One of the most polluting industries is the cement industry and, for this reason, alternative lines of research recommend the use of substitute materials for traditional Portland cement. This study proposes the use of industrial (slag and fly ash) and ceramic wastes for the total or partial replacement of Portland cement in the manufacturing of both alkaline-activated and hybrid cements. To carry out this study and evaluate the behavior of the proposed materials, different mortars were manufactured: Portland cement (CEM I), two alkaline-activated slag systems and six hybrid systems, with an 80–20% waste-to-Portland-cement ratio for all the proposed wastes. An assessment of the pozzolanic activity was carried out for the different materials. The behavior of all the systems regarding mechanical resistance and durability to abrasion was studied. All the proposed materials, especially those with ceramic wastes, showed pozzolanic activity and suitable characteristics for use in the manufacturing of alternative cements. The mortar made of slag activated with waterglass presented the highest mechanical strength and lowest porosity, but the hybrid materials presented competitive results. After being subjected to the Böhme abrasion test, their effectiveness as substitutes for Portland cement is reiterated, some of them improving their durability to wear.

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Intermetallic alloys such as titanium aluminides (TiAl) are potential materials for aerospace applications at elevated temperatures. TiAl intermetallics have low weight and improved efficiency under aggressive environments. However, there is limited information about wear behavior of these alloys and their microstructure. The present work aims to study the influence of the microstructure in the tribological behavior of TiAl intermetallic alloy (45Al-2Mn-2Nb(at%)-0.8 vol%TiB2). Wear tests were performed on samples manufactured by centrifugal casting (CC) and hot isostatic pressure (HIP). Reciprocating sliding wear test was carried out for TiAl, it was combined with different loads and frequencies. Wear tracks were analyzed through opto-digital microscopy and electron microscopy (SEM). The results obtained reveal that CC intermetallics present the lowest volume wear lost, approximately 20% less than HIP intermetallics. This good behavior could be related to the high hardness material, associated with the main microstructure where CC intermetallic has nearly lamellar microstructure and HIP intermetallics present duplex microstructure.