铝热反应中铝含量对铸渗复合层组织与性能的影响

Influence of Aluminum Content in Thermite Reaction on the Microstructures and Properties of Cast-Infiltration Composite Layer

以ZG310-570为基体、高碳铬铁为主渗剂,采用传统铸渗工艺并结合Al热反应制备了钢基表面铸渗复合材料,研究了Al含量对铸渗层组织、厚度、耐磨性的影响。结果表明,在浇注温度为1650℃,预制块(厚度为10mm)以半嵌入式置于型腔内壁中下部的条件下,当渗剂中Al粉的质量分数不大于2%时,渗层和基体间表现为良好的冶金结合,铸渗层中含有大量的M7C3、Cr7C3等硬质相碳化物,且加Al的渗层中有Al2O3硬质相的存在。随着Al含量增加,渗层厚度和耐磨性得到提高;Al含量为2%的渗层综合质量最佳,铸渗层厚度可达到15mm,其耐磨性是基体耐磨性的6.65倍。

The steel-based surface composites were fabricated with the carbon steel ZG310-570 being selected as matrix and high carbon ferrochrome as cast-penetrated agent by conventional cast-infiltrating process combined with the thermite reaction. Influences of aluminum content in thermite reaction on the microstructures, thickness and properties of cast-infiltration layer were investigated. The results show that the interfacial bonding exhibits metallurgical fusion between cast-infiltration layer and the matrix, and the cast-infiltration composites mainly consist of M7 Ca , Cr7 C3 and Alz 03 phase in the cast-infiltration layer containing aluminum powder, and the thickness and wear resistance of the composite layer are increased with the increase of aluminum content when the aluminum content is less than 2 %, the pouring temperature is 1 650 ℃, and the preforms （thickness 10 mm） are embedded in the middle-bottom location of the mold wall. The cast-infiltration layer containing 2% A1 exhibits desirable properties, where the thickness reaches to 15 mm, and the wear resistance is approximately 6.65 times higher than that of the matrix.