不锈钢管内表面钝化膜ALD制备及抗结焦性能

Preparation of passivation layers on the inner wall of stainless steel tube by atomic layer deposition and their anti-coking properties

采用原子层沉积(ALD)技术在SS316不锈钢管内壁制备了Al2O3、TiO2和Ru钝化层,研究其对抗结焦性能影响。结果表明:所制备Al2O3钝化薄膜相结构为γ-Al2O3,TiO2为锐钛矿结构,Ru为密排六方结构。钝化处理能够延长燃油循环系统工作时间,管内循环燃油在800℃保温过程中,Al2O3引起系统压降升高,而TiO2对系统的压降略有降低。对比TiO2和未钝化管的结焦形貌,TiO2钝化处理有效降低了表面焦油滴的尺寸和数量,同时在TiO2钝化管未发现丝状碳的产生,无定型碳的数量也有所降低,说明TiO2钝化层有着优异的抗结焦能力。酒精超声清洗后,TiO2和Ru钝化管胶质层完全脱落,说明其胶质层结构较为疏松或胶质层较薄;Al2O3和未钝化管胶质层只存在部分脱落,说明其胶质层和沥青质层结合力较好或有着较厚的胶质层。实验表明,TiO2和Ru钝化层抗结焦性能优于Al2O3钝化层。

Atomic layer deposition(ALD) technology was used to prepare Al2O3, TiO2 and Ru passivation layers on the inner wall of SS316 stainless steel tube, and its anti-coking performance was studied. The results show that the microstructure of the prepared Al2O3, TiO2 and Ru films is γ-Al2O3, anatase and hexagonal close-packed structure, respectively. The passivation treatment can increase the working time of fuel circulation system. During the 800 ℃ heat preservation process, the Al2O3 film causes the increase of pressure drop of the system, but the TiO2 film slightly reduces the pressure drop of the system. Compared with the bare tube, the TiO2 passivation treatment effectively reduces the size and number of tar droplets on the inner surface of the tube. At the same time, no filamentous carbon is found in the TiO2 passivation tube, and the amount of amorphous carbon is also reduced, indicating that the TiO2 passivation layer has excellent anti-coking ability. After ultrasonic cleaning with alcohol, the colloidal layers of the TiO2 and Ru passivation tubes completely fall off, indicating that the colloidal layer structure is relatively loose or the colloidal layer is thin. The colloidal layers in the bare and Al2O3 passivation tubes only partially fall off, indicating that the colloidal layer and asphaltene layer have better bonding force or thicker gelatinous layer. The experiment results show that the anti-coking performance of the TiO2 and Ru passivation layers is better than that of the Al2O3 passivation layer.