Cobalt-chromium-molybdenum

Vitahium FHS ahoy is a cobalt—chromium—molybdenum ahoy having a high modulus of elasticity. This ahoy is also a preferred material. When combiaed with a properly designed stem, the properties of this ahoy provide protection for the cement mantle by decreasing proximal cement stress. This ahoy also exhibits high yields and tensile strength, is corrosion resistant, and biocompatible. Composites used ia orthopedics include carbon—carbon, carbon—epoxy, hydroxyapatite, ceramics, etc. 

Table 2.24 Breakdown potentials (mV) for 316 stainless steel, titanium and cobalt-chromium-molybdenum alloy in oxygen-free 0.17 m NaCl solution at 37°C using a silver/ silver chloride reference electrode.

Table 2.25 Breakdown potentials for 316S12 stainless steel (cold worked), high nitrogen stainless steel (cold worked), titanium-6Al-4V and cast-cobalt-chromium-molybdenum alloy in continuously aerated aqueous acidified chloride solution 0.23 m [C1 ] pH 1.5 at 25°C. ...

Edwards e/a/. carried out controlled potential, slow strain-rate tests on Zimaloy (a cobalt-chromium-molybdenum implant alloy) in Ringer s solution at 37°C and showed that hydrogen absorption may degrade the mechanical properties of the alloy. Potentials were controlled so that the tensile sample was either cathodic or anodic with respect to the metal s free corrosion potential. Hydrogen was generated on the sample surface when the specimen was cathodic, and dissolution of the sample was encouraged when the sample was anodic. The results of these controlled potential tests showed no susceptibility of this alloy to SCC at anodic potentials. 

Edwards, B. J., Louthan, M. R. and Sisson, R. D., Hydrogen Embrittlement of Zimaloy A Cobalt-Chromium-Molybdenum Orthopaedic Implant Alloy , in Corrosion and Degradation of Implant Materials, Second Symposium, (Eds) A. C. Fraker and C. D. Griffin, 11-29 ASTM Publication STP 859, Philadelphia (1985)... 

Cobalt-chromium alloy (see Chromium and chromium compounds) Cobalt-chromium-molybdenum alloys (see Cobalt and cobalt compounds) Cobalt metal powder (see Cobalt and eobalt compounds)... 

Elevated levels of chromium in blood, serum, urine, and other tissues and organs have been observed in patients with cobalt-chromium knee and hip arthroplasts (Michel et al. 1987 Sunderman et al. 1989). Whether corrosion or wear of the implant can release chromium (or other metal components) into the systemic circulation depends on the nature of the device. In one study, the mean postoperative blood and urine levels of chromium of nine patients with total hip replacements made from a cast cobalt-chromium-molybdenum alloy were 3.9 and 6.2 pg/F, respectively, compared with preoperative blood and urine levels of 1.4 and 0.4 pg/F, respectively. High blood and urinary levels of chromium persisted when measured at intervals over a year or more after surgery. These data suggest significant wear or corrosion... 

Pauli BU. 1990. Carcinogenesis testing of sintered porous (Co Cr Mo) cobalt-chromium-molybdenum implants. U.S. Department of Agriculture/Current Research Information System. Database, July 19,... 

Van De Velde K, Ferrari C, Barbante C, Mret I, Bellomi X Hong S, and Boutron C (1999) A 200 year record of atmospheric cobalt, chromium, molybdenum, and antimony in high altitude alpine firn and ice. Environ SdTechnol 33 3495-3501. Var F, Narita Y and Tanaka S (2000) The concentration, trend and seasonal variation of metals in the atmosphere in 16 Japanese cities shown by the results of National Air Surveillance Network (NASN )from 1974 to 1996. Atmos Environ 34 2755-2770. VoELKER B, Morel F and Sulzberger B (1997) Iron redox cycling in surface waters ffects of humic substances and light. Environ Sd Tedmol 31 1004-1011. 

Stainless steel, which is typically used for bone plates, screws, and nails, is particularly susceptible to corrosion, although its chromium and molybdenum content (about 17% and 3%. respectively) helps to make it more resistant. Cobalt-chromium-molybdenum alloys exhibit excellent durability and strength, making them apposite for artificial joints, although their coefficients of friction make them unsuitable for load-bearing surfaces. 

Schmidt M., H. Weber, and R. Schon. 1996. Cobalt chromium molybdenum metal combination for modular hip prostheses. Clin Orthop 329 Suppl S35-47. 

The need to develop new materials for artificial hip joints is driven, in part, by the local and systemic biological consequences of wear debris arising from the currently used materials. As a result, most studies of artificial joint materials, such as alumina, cobalt-chromium-molybdenum alloys (CoCrMo), and ultrahigh molecular weight polyethylene (UHMWPE), concentrate on wear analyses, most reliably carried out with a hip-joint simulator and involving wear-... 

Metals are used in the cardiovascular area including heart valves, heart pacemaker leads, and heart pacemaker cases. These metals include titanium, titanium aUojrs, cobalt-chromium alloys, and cobalt-nickel alloys. Metals used for aneurism clips include cobalt-chromium-molybdenum alloys, cobalt-nickel-chromium-molybdenum allojfs, and, previously, stainless steels were used. Metal seeds are used for fractionated hyperthermia treatment of prostate disease, and corrosion analysis showed the alloy, PdCo may be suitable for the seed implants [52],... 

Kilner, T., The Relationship of Microstructure to the Mechanical Properties of a Cobalt-Chromium-Molybdenum Alloy Used for Prosthetic Devices," Ph.D. thesis. University of Toronto, 1984. 

Biocompatible materials that have been successfully used for implantable medical device packaging include titanium and its alloys, noble metals and their alloys, biograde stainless steels, some cobalt-based alloys, tantalum, niobium, titanium-niobium alloys, Nitinol, MP35N (a nickel-cobalt-chromium-molybdenum alloy). 

Peterson CD, Hillberry BM, Heck DA. Component wear of total knee prostheses using Ti-6A1-4 V, titanium nitride coated Ti-6A1-4V, and cobalt-chromium-molybdenum femoral components. J Biomed Mater Res 1988 22(10) 887-903. 

Smith SL, Unsworth A. A comparison between gravimetric and volumetric techniques of wear measurement of UHMWPE acetabular cups against zirconia and cobalt-chromium-molybdenum femoral heads in a hip simulator. Proc InstMech Eng 1999 213(6) 475-83. 

Figure 10.3 Photographs of the segregated state of binary granular mixtures of particles differing only in density after being shaken repeatedly until a steady segregation state is reached. The lighter particles are made of aluminum oxide (density p 1.31 g/cm ) and the heavier ones are made of (a) zirconium oxide (density p 2.87 g/cm ), (b) titanium alloy (density p 4.45 g/cm ), (c) cobalt-chromium-molybdenum alloy (density p 8.37 g/cm ), and (d) tungsten alloy (density p = 18.0 g/cm ), respectively. (Shi, Q. et al., Phys. Rev. E, 061302/1-4, 2007.)...

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