Effect of Ni Addition on the Corrosion Resistance of NiTi Alloy Coatings on AISI 316L Substrate Prepared by Laser Cladding

Abstract

In this paper, an equiatomic NiTi (55NiTi) alloy powder was mixed with pure Ni powder to prepare laser cladding coatings on a 316L stainless steel substrate to study the effect of Ni addition on the microstructure and corrosion resistance of the coatings. The microstructure and phase composition of the coatings were analyzed using a scanning electron microscope (SEM) with configured energy-dispersive spectrometer (EDS) and X-ray diffractometer (XRD). OCP (open-circuit potential), PD (potentiodynamic polarization) and EIS (electrochemical impedance spectroscopy) experiments were conducted by a Gamry electrochemical workstation, and corresponding eroded morphologies were observed to evaluate the coating’s anti-corrosion performance. The addition of Ni led to fine and uniform dendrites and dense microstructure under the metallurgical microscope, which were beneficial for the formation of the passive film mainly consisting of titanium dioxide (TiO2). The results show that the pitting potential of the 55NiTi + 5Ni coating was 0.11 V nobler than that of the 55NiTi coating, and the corrosion current density was less than half that of the 55NiTi coating. The corrosion initiated preferentially at the interfaces of dendrites and inter-dendritic areas, then spread first to dendrites rather than in the inter-dendritic areas.

Defect Formation Mechanism and Performance Study of Laser Cladding Ni/Mo Composite Coating

“…This may be attributed to the recrystallization of the dendrite in the heat-affected zone caused by heat cycling and the grains becoming smaller. As we all know, small grains are beneficial in terms of improving the mechanical properties of materials according to the fine-grain strengthening effect [23]. Thus, the hardness in the heat-affected zone was higher than that of the Cu matrix.…”

The Influence of Pickling Treatment Parameters on the Surface State and Pre-Passivation Behavior of Super 13Cr Martensitic Stainless Steel

“…On the basis of traditional Super 13Cr, commercial Super 13Cr is fabricated by increasing the mass fraction of the elements Ni and Mo and reducing the carbon content [14][15][16]. Meanwhile, Super 13Cr contains a fraction of inverter austenite that can improve its corrosion resistance [17][18][19][20]. Increasing the Cr content in stainless steel is a general and apparent method to improve the corrosion resistance performance [21,22], such as in the 15Cr and 17Cr stainless steel developed by JFE Holdings, Inc. (Tokyo, Japan).…”

“…Due to the low Cr content of Super 13Cr, instead of the acid pre-passivation, alkaline liquor is an ideal pre-passivation solution. However, the reports on Super 13Cr passivation to date have focused primarily on the effect of the film generated during the application on the corrosion resistance [17,29,30]. The films in these reports are actually the corrosion product caused by the corrosion medium during application.…”

Tribological Behavior of NiTi Alloy Produced by Spark Plasma Sintering Method

“…NiTi alloys exhibit good wear resistance in sliding wear and cavitation erosions, where the resistance of NiTi alloys is comparable to that of conventional alloys. It is attributed to the effect of work hardening [8]; nevertheless, the effect of NiTi alloys pseudoelastic behavior is mostly responsible for good wear resistance [9,10]. In addition, NiTi possesses damping-sensitive properties that make it a good candidate for material robots and smart materials actuators in the areas of micro-electro-mechanical system (MEMS) devices [11,12].…”