碲对灰铸铁性能的影响

Influences of Tellurium on Properties of Grey Cast Irons

碲涂料常被用于解决缸体和缸盖铸件的渗漏问题,但研究发现,碲对铸铁的石墨形态和基体组织有影响,因而会影响铸铁的力学性能。当碲的加入量较少时,会阻碍石墨的生长,使石墨变细、变短,发生弯曲,引起不规则的团块状石墨出现,石墨数量增多,导致铁素体量增多。当碲的加入量相对较多时,碲会与MnS形成共生物富集在共晶团前沿,使铁液产生成分过冷,使其按介稳定系进行凝固,导致铸铁形成白口组织。因此,生产过程中应严格控制碲涂料的质量。

The tellurium coating is often used to solve the leakage problem of cylinder blocks and heads. However, it has been revealed by investigation that the tellurium could influence the graphite morphology and matrix structure of cast irons and caused decrease of mechanical properties of cast irons. When adding relatively less amount of tellurium, Te restricts the growth of graphite and causes the graphite become finer, shorter, curved, causes some lump-shaped graphite appearing and increases the graphite count that results in increasing of ferrite content. When adding relatively big amount of tellurium, Te and MnS would combine to form paragenous compound which is accumulating at the fronts of eutectic cells and causes composition super-cooling of the iron melt. As a result, the iron melt would solidify according to the quasi-stable system and lead to formation of the white structure. Therefore, the quality of the tellurium coating must be strictly controlled in the production process.