Abstract
In order to study the effects of pulse parameters on jet electrodeposition, Ni–Co–BN (h) nanocomposite coatings were prepared on the surface of steel C1045. The samples were analyzed and characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), laser scanning confocal microscopy (LSCM), microhardness tester, and electrochemical workstation. The experimental results showed that the contents of Co and BN (h) nanoparticles in the coatings changed with the variation of pulse parameters. When the pulse frequency was 4 kHz and the duty cycle was 0.7, their contents reached maxima of 27.34 wt % and 3.82 wt %, respectively. The XRD patterns of the coatings showed that the deposits had a face-centered cube (fcc) structure, and there was an obvious preferred orientation in (111) plane. With the increase in pulse parameters, the surface roughness of the coatings first decreased and then increased, with the minimum value obtained being 0.664 µm. The microhardness of the coatings first increased and then decreased with increase in pulse parameters. The maximum value of the microhardness reached 719.2 HV0.05 when the pulse frequency was 4 kHz and the duty cycle was 0.7. In the electrochemical test, the potentiodynamic polarization curves of the coatings after immersion in 3.5 wt % NaCl solution showed the pulse parameters had an obvious effect on the corrosion resistance of the Ni–Co–BN (h) nanocamposite coatings. The corrosion current density and polarization resistance indicated that the coatings had better corrosion resistance when the pulse frequency was 4 kHz and duty cycle was 0.7.
Highlights
Wear and corrosion are the most common types of failure in parts
In order to study the effects of pulse parameters on the properties of Ni–Co–BN (h) nanocomposite coatings, Ni–Co–BN (h) nanocomposite coatings were prepared by jet electrodeposition with different pulse parameters
When duty cycle was 0.1 (Figure 2a), some different-sized globular protrusions appeared on the coating surface
Summary
Wear and corrosion are the most common types of failure in parts. The wear and corrosion processes are gradual and not very distinct thereby making it hard for people to notice them. Ni–Co alloys have high materials functional nanoparticles into the nanocomposite materials can hardness, excellent wear resistance and corrosion resistance. They are often coated on the surface of optimize the microstructure and improve the mechanical properties. Co–BN nanocomposite coatings have important significance in the improvement of material second phase has better properties in self-lubricating and wear resistance, high temperature resistance, surface properties. Electrodeposition technology has the advantages of controllable deposition process and better important significance in the improvement of material surface properties. It is one of the common methods used to prepare metaland coatings. The above tests and analysis results may be useful to provide theoretical reference for industrial production and practical application of pulse jet electrodeposition technology
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