Microstructure and tribological behavior of laser cladding TiAlSi composite coatings reinforced by alumina–titania ceramics on Ti–6Al–4V alloys

Titanium composite coatings have been fabricated by laser cladding with a mixed powder of TiAlSi and Al2O3–13%TiO2 on Ti–6Al–4V alloy substrates. The effects of different content of Al2O3–13%TiO2 on the microstructure and properties of the laser cladding titanium composite coatings have been studied. The microstructure, chemical composition, phase constituent, hardness distribution and tribological properties of the titanium composite coatings were investigated by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), Vickers micro-hardness tester and a pin-on-disc friction and wear testing apparatus, respectively. The results show that the titanium composite coatings reinforced by Al2O3–13%TiO2 mainly consist of Ti3Al, Ti3AlC2, TiAl, α-Al2O3 and TiO2. The cladding coatings possess compact and uniform structure. With the increase of Al2O3–13%TiO2 content from 0 to 20%, the microhardness of the coatings increases, which reaches a maximum of around 770 HV0.3 when the addition content is 20%. The average coefficient of friction of the titanium composite coatings with the Al2O3–13%TiO2 content of 0, 10, 20 and 30% is 0.592, 0.430, 0.435 and 0.438, respectively. The composite coating with 20% content of Al2O3–13%TiO2 particles possesses the lowest wear loss.