超音速等离子喷涂的NiCr-Cr_3C_2粒子特性对涂层性能的影响

Effect of particle character of supersonic plasma sprayed NiCr-Cr_3C_2 on coating property

采用超音速等离子喷涂法在调质45钢表面制备NiCr-Cr3C2金属陶瓷涂层，利用SprayWatch系统对喷涂过程中NiCr-Cr3C2粒子的分布状态、温度及速度等特性进行短时短距离的监测；并通过改变喷涂距离来改变喷涂粒子的特性，研究粒子特性对涂层的孔隙率、硬度与摩擦性能的影响。结果表明，在喷涂距离为90～120mm范围内，粒子的速度与温度都相对较高，在喷涂距离为110mm时，粒子的最大速度达到530m／s，平均温度为2180℃。粒子温度过高或过低都不利于获得高质量涂层，但粒子速度越大，涂层质量越好。在喷涂距离为110mm时，由于粒子速度大（平均为452m／s）、温度适中（平均温度为2180℃），沉积的NiCr-Cr3C2涂层结构致密，显微缺陷较少，具有较高的显微硬度和较低的孔隙率，分别为986Hv0.3和0．96％，并且摩擦性能较好，摩擦因数和磨损量都最小。

NiCr-CraC2 coating was deposited using supersonic plasma spray （SPS） system, and the Spray Watch system was used to monitor the particle distribution state, particle temperature and particle velocity. The coating porosity, micro-hardness and tribological property were tested to investigate the relationship between the sprayed particle character （achieved by changing the spray distance of the spray distance） and the coating property. Results show that, with increasing spray distance, the spray particle temperature and velocity increase first and then decrease; at the spray distance of 110 ram, the particle velocity reaches the highest value for 530 m/s and the average temperature is 2 180℃. In order to fabricate high quality coating, the sprayed particle temperature should not be too high or too low, while in terms of particle speed, the higher speed of sprayed particles, the higher of the quality is; at the spray distance of 110mm, the sprayed particle gains the best character of sprayed speed and temperature of 452 m/s and 2 180℃, respectively; the coating prepared at this distance has a dense micro-structure with little micro-defect, the micro-hardness and porosity are 986 HV0.3 and 0.96%, respectively, and the friction peroperty is better with the least friction coefficient and volume loss.