New process for melting red copper in induction melting furnace
Red copper is pure copper for industrial use, also known as electrolytic copper. The control of the induction melting furnace and casting process of industrial copper castings is much more difficult than that of copper alloys. This is because copper parts require high electrical and thermal conductivity, and trace impurities such as phosphorus, aluminum, arsenic, iron, tin, etc., especially phosphorus can greatly reduce the electrical and thermal conductivity of copper. Secondly, the melting point of red copper is higher than that of brass and bronze, so hydrogen absorption is serious during the smelting process, which easily leads to loose structure of the casting and a large number of pinholes.
The copper used to make crafts has no electrical and thermal conductivity requirements, so it can be
Deoxidize with phosphor copper. In the smelting process, it is only necessary to control hydrogen absorption and complete deoxidation. The smelting process is as follows.
(1) Melting copper. The copper is melted quickly in an oxidizing atmosphere, and its temperature reaches 1180～1200℃.
(2) Oxidation and degassing. After the induction melting furnace is melted, the copper liquid should be strongly oxidized to remove the hydrogen in the copper liquid. There are two commonly used methods for oxidizing copper liquid; one is to blow compressed air into the copper liquid; the other is to add oxidizing flux. Blow compressed air into the copper liquid with a minimum wind pressure of not less than 8.1kPa, and an oxidizing atmosphere should be maintained. At the end of oxidation, take samples and observe the fracture to determine the end of oxidation. When the raw material is electrolytic copper, the pattern fracture must be brick red and occupy more than 10% of the fracture area. When the raw material is T2 old material, the pattern fracture must be brick red and occupy more than 30% of the fracture area. The commonly used oxidizing flux is copper oxide, and the addition amount is 1% to 2% 3) Deoxidation. After oxidation and degassing, deoxidation should be carried out immediately. There are two commonly used deoxidation methods, one is the Aoki deoxidation method, and the other is the phosphor copper deoxidation method. Aoki deoxidation is to insert one end of the aoki (fresh pine) into the copper liquid, and use the boiling method to deoxidize. The degree of deoxidation can be judged according to the color of the test block. If the fracture of the test block is light yellow and the surface is flat, it is qualified for deoxidation. Deoxidizing with phosphor copper, phosphor copper can be added at one time, and the amount of phosphor added should be increased, and the amount of phosphor added should be 0.15% to 0.20%. The amount of phosphor copper is calculated based on the phosphor content of 10%, and the amount added is 1.5 of the total amount of copper alloy liquid. %～2.0% to ensure the removal of Cu and O. Inspection before furnace and temperature controlled casting. After the deoxidation is over, take the sample and observe it with naked eyes. When the solidified surface of the sample is flat and the mesh shows fine wrinkles, it can be cast. The casting temperature should be controlled at 1100～1150℃.
