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Al2O3, TiO2, and Al2O3-TiO2 coatings were deposited on AISI 304 stainless steel plates by the sol–gel dipping technique, and the effects of the coating composition on microstructure, wear, and corrosion characteristics were examined. Tribological features were determined by ball-on-disc sliding tests against an Al2O3 ball under a 10 N load, while corrosion properties were evaluated by potentiodynamic polarisation tests performed in 3.5% wt. NaCl solution. γ-Al2O3, α-Al2O3, and rutile phases were detected in the hybrid coatings. The highest coating thickness was obtained in single Al2O3 film and decreased with an increasing amount of TiO2 nanoparticles. The single Al2O3 layer had both the highest wear resistance and the lowest corrosion resistance. Although TiO2 addition caused an increase in the wear rate, it improved the corrosion resistance of the coating by filling the voids in the Al2O3 film. The Al2O3-TiO2 hybrid film with a relative ratio of 6:1 as a candidate for the wear- and corrosion-resistant coating decreased wear and corrosion losses of the 304 substrates by 83% and 97%, respectively. [ABSTRACT FROM AUTHOR]

The unresolved production problems including wettability and undesired intermetallic phase formation at the interface of aluminium matrix composites (AMCs) with ceramic reinforcements require a different approach to the subject. Titanium as a reinforcement is a strong candidate to overcome the current problems, without sacrificing beneficial features of conventional AMCs. This study aims to compare microstructural, mechanical and wear properties of bimetal composites manufactured by two different techniques: melt infiltration casting (MIC) and squeeze infiltration (SI). The temperature was set to 730 °C for both production methods. MIC was carried out in an open die with vacuum assistance, while SI was performed in a closed die in an atmospheric environment. Optical microscope, SEM, XRD, EDS, nanoindentation test device and ball-on-disc type tribometer with 3-mm-diameter Al2O3 ball were used for composite characterization. Al, Ti, Si and TiAl3 phases were formed in composite structure for both techniques. Homogeneous and continuous TiAl3 layer was obtained at Al/Ti interfaces. The volume fraction of TiAl3 was 20 times higher in SI than that in MIC due to long interaction time between Al and Ti. The thickness and the hardness of TiAl3 obtained were higher in SI. Abrasive and adhesive wear mechanisms were observed in worn surface examinations. The composite produced by SI showed slightly better performance against wear under the same test conditions. It was exposed to less plastic deformation and abrasive wear than composite produced by MIC. Although initial investment cost was higher, SI appeared to be more advantageous than MIC, considering the applicability in the industry. [ABSTRACT FROM AUTHOR]