Grain boundary and testing procedure: a new approach to the tribology of alumina materials

Wear performance of alumina-based ceramics - a review of the influence of microstructure on erosive wear

“…In a study, the highest toughness was attributed to the presence of reinforcement grains in the fine-grained matrix [30]. Thus, the greater wear resistance of certain samples than others can be explained by the higher toughness, which is a result of the increase in the average grain size [69].…”

“…However, controversially, certain observations suggest that wear increases with grain size increasing, from a given grain size. It is suggested that the effect of grain size on the wear behavior of alumina is strongly affected by the geometry of the contact [69]. An increase in wear resistance can also be obtained by introducing large elongated grains as reinforcement in the microstructure, which improves the fracture toughness of the composite [69].…”

“…It is suggested that the effect of grain size on the wear behavior of alumina is strongly affected by the geometry of the contact [69]. An increase in wear resistance can also be obtained by introducing large elongated grains as reinforcement in the microstructure, which improves the fracture toughness of the composite [69]. Improvements in the wear behavior, both erosive and abrasive, may be obtained with the use of reactive particles (smaller than 1 µm); however, such improvement cannot be attributed only to grain size, making it necessary to evaluate the role of intergranular phases [30,51,52].…”

Testing device compatibility and possible measurement errors in dry sliding

“…Cutting is usually performed in many labs and research organisations by the workshop technicians, who are not always aware of the importance of maintaining consistent polishing parameters throughout machining. The situation of polishing is somehow better than that of machining because although some [9][10][11] recognise its importance in yielding plausible results during subsequent tribological investigation, others still overlook its importance [8]. As a result of the above mentioned considerations it might happen that while the bulk mechanical properties of a material subjected to machining/polishing are unchanged, the mechanical properties of the top layer that would be subsequently exposed to sliding are changed somehow.…”

Improved sliding wear-resistance of alumina with sub-micron grain size: A comparison with coarser grained material

“…[9][10][11] On the contrary, in some cases, it has also been observed that increase in grain size leads to increased wear resistance properties. [12][13][14] Surprisingly, almost in all the above-mentioned studies, grain sizes involved were in the order of one micron or more. In 1996, Krell et al 11 first reported wear characteristics of sub-micron grained alumina (G ∼ 0.5 m) at different humidity levels using fretting wear-test configuration.…”