Anaerobic copper refers to pure copper without oxygen or any deoxidizing agent residues. In the production and production of oxygen free copper bars, processed anaerobic copper is used as raw material for production and casting. Anaerobic copper bars have high purity, high conductivity, good processing performance and other characteristics, and there are no other defects of copper. So what are the precautions in anaerobic copper casting?
1. Overcome casting cracks
For the foundry workers, the casting crack can be overcome by improving the surrender of the mud core. This method is not effective for the casting of anaerobic copper. The method of reducing the temperature gradient of the casting wall is a more effective method worth paying attention to.
2. Argon protection pouring
Because anaerobic copper has a strong tendency of oxygen and inspiration, it is necessary to do a good job in the oven and pouring of copper liquid protection measures, copper liquid protection can be used coal flame, nitrogen, argon, etc., with argon protection, closed pouring method can make the oxygen content of the casting almost no increase.
3. The selection of paint
The pouring temperature of anaerobic copper is generally controlled at about 1200℃, which requires the coating to have good adhesion and sufficient refractoriness. For anaerobic copper, it is better to use zirconium paint or spray acetylene flame smoke black on zirconium paint. Practice has proved that the casting surface poured out with this kind of coating is smooth, no signs of gas, and the smoke black has deoxidation.
4. The use of metal type temperature
The use of metal mold temperature has an effect on the crack, density, surface finish, subdermic pores of the casting. The real factor that determines the use of metal mold temperature is mainly to ensure that the adsorption of water in the casting mold and the casting does not produce cold insulation casting defects. It has been proved by practice that the metal mold of pouring oxygen-free copper is better controlled at about 150℃.
5. Technological measures
The casting of anaerobic copper is more difficult, and it also needs to assist other processes, such as the control of pouring speed, the design of pouring system, etc. The principle of non-ferrous metal casting can be applied and the characteristics of the casting itself can be combined with reasonable selection of technological measures.
6. Control of sequential solidification
There are many factors affecting the solidification of castings, such as casting material, casting speed, casting temperature, casting part wall thickness, alloy composition, etc. For the straight cylinder type anaerobic copper cast with uniform thickness, rain pouring can be adopted to achieve the purpose of sequential solidification. For the non - oxygen copper casting with uneven thickness, the casting can be sequentially solidified by drainage from thick wall and supplemented by riser. For the castings that are not allowed to be drained from the thick place and must be drained from the thin place, cold iron can be added in the thin place or the thick wall place, or both can be used to make the castings achieve the purpose of sequential solidification.