Phosphor copper is used as a deoxidizer in copper alloys.
Phosphor copper is a master alloy of copper and phosphorus used primarily as a powerful deoxidizing agent in metal casting and as an essential component in brazing alloys. It improves the quality, strength, and corrosion resistance of copper-based metals.
Composition and Properties
Phosphor copper is an intermediate alloy, typically containing a high percentage of phosphorus (commonly 8%, 10%, or 15%), which is added to molten copper to achieve specific material properties.
Deoxidizing agent: Phosphorus has a strong affinity for oxygen and reacts with it to form stable oxides, effectively removing oxygen from molten metal. This prevents gas porosity and embrittlement, resulting in denser, higher-quality castings.
Alloying agent: When added to copper, brass, or bronze, phosphorus enhances the strength, hardness, wear resistance, and fluidity of the resulting alloy.
Melting point modifier: The addition of phosphorus lowers the melting point of the copper alloy, which is advantageous in applications like low-temperature welding and brazing.
Corrosion resistance: While copper is already corrosion-resistant, the addition of phosphorus further enhances this property.
Conductivity: The electrical and thermal conductivity of the alloy decreases as more phosphorus is added; however, the resulting phosphor bronze still offers good conductivity suitable for many electrical applications.
Common Applications
Phosphor copper itself is a raw material, typically sold in forms like shot (granules), waffle plates, tablets, or rods for use in various industrial processes. Its primary applications are:
Brazing and soldering: Copper-phosphorus alloys (often with added silver) are widely used in the HVAC, refrigeration, and plumbing industries to join copper pipes and tubing because they are self-fluxing on copper and flow smoothly.
Master alloy production: It is the key ingredient used to manufacture phosphor bronze alloys, which are then used to make springs, electrical contacts, bearings, bushings, and marine components due to their superb spring qualities, high fatigue resistance, and excellent wear resistance.
Foundry use: In foundries, phosphor copper shot is added to molten metal to improve casting fluidity and create dense castings free of defects.
Aluminium industry: Specific grades (like 8% phosphor copper) are used as a grain refiner or nucleant for certain aluminum-silicon casting alloys to enhance their properties.
