DEEP HOLE DRILLING INSERTS,LATHE MACHINE CUTTING TOOLS,CARBIDE INSERTS

Cesium tungsten bronze (Cs_xWO₃) powders were synthesized by hydrothermal reaction at 190 °C by using sodium tungstate and cesium carbonate as raw materials, and the effects of N₂ annealing on the microstructure and near-infrared (NIR) shielding as well as heat insulation properties of Cs_xWO₃ were investigated. The results indicated that the synthesized Cs_xWO₃ powders exhibited hexagonal Cs_0.32WO₃ crystal structure, and subsequent N₂ annealing could further improve the crystallinity of Cs_xWO₃ particles.

Moreover, the NIR shielding and heat insulation properties of Cs_xWO₃ could be further improved after N₂ annealing at appropriate temperature for a period of time. Particularly, the 500 °C-annealed Cs_xWO₃ products in the N₂ atmosphere showed the best NIR shielding and heat insulation properties. When the N₂ annealing temperature was higher than 700 °C, the NIR shielding properties decreased again. The 800 °C-annealed samples in the N₂ atmosphere showed higher visible light transmittance, however, the NIR shielding properties were lower than that of the non-annealed samples.

carbide Threading Inserts

Due to historical reasons, sometimes the oxides of tungsten bronze are also referred as bronze in the literature, bronze oxide can be represented as the formula A_xMO_n. In A_xMO_n Formula, A is positively charged atoms, M is a transition metal, n can be either an integer or a non-integer. A_xMO_n has following characteristics in structure. (1) the M in MOn is usually octahedral, and it’s often covalently linked between M-O. The octahedra further connected to form a skeleton structure with polyhedral open pores; (2) A_xMO_n partial skeleton structure is similar with Common Turning Inserts MO_n; (3) A is constantly electropositivity atom, filling cavities in the skeleton; (4) With the filling of A, transition metal M appears allotropy divalent ions, that becomes mixed valence ion, thereby forming a nonstoichiometric compound.

Semiconductor photocatalysts are highly praised for their stable physical and chemical properties, wide distribution on the earth, easy access, low cost and no secondary pollution. As a member of transition metal oxides, tungsten trioxide (WO₃) is an indirect bandgap n-type semiconductor material with a band gap of 2.2-2.8eV. It has good absorption of visible light, so it is a very promising semiconductor photocatalyst.

Core-shell is a nano-scale orderly assembly structure formed by coating another nano-material by chemical bonds or other forces. Core-shell structure, due to its unique structural characteristics, integrates the properties of both internal and external materials and complements each other's shortcomings. It is an important research direction of morphological determinants in recent years. It has broad application prospects in catalysis, photocatalysis, batteries, gas storage and separation. At present, the preparation methods of tungsten trioxide fibers with core-shell structure include electrospinning, impregnation and chemical coating.

Electrospinning technology is a fast and simple method for preparing nanofibers. It has many advantages, such as simple manufacturing device, low spinning cost and various kinds of spinnable materials. It has great progress not only in laboratory research, but also great potential for industrialization. Therefore, it is of great industrial value and social significance to prepare tungsten trioxide nanofibers in batches by electrospinning and use them as photocatalysts.

The core-shell structure tungsten trioxide fibers are prepared by dissolving ammonium metatungstate in water and adding polyvinylpyrrolidone to adjust the ratio of raw materials to obtain the precursor solution. The precursor solution with good conductivity and viscosity is prepared by electrospinning process. After calcination, the core-shell structure tungsten trioxide with different surface morphologies is prepared. Nanofibers. Its specific operation process includes:

The 2.5G ammonium metatungstate hydrate was dissolved in 5 ml deionized water, and the polyvinylpyrrolidone (PVP) with molecular weight 13000 was added to 1 g. The precursor solution was obtained by stirring the solution to be uniform and transparent. Then the white cloth-like primary spun fibers were obtained by uniaxial electrospinning with voltage of 15KV, receiving distance of 12cm and driving speed of 0.01ml/min. The primary spun fibers were placed on horses. Tungsten oxide nanofibers with core-shell structure were obtained by calcining at 550 ℃, heating rate 5 / min, holding for 30 minutes, and natural cooling to room temperature.

Tungsten trioxide nanofibers with core-shell structure were prepared by electrospinning technology. The process was simple, the raw materials were easy to obtain, and water was used as solvent without any Lathe Machine Cutting Tools other additives. The prepared tungsten oxide had high purity, uniform diameter distribution, large aspect ratio, strong controllability of morphology, strong performance, and was easy to realize industrial mass production.

What is the working principle of tungsten alloy multi-leaf collimator? Let's begin with some pieces of information of multi-leaf collimator. Tungsten alloy multi-leaf collimator, which was developed to replace the traditional lead blocks, are used on linear accelerators to provide conformal shaping of radiotherapy treatment beams. And specifically, conformal radiotherapy and intensity modulated radiation therapy can be delivered using multi-leaf collimators. The multi-leaf collimator has movable tungsten alloy leaves to block some fraction of the radiation beam. Typically, multi-leaf collimators have 52-160 tungsten alloy leaves, arranged in pairs. So, what is the working principle of tungsten alloy multi-leaf collimator?

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Drilling Inserts

Working Principle of Tungsten Alloy Multi-Leaf Collimator

The multiplex motor is used to drive the screw rod to rotate, thereby pushing the tungsten alloy leaves forward or backward, so that the multiple tungsten alloy leaves at the two ends can be enclosed into a figure with the same shape as the tumor site that needs to be irradiated, and thereby X-rays emitted by the medical electron linear accelerator passing through to achieve the purpose of radiotherapy. In other words, tungsten alloy leaves play an important role in shielding X-rays to reduce radiation damage to patients.

With the development of social economy, there are many applications requiring smart frame circuit breakers to have higher electrical life. Therefore, it is necessary to develop a kind of material with strong resistance to arc erosion as static contacts, which can be used in pairs with AgW50 dynamic contacts, so as to greatly improve the electrical life of intelligent frame circuit breakers and meet the requirements of various applications.

In order to replace the out-of-date Ag-Ni carbide contacts, some scholars added tungsten carbide into the Ag-Ni contacts to make a new Ag-Ni carbide contact material. It is known that this kind of Ag-Ni carbide contact material has strong arc erosion resistance and can greatly improve the electrical life of low-voltage intelligent frame circuit breakers when used in pairs with the existing AgW50 contacts.

The preparation process of silver nickel tungsten carbide contact material includes: selecting tungsten carbide powder with average fineness of 1 micron, - 200 mesh silver powder and - 300 mesh nickel powder, weighing 20 kg of silver-nickel carbide powder according to the following weight percentages (tungsten carbide 25%, nickel 1.55%, residual silver). Putting the powder into 30-liter V mixer for 2.5 hours, mixing the mixed silver nickel tungsten carbide powder and 180 kg of 6m. The high purity nickel ball and 4400 ml deionized water were put into a 100 liter drum ball mill for ball milling (45 rpm). The ball milling time was 30 hours. The powder was taken out and dried for 3 hours (the nickel content in the powder material was 2%) at 120 ℃. The powder was annealed at 700 ℃ in hydrogen atmosphere for 2 hours. The powder was annealed in steel mould under 6 T/cm² pressure. The billet is pressed and sintered at 900 C in hydrogen atmosphere for 1.5 hours. The billet is repressed in steel mould under 10.5T/cm² pressure. The billet is annealed at 500 ℃ carbide insert quotation in hydrogen atmosphere for 50 minutes. The silver nickel tungsten carbide contact can be obtained.

The silver nickel tungsten carbide static contacts and silver-tungsten 50 dynamic contacts are paired and installed on a low-voltage intelligent frame circuit breaker with rated current of 1600 A. The test proves that the silver nickel tungsten carbide static contacts and silver-tungsten 50 dynamic contacts can match the requirements of the test project stipulated by the circuit breaker, and the electric life of the circuit breaker is greatly improved, reaching more than 8000 times.