掺杂镍对镁合金表面冷喷涂锌基涂层性能的影响

目的研究镍添加对冷喷涂锌基涂层耐蚀性的影响,为镁合金提供有效的防护涂层。方法采用低压冷喷涂技术在镁合金基体表面分别制备锌基和锌/镍基复合涂层,通过微观观察、摩擦磨损实验、电化学极化法和电化学阻抗谱测试及全浸泡腐蚀试验,研究镁合金表面冷喷涂涂层的结构、摩擦磨损行为和耐蚀性。结果镁合金表面冷喷涂锌基涂层后,其硬度和耐磨性得到显著提高,掺镍后的锌/镍基涂层具有更高的硬度和耐磨性。锌基和锌/镍基涂层均能为镁合金提供腐蚀防护,锌/镍基涂层比锌基涂层具有更好的耐蚀性。相对镁合金来说,锌基涂层和锌/镍基涂层的自腐蚀电位分别正移了260 mV和560 mV;长期腐蚀后锌/镍基涂层形成了更致密的腐蚀产物膜,腐蚀电阻显著高于锌基涂层。结论冷喷涂锌基和锌/镍复合涂层均能对镁合金提供防护作用,掺杂镍后的锌/镍基复合涂层具有更高的硬度、耐磨性和耐蚀性。

Effect of Mixing Ni on Properties of Cold Sprayed Zn-based Coating on Mg Alloy

The work aims to study the effect of nickel addition on the corrosion resistance of cold sprayed Zn-based coatings and provide an effective protective coating for magnesium alloys. Zn-based coatings and Zn/Ni-based composite coatings were deposited on Mg alloy respectively by low pressure cold spray (LPCS) method. The structure, friction-wear behavior and corro-sion resistance of the cold sprayed coatings on Mg alloy were investigated by microscopic observation, friction and wear ex-periment, electrochemical polarization method, electrochemical impedance spectrum test and total immersion corrosion test. The hardness and wear resistance of Mg alloy surface were improved significantly after cold sprayed Zn-based and Zn/Ni-based coatings, coating was while deposited and Zn/Ni-based coatings had higher hardness and resistance corrosion. Both of the Zn-based and Zn/Ni-based coatings could provide corrosion protection for Mg alloys, while Zn/Ni-based coating showed better corrosion resistance than Zn-based coating. In comparison with bare Mg alloy, the free corrosion potential of Zn-based coating and Zn/Ni-based coating was positively shifted by 260 mV and 560 mV, respectively. After long-term corrosion, the Zn/Ni-based coating formed a denser corrosion product layer, accompanied with higher corrosion resistance value than the Zn-based coating sample. Cold sprayed Zn-based and Zn/Ni-based coatings can both provide corrosion protection for Mg alloy, but Zn/Ni-based composite coating has better hardness and wear and corrosion resistance.