Study on surface roughness generated by micro-blasting on Co-Cr-Mo bio-implant

Abstract

Specific surface treatments to enhance adhesion, osseointegration and other area-related processes contribute greatly to the cost of manufacturing functional products. It is thus necessary to develop a productive and cost-efficient surface treatment technique for modifying the surface of bio-medical alloys such as Co-Cr-Mo to improve their bio-functionality. This study estimates the capabilities of the micro-blasting technique for a developed bone/implant interfacial area. Eight abrasive fractions of white aluminium oxide were comprehensively measured and blasted at a Co-Cr-Mo substrate. Then, this substrate was analysed in terms of nine roughness parameters. We found no significant variation in convexity, circularity or aspect ratio among 5–300 µm particles. The amplitude and space parameters of the eroded surface were proportional to the particles’ kinetic energy, and two hybrid parameters were subject to the particle size effect. The working hypothesis is that the particle size effect on the wear rate and root mean square (RMS) gradient of the surface slope are two aspects of one phenomenon. The size effect is known in a wear issue, yet this is the first time the size effect has been reported in relation to surface morphology. Variation in the RMS gradient with variation in particle size was analytically explained by the relative bluntness theory. The developed interfacial area was proportional to the impact energy and inverse to the tip radius of the particle. Blasting of angular abrasives larger than 60 µm was capable of doubling the surface area, while blasting of abrasives larger than 300 µm produced appropriate topography for mechanical fixation at the bone/implant interface.