How to choose the right nodulating agent
An additive used to promote the crystallization of graphite into spheres in ductile iron. General application, cast iron casting. However, there are many kinds and contents of nodulating agents in the market. Therefore, it is also very important to choose the right nodulating agent.
According to the reaction thermodynamics and reaction kinetics of the spheroidized elements in molten iron, the factors influencing the quality of the spheroidizing agent in the production process and the factors influencing the use process of the foundry, the standards for judging the quality of the spheroidizing agent are put forward as follows:
(1) affinity of spheroidized elements with sulfur, oxygen and other elements in molten iron. It has a strong affinity, and forms compounds with it, as the foreign core in the solidification process of molten iron, such as rare earth, magnesium, calcium and other spheroidized elements.
(2) the ability of spheroidizing elements to change the morphology of graphite from flake to spheroid.
(3) The density and boiling point of the spheroidizer are lower than that of liquid iron. Low density can automatically float in molten iron, the boiling point is lower than the temperature of molten iron treatment, magnesium can be converted into a gaseous state at the temperature of treatment, there is a self-stirring effect, so as to improve the effect of spheroidization.
(4) the content of magnesium oxide in the spheroidizer is equal to about 10% of the content of magnesium.
(5) nodulating agent dense, no segregation, no shrinkage porosity, no pulverization.
(6) the particle size distribution of the spheroidizer is uniform, no powdery alloy, obtuse Angle multi-deformation particles is better.
(7) The above conditions basically cover the quality requirements in the production and use of nodulating agent, so it can be used as a unified standard for quality determination by both parties.
As a kind of additive which is widely used in cast iron industry, the quality and performance of spheroidizer are very important. Therefore, on the basis of choosing high-quality products, the spheroidizer is added and used according to the instructions to achieve the best use effect.
