Internal stress assisted nitrogen diffusion in plasma nitrided medical CoCr alloys

Galdikas, Arvaidas; Petraitienė, Akvilė; Moskaliovienė, Teresa

doi:10.1016/j.vacuum.2015.05.029

Cited by 9 publications

(3 citation statements)

References 37 publications

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“…For example, it has good wear resistance, crevice corrosion resistance, and pitting resistance [4,5]. It also has high abrasion resistance, fatigue strength along with good workability and ductility [6,7].…”

Section: Introductionmentioning

confidence: 99%

Effect of process parameters on the microstructure and mechanical properties of vacuum hot-press sintered Co-50 mass% Cr alloys

Chang

Huang³

et al. 2018

Powder Metallurgy

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In the present research, two different compositions of submicron-structured cobalt (800 ± 45 nm) and chromium (700 ± 50 nm) powders are mixed to fabricate Co-50 mass% Cr alloys by the vacuum hot-press sintering technique. This study imposes various hot-press sintering temperatures (1150, 1200, 1250 and 1300°C) and pressures (20, 30, 40 and 50 MPa) while maintaining the sintering time at 1 h, respectively. The experimental results show that the optimum parameters of hot-press sintered Co-50 mass% Cr alloys are 1200°C at 50 MPa for 1 h. Meanwhile, the sintered density reaches 7.73 g cm −3 , the closed porosity decreases to 0.31%, and the hardness and transverse rupture strength values increase to 80.6 ± 0.3 HRA and 1052.9 ± 17.5 MPa, respectively. Grain growth is not obviously generated after 1200°C hot-press sintering at 50 MPa for 1 h. Consequently, the optimal solid-phase sintering process effectively improved hot-press sintered Co-50 mass% Cr alloys, which resulted in the good properties.

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Section: Introductionmentioning

confidence: 99%

Effect of process parameters on the microstructure and mechanical properties of vacuum hot-press sintered Co-50 mass% Cr alloys

Chang

Huang³

et al. 2018

Powder Metallurgy

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“…A. H. Heuer proposed that the driving force for nitrogen diffusion is not only the concentration gradient, but also the gradient of the compositionally induced internal stress. 34) Apart from the increase of sulfur element content on the surface of unnitrided sample, the content of sulfur and oxygen on the other samples has little change. But due to the EPMA analysis is based on line scanning, the analysis results have certain contingency.…”

Section: Cross-section Investigation and Microhardnessmentioning

confidence: 92%

Effect of Low-temperature Nitridation on Sulfide Stress Corrosion of 321 Austenitic Stainless Steel in H<sub>2</sub>S-Containing Environments

Wang

Fan

et al. 2019

ISIJ Int.

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The effect of low-temperature nitridation on corrosion resistance and sulfide stress corrosion (SSC) behavior of 321 austenitic stainless steel in H 2 S-containing environments was investigated. Varying fourpoint bend loading of 80 pct yield stress, 100 pct yield stress, 120 pct yield stress were respectively applied to nitrided 321 austenitic stainless steels. Although no macroscopic corrosion cracking is observed, pits are formed on the alloy surfaces. As the bending stress increases, the numbers and depths of pitting corrosion on the surface of the nitrided samples are getting more and more serious. Under 100 pct YS, the surface of unnitrided sample is completely destroyed and a series of jagged corrosion pits appear. The corrosion degree of the tension side is more serious than that of the compression side for a same sample. The result demonstrates that the low-temperature liquid nitridation can effectively improve the stress corrosion resistance and SSC behavior. The low-temperature nitrided sample has better stress corrosion resistance than the unnitrided sample in H 2 S-containing environments and the SSC resistance of 321 austenitic stainless steel can be apparently improved by low-temperature nitridation.

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“…Moreover, CoCr alloys are also used in electronic materials, such as the porcelain-fused-tometal restorations. Thus, how to increase the hardness, strength and electrical properties of CoCr alloys and in turn reduce the release of metal ions is technologically and clinically important research topic [7,8].…”

Section: Introductionmentioning

confidence: 99%

Archives of Metallurgy and Materials

Chang,

Huang

2020

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In this research, Co-30 mass% Cr alloys were fabricated by a vacuum hot-press sintering process. Different amounts of submicron cobalt and chromium (the mean grain size is 800 and 700 nm, respectively) powders were mixed by ball milling. Furthermore, this study imposed various hot-press sintering temperatures (1100, 1150, 1200 and 1250°C) and pressures (20, 35 and 50 MPa), while maintaining the sintering time at 1 h, respectively. The experimental results show that the optimum parameters of hot-press sintered Co-30 mass% Cr alloys are 1150°C at 35 MPa for 1 h. Meanwhile, the sintered density reaches 7.92 g•cm -3 , the closed porosity decreases to 0.46%, and the hardness and transverse rupture strength (TRS) values increase to 77.2 HRA and 997.1 MPa, respectively. While the hot-press sintered Co-30 mass% Cr alloys at 1150°C and 20 MPa for 1 h, the electrical conductivity was slightly enhanced to 1.79 × 10 4 S•cm -1 , and the phase transformation (FCC → HCP) of cobalt displayed a slight effect on sintering behaviors of Co-30 mass% Cr alloys. All these results confirm that the mechanical and electrical properties of Co-30 mass% Cr alloys are effectively improved by using the hot-press sintering technique.

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Internal stress assisted nitrogen diffusion in plasma nitrided medical CoCr alloys

Cited by 9 publications

References 37 publications

Effect of process parameters on the microstructure and mechanical properties of vacuum hot-press sintered Co-50 mass% Cr alloys

Effect of process parameters on the microstructure and mechanical properties of vacuum hot-press sintered Co-50 mass% Cr alloys

Effect of Low-temperature Nitridation on Sulfide Stress Corrosion of 321 Austenitic Stainless Steel in H<sub>2</sub>S-Containing Environments

Archives of Metallurgy and Materials

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