超音速火焰喷涂TiB_2-40Co金属陶瓷涂层抗热震性能

Thermal Shock Behavior of TiB_2-40Co Composite Coatings Deposited by HVOF

通过超音速火焰喷涂技术在不同氧气流量条件下将3种Ti B2-40Co金属陶瓷涂层喷涂在Q235钢基体表面,研究3种涂层在600℃不同热震循环次数和800℃条件下的抗热震性能。通过扫描电子显微镜和X射线衍射仪对3种涂层在不同条件下热震后的表面和截面形貌及物相结构进行分析。研究结果表明,在600℃热震条件下,随着氧气流量的增加,涂层的抗热震性能降低,并在热震次数为150次,氧气流量为482 L/min时,涂层中裂纹较多且失效最快。在800℃热震条件下,3种涂层的抗热震次数明显减少,其中以氧气流量为482 L/min时涂层表面和截面产生的裂纹最多。通过对3种涂层在不同热震条件后的XRD分析发现,涂层的主要物相为Ti B2和Co两相,并发现涂层中存在一定的Ti O2氧化相。

Three kinds of TiB_2-40 Co coatings were deposited on Q235 steel substrates by a high velocity oxygen fuel(HVOF) method under different oxygen flow rates. The thermal shock behavior of the three as-sprayed TiB_2-40 Co coatings was investigated at 600 oC with different thermal shock cycling number and at 800 oC. The surface and cross-sectional morphologies of coatings after thermal shock test were analyzed by scanning electron microscopy(SEM). And X-ray diffraction(XRD) was employed to characterize the phase compositions of coatings. The results show that with the increase of the oxygen flow rate, thermal shock property of the coating decreases at 600 oC thermal shock test. Moreover, the amount of cracks of the coating at 150 thermal shock cycling times and 482 L/min oxygen flow rate is more than that of other coatings. The number of thermal shock cycles of three kinds of the coatings is obviously reduced at 800 oC, especially the coating with 482 L/min oxygen flow rate. By analyzing the phase compositions of three coatings after thermal shock, it is shown that the main phase compositions of the coatings are composed of TiB_2 and Co, and there is also TiO_2 phase in the coatings.