Electrochemical corrosion behavior of hot-pressing sintered WC-Al 2 O 3 composite in alkaline and acidic solutions
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Electrochemical corrosion behavior of hot-pressing sintered WC-Al2O3 composite in alkaline and acidic solutions Bin Han1, Shigen Zhu1,2,* Ping Di1 1 2
, Weiwei Dong1, Yunfeng Bai1, Hao Ding1, Yilan Luo1, and
College of Mechanical Engineering, Donghua University, Shanghai 201620, People’s Republic of China Engineering Research Center of Advanced Textile Machinery of the Ministry of Education, Shanghai 201620, People’s Republic of China
Received: 13 August 2020
ABSTRACT
Accepted: 31 October 2020
In this study, WC-Al2O3 composite was fabricated by vacuum hot-pressing sintering. The corrosion behavior of WC-Al2O3 composite in NaOH and H2SO4 solutions was investigated by electrochemical measurements. The corrosion mechanisms were analyzed and revealed in light of corrosion morphology observation and composition characterization. The results confirmed that WCAl2O3 composite possessed higher corrosion resistance than WC-Co hard metal in H2SO4 solution. Conversely, WC-Al2O3 composite behaved similar corrosion resistance compared with WC-Co hard metal in NaOH solution. The key reason for higher corrosion resistance in H2SO4 solution is the stable WO3 passive film. The oxidation of WC phase leads to neck cracks along with grain boundaries, which is attributed to the preferential corrosion of grain boundary and the stress derived from the volume expansion during polarization and drying processes. In NaOH solution, the corrosion mechanism of WC-Al2O3 composite mainly attributed to the dissolution of WC phase, but Al2O3 phase is relatively stable.
Published online: 12 November 2020
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Introduction The classical WC based cemented carbides are widely used in various industries due to the combination of their performances such as excellent mechanical properties and tribological properties [1–4]. Among the hard metals, WC-Co cemented carbide is the most
common kind of hard materials, which could be used as wire drawing dies, mining and cutting tools [5, 6]. Co is the standard binder for WC based hard metals due to its excellent wettability with WC phase, which results in liquid-phase sintering with outstanding hardness and toughness [7, 8]. It is well known that Co binder can enhance the fracture toughness of WC based cemented carbide, but it also has many
Handling Editor: Joshua Tong.
Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10853-020-05521-6
J Mater Sci (2021) 56:4120–4134
disadvantages such as expensive cost, low melting point, environment toxicity and poor oxidation/corrosion property, which limit the application in various industries and shorten the service life [9, 10]. Therefore, many related efforts have been made to enhance the corrosion property of WC based cemented carbides [6, 11–16]. Generally speaking, in the design of cemented carbides, mechanical properties and tribological properties are usually considered as the main factors. With the development of industry, cemented carbides also have great promis
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