Optimization of Functional Performance of Additively Manufactured Cobalt-Chromium-Molybdenum Alloy for Dental Implants

Abstract

Laser Engineered Net Shaping (LENS) allows the manufacture of geometries that include complex structures that are difficult to manufacture with conventional manufacturing methods. Recent developments in additive manufacturing technologies offer a pathway for the clinical success of dental surgeries. Cobalt chromium alloys are used for dental implant applications due to their excellent characteristics. To solve the LENS fabrication challenge, this work utilized response surface methodology (RSM) to investigate the influence of LENS deposition parameters on the microstructural and mechanical performance of the manufactured samples for dental implant applications. Central Composite Design (CCD) was used to design the experiments. The experiments were carried out to investigate the influence of the scanning speed, laser power and powder feed rate on the mechanical performance and microstructural characteristics of CoCrMo alloy fabricated by LENS process. Analysis of statistical data demonstrated that microhardness and porosity were both significantly influenced by laser scan speed and powder feed rate, while surface roughness is impacted substantially by laser scan speed and laser power. The analysis of the responses revealed that the optimum factors were at a scan speed of 5.3 mms−1, powder feed rate of 4.748 gmin−1 and laser power of 386.896 W to give surface roughness, porosity, and microhardness responses of 8.7775 µm, 0.06 %, and 387.4286 HV, respectively. The models revealed a strong interaction between the actual experimental data and RSM-predicted responses. The X-ray Diffraction (XRD) pattern of the samples revealed sharp peaks correlating with the phases of CoCrMo alloys that include 𝛾 face-centered cubic (FCC) phase and 𝜖 hexagonal close-packed (HCP) phase. In addition, the wear test on the optimum samples indicates an improvement in wear resistance after heat treatment. The results of this research will serve as a guide for determining suitable LENS input factors for the manufacture of dental implants.