*Article* **Corrosion Resistance of Heat-Treated Ni-W Alloy Coatings**

#### **Magdalena Popczyk 1, Julian Kubisztal 1, Andrzej Szymon Swinarew 1,2, Zbigniew Wa´skiewicz 2,3, Arkadiusz Stanula 2 and Beat Knechtle 4,\***


Received: 30 January 2020; Accepted: 3 March 2020; Published: 6 March 2020

**Abstract:** The paper presents research on evaluation of corrosion resistance of Ni-W alloy coatings subjected to heat treatment. The corrosion resistance was tested in 5% NaCl solution by the use of potentiodynamic polarization technique and electrochemical impedance spectroscopy. Characteristics of the Ni-W coatings after heat treatment were carried out using scanning electron microscopy, scanning Kelvin probe technique and X-ray diffraction. Suggested reasons for the improvement of properties of the heat treated Ni-W coating, obtained at the lowest current density value (125 mA·cm<sup>−</sup>2), are the highest tungsten content (c.a. 25 at.%) as well as the smallest and the most homogeneous electrochemically active surface area.

**Keywords:** Ni-W alloy coating; heat treatment; corrosion resistance
