Investigating the kinetics of layer development during the color etching of low-carbon steel with in-situ spectroscopic ellipsometry.

Color etching is a useful corrosive process, widely applied in metallography to study the microstructure of metals. To prove the existence of the previously hypothesized steady-state etching rate, in-situ investigations were performed with spectroscopic ellipsometry during the color etching of ferritic materials. Kinetic information regarding the refractive index, extinction coefficient, and layer thickness were used to calculate the steady-state layer buildup rate, which was 1.

Surface analytical studies of maxillofacial implants: influence of the preoperational treatment and the human body on the surface properties of retrieved implants.

In the present work, surface analytical investigation of unimplanted as well as retrieved pyrolytic carbon-covered carbon/carbon composite implants and Ti osteosynthesis plates is reported. The Ti plates were covered by a 200-nm-thick, anodically and thermally formed TiO2 layer. Our results suggest that although the oxide layer on the Ti miniplates remained stable during the time spent in the human body, there is still material transport between the implant and the human body.

SEM and EDS investigation of a pyrolytic carbon covered C/C composite maxillofacial implant retrieved from the human body after 8 years.

The long term effect of the human body on a pyrolytic carbon covered C/C composite maxillofacial implant (CarBulat(Tm)) was investigated by comparing the structure, the surface morphology and composition of an implant retrieved after 8 years to a sterilized, but not implanted one. Although the thickness of the carbon fibres constituting the implants did not change during the 8 year period, the surface of the implant retrieved was covered with a thin surface layer not present on the unimplanted implant. The composition of this layer is identical to the composition of the underlying carbon fibres.

Correlation between the grain orientation dependence of color etching and chemical etching.

A gray cast iron specimen was investigated by color and chemical etching with optical and atomic force microscopy, and the effect of grain orientation on the effectiveness of etching was examined. It was proven that the grain orientation dependence of chemical and color etching is just the opposite, and that the specimen surface after color etching is not uniformly smooth. Explanation for the layer structure of the color etched iron specimen is given.

[Carbon/carbon implants in oral and maxillofacial surgery--Part 2].

In their previous report, the authors presented observations regarding the long-term application of carbon/carbon implants. After evaluating the good functional and aesthetic results, the effect of the human body on the structure and morphology of the implants was investigated with state of the art methods. An implant retrieved from the body after eight years was compared to implants which were sterilized but not implanted (reference).

Effect of grain orientation on chemical etching.

The effect of grain orientation on the effectiveness of pre-etching before color etching was investigated by the help of electron back scattering diffraction and atomic force microscopy in case of cast iron. Strong correlation was found between the angle between the specimen normal and the [001] orientation of the ferrite grains and the depth of the etching. If the angle between the specimen normal and the [001] direction of the ferritic grain is small, then the speed of the etching is low, but the lateral variation of the etching speed within the grain is larger.