热喷涂涂层结合强度的冲击测量法

Evaluation of Impact Indentation Adhesion Test of Thermal Spray Coatings

讨论了一种新型快速定性评价热喷涂层结合强度的冲击测试方法,采用自由落体的落锤冲击设备对涂层进行冲击试验,并采用声发射技术进行动态监测,以定性分析涂层结合强度。首先用超音速等离子喷涂技术分别制备了组织致密,性能良好的Ni Cr金属、Cr_2O_3陶瓷涂层。采用90°和120°金刚石压头、120°及Ф2 mm球形硬质合金压头试验,其中120°硬质合金压头更适合冲击法测试涂层结合强度。随着冲击能量的提高,声发射的能量计数也不断提高,但是落锤高度超过400 mm后,能量计数变化不大,说明在400 mm时涂层发生了破坏。对基体金属、Ni Cr涂层、以及有无Co Cr Al Y为结合层的Cr_2O_3陶瓷涂层进行对比测试,发现声发射能量计数峰值随着涂层结合强度的增强而降低。

A novel evaluation method of rapid and qualitative impact indentation method for the adhesion strength of thermal spray coatings was discussed.A free fall drop weight impact device was used in the test with the acoustic emission （AE） technique. Dense NiCr and Cr2O3 coating with high performance were prepared by supersonic plasma spraying techniques firstly. NiCr coating was impacted by four kinds of indentation heads with 90°, 120° diamond cone, 120° carbide cone and Ф 2 mm carbide sphere. The test results showed that 120° carbide head was the best indenter. The effect of the impact energy on the test was discussed. It was found that the energy count of AE signals was as a function of the impact energy. When the drop height was over 400 mm, little change of energy counts was observed, which indicated that coating failure was occurred when the impact energy was the height of 400 mm. Comparing with the results of substrate material, NiCr metal coaing, Cr2O3 cermic coating with and without CoCrAlY bonding coating, it is concluded that the maximum of AE energy count decreases with the increase of the bonding strength of the thermal spray coatings.