Mechanical Properties of Co-Cr-Mo Alloy in Dependence in the Composition and Production (original) (raw)
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The tribological behavior of two cobalt-base alloys-an as-cast high-carbon and a wrought low-carbon Co alloy-that are used as hip implant materials is examined in this work. This work discusses the experimental results of cobalt-cobalt wear pairs, in wrought and as-cast conditions, where the amount of hexagonal phase is systematically modified through an isothermal aging treatment. Fully FCC and HCP Co alloys are tested versus alloys with various volume fractions of HCP phase (0.05 to 1.0 vol-ume fractions). Preliminary results indicate that Co-Cr-Mo/Co-Cr-Mo alloy pairs both possessing an HCP matrix microstructure tend to exhibit outstanding wear properties.
Microstructural Characterization of Co-Cr-Mo-W Alloy as Casting for Odontological Application
Interest in the analysis and material characterization is rising due to the necessity of the adequate material selection based on system performance in study. The analysis and knowledge of the microstructure and the mechanical properties of any material are of utmost importance since it aims primarily to estimate the performance during the material life span, minimizing the possibility of degradation and undesirable flaws during product utilization. Co-Cr-MoW alloys have been well accepted in odontology as prosthesis material, due to its high mechanical resistance, good corrosion resistance and exceptional biocompatibility properties. This study aims to characterize the microstructure of a cobalt based alloy (Co-Cr-MoW) obtained through vacuum casting process. Optical microscopy, electronic sweeping microscopy and X-ray were employed and Vickers hardness test with loads of 100 gf, 500 gf and 1000 gf during 10 s. Microstructure casting is characterized by a Co-fcc dendritic matrix with a secondary phase, as well as M 23 C 6 precipitate carbides in the interdendritics zones and grain boundaries. The precipitation of carbides represents the main device of strengthening in the cast state for these types of alloys and is also responsible for its lower mechanical properties. The material attained hardness between 25 and 35 HRC, meeting the ASTM F75 standards.
AIP Conference Proceedings, 2014
Cobalt-based alloys are widely used as total hip and knee replacements because of their excellent properties, such as corrosion resistance, fatigue strength and biocompatibility. In this work, cobalt alloys with variation of Cr (28.5; 30; 31.5; 33, and 34.5% wt) have been synthesized by smelting method began with the process of compaction, followed by smelting process using Tri Arc Melting Furnace at 200A. Continued by homogenization process at recrystallization temperature (1250º C) for 3 hours to allow the atoms diffuses and transform into γ phase. The next process is rolling process which is accompanied by heating at 1200º C for ± 15 minutes and followed by quenching. This process is repeated until the obtained thickness of ± 1 mm. The evaluated material properties included microstructure, surface morphology, and hardness value. It was shown that microstructure of cobalt alloys with variation of Cr is dominant by γ phase, thus making the entire cobalt alloys have high hardness. It was also shown from the surface morphology of entire cobalt alloys sample indicated the whole process of synthesis that had good solubility were at flat surface area. Hardness value test showed all of cobalt alloys sample had high hardness, just variation of 33% Cr be in the range of ASTMF75, it were 345,24 VHN which is potential to be applied as an implant prosthesis.
2011
Dedication: This research project is dedicated to all who have supported the development of dentaltechnology in Ghana. il ABSTRACT ln this age of technological advancement in dentistry, the traditional method of manufacturing removable partial denture frameworks could be supplemented with rapid manufactured (RM) denture frameworks when the technology is fully developed. The RM technology has the potential to provide a better corrosion resistance, accuracy, high strength and density, reduce time and labour and eventually provide low cost restorations compared to the traditional 'lost wax technique' which is considered laborious and time consuming. However, fundamental independent tests including tensile and corrosion tests must be completed to move current researches from a proof of concept stage towards rn vivo pertormance studies if patients' safety is to be guaranteed. At the time of the presenl in vitro study, no published literature was found to have made a comparison between cast and RM dental alloys to investigate their tensile and corrosion properties. Test specimens and procedures used in this project were in accordance with BS EN ISO 22674:2006 for dental metallic restorations' During the corrosion test, electrobrightened and highly polished samples of an RM cobalt-chromium alloy were compared with those manufactured with a cast cobalt-chromium alloy. An RM as-received heat and non-heat treated cobaltchromium samples were also compared. The samples were immersed in artificial saliva (0.1M saline lactic acid) with pH 2.3+0.1 at a temperature of 37+0.1'C for 1 , 4, 7, 14, 21, 28, 35 and 42 days. The analytes were verif ied qualitatively for cobalt, chromium and molybdenum and quantitatively for released metal ions using an atomic absorption spectrometer. Results from the tests showed that the RM alloy had better ductility, modulus of elasticity, resilience, toughness and corrosion resistant properties. ln addition, surprisingly, electrobrightened samples released fewer metal ions than polished samples. RM as-received heattreated specimens released more metal ions than the non-heat treated as-received samples. The pedormance of the RM alloy has been largely linked to the manufacturing technique. Futther studies are recommended.
Microstructural Characterisation of Co-Cr-Mo Casting Dental Alloys
Advances in Science and Technology Research Journal
Metal biomaterials, including casting alloys, are the largest group of biomaterials used in den-tal prosthetics and maxillofacial surgery. Despite the scientific reports on the harmful effects of certain metals on living organisms, and due to the absence of non-metallic substitute materials ex-
SELECTED PROPERTIES AND TRIBOLOGICAL WEAR ALLOYS Co-Cr-Mo AND Co-Cr-Mo-W USED IN DENTAL PROSTHETICS
The presented work provides the results of the abrasive wear resistance tests performed on Co-Cr-Mo and Co-Cr-Mo-W alloys with the use of the Miller’s apparatus. The analyzed alloys underwent microstructure observations as well as hardness measurements, and the abraded surfaces of the examined materials were observed by means of electron scanning microscopy. The performed examinations made it possible to state that the Co-Cr alloys characterized in a high hardness, whereas the changes in the mass decrement were minimal, which proved a high abrasive wear resistance.
The effect of ion implantation on the wear of Co–Cr–Mo alloy
Vacuum, 2007
The effect of C+N and O ion implantation upon tribological properties of Co-Cr-Mo alloy was studied for fluence range 3-7 Â 10 17 cm À2 and implantation temperature range 200-400 1C. Phase structure changes and implanted ion distributions were determined. A marked improvement of the wear rate was noticed. Higher implantation temperatures reduce the improvement. No traces of nitride or carbide phases have been found but chromium oxide phase has been detected after O implantation. r
Acta Biomaterialia, 2012
The microstructure and mechanical properties of as-cast Co-(20-33)Cr-5Mo-N alloys were investigated to develop ductile Co-Cr-Mo alloys without Ni addition for dental applications that satisfy the requirements of the type 5 criteria in ISO 22674. The effects of the Cr and N contents on the microstructure and mechanical properties are discussed. The microstructures were evaluated using scanning electron microscopy with energy-dispersive X-ray spectroscopy (EDS), X-ray diffractometry (XRD), and electron back-scattered diffraction pattern analysis. The mechanical properties were evaluated using tensile testing. The proof strength and elongation of N-containing 33Cr satisfied the type 5 criteria in ISO 22674. e-phase with striations was formed in the N-free (20-29)Cr alloys, while there was slight formation of e-phase in the N-containing (20-29)Cr alloys, which disappeared in N-containing 33Cr. The lattice parameter of the c-phase increased with increasing Cr content (i.e. N content) in the N-containing alloys, although the lattice parameter remained almost the same in the N-free alloys because of the small atomic radius difference between Co and Cr. Compositional analyses by EDS and XRD revealed that in the N-containing alloys Cr and Mo were concentrated in the cell boundary, which became enriched in N, stabilizing the c-phase. The mechanical properties of the N-free alloys were independent of the Cr content and showed low strength and limited elongation. Strain-induced martensite was formed in all the N-free alloys after tensile testing. On the other hand, the proof strength, ultimate tensile strength, and elongation of the N-containing alloys increased with increasing Cr content (i.e. N content). Since formation of e-phase after tensile testing was confirmed in the N-containing alloys the deformation mechanism may change from strain-induced martensite transformation to another form, such as twinning or dislocation slip, as the N content increases. Thus the N-containing 33Cr alloy with large elongation is promising for use in dentures with adjustable clasps through one piece casting.
The properties of a wrought biomedical cobalt-chromium alloy
Journal of Materials Science, 1994
Two wrought biomedical cobalt-chromium alloys have been developed, and their mechanical properties and corrosion resistance determined by means of tensile and hardness tests and by electrochemical potential-time curves for isolated specimens in a 6.0 wt % NaCI solution at room temperature. In comparison with a current dental alloy, SC-H, and the basic type 18-8 austenitic stainless steel, it is shown that alloy II (chemical composition in wt% : 0.11 C, 22.07 Cr, 15.20 Ni, 3.75 Me, 9.30W, balance Co) has superior properties. The alloy has a high strength together with a good ductility which permits adequate workability. Also, both cobalt-chromium alloys show a passive behaviour in 6.0 wt % NaCI solution, whereas the basic type 18-8 austenitic stainless steel shows a fluctuating potential and is thus susceptible to pitting, making it unsuitable for surgical implants.