Papers by Keyword: Co-Cr

Abstract: This paper investigates tribocorrosion properties of binder jet additive-manufactured Co-Cr-Mo (F75) parts. Various parameters, including sintering atmosphere and post heat treatment processing, were examined to understand their effect on open circuit potential, friction, wear coefficient, and hardness. Results demonstrated that samples sintered in N₂-5%H₂ atmosphere have more noble potential up to-0.13V and lower wear coefficient down to 4.85e-6 mm³/N.m in comparison with samples sintered in vacuum. Solutionizing and aging (SHT-A) significantly increases hardness up to 626HV and lowers wear coefficient which means that the sample is more resistant to wear compared to as-sintered (AS) samples. However, heat-treated samples present slightly lower initial potential which means that these samples are more chemically active. This is because of the phase transformation of the matrix from FCC Co (γ phase) in AS condition to HCP Co (ε phase) + Co-Cr intermetallic (σ phase) in SHT-A condition, and different precipitate (carbides and nitrides) formation between these samples.

Abstract: The article presents a study of selective laser melting process (SLM) namely a study of stable track formation by the example of Co-Cr alloy. The characterization of the main process factors, which have an influence on the parts’ functionality, is developed. The experimental work for the research of two main factors as laser beam power and scanning speed showed the technological gaps for the formation of the stable tracks. The characterization of the non-stable single tracks’ defects is established. The new data about the main physical effects in the treatment zone is received by optical diagnostics of the process.

Abstract: This paper presents a comparative bibliographic study of different materials with elevated biomechanical biocompatibility regarding the stent-blood vessel interaction. Only the materials used in coronary stents’ manufacturing are considered: stainless-steel (316L), Cobalt-Chromium alloys (CoCrMo, CoNiCrMo), Nickel-Titanium alloys (Nitinol), Tantalum. The main characteristics that result from the stress-strain curve of each material are presented, as well as the biocompatibility and durability. The stainless-steel has good mechanical properties, excellent biocompatibility and low price. Cobalt-Chromium alloys have excellent mechanical properties, excellent biocompatibility, acceptable shape memory properties, but high density and low flexibility. The Nitinol represents the best choice, with excellent mechanical properties, excellent biocompatibility, good corrosion resistance, high flexibility (super-elastic behavior), low density, but high price. Tantalum alloys present the best biocompatibility and high flexibility, but the mechanical properties are relative modest.