Anodic plasma electrolytic deposition of composite coating on ferrous alloys with low thermal conductivity and high adhesion strength

SURFACE & COATINGS TECHNOLOGY

卷:398

Article

Zhao, Chen¹  Sun, Jiayi¹  Nie, Xueyuan¹  Tjong, Jimi²  Matthews, D. T. A.³ 

[1] Univ Windsor, Dept Mech Automot & Mat Engn, Windsor, ON N9B 3P4, Canada

[2] Ford Motor Canada, Powertrain Engn Res & Dev Ctr, Windsor, ON N9A 6X3, Canada

[3] Univ Twente, Fac Engn Technol, Dept Mech Solids Surface & Syst, De Horst 2, NL-7522 LW Enschede, Netherlands

关键词: Plasma electrolytic aluminating;    Thermal conductivities;    Thermal stability;    Adhesive strength;    Composite coating;   

DOI  :  10.1016/j.surfcoat.2020.126081

来源: Elsevier

【 摘 要 】

This work reports the preparation of oxide-based ceramic composite coatings as potential thermal barrier coatings (TBC) on ferrous alloys, targeting automotive applications. The coatings are shown to have excellent adhesion due to fabrication by plasma electrolytic aluminating (PEA), an anodic plasma electrolytic deposition process. The PEA process was conducted in an aluminate-containing aqueous electrolyte under a high voltage. The coating has superior adhesion (> 60 MPa) and low thermal conductivity (similar to 0.5 W/mK) measured by the adhesive tensile test and steady-state heat flow methods, respectively. Scanning electron microscope (SEM) observations reveal that the coatings have numerous mesopores. X-ray diffraction (XRD) analysis shows that the coating mainly consists of alpha-Al2O3 and hercynite (FeAl2O4) with (ultra-)fine grain size. Amorphous phases are also identified in the coatings. These mesopores, fine grain size and amorphous phases contributed to the low thermal conductivity of the coating. The hercynite phase indicated that the substrate was involved in the PEA reaction and thus the coating had a metallurgical bonding to the substrate. After cyclic thermal shock tests (quenching from 425 degrees C to 20 degrees C in water 100 times), the coating retained its porous structure without spallation. The results demonstrate that the ceramic composite coating may be a good candidate for thermal management of automotive engines.

【 授权许可】

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