**5. Conclusions**

Composite Ni–P/MWCNT films were successfully obtained by electroless deposition on the API 5L X80 substrate. MWCNT loading in the plating bath did not affect the thickness of the deposited layer, but reduced the size of the nodules on the coating, compared to the conventional binary Ni–P film. Adhesion strength was improved by adding the CNTs. The corrosion resistance of the composite films was increased due to the intrinsic low reactivity of the carbon nanotubes. This aspect was also evidenced by SECM analysis in the surface generation/tip collection mode (SG/TC). The SECM maps of the composite films with higher MWCNT loadings revealed low electrochemical activity for the Fe2+ oxidation reaction.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/2075-4 701/11/6/982/s1, Figure S1: EDS mapping of the cross-section for the CNT-0.50 film: (A) SEM micrograph; (B) Ni; (C) P; (D) Fe.; Figure S2: EDS mapping of the cross-section for the CNT-1.0 film: (A) SEM micrograph; (B) Ni; (C) P; (D) Fe.

**Author Contributions:** Conceptualization: M.C.L.d.O. and R.A.A.; Methodlogy: R.A.A., R.M.P.d.S. and N.B.d.L.; investigatFion: J.T.D.d.O., O.V.C. and L.A.d.O.; Writing-original draft preparation: M.C.L.d.O. and R.A.A.; Supervision: R.A.A.; funding acquisition: R.A.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by CNPq (Process 470944/2013-7).

**Institutional Review Board Statement:** Not Applicable.

**Informed Consent Statement:** Not Applicable.

**Data Availability Statement:** The data obtained in this study are available from the corresponding. **Acknowledgments:** Usiminas (Brzil) is kindly acknowledged for providing the pipeline steel used in this work. The Multiuser Experimental Facilities (UFABC) is acknowledged for the experimental support to this work.

**Conflicts of Interest:** The authors declare no conflict of interest.
