1. Overhaul the contact gap of tungsten points in distributor.

Firstly, opening the cover of the distributor, then shaking and rotating the engine, overhauling whether tungsten points of the distributor is in good state, and checking the contact gap, if the gap is less than 0.37mm, you need to check the degree of tungsten points ablation, if not, you don’t need to.

If the degree of tungsten points ablation is severe, then:
putting on the gloves and removing the tungsten points, and placing them on a flat stone;
pouring some oil in your hand, and pulling back and forth to polish tungsten points and to prevent partial wear, besides, you must not swing it .

If the degree of tungsten points ablation is not severe, then:
smoothing ablation by using platinum sand bar or fine sandpaper. If you use fine sandpaper, you can turn it over, so its sand finish is outwardly to polish tungsten points, then turn it back, and erase the dirt left by milling until tungsten points are clean.



 

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Tungsten polymer (also known as tungsten poly) is a composition of various resins and tungsten powder which are mixed together through special metallurgical technology. The resins may include ABS (acryloynitrile butadiene styrene), PP (polypropylene), PBT (polybutylene terephthalate), PA (polyamide), PU (polyurethane), and TPE (thermoplastic elastomer), etc.

Properties of tungsten polymer include:
• High density ( ≥ 11.34 g/cm^3)
• Improved radiation shielding performance
• Improved flexibility properties
• Easily malleable
• No toxic constituents
• Resistance to corrosion by weather elements
• Resistant to corrosion by chemical and organic solvent resistance
• Insoluble in water
• No harmful effects when handling or processing

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Tungsten polymers are being introduced as an effective lead alternative in a variety of applications for which lead has traditionally been used. This push for alternatives is due to the threat that lead poses to the environment and to human health. Recent studies show that the heavy usage and poor disposal of lead products for decades has caused irreversible effects to the environment and as such lead is now ranked as the second most hazardous substance by the United States government. Due to tungsten polymer has high density (13g/cc), excellent radiation attenuation properties, and environmental friendly, it is widely used to produced radiation shielding to replace lead.

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In most cases, high-density materials are more effective than low-density alternatives for blocking or reducing the intensity of radiation. However, low-density materials can compensate for the disparity with increased thickness, which is as significant as density in shielding applications. While lead is the most suitable element for the prevention of the movement and penetration of the radiation there is also a better solution. Tungsten polymers are the next big thing.

The popularity of tungsten polymers is slowly rising due to the fact that tungsten is disposable unlike lead which has become an environmental hazard of late. Lead is not biologically degradable whereas tungsten is and thus the decrease in popularity. Tungsten polymers also do not pose any health risks associated with lead. The primary application of tungsten polymers is in replacing lead, for which these polymers are already being utilized extensively.

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Tungsten (W) is a very heavy metal powder that is compatible with virtually all polymers at very high loadings by weight. It is dark gray in color and can produce a matte finish in high concentrations, providing substantial restrictions for color matching. Tungsten polymer (also known as tungsten poly) is a composition of various resins and tungsten powder which are mixed together through special metallurgical technology. Due to tungsten polymer has high density (13g/cc), excellent radiation attenuation properties, and environmental friendly, it is widely used to produced radiation shielding. Tungsten polymer radiation shielding can be abrasive on processing equipment, and it is a filler of choice in very thin walled devices where radiopacity.

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The lattice-vibration Raman spectrum of calcium tungstate has been measured, using excitation by a He-Ne laser. Eleven of the thirteen long-wave-length phonon modes which are Raman active in first order have been detected. Polarization studies have revealed the group-theoretical symmetries of ten of the phonons. The linewidths and relative intensities of the Raman peaks have also been measured. These results complement the information obtained from the infra-red reflection spectrum of calcium tungstate. The frequencies of the infrared and Raman active phonons are discussed in terms of the normal modes of the lattice.

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A technique which may be used to determine the light conversion efficiency (defined below) of thin fluorescent crystals is presented. The illuminance associated with the visible spectrum emitted by the material under a pulse of x rays and incident on a light intensifier tube is amplified by the tube and is eventually recorded by a photographic film placed on the other side of the tube. A calibration curve relating the conversion efficiency of the crystal (regarded as an unknown variable) and the resulting film density is first obtained analytically. This is then used, in conjunction with the experimentally measured film density, to yield the conversion efficiency. An application of this technique was made to the case of a calcium tungstate crystal, for which a conversion efficiency of [equiation] was determined.

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Interferometric measurements of the linear thermal expansion coefficients are reported for thec andacrystallographic axis directions of calcium tungstate in the temperature range 30–270°K. The results are believed to be accurate to within 2% at 270°K, falling to 25% at 30°K. The reduced mean Grüneisen parameter (χ _s γ _mean ) = βV/C _t, calculated from the volume expansion coefficient β and earlier heat-capacity measurements, falls with diminishing temperature. Detailed identification of contributions to the thermodynamic properties arising from translational, rotational, and internal modes of vibration is prevented by spectral overlap. The quasiharmonic approximation has been applied to calculate provisional reduced moments of a representative vibrational frequency spectrum, which are in qualitative accord with earlier findings based upon observations of infrared reflection and first-order Raman spectra.

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The temperature dependences from 4.2 to 300 K of the seven adiabatic elastic constants of CaWO₄ have been determined by measurements of ultrasound wave velocities using the `sing-around' and pulse superposition methods. The adiabatic elastic constants have been calculated from the measured ultrasound wave velocities by a perturbation method using just seven of the eleven measured velocities and by an iterative method using all the measured velocities; agreement has been found between the two sets of values. The complementary data on the thermal expansion and heat capacity at constant pressure of CaWO₄ have been used with the present results to find the isothermal elastic constants, the heat capacity at constant volume, the Grüneisen parameters, and the Debye characteristic temperature at 0 K. The Debye characteristic temperature has been found from the heat capacity at constant volume from 10 to 300 K after subtraction of the Einstein heat capacity terms from the total heat capacity.

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A calcium tungstate X-ray phosphor is disclosed which consists essentially of a calcium tungstate host and from about 50 to about 200 parts per million, based upon the weight of the host, of vanadium as a dopant. The disclosed phosphor exhibits no detectable lag or persistence and is appreciably brighter than prior X-ray phosphors. A process for producing the phosphor is also disclosed which process comprises forming an aqueous reaction media of a water-soluble calcium source and a water-soluble tungstate source having an excess of calcium, maintaining a temperature of above about 80°C for a time sufficient to form solid calcium tungstate having a stoichiometric excess of calcium, separating the solid calcium tungstate, adding from about 50 to 200 ppm of a vanadium source and a fluxing material, heating said calcium tungstate to a temperature of between about 700°C and 1150°C for a sufficient time to form a phosphor composition and washing the phosphor with sufficient water to remove any residual water soluble contaminants. An optional process is to add, in addition to the vanadium source, from about 0.05% to about 1.0%, based upon the weight of the host, of tungsten trioxide.

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