Enhancing wear rate of high-density polyethylene (HDPE) by adding ceramic particles to propose an option for artificial hip joint liner

Abstract

Wear of total hip prosthesis is a significant clinical problem that nowadays involves a growing number of patients. To acquire further knowledge on the tribological phenomena that involve hip prosthesis, wear tests must be done on new biomaterials to increase life of orthopaedic implants, the average serviceability of an artificial hip joint is around 15 years, this average looks fine for a patient over 60 years old while number of young patients is increasing due to life style or accidents which raise a caution for researchers to propose new materials or design in order to extend the average over 15 years. In this work an experimental work that concerned with improving HDPE for acetabular liner part, which is improved by adding ceramic (Alumina and Zirconia) to form hyper-composite material, a three percentages of ceramic (3%, 6% and 9%) will be added to remaining percentage of polyethylene which is tested with Pin on Disc wear test machine and the results obtained for specific wear constant (k) are (2.08, 1.28, 0.77 and 1.40)*10-4 mm3.N-1.m-1, The results shows that the composite with (94% HDPE, 4.8% Alumina and 1.2% Zirconia) has least wear rate among other composites, percentage of alumina to zirconia is kept at 80:20 as studies have shown that at this percentage best properties are gained as the density is at highest level. Microhardness is also tested for all specimens and showed a mild increment in hardness as ceramic content increase, although hardness increased but this does not necessarily impose lower wear rate as the equation of specific wear rate is derived from Archard equation which is based on theoretic model of hemispherical asperities with a constant (K) that compensate for asperities shape and other factors.