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Copper-phosphorus alloy advantages of copper brazing

Author:admin     Date :2012/9/26 1:56:19     Popularity:
Copper phosphorus alloy brazing copper self-fluxing characteristics showed only one of the advantages of this type of alloy family.
 Copper phosphorus brazing alloy mainly used for welding copper, especially in refrigeration, air conditioning copper pipe and electrical conductors. Copper phosphorus alloy and silver-copper-phosphorus alloy initially in the United States in 1914 to obtain a patent, but it can be widely used until after World War II. During that period, the new refrigerant instead of ammonia and promote the extensive use of copper in the growing market of air conditioning (including homes, offices and other workplaces); fact, this is thanks to the Westinghouse Company, since the Second World War copper - phosphorus system after the rapid development of the air conditioning and refrigeration industry.
 
The role of phosphorus in phosphorus copper alloy?
To reduce the melting temperature of copper (temperature inhibitor)
Increase the flowability of the copper in the liquid state
To play the role of the reducing agent or brazing agent and copper together
Reduce the ductility of copper
 
Phosphorus has played a significant role in reducing the degree of the melting of copper; copper into liquid melting degree varies according to the content of phosphorus. When heated to melting degrees brazing alloy becomes completely liquid, and when the alloy is cooled to this temperature is completely converted into solid state. The main side effect is to reduce phosphorus in phosphorus copper alloy ductility of copper. The phosphorus content of 8-8.5% of the time, the solder alloy in the state of heat and cooling are difficult to mold, especially a cold forming. Phosphorus be obtained at a higher content of any performance of the manufacturing cost thereof will be offset.
That silver can improve the ductility of the copper-phosphorus alloys, this is actually a misunderstanding; silver in the alloy plays a role similar to phosphorus. Silver to decrease in the degree of melting of copper but also weakened its ductility; Fortunately, silver copper ductility regardless of phosphorus are much smaller than the ratio extent, the use of silver has degradation temperature the characteristics, you can select a similar melting silver copper phosphorus brazing filler metal, but the latter contains less phosphorus and copper phosphorus alloy. In fact, the content of less phosphorus but will make the alloy more ductile, rather than the addition of silver.
Similarly, copper-phosphorus alloy and silver-copper-phosphorus alloy liquidity also follow ductility similar characteristics. As the phosphorus content increases, the fluidity of the liquid alloy is also accordingly increased. The flowing alloy mated capillary action space to obtain a capillary attraction to retain its liquid state. With the addition of silver, the amount of phosphorus can be reduced, but its flowability when the alloy is melted weak; so less phosphorus content of the high silver brazing material can be filled with a larger workpiece gap and the generation of large joints. According to the second chapter of the American Welding Society AWS Brazing Manual, it is recommended that the joint gap of 0.001-0.005 inch for the family of copper-phosphorus alloys, used in joints less than 1.0 inches in length, and then select the connector length greater than 1.0 inches 0.007-0.015 inch joint gap.
Welding of copper and copper copper phosphorus alloy showing the the biggest advantage is its self-fluxing; flux but you need to use when welding brass, bronze, and other special occasions such as silver, tungsten, molybdenum. Copper-phosphorus alloy showing the connection of copper and copper from self-fluxing phosphorus element held attraction oxygen. Torch with oxygen the brazing the phosphorus will and oxygen in the air and flames mixed.
Phosphorus addition to the oxidation reaction occurs in the welding, and the workpiece surface is mixed. Whether phosphorus losses caused by mixing or the oxidation reaction occurs, will result in changes in the performance of the remainder of the liquid occurs when the formation of the joint. In most cases, the change performance of the liquid is more viscous, elevated melting degree. Copper phosphorus brazing alloy applications, regardless of filamentous, strip or prefabricated, must pay attention to reduce the possibility of any of phosphorus oxidation. The phosphorus content of any minor change in the flow properties of the liquid metal to produce a significant effect.