We prepared YSZ-based composite coatings with CaF

2

/Al2O

3

as additives using atmospheric plasma spraying (APS). We prepared two groups: Group A (YSZ + 6% CaF

2

+ 6% Al

2

O

3

) and Group B (YSZ + 12% CaF

2

+ 12% Al

2

O

3

)

and investigated their tribological performance and lubrication mechanisms across a wide temperature range (room temperature –1100 ℃ ). Results show that Group B

with higher additive content

exhibited lower room-temperature Vickers hardness

(337HV

0.5

) than Group A (423HV

0.5

)

but achieved a significantly reduced friction coefficient of 0.22 at 800 ℃. At low temperatures (≤400 ℃)

mechanical strength dominated friction behavior

while at high temperatures (≥600 ℃)

CaF

2

actively reduced shear strength through ductile-to-brittle transition

synergizing with Al

2

O

3

to dynamically form oxide glaze layers that enhanced lubrication. At 1100 ℃

Group A developed a stable glaze layer via Ca diffusion and CaZrO

3

formation

lowering the friction coefficient to 0.16

whereas Group B failed due to excessive additive content.