If the gap of tungsten contacts of distributor is reduced, then: the closing time of tungsten contacts will be prolonged; ignition coil ignition energy will store more; before the tungsten contacts opening, current formed in the primary coil will be relatively large; when the tungsten contacts are opened, the maximum secondary voltage is relatively high.

If the gap of tungsten contacts of distributor is increased, then: the closing time of tungsten contacts will be shortened, which resulting in ignition energy reduction and the maximum secondary voltage drop. And because the opening time of tungsten contacts open ahead, it will cause that ignition advance angle increases.

However, the gap of tungsten contacts of distributor is not too small. If the gap is too small, when tungsten contacts are closed, it will form a strong contact spark and lost the primary ignition energy, resulting in tungsten contact ablation. And because the cutoff of primary current circuit is not complete, so the maximum secondary voltage will be reduced.




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The preparation of silver tungsten contacts can be powder metallurgy or infiltration method.

Silver material characteristics:
Low melting point, low hardness, volatile, low wear resistance, good thermal conductivity characteristics;
When the load is large, the silver contacts material is easier to form an arc and welding;
Because silver has low hardness and volatile characteristics, so under the effect of DC, silver film will form electrical erosion and spikes;
At high temperature and humid environment, silver will form silver sulfide film in the surface of sulfur or sulfur compounds.

Tungsten content of silver tungsten contacts material is usually around 20% -80%, silver tungsten contacts advantages: they own good oxidation resistance, good electrical and thermal conductivity, arc erosion resistance, excellent electrical wear resistance ability and good anti-welding capability. Silver tungsten contact shortcoming: contact resistance is unstable. When the silver tungsten contacts frequently running because the contact surface of silver and tungsten will produce a mixed oxide, the splash degree of contact resistance of the film surface will increase.

Silver tungsten contacts application: it is widely used in thermostats, circuit breakers, micro-switches, etc., and can also be used for electrical contacts, high current heavy equipment.




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The normal value of tungsten contacts gap of the distributor is generally around 0.35mm-0.45mm. If the gap is large than normal value of 0.1mm, the engine will use more petrol than 3% of fuel; if small  than 0.1mm, then 5％of fuel.

Ignition energy, ignition advance angle and the maximum secondary voltage will affect the automotive ignition system performance. If the ignition energy is insufficient, it will cause the mixture gases do not ignite properly. If the ignition advance angle is too small or too large, so the mixture gases will not normally burn after ignition. If the maximum secondary voltage is low, then the spark plugs do not flash over normally. These factors will make the power of engine decline, fuel consumption rise and dysfunction and so on. So, appropriate tungsten contacts gap of the distributor can mitigate the impact of car ignition energy, ignition advance angle and the maximum secondary voltage to car ignition system.




Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
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For trivalent praseodymium (Pr³⁺) and quadrivalent praseodymium (Pr⁴⁺) codoped CaMO₄ (M = W, Mo) powders, the luminescence propriety of matrix is obviously influenced by carrier concentration. The light emission intensity of CaWO₄ matrix decreases exponentially with increasing of Pr concentration because oxygen-deficient obtains an electron supplied by Pr³⁺ (5d). However, the light emission intensity of CaMoO₄ is enhanced by Pr codoping because the quasi-free electrons increase the probability of radiative combination. The difference of photoluminescence properties in the two materials are attributed to the bonding character of M and O in the CaMO₄ structure.

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