14250 battery

　　14250 battery production technology - the necessity of adding tin to lead-calcium 14250 battery welding rods

　　This is a very important issue. In the production of traditional lead-acid batteries, the welding rod alloy does not need to be tinned. In addition, some corrections are made to the statement that the welding rod used for DZM 14250 battery welding is the same alloy as the grid. First of all, it should be explained that the alloy used in lead-acid batteries is lead-calcium-tin-aluminum for the negative electrode. The positive electrode is lead-antimony-cadmium. Because the melting points of the positive electrode alloy are similar, especially the presence of antimony, its melting point is close to that of the low-antimony alloy 270℃, which will not affect welding. But the negative electrode is different, because the melting points of each element in the quaternary alloy of the negative electrode are: the melting point of lead is 327℃, the melting point of calcium is 839℃, the melting point of tin is 231℃, and the melting point of aluminum is 660℃. Let me explain the lead-based alloy. The so-called lead-based is a synthetic metal made mainly of lead and other small or trace elements.

　　14250 battery production technology - the necessity of adding tin to lead-calcium 14250 battery welding rods As can be seen from these metals, their melting points are very different. Under the same heating conditions, it is impossible to melt at the same time. High-melting-point metals oxidize quickly at high temperatures, and an oxide film is formed on their surface when they are close to the melting point. The melting point of most metal oxides is more than twice that of their original metals. If you want to melt it again, it is impossible to do it with an ordinary welding gun and operating techniques.

　　Let's talk about the melting process during welding. When the alloy is melted as a whole, the two relatively high-melting-point metals contained in the plate are not actually melted, but dispersed and decomposed. Because as a whole, it is called an alloy, but as a unit, calcium and aluminum still exist. At this time, calcium and aluminum can be called infusible substances free in the low-melting-point metal melt. Pure lead itself has very poor ductility and fluidity. If elements such as antimony and tin are not added to pure lead, it cannot be cast (pure lead has been used to produce batteries before, but the grids are die-cast). The welding rod is the main filler of the busbar, and the plate ear occupies about 1/3. The function of the busbar is to connect the plates of uniform polarity in a pole group in parallel and transmit the power of these plates to the external circuit through the busbar. The melting point of lead-tin alloy is 183℃. Under the same temperature conditions, the melting time of lead-tin alloy is more than 1/3 shorter than that of pure lead. Here comes the following question: low eutectic metal, welding rod does not contain high melting point metal, there is no oxidation problem, but the plate contains high melting point metal. Oxidation process of plate ear: As soon as the welding torch flame touches the plate ear, there is a process of low melting point metal melting and high melting point metal oxidation, but it must be noted that the oxidation rate of aluminum in an oxygen-rich environment is extremely fast.

　　Because there is aluminum in this alloy, the purpose is to prevent the loss of calcium in the molten state. Therefore, there is a requirement for the amount of low eutectic metal, the purpose is to achieve mutual fusion of the plate ear alloy and the welding rod alloy in a relatively uniform time period.

　　It can be understood that as long as the molten body of the electrode alloy can reach the plate ear in the first time and meet with the low eutectic alloy of the plate ear, there will be no false welding. However, when the welding technology is not mature (flame, technique, and time are not well controlled), false welding will still occur.

　　For this reason, I think it is necessary to apply dual control to our welding at this stage. Explain the so-called special alloys for positive and negative electrodes. This special refers to the alloys used for positive and negative grids. If the positive electrode uses the grid alloy as a welding rod, it is OK. But the negative electrode is impossible. It can't be welded at all. When the alloy ratio was high calcium and low tin, the amount of tin added to the electrode alloy was 2%. Now the amount of tin added is between 0.8% and 1%. If this amount is less, the low eutectic metal in the molten pool is insufficient during welding, resulting in uneven welding quality.

　　In addition, the cadmium in the positive electrode and the calcium in the negative electrode cannot be mixed together. These two metals cannot be simply formulated into an alloy. These two components together will cause the metal texture to be scattered. In actual applications, if the positive electrode alloy is mixed into the negative electrode alloy, it will cause the busbar to crack, which will have a fatal impact on the quality of the 14250 battery.

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