丙烷流量对火焰喷涂TiB_2-50Co涂层抗热震性能的影响

Influence of propane content on thermal shock property of high velocity oxygen fuel sprayed TiB_2-50Co coatings

将在不同丙烷流量条件下采用超音速火焰喷涂技术制备的3种TiB2-50Co进行热震试验,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,通过水淬法测试涂层的抗热震性能。结果表明,在600℃条件下,随着热震次数的增加,涂层中的表面和截面裂纹扩展随之更长而深,并在热震循环次数为150次时涂层中出现了网状或交叉裂纹;在800℃条件下,涂层热震失效循环次数明显减少,涂层中裂纹扩展更为严重,其中No.3涂层(丙烷流量为36L/min)抗热震性能最差。通过对3种涂层在不同热震条件后的XRD分析可知,涂层的主要物相为TiB2和Co两相,并发现涂层中存在一定的TiO2氧化相。

Three kinds of TiB2-50Co coatings were deposited by high velocity oxygen fuel（ HVOF） method under different propane flow rate,and the thermal shock behavior of TiB2-50Co coatings was investigated at 600 ℃ with different thermal shock cycling number and at800 ℃. The surface and cross-sectional morphology of the 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 the coatings. The properties of thermal shock resistance were performed by water quenching method. The results show that with increasing of thermal shock cycles at 600 ℃,the surface and cross-sectional cracks are longer and bigger,and there are a network of cracks appeared in the coatings after 150 thermal shock cycles at 600 ℃. The number of thermal shock cycles of three kinds of the coatings is obviously reduced at 800 ℃,and the cracks more seriously propagate in the coatings,especially the coating with 36 L / min propane flow rate. By analyzing the phase compositions of three coatings after thermal shock,the main phase compositions of the coatings are composed of TiB2 and Co,and there also is TiO2 phase in the coatings.