刘琪,桑可正,曾德军.多孔SiC表面WC+W2C涂层的制备及其结构研究[J].表面技术,2022,51(3):226-233.
LIU Qi,SANG Ke-zheng,ZENG De-jun.Preparation and Structure of WC+W2C Coating on Porous SiC Surface[J].Surface Technology,2022,51(3):226-233 |
| 多孔SiC表面WC+W2C涂层的制备及其结构研究 |
| Preparation and Structure of WC+W2C Coating on Porous SiC Surface |
| 投稿时间：2021-09-26 修订日期：2021-12-30 |
| DOI：10.16490/j.cnki.issn.1001-3660.2022.03.024 |
| 中文关键词: 润湿性 溶胶凝胶 碳化硅 涂层 WC+W2C |
| 英文关键词:wettability sol-gel silicon carbide coating WC+W2C |
| 基金项目:陕西省自然科学基金研究计划项目(2018JQ5120) |
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| 中文摘要: |
| 目的 改善金属与SiC的润湿性，避免金属熔渗过程中损伤多孔SiC基体。方法 采用氧化烧结法制备了多孔SiC基体，再采用溶胶氢还原法于900 ℃在多孔SiC表面制备了WC+W2C涂层。通过X射线衍射仪和扫描电子显微镜研究了涂层的结构和组成，以及热处理温度、时间和溶胶吸收次数对涂层的影响。结果 热处理温度为900~1100 ℃时，W与C发生反应并形成了WC与W2C，但温度增加至1350 ℃时，涂层与基体发生反应，形成了WSi2化合物。在900 ℃时，随着热处理时间从1 h增加至3 h，涂层颗粒聚集长大，颗粒之间的距离增加。随着吸胶次数的增加，经还原后的涂层颗粒数量增多，平均粒径不断增加，吸胶5次后，涂层颗粒所占表面区域面积百分比达到饱和，约为40%。吸胶6次后，涂层颗粒的平均粒径达到0.53 μm。结论 WC+W2C涂层以颗粒状分布在基体表面形成涂层。通过增加吸胶次数到6次，可以有效地增加涂层颗粒的数量以及所占面积百分比。基于涂层与金属润湿效果的最佳工艺条件是在试样吸胶6次后进行还原热处理，还原温度为900 ℃，时间为1 h。 |
| 英文摘要: |
| To improve the wettability of the metal with SiC and to avoid damage to the porous SiC substrate during the infiltration process. A certain amount of SiC powder was mixed with about 5wt.% alcohol-soluble phenolic resin. Then, the ϕ15 mm×4 mm specimens were obtained by cold pressing with 84 MPa press for 1 min. Finally, porous SiC substrates were prepared by oxidation sintering. The raw materials were prepared according to the mass ratio of ammonium metatungstate, citric acid, ethylene glycol and water-soluble phenolic resin 6:3:2:0.84. By adjusting the heating time to control the evaporation of solvent deionized water, the molar ratio of W to C is 1:2 and the solid content of ammonium metatungstate is 50%. One side of sintered porous SiC ceramic sample is immersed in the sol, and the pore of SiC ceramic was automatically impregnated with the sol by capillary force. When the surface of SiC ceramic sol exudated, took out the sample and filter paper to scrape off the surface of excess sol, and then dried. Finally, the sample was placed in a tubular furnace to begin hydrogen reduction. Samples with WO3 layer were obtained by heating them to 500 ℃ at a heating rate of 10 ℃/min for 3 h. Then it was heated to 800, 900, 1000, 1100 and 1350 ℃ at a heating rate of 10 ℃/min for 3 h (among which, 1 h, 2 h and 3 h were set at 900 ℃), and WC+W2C coating was obtained. In addition, WC+W2C coatings could be obtained on the porous SiC surface by the sol-gel hydrogen reduction method at 900 ℃. The structure and composition of the coating, the effects of heat treatment temperature and time as well as the times of suction of the sol on it, were studied by X-ray diffractometry and scanning electron microscopy. The results showed that W and C could react and form WC and W2C when the heat treatment temperature was between 900 ℃ and 1100 ℃, but the coating reacted with the substrate and the WSi2 compound appeared when the temperature was increased to 1350 ℃. With the increase of heat treatment time at 900 ℃, the coating particles gradually gathered and grew, and the distance between coating particles became larger. With the increase of suction times, the number and the average size of the particles after reduction increased. By 5 times of suction of sol, the percentage of surface area occupied by the coating particles reached saturation, which was about 40%. The average particle size of the coating particles reached 0.53 μm by 6 times of suction. It can be concluded that coating is formed by WC+W2C, which appeared as particles and distributes on the porous SiC substrate. The number of the particles and the percentage of area occupied can be effectively increased by increasing the number of sol suction to 6 times. The best technological condition based on the wetting effect of coating and metal is that the sample is treated at 900 ℃ for 1 hour after suctioning the sol by 6 times. |
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