Fabrication and Mechanical Properties of Porous Co&amp;ndash;Cr&amp;ndash;Mo Alloy Compacts without Ni Addition

Nomura, Naoyuki; Abe, Mariko; Kawamura, Atsushi; Fujinuma, S.; Chiba, Akihiko; Masahashi, Naoya; Hanada, Shuji

doi:10.2320/matertrans.47.283

Cited by 13 publications

(5 citation statements)

References 6 publications

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“…2 shows X-ray profiles of Co-29Cr-6Mo compacts hot-pressed at 1223 K and 40 MPa for 7.2 ks in vacuum or nitrogen atmosphere. In the V compact, the ε phase exists dominantly and the phase is weakly confirmed, which agree with the previous study [4]. In the N compacts, the γ phase is observed.…”

Section: Resultssupporting

confidence: 92%

“…The porous Co-Cr-Mo coating on the implants as well as the substrate Co-Cr-Mo alloy, should not contain Ni since the release of metal ions at the large interface between body fluid and metal [3] presents great concern. In the previous paper, the mechanical properties of the porous Co-Cr-Mo alloy compacts without adding Ni were evaluated [4]. The as-hot-pressed compact shows the limited elongation because the σ phase precipitates during sintering.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Nitrogen on Microstructure of Porous CoCrMo Alloy Compacts for Biomedical Applications

Nomura

Abe

Lee³

et al. 2007

MSF

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Porous Co-29Cr-6Mo alloy compacts were fabricated and their microstructures were examined. The Co-29Cr-6Mo alloy powders were atomized by using Plasma Rotating Electrode Process (PREP) in an Ar atmosphere. These powders were hot-pressed at 1223 K in Ar or nitrogen and annealed at 1473 K in vacuum or nitrogen. X-ray analysis revealed that the γ phase (f.c.c.) mostly exists in the compact hot-pressed in nitrogen although the ε phase (h.c.p.) is dominant in the compact hot-pressed in Ar. In addition, precipitates are observed at the interdendritic region in the compact hot-pressed in nitrogen. These results suggest that the Co-29Cr-6Mo alloy powders react with nitrogen to stabilize the γ phase. Accordingly, the constituent phase in the Co-29Cr-6Mo alloy is strongly affected by the atmosphere during hot-pressing.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Effect of Nitrogen on Microstructure of Porous CoCrMo Alloy Compacts for Biomedical Applications

Nomura

Abe

Lee³

et al. 2007

MSF

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“…The lamellar function gives the information about the distance between the layers. Nomura et al 37 and Telu et al 38 also examined the lamellar formation of Co-Cr alloys by using XRD analysis. Telu et al 38 showed that decreasing the bilayer thickness increased the homogeneity of the alloy.…”

Section: Discussionmentioning

confidence: 99%

Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness

et al. 2013

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PURPOSEThe aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique.MATERIALS AND METHODSFive groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 × 2 × 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukey's HSD test was used for post hoc analysis. P values of <.05 were accepted as statistically significant.RESULTSThe general nanostructures of the samples were composed of small spherical entities stacked atop one another in dendritic form. All groups also displayed different hardness values depending on the manufacturing technique. The annealing procedure and environment directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 ± 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 ± 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 Å).CONCLUSIONAfter the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic substructures. The dentists should be familiar with the materials that are used in clinic for prosthodontics treatments.

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“…However, the compressive strength of the compacts with porosity of that range is slightly lower than that of the human bone. In order to improve the strength, Nomura et al (6), (7) prepared nitrogen added porous Ti compacts and porous Ti-15Mo-5Zr-3Al compacts.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Macroscopic Elastic Properties of Porous Compacts Prepared by Powder Pressure Sintering for Biomedical Implant

Taguchi

Kurashige

2007

JMMP

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Macroscopic elastic properties of porous compacts prepared by applying uniaxial pressure in powder sintering are numerically estimated, with their biomedical application in mind. The estimation is based on a three step simulation method similar to the previous one. It is found that the compaction by the pressure and the sintering lead to increase in the macroscopic elastic moduli in the pressure direction, which is made to coincide with that of gravity in packing. It is also found that these moduli are larger than those in the direction normal to the pressure by 20% to 40%. Those for the less sintered compacts whose porosity ranges from approximately 32% to 37 % fall in those of human cortical bone and show similar behavior to those of artificial implants.

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Fabrication and Mechanical Properties of Porous Co–Cr–Mo Alloy Compacts without Ni Addition

Cited by 13 publications

References 6 publications

Effect of Nitrogen on Microstructure of Porous CoCrMo Alloy Compacts for Biomedical Applications

Effect of Nitrogen on Microstructure of Porous CoCrMo Alloy Compacts for Biomedical Applications

Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness

Evaluation of Macroscopic Elastic Properties of Porous Compacts Prepared by Powder Pressure Sintering for Biomedical Implant

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