Influence of Filler Metal on Electrochemical Characteristics of a Laser-Welded CoCrMoW Alloy Used in Prosthodontics

Lukasz Reimann; Zbigniew Brytan; Grzegorz Jania

doi:10.3390/ma15165721

Influence of Filler Metal on Electrochemical Characteristics of a Laser-Welded CoCrMoW Alloy Used in Prosthodontics

Materials (Basel). 2022 Aug 19;15(16):5721. doi: 10.3390/ma15165721.

Authors

Lukasz Reimann¹, Zbigniew Brytan², Grzegorz Jania³

Affiliations

¹ Materials Research Laboratory, Faculty of Mechanical Engineering, Silesian University of Technology, Konarskiego St. 18a, 44-100 Gliwice, Poland.
² Department of Engineering Materials and Biomaterials, Faculty of Mechanical Engineering, Silesian, University of Technology, 44-100 Gliwice, Poland.
³ Dental Engineering Laboratory Grzegorz Jania, 48-200 Prudnik, Poland.

Abstract

This paper sought to determine corrosion resistance changes in the artificial saliva of a CoCrMoW-based alloy used for dental prostheses under Nd:YAG laser welding with CoCr alloy and stainless steel wire filler metals. The paper presents the corrosion characteristics of such joints, including the next stage of porcelain-fused-to-metal (PFM) firing. Corrosion tests were performed by electrochemical methods registering anodic polarization curves and electrochemical impedance spectroscopy (EIS). The microstructures were assessed by scanning microscopy (SEM) and chemical composition analysis (EDS) at the connection and heat-affected zones. Welding CoCrMoW alloy with and without a filler material increased the open circuit potential of the samples by 40-100 mV compared to unwelded base alloy. At the same time, a potentiodynamic test showed a polarization resistance R_pol reduction in welded samples, both for CoCr and stainless steel wires, as compared to the base CoCrMoW material. On the other hand, when comparing the current density and polarization resistance between materials welded with two different filler metals, better results were obtained for samples welded with stainless steel wire. The polarization resistance R_pol for the base alloy was 402 kΩ·cm², for the CoCr wire weld it was 436 kΩ·cm², and the value was 452 kΩ·cm² for stainless steel wire welds. Comparing polarization resistance R_pol from the Tafel analysis and the total charge transfer resistance from Rp_(EIS) from EIS, the CoCrMoW alloy welded with a stainless steel wire after heat treatment equaled or even slightly exceeded the corrosion resistance of the base alloy and alloy welded with dedicated CoCr wire after heat treatment. These results indicated the possibility of using stainless steel wire for the laser welding of CoCrMoW alloys dental prostheses, including the next stage of PFM, without sacrificing the corrosion resistance of such connections, and this was confirmed by most electrochemical parameters.

Keywords: CoCr alloys; CoCrMoW alloys; EIS; LBW; biomaterials; corrosion resistance; dentures; prosthodontic; stainless steel.

Grants and funding

This research received no external funding.