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Vacuum Heat Treatment Furnace

Vacuum Sintering Furnace

Vacuum Brazing Furnace

Vacuum Brazing of Cast Iron

1. Brazing Materials

(1)Brazing cast iron brazing mainly uses copper and zinc brazing material and silver brazing material, commonly used copper zinc brazing grade is B-Cu62ZnNiMuSiR, B-Cu60ZuSnR and B-Cu58Zn FeR and so on, brazed cast iron joint tensile strength generally reached 120 to 150MPa, on the basis of copper and zinc brazing material, add Mn, Ni, Sn and Ai and other elements, can make brazing head and mother material and other strength.

The low melting temperature of silver copper brazing material, brazing cast iron can avoid the production of harmful tissue, brazing head performance is good, especially with Ni brazing materials, such as B Ag50CuZnCdNi and B-Ag40CuZnSnNi, enhance the combination of brazing material and cast iron, especially suitable for ball-ink cast iron brazing, can make joints and master materials and other strength.

(2) When brazing agents use copper and zinc brazing cast iron, the main combination of FB301 and FB302 brazing agents, that is, borax or borax and boric acid mixture. In addition, H3B0340%, Li2C0316%, Na2C0324%, NaF7. 4% and NaC112. 6% of the brazing agent works better.

2. Brazing Technology
Before brazing cast iron, carefully remove graphite, oxides, sand and oil from the casting surface. The removal of oil can be done by organic solvent scrubbing, while the removal of graphite and oxides can be done by mechanical methods such as sandblasting or blasting of pellets, or by electrochemical methods. In addition, it can be removed by burning graphite with oxidizing flame.
Brazing cast iron can be used in flame, furnace or induction and other heating methods, because the cast iron surface easy to form Si02, so that the protection of the atmosphere of brazing effect is not good, to help generally use brazing agents for brazing. When brazing larger workpieces with copper and zinc brazing materials, sprinkle a layer of brazing agent on the cleaned surface and then put the workpiece in the furnace for heating or with a torch. When the workpiece is heated to 800 degrees C left
On the right, add the supplement and heat it to the brazing temperature, then scrape the needle at the edge of the connector to melt the brazing material into the gap. In order to improve brazing strength, 20min annealing is carried out after brazing at 700 to 750 x C, and then slow cooling is carried out.
Excess brazing agents and residues can be removed by rinsing with warm water. If it is difficult to remove, it can be washed with 10% sulfate solution or 5% to 10% phosphoric acid solution, and then washed with clean water.