Biomedical subjects

E Strandman

Publications and source records attributed to E Strandman.

22 records · Page 2Linked to original sources

PubMed1976

The influence of different heat treatments on a dental Co-Cr alloy.

The change in microstructure and hardness in a cast Co-Cr alloy (type A) with a carbon content of 0.45% was studied both when the alloy was aged at temperatures between 600 degree C and 1200 degrees C and when it was isothermically heat-treated at temperatures between 800 degrees C and 1000 degrees C after solubility treatment at 1200 degrees C. Furthermore, studies were undertaken on how aging at 800 degrees C, solubility treatment at 1200 degrees C and isothermal heat treatment at 800 degrees C after solubility treatment at 1200 degrees C affected the mechanical properties. The results showed that both aging and isothermal heat treatment could change both microstructure and hardness. The changes in the mechanical properties by heat-treatment, however, did not improve the usefulness of the alloy in dentistry, principally because the elongation was reduced. The change in microstructure explained the change in hardness and in mechanical properties. It was interesting to note that the properties of a Co-Cr alloy were not affected by heat-treatment at temperatures below 600 degrees C. This means that addition of gold alloys, which are soldered to a base of Co-Cr, can be both homogenised and/or hardened without affecting the properties of the Co-Cr alloy.

Carbon↗

PubMed1976

An equipment for standardized casting of Co-Cr alloys in dentistry.

The temperature and the chemical character of an acetylene-oxygen flame change with change in the gasmixture. When heating a Co-Cr alloy with this flame both temperature and chemical character in the parts of the flame used may influence the temperature increase of the alloy. To study the influence of different acetylene-oxygen flames on the heating process of dental Co-Cr alloy, a gasmeasuring and casting equipment was constructed. This made it possible to cast in a standardized way.

Acetylene↗

PubMed1976

On the characteristics of acetylene-oxygen flames used in dental casting.

In a specially designed casting and gas measuring equipment the melting process used in dentistry for Co-Cr alloys using the acetylene-oxygen flame as heating source were investigated. The influence of different gas mixtures in the flame and different crucible temperatures on: 1. The temperature increase in the alloy. 2. The melting time of the alloy. 3. The temperature in the alloy when all the metal has melted and forms the spherical shape--the Bull's eye stage. 4. The melting time when different amounts of alloy were used in the melt. 5. The temperature increase and melting time when flux are used. 6. Different distances between the torch and the alloy. were studied. The results showed that the melting process is mainly governed by the heating effect and the chemical character of the parts of the flame used and also on the initial temperature of the crucible.

Acetylene↗

PubMed1976

Influence of different types of acetylene-oxygen flames on the carbon content of a dental Co-Cr alloy.

The influence of different acetylene-oxygen flames on the carbon content of a dental cobalt-chromium alloy, type A, was studied under standardised casting conditions. The alloy was cast, both immediately after the formation of the Bull's eye and after prolonging the melting time. Further, the effect of re-casting, varying the amount of alloy casted and using different sections of the same acetylene-oxygen flame when melting was studied. The results showed on the one hand that the chemical character of the section of flame used and not the gasmixture as such determined the carbon content of the casting, and on the other that the acetylene-oxygen flames can increase but not decrease the carbon content in the casting. Increase of the carbon content of a cobalt-chromium alloy causes a considerable change in its microstructure.

Acetylene↗