Further, two PVP concentrations with the two solvents (i.e.,
0 and 15 wt% in the deionized water and the bovine serum solution)
were compared in the wear test of the Ti6Al4V–UHMWPE
pair. Higher compression load (5.29 N), longer stroke length
(18.5 mm), higher frequency (2 Hz), and longer test period (4 h)
were selected from the ASTM F732 test standard to accelerate the
wear of the samples. Then both three-dimensional morphology
and volume of the wear tracks on the UHMWPE discs were measured
by a three-dimensional confocal microscope phase shift
MicroXAM-3D (KLA-Tencor Corporation, California, USA). The
volume of the wear tracks was calculated by multiplying the
average cross sectional area of the wear tracks and the stroke
length. The temperature during the whole friction and wear tests
was controlled at 37 1 ± °C for simulating the in vivo temperature
of the joint prosthesis. The wear test was performed three times
for each PVP solution