The Effect Of CVD Preparation Process On The Brittleness Of 6.5% Si Silicon Steel

The Property of silicon steel which depends on the content of silicon will be improved as the increasing of silicon content, the resistivity and permeability will increase, but the core loss will reduce, especially when the silicon content increased to 6.5%, silicon steel will perform some excellent soft magnetic properties such as high magnetic conductivity, low iron loss and nearly zero magnetostriction.However,silicon steel with 6.5%Si will become very brittle and has little ductility which makes it cannot be manufactured by conventional cold rolling method,CVD method avoids the low rolling yield characteristics successfully, but the sample performance are closely related with preparation process conditions such as temperature, atmosphere, oxygen content, SiCl4 concentration and so on.So it is significant for us to prepare 6.5%Si steel by CVD method and research on the effects of different process conditions on the brittleness to improve its brittleness.This paper described the experimental equipment and manufacturing process of CVD method, and the test and control method of temperature and oxygen content, verified the relationship between the SiCl4 concentration and bath temperature, determined the CVD reaction heating mode. After determining the process conditions, different mechanical property simples were prepared through a single control of preparation process.For quantitative analysis of brittleness, design and manufactured a three point bending machine, by comparing the reduction of specimens and load-displacement curve to evaluate brittleness. Based on the experimental result did further microstructure analysis, such as samples SEM observation, EDS,SEM fracture scanning. Did research of the effect of coarse grains, grain boundary oxidation and Kirkendall voids on brittleness by analysis of the samples prepared by different process parameters, the results show that to control reaction temperature, to minimize the oxygen content o, and to reduce the concentration of SiCl4 can reduce the brittleness 6.5% Si silicon steel; Did research of the effect of annealing treatment and element Sn on brittleness by changing substrate conditions, the results show that annealing treatment caused inhomogeneous grain increased brittleness, Sn prompts Si spread evenly, making toughness better.