超声波辅助镍基金属镀层的制备及其性能研究

发布时间：2019-03-27 18:46

【摘要】：工业的进步、生活水平的提高,人们对材料的功能性提出了更高的要求,既要求材料具有装饰性,观赏性,又要求提高材料机械性能,例如:硬度、耐磨损性、耐腐蚀性,但是全部具有这些性能的材料少之又少,并且造价昂贵。低碳钢是生产生活中使用频率最高的材料,不管是建筑物或是机械零部件,常见的都是碳钢材料,低碳钢的缺点是强度低,硬度小,表面易被腐蚀,所以人们通过一些表面加工技术改善低碳钢的使用寿命,比如:激光原位生长、溅射、化学镀、喷涂、电沉积。其中激光原位生长和溅射适合在实验室研究,由于条件限制难以在工业中发挥作用。喷涂应用较为广泛,但相对电沉积技术,涂层质量较差。化学镀方法相对电沉积,避免了材料形状的限制,但是其沉积液相对不稳定,镀层质量难以控制。综合而言,电沉积技术操作相对简单,成本低,易控制,镀层质量较好。本文采用超声波辅助直流电沉积技术成功制备Ni-Mo合金镀层和Ni-Mo/GO复合镀层,并研究沉积液中镍钼摩尔比、超声功率、氧化石墨烯(GO)对Ni-Mo合金镀层微观形貌、晶粒生长、粗糙度、硬度、耐腐蚀性、高温稳定性的影响;结果显示镀液中镍钥摩尔比降低(钼含量增加)有助于镀层结构从纳米晶转变为纳米晶/非晶结构,镍钼摩尔比为6:1时,镀层平滑、致密。镍钼摩尔比10:1及4:1时,镀层产生微裂缝,耐腐蚀性降低。超声波辅助Ni-Mo合金镀层研究表明,适当的超声功率(180 W)提高镀层致密性,成核速度加快,降低镀层晶粒尺寸(44 nm),提高镀层硬度(719 HV)和耐腐蚀性,降低表面粗糙度(3.587 nm)。过大的超声功率(270 W)对镀层造成不利的影响,增加晶粒尺寸(50 nm),镀层的硬度(681 HV)和耐腐蚀性能降低。GO的加入使镀层表面覆盖了一层屏障,当外力作用在镀层表面时,GO阻止金属合金发生位错运动,提高了镀层的硬度(825 HV)。热重测试表明镀层中GO的加入增强镀层高温稳定性,延缓金属生成金属氧化物的时间。电化学阻抗和塔菲尔测试表明,GO延缓了腐蚀介质对基体的侵蚀,腐蚀电位正移,腐蚀电流密度降低,大大提高了镀层耐腐蚀性能。
[Abstract]:With the progress of industry and the improvement of living standard, people put forward higher requirements for the functionality of materials, which require both decorative, ornamental and mechanical properties, such as hardness, wear resistance, corrosion resistance, etc. But all of the materials with these properties are rare and expensive. Low carbon steel is the most frequently used material in production and daily life, whether it is a building or a mechanical part, and the common material is carbon steel. The disadvantages of low carbon steel are low strength, low hardness and easy to be corroded on the surface. So people improve the service life of low carbon steel by surface processing technology, such as laser in-situ growth, sputtering, electroless plating, spraying, electrodeposition. Laser in-situ growth and sputtering are suitable for laboratory research, but it is difficult to play a role in industry due to the limitation of conditions. Spraying is widely used, but the coating quality is poor compared with electrodeposition technology. Compared with electrodeposition, the electroless plating method avoids the limitation of material shape, but the deposition solution is relatively unstable and the coating quality is difficult to control. Overall, electrodeposition technology is relatively simple to operate, low cost, easy to control, and the coating quality is better. In this paper, Ni-Mo alloy coating and Ni-Mo/GO composite coating were successfully prepared by ultrasonic assisted direct current electrodeposition, and the microstructure of Ni-Mo alloy coating was studied by Ni / Mo molar ratio, ultrasonic power and graphene oxide (GO). Effects of grain growth, roughness, hardness, corrosion resistance and high temperature stability; The results show that the decrease of Ni / Mo molar ratio (increase of Mo content) in the bath is beneficial to the transformation of the coating structure from nanocrystalline to nanocrystalline / amorphous. When the molar ratio of Ni to Mo is 6: 1, the coating is smooth and compact. When the molar ratio of Ni to Mo is 10:1 and 4: 1, the coating produces micro cracks and the corrosion resistance is reduced. Ultrasonic assisted Ni-Mo alloy coatings showed that proper ultrasonic power (180W) improved the compactness and nucleation speed, decreased the grain size (44 nm), increased the hardness (719 HV) and corrosion resistance of the coatings), and improved the coating hardness (719 HV) and corrosion resistance. Reduce Surface Roughness (3.587 nm).) Excessive ultrasonic power (270W) had an adverse effect on the coating, and increased grain size (50 nm), coating hardness (681W) and decreased corrosion resistance). The addition of go covered the coating surface with a barrier. When the external force was applied on the surface of the coating, GO prevented the dislocation movement of the metal alloy and increased the hardness of the coating (825 HV). Thermogravimetric tests showed that the addition of GO into the coating enhanced the high temperature stability of the coating and delayed the formation of metal oxides. Electrochemical impedance (EIS) and Tafel test showed that GO delayed the corrosion of the substrate, positively shifted the corrosion potential and decreased the corrosion current density, which greatly improved the corrosion resistance of the coating.
【学位授予单位】：上海应用技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4

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