激光熔覆锡基巴氏合金的微观组织及性能

Microstructures and Properties of Tin-Based Babbitt Metal Prepared by Laser Cladding Deposition

锡基巴氏合金具有较低的摩擦因数、良好的耐磨性及抗胶合性,已被广泛用作高性能轴承零部件表面的耐磨材料。为改善传统浇注锡基巴氏合金中存在的缺陷并减少材料浪费,采用激光熔覆技术在20钢基体表面熔覆锡基巴氏合金,并将其与采用静止浇注、离心浇注工艺制备的合金进行对比。对三种合金层的微观组织、元素分布、显微硬度、摩擦磨损性能及内部质量进行检测和分析,结果表明:激光熔覆锡基巴氏合金的微观组织小于传统浇注合金的微观组织,且沿沉积方向的微观组织呈明暗交替的带状分布特征;激光熔覆合金层的显微硬度高于静止浇注合金层的显微硬度,与离心浇注工艺的相近;在干摩擦条件下,激光熔覆锡基巴氏合金的摩擦因数较传统浇注合金的大,其磨损机制以磨粒磨损为主;超声波和着色渗透无损探伤结果表明激光熔覆锡基巴氏合金层内无明显缺陷,与钢背结合良好。

Tin-based Babbitt metals are widely used as wear-resistant materials on the surface of high-performance bearing parts because of its low friction coefficient,good wear resistance and excellent anti-adhesion.To improve the defects in tin-based Babbitt alloy prepared by traditional casting and reduce material waste,laser cladding deposition(LCD)was used to fabricate tin-based Babbitt metal on the surface of 20 steel substrate,and the laser cladded Babbitt metal was compared with the alloys prepared by other two preparation processes,namely,the static casting and the centrifugal casting.The microstructure,element distribution,microhardness,friction and wear performance,and internal quality of the alloy layers were tested and analyzed.Results show that the microstructure size of tin-based Babbitt metal prepared by LCD is smaller than those of cast alloys,and the microstructure along the deposition direction is characterized by banded distribution of light alternated with darkness.Besides,the microhardness of the alloy layer prepared by LCD is significantly higher than that of the alloy prepared by static casting process and similar to that of the alloy prepared by centrifugal casting process.Nevertheless,in the case of dry friction,the friction coefficient of tin-based Babbitt metal prepared by LCD is greater than that of the alloys prepared by traditional casting process,and its wear mechanism is mainly abrasive wear.Additionally,ultrasonic and dye-penetration nondestructive tests indicate that there are no obvious defects in the tin-based Babbitt metal layer prepared by LCD,and it is well bonded to the steel back.