SURFACE CHARACTERIZATION AND BIOLOGICAL EVALUATION OF SPARK-ERODED SURFACES
Forty commercially pure titanium implants were prepared with a spark-eroding process in order to create highly increased surface roughnesses. Two degrees of roughness were achieved by altering the applied current. Surface topographical characterization was performed with SEM and an optical profilometer. The surface composition and oxide layer were investigated using Auger scanning microscopy. In the present study, there was a large difference between the stipulated and measured surface roughness, indicating the need for a careful surface characterization in each new study. After 12 wk in rabbit bone, no statistically significant difference was found with respect to peak removal torque and histomorphometric analyses. The results from the present study provide no support for further increase of the surface roughness than that possible to achieve with a blasting technique.
This paper presents the methodology and the physical models implemented in our computational code to predict the flow field over a Mars Sample Return Orbiter entering a Mars-like atmosphere. Because no validation against flight data or experiments can be done at present, the results obtained here are compared to other computed results for verification purpose. The predicted flow fields show that the chemical species CO and CO2, that are highly radiative species, are present in a large amount and at high temperature in the shock layer and in the wake of the flow past the orbiter.