The industry has gone to ceramic tiles imbedded in rubber for the following reasons:
1) The rubber allows the use of small flat tiles without creating problems on the circumfrence of the pulley.
2) The rubber provides an impact cushion, which helps prevent tile breakage or loss when material gets caught between the pulley and belt.
3) Production costs are lower if the tiles can be cast in sheet rubber pads.
As far as documentation concerning the use of tile directly on the pulley is cincerned, I am not aware of any studies. I can however suggest two potential problems -- cost and service life. The cost to have tile made to fit the individual pulley circumfrences and to glue them in place individually is probably higher than what is acceptable. The service life of the tiles should be lower than that of the rubber backed ones due to the lack of cushioning.
Finally, are you sure that you need ceramic lagging?
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