Effect of TiO2 and ZrO2 reinforcements on properties of Al2O3 coatings fabricated by thermal flame spraying

Tribological Properties of Alumina-Zirconia Composite Coatings Prepared by Plasma Spraying

“…The reasons for the lowest friction coefficient and wear rate as in the pure alumina coatings could be mainly due to the presence of a strong phase: γ-Al 2 O 3 , brought forth due to the α→γ transformations from well-melted particles aiding a better surface morphology subject to efficient substrate cooling [7]. With respect to the alumina-zirconia A5Z coatings, the well-spread tetragonal phase which aids in the formation of a stronger and tougher matrix, could have been seen in application here [6]. With A10Z, the negative effect of both interfacial-voids and crevices as seen from the morphology, could have outweighed the tetragonal-phase effect as observed in the former, leading to a measurable wear and the highest friction coefficient in comparison.…”

“…In order to compliment the properties of alumina, it has been observed that a ceramic such as zirconia proliferates the toughness, dimensional stability as well the wear resistance, when added to the matrix [5]. It was estimated that with a 25 wt.% reinforcement of ZrO 2 into Al 2 O 3 , the average friction coefficient was 0.45 for a vertical load of 30 N [6]. B. Liang et al even demonstrated a condition wherein the friction dropped to ~0.2 with 70 wt.% of zirconia in the alumina-zirconia composite coating with a wear rate of ~3 x 10 -5 mm 3 /Nm, and in some other cases even half of the latter [5].…”

“…B. Liang et al even demonstrated a condition wherein the friction dropped to ~0.2 with 70 wt.% of zirconia in the alumina-zirconia composite coating with a wear rate of ~3 x 10 -5 mm 3 /Nm, and in some other cases even half of the latter [5]. Therefore, to amalgamate both would be to derive at the least, a condition of superior hardness (alumina) and higher toughness (zirconia), which are imperative mechanical properties [5][6]. In this research here, we have employed zirconia additives into an alumina matrix to study the effect of the former's concentration on the tribological properties of the alumina-composite coatings.…”

Improvement of the Tribological Properties of Alumina Coatings by Zirconia Addition

“…However, despite their high hardness, the alumina coatings are brittle and have relatively high friction coefficients under dry sliding conditions. In order to improve the toughness, brittleness, thermal or tribological properties of alumina coatings, various additives such as ZrO 2 [7][8][9][10], TiO 2 [7,11], graphite [12], and graphene nanoplatelets [13] are used.…”

“…One of the most common additives used to improve the thermal, corrosion, tribological and mechanical properties of alumina coatings is zirconium oxide [5][6][7][8][9]14,15,[17][18][19][20][21][22][23][24][25]. It was demonstrated that the yttria partially stabilized zirconia (YSZ)-Al 2 O 3 composite coatings can be used as common thermal barrier coatings for jet engines, gas turbines or diesel engines [5,23,24].…”