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Many biomaterials are being developed to repair or replace articular cartilage. One of these materials, a poly(vinyl-alcohol) cryogel (PVA-c) may exhibit the mechanical properties required to withstand the harsh environment of diarthrodial joints. To better understand how PVA-c friction is affected by different variables employed in bench top testing to simulate joint conditions, a six-factor, two-level fractional–factorial experiment was developed. Factors included temperature, lubricant, material stiffness, load, sliding speed, and surface roughness. Static and dynamic friction were found to depend significantly on material stiffness and roughness, increasing as material stiffness and roughness increased. Dynamic friction was also inversely proportional to sliding speed. Overall static and dynamic friction for all variables was 0.285±0.091 and 0.143±0.066 (average±S.D.), respectively. Material deformation and other factors may have contributed to the higher than expected friction levels. Frictional behavior of this PVA-c against stainless steel does not follow Amonton’s friction law, nor does it follow friction models based on repulsion and adsorption theories.

The stereographic scanning electron microscopy (SEM) imaging was used to investigate the wear mechanism in wire electrical discharge machining (EDM) truing of metal bond diamond wheels for ceramic grinding. A piece of the grinding wheel was removed after truing and grinding to enable the examination of wheel surface and measurement of diamond protrusion heights using a SEM and stereographic imaging software. The stereographic SEM imaging method was calibrated by comparing with the profilometer measurement results. On the wheel surface after wire EDM truing and before grinding, some diamond grain protruding heights were measured in the 32 μm level. Comparing to the 54 μm average size of the diamond grain, this indicated that over half of the diamond was exposed. During the wire EDM process, electrical sparks occur between the metal bond and EDM wire, which leaves the diamond protruded in the gap between the wire electrode and wheel. These protruding diamond grains with weak bond to the wheel were fractured under a light grinding condition. After heavy grinding, the diamond protrusion heights were estimated in the 5–15 μm range above the wear flat. A cavity created by grinding debris erosion wear of the wheel bond could be identified around the diamond grain.

A high silicon (Si)-containing aluminum–silicon (Al–Si) alloy surface weld overlay, deposited on 319 Al alloys, has been developed at Oak Ridge National Laboratory (ORNL) in order to improve surface-dependent properties, like resistance to wear. The overlay deposition process relies on standard techniques for Al manufacturing, therefore no unusual equipment is required. Microscopic examination of the high Si Al–Si weld overlays show a fine eutectic microstructure containing large Si particles, with the overall microstructure characteristic of a hypereutectic Al–Si alloy, similar to 390 Al alloy. The deposition process is versatile enough to be able to place the overlay in critical areas where high wear resistance is needed, thus reducing the overall cost of a component. In order to quantify the wear resistance of the high Si Al–Si overlays, they have been evaluated alongside 390 Al alloy which exhibits high wear resistance. Pin-on-disk (POD) wear tests have been performed on heat-treated (HT) and non-heat-treated specimens consisting of the high Si Al–Si overlays deposited on 319 Al alloy, bulk 390 Al alloys, and bulk 319 Al alloys. The high Si Al–Si weld overlay shows potential as a replacement of bulk 390 Al alloy for applications requiring high wear resistance.