The aim of this study was to evaluate the effect of different polymeric protections applied on ceramic tiles on their mechanical and water absorption properties. Three conservation products were used: the acrylic polymer Paraloid B-72 and two alkoxysilane-based formulations (tetraethoxysilane (TEOS) and IN2210, a polidimetilsiloxane-based formulation). The coatings were applied onto handmade tiles manufactured according to a 18th century procedure. Different application procedures (immersion, brushing, and spraying) were tested. The protection effectiveness was assessed through capillary water absorption and four point bending tests. The mineralogical characterization of tiles was undertaken by XRD. The best protective properties of the tiles were achieved by immersion treatments with Paraloid B-72 based on the protocols followed by the museums restoration departments. Nevertheless, the results of the present work show that the second immersion in Paraloid B-72 solution, commonly made, can be eliminated, as it does not provide any significant increase in the hydrophobic or mechanical properties of the tiles. As a result, there are obvious economical benefits, as the coating process became less time-consuming and more environmental friendly, as the amount of organic compounds is reduced. On the other hand, the use of small volumes of Paraloid B-72 solution applied by brush, or IN2210 sprayed can provide good results, if the only purpose of the treatment is the increase of the hydrophobic properties.

No abstract

No abstract

No abstract

This work examined some pre-alloyed cobalt-, iron-, and copper-based powder binder systems—such as those launched commercially under the brand names of Cobalite and Next—in terms of their as-sintered physical-mechanical properties, namely, apparent density, Young´s modulus, yield strength, rupture strength, rupture strain, toughness modulus, and Vickers hardness. These types of sintered products are traditionally used in the fabrication of diamond impregnated tools for cutting granite stones. The following powder binder systems were evaluated: Cobalite HDR pre-alloyed powder, Next 300 pre-alloyed powder, and four other mixtures of these with Cu and Fe powders: Cobalite HDR + 20 wt% Cu; Cobalite HDR + 20 wt% Fe; Next 300 + 20 wt% Cu; Next 300 + 20 wt% Fe. The evaluation methodology aimed to establish criteria for developing new diamond tools and, therefore, it included the measurement of several technological parameters directly related to the cutting performance of the tools (e.g., energy consumption measurements made exclusively in the tool drive motor, forces generated in the tool, tool consumption per unit weight of stone removed by the cutting). The results show the adequacy of the methodology for the optimisation of diamond retention capacity of these types of metal matrices and for improving the working performance of the diamond tools.