Theoretical considerations that lead to the design of strong and ductile cobalt (Co)base alloys were discussed in part I of this series of articles.' It was hypothesized that the composition 40 Co-30 nickel (Ni)-30 chromium (Cr) is an acceptable compromise for the requirements of an alloy base. It also was found that tantalum (Ta) may have the qualities that are acceptable for an additional ele...

The classical wear mechanisms abrasion, fatigue, and adhesion are the most frequent causes of surface changes of ultra high molecular weight polyethylene (UHMWPE) in artificial joints. The counterpart material has a strong influence on the wear and friction behavior of artificial joints due to its abrasive properties and adhesive interaction with UHMWPE. The formation of a transfer layer on the...

Most total knee replacement joints consist of a metal femoral component made from a cobalt-chromium- molybdenum (CoCrMo)-alloy and a tibial component with an ultrahigh molecular weight polyethylene (UHMWPE) bearing surface. Wear of the UHMWPE remains the primary disadvantage of these implants. The allergic potential ascribed to CoCrMo-alloys is a further concern. Other metallic alloys with and ...

Direct metal laser sintering (DMLS) is a selective laser melting (SLM) manufacturing process that can produce near net shape parts from metallic powders. A range of materials are suitable for SLM; they include various metals such as titanium, steel, aluminium, and cobalt-chrome alloys. This paper forms part of a research drive that aims to evaluate the material performance of the SLM-manufactur...

The effect of additions of tantalum (Ta) to a 40-30-30 cobalt (Co) -chromium (Cr) nickel (Ni) alloy has been studied for several years at the University of Michigan. Mechanical properties of a series of these alloys have been reported by Mohammed and Asgar.1 Those results showed that an alloy containing 13% Ta would have an ultimate tensile strength of 124,000 psi, a yield strength of 90,000 ps...

The electrodeposition of Ni–Co alloy from a nickel Watt’s solution in the absence and presence of a permanent parallel magnetic field (PPMF) to the plane of deposition (perpendicular to direction of current) produced a deposited layer with mostly fine grain structure. The deposited layers have been characterized by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). It was fou...

The membranes surrounding seven loose cementless acetabular implants were shown to contain polyethylene particles, birefringent in polarised light. Three of these implants were made of titanium alloy and the membranes around these contained titanium particles as well. There was no metallosis around the four implants made of chromium-cobalt-steel alloy. Both titanium and polyethylene particles c...

Two widely used jewellery investment casting alloys (platinum with 5 wt% ruthenium (Pt-5Ru) and platinum with 5 wt% cobalt (Pt-5Co)) suffer from poor castability and other drawbacks. In this work thermodynamic calculations of alloy properties were employed to optimise the alloy compositions. Segregation behaviour appeared to be important for the melting range. Scheil simulations were used to si...

A simple, sensitive and interference-free method was proposed for the determination of arsenic, based on the generation of volatile arsenic trichloride coupled with atomic fluorescence spectrometry. Thiourea, together with l-ascorbic acid, was used to reduce As(V) to As(III), and the chloride generation was based on the reaction between As(III) and hydrochloric acid. Under the optimized experim...

BACKGROUND Recasting the base metal alloys is done as a routine procedure in the dental laboratories whenever there is casting failure or to decrease the unit cost of a fixed partial denture. However, this procedure may affect the metal ceramic bond. Furthermore, it is unclear, as to which test closely predicts the bond strength of metal-ceramic interface. The aim was to compare the bond streng...