Filled glass–ceramic composites, like low‐temperature co‐fired ceramics (LTCC), must densify at temperatures <900°C. The densification mechanism of LTCC is often described by liquid‐phase sintering. The results of this paper clearly show that densification of ceramic‐filled glass–composites with a glass content above 60 wt% can be attributed to viscous sintering, which is decisively controlled by the viscosity of the glass during the heat treatment. This is demonstrated by the experimental determination of the viscosity of a MgO–Al2O3–B2O3–SiO2 glass dependent on temperature, by investigation of the wetting behavior of the glass on the ceramic filler mullite, and of the microstructural development. It was found that the glass does not wet the filler material in a temperature range up to 1000°C. Therefore, liquid‐phase sintering can be excluded. Independent of any wetting effect and therefore in the absence of capillary forces, densification starts at a temperature of 750°C, which corresponds to a viscosity of 109.5 dPa·s. This densification can be attributed to viscous flow of the glass matrix composite.
From the obtained results it can be concluded, that titanium deposited onto a femoral head during dislocation will be abraded within the harder alumina-on-alumina bearing couple during normal gait and will subsequently be released into the body by synovial fluid. In case of a ceramic-on-polymer bearing the deposited metal seems to be more harmful. The increased surface roughness of the femoral head within the tribological pairing probably initiates damage of the polymeric acetabular inlay and increases the wear of the bearing surface through a third-body wear mechanism resulting in the release of high amounts of PE.
A binary Ta–Ti thin film composition‐spread materials library is prepared through magnetron sputter co‐deposition. An automated microelectrochemical investigation on selected surface areas, corresponding to a concentration gradient of Ti varying from 0.5 to 36 at %, is achieved by using a scanning droplet cell. Simultaneously, during the anodic oxide growth, a small alternating current (AC) voltage is superimposed on the increasing direct current (DC) potential in order to record the capacitance of the mixed‐metal oxide by using alternating current linear sweep voltammetry (AC‐LSV). Valve metal behavior, with the current stabilizing after an initial rapid increase, is found for all investigated compositions. AC‐LSV allows the ratio of the formation factor to the relative permittivity for different compositions to be calculated.
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