Severe wear behaviour of alumina balls sliding against diamond ceramic coatings

Abstract

At present alumina is the most widely used bio-ceramic material for implants. However, diamond surface offers very good solid lubricant for different machinery, equipment including biomedical implants (hip implants, knee implants, etc.), since the coefficient of friction (COF) of diamond is lower than alumina. In this tribological study, alumina ball was chosen as the counter body material to show better performance of the polycrystalline diamond (PCD) coatings in biomedical load-bearing applications. Wear and friction data were recorded for microwave plasma chemical vapour deposition (MWCVD) grown PCD coatings of four different types, out of which two samples were as-deposited coatings, one was chemo-mechanically polished and the other diamond sample was made free standing by wet-chemical etching of the silicon wafer. The coefficient of friction of the MWCVD grown PCD against Al 2 O 3 ball under dry ambient condition was found in the range of 0.29-0.7, but in the presence of simulated body fluid, the COF reduces significantly, in the range of 0.03-0.36. The samples were then characterized by Raman spectroscopy for their quality, by coherence scanning profilometer for surface roughness and by electron microscopy for their microstructural properties. Alumina balls worn out (14.2 × 10 −1 mm 3 ) very rapidly with zero wear for diamond ceramic coatings. Since the generation of wear particle is the main problem for load-bearing prosthetic joints, it was concluded that the PCD material can potentially replace existing alumina bio-ceramic for their better tribological properties.

Some Aspects of Diamonds in Scientific Research and High Technology

“…They also could observe worn out diamond film surface; and profilometer scan wear volume data revealed wear rate less than 10 −7 mm 3 /N m. Bogatov et al [135] also reported >10 −7 mm 3 /N m wear rate of diamond film sliding against silicon nitride ball (ball characteristics were same as used in the present work) with 0.12 COF after 24,000 sliding cycles. But in the our present experiments with diamond disc, no wear track could be seen on the diamond disc surfaces sliding against silicon nitride balls-as also it was observed against alumina balls in authors' previous paper [131]. Only the balls worn out and the presented wear data of balls are in tandem with the reported literatures.…”

“…Both the polished and the corresponding opposite nucleation side were made to rotate against 3 mm diameter Si 3 N 4 counter-face ball under machine oil lubrication. The coefficient of friction was found to be very low in compare to our earlier study of the similar polished/unpolished diamond surfaces against alumina balls [131]. Here also the diamond surfaces do not wear, but the counter body Si 3 N 4 wears out, although not as severe as alumina ball which worn out under dry and SBF lubricating conditions by travelling half of the distance travelled by Si 3 N 4 balls in the present case.…”

“…The Hertzian contact pressure was calculated to be 26.2 GPa when 3 mm diameter ball was made to rotate against PCD disc surfaces under 5 N normal load as shown in schematic Figure 11a. The worn out ball was investigated under optical microscope (Figure 12) and the wear data was calculated as described in authors previous work [131]. It was found that the wear rate for the polished white PCD surface is very small 4.08 × 10 −7 mm 3 /N m and the wear rate for its corresponding nucleation side is much higher 3.95 × 10 −5 mm 3 /N m. The hardness of the polished side was found ~28 GPa, whereas its nucleation side was much softer with ~10 GPa nanohardness.…”

Abrasion Power of Ti and Ni Diamond-Coated Coatings Deposited by Cold Spray

“…Tests were performed by means of an Anton Paar TRB tribometer compliant with the ASTM G99 and ASTM G133 standards [21,22]. Testing conditions adopted for the experimental campaign are reported in Table 5 according to previous studies and scientific literature [23][24][25]. In particular, local linear speed was varied, while the length run L was the same for all specimens (150 m).…”

Introductory Chapter: Engineering Applications of Diamond

“…Wear is the major cause of economic loss due to the energy that is lost in overcoming the mechanical friction within the moving mechanical assemblies. Diamond tribology [55,56] is an important engineering application.…”