Molybdenum carbide has a high melting point and hardness, good thermal stability and mechanical stability, and excellent corrosion resistance and other characteristics. Molybdenum is a silvery white refractory metal, a melting point of 2615 ℃, density of 10.2 g / cm 3, the expansion coefficient is small, a special tube is almost the same coefficient of expansion of the glass. Molybdenum stable at room temperature is higher than 600 ℃, rapidly oxidized.
2013年11月18日星期一
Projection welding spot is tungsten carbide plate larger than the electrode face significantly
Phase material weldability is poor, therefore , domestic rice Chuan Liu products connections using riveting process . To this end , the development of a single- cycle pulse of platinum foil projection welding of new technology, the two layers as well as the non- cushion foil product key is welded directly . After the lamp is designed with raised bumps , bumps at the current can be concentrated on the internal heat source and increases the distance between the electrode surfaces , easy to form a
tungsten carbide plate in the thickness direction . Meanwhile, the projection welding electrode end face larger than the spot welding , a significant increase of the contact area of the electrode and the workpiece , reducing the welding
sandblasted tungsten target and the surface of the heating strength , effectively reduce the sticking of the electrode . Further , since the projection welding heat input can be reduced ( reduced welding current ) , reducing grain products grown , heat welding of the aluminum to improve brittleness . Designed bumps and tested in practice , the choice is less detailed projections play an important part of the benefits . The choice of the shape of the bumps on the suppression of the bump foil tears , generally spherical shape. Spherical bumps having a high strength welded joints , and conical -shaped bumps can remove the residual stress concentration at the bottom and the maximum circumference of the cracks , at the same time , the crush bumps process also easy to produce and move along splash.
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