Seneca sandstone on the Smithsonian Castle and gateposts is discolored in patches owing to the Mn-rich phase being deposited into two zones: (1) a vanishingly thin patina, and (2) nanoparticles coating grain boundaries and pores in the uppermost ~200 250 μm of the stone.
The first mechanism leads to localized debonding at the TGO/bond coat interface due to increasing out-of-plane tensile stresses at ridges that form along bond coat grain boundaries.
It is found that the synergy effect of micro-texture, composite coating and boundary film of water improves the tribological properties of the materials.
The objective of this study is to understand the role of friction modifiers and antiwear additives on the durability of DLC coating under boundary lubrication conditions.
In this work, the friction and wear properties of a DLC coating under boundary lubrication conditions have been investigated and the tribological performance compared with that of an uncoated steel system.
According to the results of microstructure observation and composition analysis, the mechanism of failure was proposed as follows: micro-cracks are first initiated in the YSZ top coat along columnar boundaries, and then propagate through the whole top coat.
The failure mechanism of the EB-PVD TBCs was proposed as follows: during thermal cycling, microcracks are initiated preferentially in the ceramic top coat along columnar boundaries and then extend through and along the top coat.
When I was ten years old, while batting in a cricket game, I looked over to the side of the pitch to see a tall, snowy-haired man in a long, grey coat stalking the boundary edge.
Inclusions represent grain cores and behave viscoplastically via dislocation glide while the coating represents both grain boundaries and triple junctions.
Experimental results showed that Hf was successfully incorporated and precipitated Hf-rich particles were observed on the coating surface, along grain boundaries within the additive layer, and at the interface between the additive layer and the interdiffusion layer.
