter route.A thermal plasma process was applied to produce nanosized Tungsten Carbide Inserts using ammonium paratungstate (APT) as the starting material.

    LNPU Milling Inserts

    The experimental Carbide Inserts procedures are as follow:

    Nanosized Tungsten Carbide Inserts was synthesized in a thermal plasma reactor, in which ammonium paratungstate (99.9%) was used as the precursor and hydrogen (99.9%, H2) was used as the reducing agent.

    The synthesized Tungsten Carbide Inserts and submicron Tungsten Carbide Inserts were each mixed with 2 wt.% of wax. The wax was used to decrease friction between the particles as well as between the powder and the press die in the subsequent compaction process. In order to prepare nanosized Tungsten Carbide Inserts, the submicron Tungsten Carbide Inserts mixed with 2 wt.% of wax was milled using a High Energy-Dual Planetary Mill (HE-DPM) for 6 h. The ratio of WC balls to powder was 10:1 by weight and heptane was used as the milling media. The Tungsten Carbide Insertss were cold-pressed by the use of Carver Laboratory Press under 5 tons (∼242 MPa) holding for 1 min using a WC–Co die of 16.2 mm diameter. Then, the green compacts were sintered under flowing H2 atmosphere at 1400 °C for different holding times of 1, 30 and 60 min, in which the ramping rate of tube furnace to increase the temperature up to 1400 °C was 10 °C/min and the cooling rate to room temperature was also 10 °C/min.

    LNPU Milling Inserts

    The produced Tungsten Carbide Insertss were analyzed by XRD (Siemens, D5000) and its morphology was examined by TEM (FEI, Tecnai30). The Tungsten Carbide Insertss and sintered compacts were analyzed using analytical scanning electron microscopy (SEM, Topcon sm-300). The grain size of produced W powder was calculated from the XRD pattern by applying the Scherrer equation or the Stokes and Wilson equation.

    In conclusion, In the present work, nanosized W powder with an average particle size of 25 nm was synthesized by a thermal plasma process using ammonium paratungstate (APT) as the precursor. Comparing with submicron W powder (0.5 μm average size) and nanosized W powder (23 nm average size) produced from the latter by high energy milling. The hardness of the compact of the plasma-synthesized powder (315 VHN) sintered at 1400 °C was higher than that of submicron-sized powder (193 VHN) and was similar to that of the milled powder (309 VHN). The plasma-synthesized powder, however, yielded a compact with much lower tendency to form cracks than the milled powder.


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    Characteristics of Tungsten Carbide Die

    2024.03.18 Monday 17:04
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      Characteristics of tungsten carbide are high hardness, good wear resistance and high compressive strength, so it is suitable for making dies such as powder metallurgy dies, such as tungsten carbide pressing dies.  Tungsten carbide in China started late, but it has Carbide Aluminum Inserts developed rapidly. At present, the tungsten carbide die has been basically serialized and standardized. From the development of recent years, the theory of research and design of tungsten carbide dies is more thorough, more scientific and more widely used. CNMG Cast Iron Inserts 1, High Hardness and Good Wear ResistanceThe hardness of the tungsten carbide is next to diamond and cubic boron nitride. Its hardness range is HRA86-94. The lowest hardness of the tungsten carbide (HRA84-86) is greater than the maximum hardness of the tool steel (HRC64-69). The wear resistance of high tungsten carbide inserts cobalt tungsten carbide die is better than that of HRC63-65, and the die life is longer. 2, High Modulus of ElasticityThe modulus of elasticity of the tungsten carbide is 3-4 times that of the tool steel, which means that the mould has a higher ability to resist deformation. Under the working stress of pressing, the deformation of the tungsten carbide die is smaller than that of the steel die. As a result, the size of the product and the size of the die are very close, so the machining accuracy of the product is high. At the same time, due to the higher modulus of elasticity and smaller elastic aftereffect, it has the advantages of controlling the crack of the blank. The deflection is much smaller when it is subjected to force, which is of special value for the manufacture of longer mold parts with thin and sharp edges. 3, Low Friction CoefficientWhen draw metal materials are made, electrical energy consumption can be greatly reduced. At the same time, it has little adhesion to metal material processing (affinity), which makes the mold surface is not easy to injury nap. Therefore, the tungsten carbide die not only has a high life span, but also has good surface quality, which can even be processed in mirror surface. Thus, the subsequent buffing, polishing, and other processing procedures of the products can be omitted. 4, Superior Hot PropertyThe thermal expansion coefficient of tungsten carbide is only 1/2 of steel. So even if the temperature increases at work, the error of the mold size is 1 times smaller than that of the steel mold. 
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      Types of Tungsten Carbide End Mills¡¿Drills and Diagrams ­½

      2024.03.13 Wednesday 12:11
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        In part 8, we know about Plastic Cutting-Square, 2 Flute Upcut, Plastic Cutting-Square, 0 Flute Upcut, etc. And here in this part we will go on showing more diagrams of tungsten carbide end mills.

        Here we show more types of tungsten carbide end mills/Drills, such as Square End Mills-Long Reach, Square End Mills-Miniature, etc., each type has different shape and application according to it's own work piece. From the below diagrams with the brief names we can have a direct knowledge on the basic figures and their respective functions.

        Carbide Turning Inserts BLMP Milling Inserts

        (To be continued. This article is divided into 11 parts and this is part 9, for part 8 please refer to:https://www.estoolcarbide.com; for part 10 please refer to:https://www.estoolcarbide.com)

         

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        Chemical Etchants of Tungsten Points

        2024.03.05 Tuesday 16:56
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          1. The chemical etchants of silver tungsten points, tungsten copper points, tungsten points, silver-nickel points, tungsten, copper and nickel points and other points are:
          tungsten carbide inserts Ammonia                            50ml
          Or hydrogen peroxide solution (30%)      10-30ml.
          Use of points as follows: using a freshly prepared solution to wipe the surface of the points about 10 seconds.

          2. The chemical etchants of tungsten, nickel or tungsten carbide particles in silver-nickel points, copper tungsten points, silver tungsten points, silver tungsten carbide points are: potassium ferricyanide mixture, among them,
          A. NaOH(KOH)    10g         water     90ml
          B. K3[Fe(CN)6]     10g         water     90ml
          Use of points as follows: mixing A and B, and wiping the surface of the points.

          3. The chemical etchants of tungsten particles in copper tungsten points and silver tungsten points are: hydrochloric acid solution and potassium ferricyanide mixture, among them,
          A. NaOH(KOH)    10g    Water 90ml
          B. K3[Fe(CN)6]     30g    Water 70ml
          Use of points as follows: mixing A and B, and wiping the surface of the points.

          4. The chemical etchants of pure copper, copper alloy are: hydrochloric acid solution and ferric chloride, among them,
          Ferric chloride                    5g
          Water                           50ml
          Hydrochloric acid (concentrated)     50ml
          Use of points as follows: wiping.

          5. The chemical etchants of pure silver, copper graphite are: ferric chloride solution, among them,
          Ferric chloride                    10g
          Water                           50ml
          Carbide Grooving Inserts Use of points as follows: wiping.

           

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          Smart Glass Electrochromic Device Prepared Based on Tungsten Oxide Films

          2024.03.02 Saturday 17:08
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            In the past few decades, electrochromic devices have received great attention from researchers in related fields in the materials industry. Electrochromism is a reversible change in optical properties (such as absorbance and transmittance) of a material under low electric fields. Electrochromic devices have a wide range of applications, including reflective displays, smart windows, information displays, and electrochromic paper.

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            Tungsten trioxide (WO3) has been considered an excellent EC material. However, its drawbacks such as poor stability and slow switching time have limited its large-scale applications. Although amorphous WO3 thin films have demonstrated good optical performance and high coloration efficiency they still suffer from poor electrochromic repeatability, longer response time and stability.

            SNMG Aluminum Insertstungsten carbide inserts

            Smart glass electrochromic device has been prepared based on tungsten oxide films, the tungsten trioxide films exhibited good optical modulation and high electrochromic performance. The synthesis of the WO3 films-based electrochromic device is as following steps:

            Ammonium tungstate hydrate ((NH4)6W12O39.xH2O, Alfa Aesar) and oxalic acid (C2H2O4, Merck) are used as oxidizer and fuel, respectively. The oxidizer-to-fuel ratio (O/F) is maintained at 1. According to the reaction given in the equation. (1) Weigh 6.08 g of hydrated ammonium tungsten oxide and 2.27 g of oxalic acid. The two chemicals were dissolved in 15ml of distilled water. Then, the two solutions were mixed and magnetically Cemented Carbide Inserts stirred for 15 minutes. Use a heating mantle to initiate a combustion reaction at 300°C. Within a few seconds, the reaction was completed, and the synthesized powder was washed several times with ethanol. After filtration, the powder was dried at 80°C overnight. Due to the explosive nature of the reaction, the amount of powder obtained is less than the theoretical value.

            For comparison, the following steps were performed on commercial tungsten oxide powder (purity 99.8%, Alfa Aesar) and synthesized WO3 powder to obtain a thin film under the same conditions. SCS-WO3 and C-WO3 powders were prepared with particles with a diameter of 1 cm and a thickness of 0.14 cm, respectively, and then sintered at 850°C for 8 hours. The cleaning procedures for ITO (Indium Tin Oxide) and Corning glass substrates are ultrasonically cleaned in acetone, deionized water, alcohol, and deionized water. Each step includes 10 minutes. Two kinds of particles prepared by electron beam evaporation in a copper boat are deposited on the substrate of the WO3-x thin film. During the evaporation process, the vacuum degree is about 8.2×10-6 Torr. During the coating process, the substrate is kept at room temperature, and the deposition rate is 2Å/s.

            In summary, smart glass electrochromic device has been prepared based on tungsten oxide films, the tungsten trioxide films exhibited good optical modulation and high electrochromic performance. It is found that the SCS-WO3 thin film evaporated by electron beam exhibits an amorphous, homogeneous and uniform structure, and has high-efficiency electrochromic properties (ΔT=68% at 550nm and CE=60cm2/C) and C-WO3 thin film (ΔT=58% at 550nm and CE=44cm2/C) has high coloring efficiency and optical transmittance modulation. In addition, the two samples also showed rapid coloring and bleaching speeds during the ±1V switching period. Then, Nafion electrolyte is used to manufacture an all-solid ECD based on SCS-WO3 (ΔT=63% at 550nm and CE=97cm2/C). In the future, the innovative SCS-WO3 film can be directly and widely used in energy-saving smart display applications.


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            WO3 SCR Waste Denitration Catalyst Recovery Process

            2024.02.28 Wednesday 16:35
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              There are four processes for recycling waste tungsten trioxide SCR denitration catalyst as Carbide milling inserts following:1. The waste tungsten trioxide SCR denitration catalyst was crushed and re-added to the new manufacturing process of catalyst. In this process, the amount of recovery catalyst is limited, thus the goal of recycling all the waste catalyst can’t be realized.2. The material carried out sodium treatment and roasting→precipitate V by ammonium chloride from the leachate→ precipitate tungsten by calcium chloride→ de-integrating the Na4TiO4 by sulfuric acid; or sodium treatment and roasting→ precipitate tungsten by calcium chloride→ realize the separation of tungsten and V by forming ammonium paratungstate.Such technology has the following properties:(1) The material should be crushed before roasting, and always require the particle size equals to or less than 200μm, Carbide Milling Inserts otherwise it will cause a serious loss of fly ash and large amounts of carbon dioxide emissions in the calcination process;(2) The heat cannot get fully used;(3)The separation step and impurity removal method of waste tungsten trioxide denitration catalyst isn’t well considered, and cause the purity of recovered products limited;(4) does not form a good cycle of process wastewater reuse.
              ONHU Milling Inserts

              3. Two times of electrolysis with strong electrolyte solution→ adjust pH with ammonium to precipitate vanadium. The industrial application and energy consumption of this process is unknown; besides, W, Ti and other components cannot be separated for recycling.4. The pretreatment of removing ash→ alkaline leaching at high temperature and pressure→ removing impurities with magnesium salts→ precipitate tungsten and vanadium with calcium salts→ de-integrating the tungsten, vanadium and calcium salts→ extract vanadium→ prepare the material which is rich in titanium→ wastewater reuse treatment. This is the better treatment processing with purity of the recovered products well controlled; moreover, elements Na and Cl well recycling and the energy get fully used.
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              Multileaf Collimators to Match Every Shape

              2024.02.22 Thursday 14:55
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                In order to target radiation precisely to the diseased tissue, it is necessary to use multileaf collimators.

                First of all, X-ray images are produced to determine the precise position and outline of the tumor. Following this 3-dimensional measurement, Cemented Carbide Inserts an electric motor moves each individual leaf in the collimator to the correct position – with up to 120 leaves being used to shape the outline of the tumor with millimeter accuracy. Then, the tumor is exposed to high energy radiation. During this process, the tumor is radiated by turning the gantry with the multileaf collimator 360° around the patient. To protect the surrounding healthy tissue, a highly precise multileaf collimator is necessary. To protect the environment from unwanted radiation, different shielding parts are widely used.


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                Nano Structured Crystalline Tungsten Oxides

                2024.02.19 Monday 10:14
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                  Tungsten oxides, as one of the important oxide semiconductors, are the most widely investigated materials for EC devicesbecause they can be used as intercalation host for H+, Li+, Na+,and Zn2+ to form tungsten bronze with blue color due to their special tunnel structure. 

                  With the development of tungsten oxide Carbide Inserts films, nowday it has been widely used in many area such as energy-saving smart windows,high contrast displays, sunroofs, and antiglare mirrors.but after many studies found amorphous tungsten oxide films have poor electrochemical stability, so research work has been mainly focused on nano structured crystalline tungsten oxides. For instance, some researcher reported that WO3 nano particles showed greater charge density for proton intercalation and comparable coloration efficiency compared with conventional amorphous WO3 films. Researcher fabricated WO3 nanowires and investigated their electrochromic property. They found that the nanowires showed fast optical response time and high coloration efficiency. Researcher also reported that WO3 nanorods exhibited high electrochromic stability and comparable color display, contrast and coloration/bleaching response.

                   

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                  Cemented carbide blades Wear Characteristics in Drilling limestone­º

                  2024.01.31 Wednesday 16:26
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                    3.3. Wear mechanism of cemented carbide blade drill rock with water jet

                    The failure type of the cemented carbide blades in water jet drilling is not the same as that in dry drilling. Fig. 6 shows the SEM micrographs (500×) of damaged surfaces of blades in the experiments. Fig. 6 (a) is the typical brittle fracture morphology in dry drilling. No serious fractures are detected in the drilling experiments with water jet under the same zoom scope and the surfaces mainly show wear morphology.

                    There are mainly three reasons to explain the different results. Firstly, water jet can effectively decrease the surface temperature and thermal stress. Secondly, the water jet provides impact force to crack the limestone, and it helps to decrease the mechanical force on the blade. Thus, the sum of thermal stress and mechanical stress which can induce serious brittle fractures could be lower than the material strength of the blade in drilling with water. In the third place, the water jet with higher pressure could form a comparatively cooler water layer to lubricate the blade, and could rush away the hard abrasive particles in the rock like a polisher. Therefore, the surface of the blade in water jet drilling is much smoother than that in dry drilling, and the wear rate will decrease while the water jet pressure increases.

                    Although wide range of brittle fractures is avoided, but there will still be surface damages on the blades in rock drilling with water jet. Fig. 7 shows micrographs of typical wear surfaces of cemented carbide blades in limestone drilling with water jet. It is obvious that point 1, on the edge of the blade, is rougher than point 2. In fact, the two points could reflect the wearing process of cemented carbide blades in limestone drilling with water jet.

                    The wearing process of cemented carbide blades in limestone drilling with water jet could be divided into two stages. Initially, under water jet-assisted condition, micro cracks appear on the edge of the blade, probably caused by local mechanical abrasion and thermal stress which is induced by the fl ash temperature. The grain size and its distribution on the surface can be seen in Fig. 7 (d). The Co phase is much softer than the WC phase and it is easy to be worn. So when the blade mills the rock, Co phase is worn firstly and with particles washed away by the water jet, the porosities between grains are larger and the surface of the blade becomes more uneven.

                    Then, this kind of micro surface damage expands from the edge to the center of the blade surface. While the drill bit is rotating in the rock, the edges and corners of grains will be polished as mentioned before, shown in Fig. 7(e). And this polishing process continues from the edge to the center of the blade surface. When the drill bit drills into the rock continuously, the polished tungsten carbide inserts surface on the edges will form new micro cracks which then extend to the center of the blade surface because of mechanical abrasion and thermal stress caused by flash temperature.

                    Therefore, this roughing-polishing process is repeated from the edge to the center of the blade surface constantly, and the blade will became thinner and thinner until it cannot work.

                     

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                    How Is Gold-Plated Different From Real Gold¡©

                    2024.01.31 Wednesday 14:32
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                      Not all gold is made from pure gold. In some cases, a piece of jewelry contains metal covered with gold to imitate pure gold. This lowers the cost of producing gold, which lowers the price of buying gold. Real gold and gold-plated metals have characteristics that allow experts to distinguish them.

                      Gold Plating Process
                      Gold-plating involves an electrochemical process Carbide Grooving Inserts whereby jewelers place thin molecules of gold on a base metal like copper or brass. Some gold-plated products are not created using real gold, but something that has a gold color. The gold color is eventually worn down by pollutants and salts. Gold-plated jewelry lacks the durability of authentic gold jewelry.

                      Gold Mining
                      Miners remove gold from the earth and from water using various methods, including gold panning and dry washing. The extracted gold is either pure gold or has mercury and silver included. The gold must be refined so it has a market value. Miners can remove the mercury from the gold by heating it until it vaporizes. However, refiners must take steps to avoid inhaling the toxic mercury fumes. People later melt down gold into different forms, such as gold bars and coins.

                      Properties
                      Gold is non-magnetic. Carbide Inserts Gold-plated products sometimes contain magnetic metals like steel, which will be drawn to a magnet. Base metals also react to nitric acid, while gold will not. However, gold testers using nitric acid should know what they're doing, since the acid can seriously burn the skin.

                      Distinguishing
                      Jewelers cannot legally sell a product as gold unless it has at least 10 karats. However, without sophisticated tests, distinguishing between 10 and nine karat gold can be difficult. When seeking real gold, consumers should shop at stores that have quality assurance programs and test their pieces. In addition, gold that has poor quality workmanship is likely to be gold-plated instead of pure gold.

                       

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