Cailiao Baohu (Dec 2022)
Friction， Wear and Debris Characteristics of Artificial Joint CoCrMo-UHMWPE Pair under Different Contact Stresses
Abstract
Osteolysis of prosthesis caused by wear debris is one of the key factors leading to clinical failure of artificial joints. In order to understand the friction， wear and debris characteristics of prosthesis materials and optimize the tribological design of prosthesis， the most commonly used cobalt chromium molybdenum-ultra-high molecular weight polyethylene (CoCrMo-UHMWPE) pair was selected as artificial joint， and neonatal bovine serum solution was used as the lubricant. Subsequently， a 50，000 reciprocating sliding wear experiment was carried out under the point-to-surface contact stresses of 22， 35， 48 and 60 MPa， respectively. The friction coefficient， wear amount and wear morphology of the CoCrMo-UHMWPE pair were studied by multi-functional friction and wear testing machine， metallographic microscope， scanning electron microscope and other instruments， and then its friction and wear characteristics were characterized. Furthermore， the quantity，size， morphology and distribution characteristics of wear debris were studied by acid decomposition method. Results showed that the contact stress had a significant effect on the friction， wear and wear debris characteristics of the CoCrMo-UHMWPE pair. With the gradual increase of contact stress， the friction coefficient of CoCrMo-UHMWPE pair changed little but had a downward trend， the wear amount increased significantly and presented a certain linear relationship， and the wear morphology also showed more serious furrows and scratches. In terms of wear debris characteristics， the increase of contact stress led to a significantly increase of the number of wear debris with a size smaller than 5 μm，but the total amount of wear debris first increased and then decreased. Besides， the typical morphology of wear debris was mainly blocky， accompanied by a small amount of spherical and flaky wear debris of smaller sizes.
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