Date of Award

Spring 1992

Document Type

Thesis

Degree Name

Master of Science in Biomedical Engineering - (M.S.)

Department

Biomedical Engineering Committee

First Advisor

Michael Pappas

Second Advisor

David S. Kristol

Third Advisor

Clarence W. Mayott

Abstract

Materials are a factor in the performance of articulating orthopedic implants. An oscillating tribometer is utilized to investigate mechanisms of wear and friction of TiN (titanium nitride) coated on Ti-6Al-4V (titanium) alloy against UHMWPe (ultra high molecular weight polyethylene). Three thicknesses of TiN coating (1.76 pm, 4.15 µm, and 10.5 µm) are used to evaluate the performance of each in UHMWPe wear reduction and coating integrity. An uncoated Co-Cr (cobalt chromium) coupon is used against UHMWPe pins for control purposes. Oscillations are carried out to 10 million cycles to discover and evaluate short- and long-term wear mechanisms. Mass differentials and torque are recorded for each test at specific intervals in order to establish wear volumes and rates of the UHMWPe, and coefficients of friction. Profilometries and polarized light photomicrography are performed at test conclusion to observe any alteration in physical condition which occurred during each test. Analysis of the results reveals the benefit of reduced wear from a TiN/Ti-6AI-4V coating-substrate system coupled with UHMWPe. Use of TiN/Ti-6Al-4V enables a reduction in abrasive wear and a reduction and delay in the onset of adhesive wear and associated UHMWPYTe transfer films. UHMWPe wear decreases with thinner TIN coatings, realizing up to two-thirds reduction in wear over a Co-Cr-UHMWPe system. Even with a rougher surface a TiN-UHMWPe system (pre-test Ra = 0.07-0.11) benefits with a minimum of one-third reduction in UHMWPe wear over the smoother Co-Cr-UHMWPe system (pre-test Ra = 0.03).

Share

COinS