采用超声振动辅助激光熔覆工艺, 在GCr15轴承钢表面制备了钴基合金涂层, 在750 ℃/100 h条件下分析了试样的微观结构和高温氧化行为。结果表明：超声振动并未改变熔覆层的相组成, 只是在近表层形成了更加均匀细小的等轴晶组织。涂层经100 h高温氧化后遵循抛物线氧化规律。相比于传统的激光熔覆涂层, 超声振动辅助激光熔覆涂层表面形成的氧化膜更加细小致密, 且无明显的氧化破裂和剥落缺陷, 同时伴随大量高温稳定性好的CoCr2O4尖晶石相生成, 氧化增重与氧化速率常数分别减小了19.2%和50.8%, 涂层的抗高温氧化性能进一步提升。

The Co-based alloy coatings are prepared on the GCr15 bearing steel surfaces by the ultrasonic vibration assisted laser cladding technique. The microstructure and the high-temperature oxidation behaviors are analyzed in detail under the condition of 750 ℃/100 h. The results show that the ultrasonic vibration does not change the phase compositions of cladding layers and only more uniform and fine equiaxed structures are formed in the near surface layers. After high-temperature oxidation for 100 h, the coating follows the parabolic oxidation rule. Compared with those of traditional laser cladded coatings, the oxidation films on the surfaces of coatings by ultrasonic vibration assisted laser cladding are finer and denser, and there are no obvious oxidative cracks and spalling defects. Meanwhile a large number of high-temperature CoCr2O4 spinel phases with good stability are generated. The oxidation weight gain and oxidation index are reduced by 19.2% and 50.8%, respectively. The high-temperature oxidation resistance is enhanced.